CA1136920A - Fish canning process - Google Patents
Fish canning processInfo
- Publication number
- CA1136920A CA1136920A CA000341980A CA341980A CA1136920A CA 1136920 A CA1136920 A CA 1136920A CA 000341980 A CA000341980 A CA 000341980A CA 341980 A CA341980 A CA 341980A CA 1136920 A CA1136920 A CA 1136920A
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- Prior art keywords
- salmon
- milligrams
- curd
- extract
- fish
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Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B4/00—General methods for preserving meat, sausages, fish or fish products
- A23B4/14—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12
- A23B4/18—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12 in the form of liquids or solids
- A23B4/20—Organic compounds; Microorganisms; Enzymes
- A23B4/22—Microorganisms; Enzymes; Antibiotics
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B4/00—General methods for preserving meat, sausages, fish or fish products
- A23B4/005—Preserving by heating
- A23B4/0053—Preserving by heating with gas or liquids, with or without shaping, e.g. in form of powder, granules or flakes
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Wood Science & Technology (AREA)
- Zoology (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Microbiology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Meat, Egg Or Seafood Products (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improvement in a fish canning process comprising applying to a cut surface of the fish a proteolytic enzyme.
There is a marked reduction in curd formation as a result.
The oil colour is also improved. The process of particular interest is salmon canning.
An improvement in a fish canning process comprising applying to a cut surface of the fish a proteolytic enzyme.
There is a marked reduction in curd formation as a result.
The oil colour is also improved. The process of particular interest is salmon canning.
Description
113~920 This invention relates to a method of reducing curd formation in a salmon canning process.
The canning of salmon is an important industry in a number of countries. Canned salmon are particularly important to the economy of British Columbia. In 1978 the wholesale value of canned salmon was $116 million dollars which represents 23~ of the wholesale value of fishery products in the province.
That year British Columbia packed 1.1 million 48 lbs cases.
The United States packed 3.3 million cases and Japan 1.7 million.
The production and export of canned salmon has always been an important economy of British Columbia fish processing industry. During the past decade its role has diminished slightly due to the emergence of other markets for other fishery products, such as herring roe, and an increasing trend in recent years towards marketing salmon in fresh and frozen form.
Technological innovations and processing problems relating to salmon canning have been slight. The basic machinery used for steaking, filleting, sealing and retorting has remained virtually unchanged for many decades. One long recognized problem periodically brought to the attention of researchers however is the formation of excess curd on the cut surfaces of canned salmon. The curd, which appears as an offwhite, jelly-like mass, largely results from the heat coagulation of soluble proteins exuded from the cut surfaces of salmon flesh. The curd detracts from the appearance of the canned product.
Attempts have been made to reduce or eliminate this formation of curd. For example brining the salmon segments prior to canning is reported to reduce curd formation by 9~
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virtue of the salt solution diluting most of the soluble proteins from the cut surface of the segments. Similarly the use of disodium dipicolinate and urea solutions have been reported to reduce curd formation. As these procedures require hand filling of individual cans however, the methods are economically unfeasible and are not acceptable to the established canning systems employed. Other steps advocated have been subjecting the surfaces of canned salmon to steam treatment before the lids are placed on the cans. However, this method has not proved successful during a fairly large scale trial by a commercial canning firm in British Columbia.
The present invention has provided a method in which a substantial reduction of curd formation is possible. The invention is based on the idea that if the porteinaceous exudate can by hydrolyzed into small, non-coagulable fragments of polypeptides and peptides then the amount of curd formed would be appreciably reduced or even eliminated completely.
Accordingly, the present invention is a method of reducing curd formation in a salmon canning process. The method comprises application of proteolytic enzymes or a combination of enzymes to a cut surface of the salmon prior to the retorting process.
In a preferred aspect the enzyme is natural papaya latex applied as a water extract. Other proteoloytic enzymes that have proven useful include pancreatic protease,papainase, trypsin, ficin, bromelain, prolase, chymopapain and pepsin. Hog pancreatic lipase, and wheat germ lipase have also proved useful.
Salmon that has been treated includes sockeye salmon, coho salmon, pink salmon, chum salmon and spring (Chinook) salmon. Steelhead has also been treated.
In a preferred aspect in the treating of sockeye salmon ~3~9ZO
the method comprises applying to a cut surface of the salmon, while in the can, a water extract from natural papaya latex powder containing 10 to 15 milligrams of extract protein, or 9.4 to 14.1 units of protease activity, as defined in "Methods in Enzymology" (1970), Vol. XIX, p 227.
In the treatment of pink salmon the preferred method is applying to a cut surface of the salmon two to five milligrams per can of a water extract of natural papaya latex powder containing two to five milligrams of extract protein, or 1.9 to 4.7 units of protease activity, as defined in "Methods in Enzymology" (1970), Vol. XIX, p 227.
It has also been observed that the color of the oil in the can can be improved by adding the water extract of natural papaya latex powder containing two to 45 mg of extract protein.
The following experimental information illustrates the invention:
MATERIALS AND METHODS
A. PRELIMINARY LABORATORY EXPERIMENTS
Proteolytic enzyme products were purchased from Sigma Chemical Co., St. Louis, Mo, and described by them as:
i. "Crude Powder, Type II - purified from papaya latex", ii. "Pancreatic Protease, Type I, crude", iii. "Papainase, twice crystallized".
Other enzymes were obtained from U.S. Biochemical Corp., Cleveland, Ohio.
Preparation of enzyme extract from crude papaya latex powder, The coarse powder was suspended in 10 volumes of cold de-ionized water, stirred for 20 minutes and centrifuged for 20 minutes at 15,000 x 9 in a refrigerated centrifuge. The clear amber supernatant fluid (protein concentration, usually about 45 mg/ml) was further diluted ~13~92~
with water to achieve the required protein concentration for a given experiment.
Aqueous extracts were similarly prepared from purified papainase and from crude pancreatic protease pOwder Porteolytic activities of the extract were esti-mated according to Arnon, 1970 Methods in Enzymology, Aca-demic Press, Vol. XIX, 226. Activity was related to the increase in optical absorbency at 280 nm by trichloroacetic acid-soluble digestion products of casein, under stand-ardized conditions. Protein was measured by the biuret method according to Gornall, et al, J. siOl. Chem. 177,751 (1949) using commercially prepared serum albumin solution as reference, and by the Kjeldahl method. Lipids were extrac-ted with a 3:1 mixture of ethyl alcohol and petroleum ether.Two species of salmon, coho (I. kisutch) and sockeye (0.
nerka) were used in preliminary trials on curd reduction.
Both species were purchased locally in the unfrozen form.
The sockeyes had been transported in a slush ice system from the fishing grounds to a local fish processing plant. Since they appeared to be in excellent condition, they were allowed to "age" from 3 to 7 days in the laboratory cold room before experimental canning trials were undertaken.
This action was taken on the assumption that a longer post-mortem period would enhance curd formation. Some sockeyes were stored at -30C for the same reason.
Salmon were cut into segments, weighed and packed into cylindrical ("1/2 - lb") cans. The amount of flesh in each can ranged from about 180 to 220 g. Common salt 113~gZ0 (sodium chloride), 1.5 g, was added to the bottom of each experimental can.
After the cans were filled, protease-containing extracts~ usually 1.0 ml, were carefully spread over the entixe exposed superior surfaces of the flesh with a volu-metric -4a-1136i9Z~
pipet and the cans vacuum-sealed in a Rooney (Trade Mark) closing machine. Reference control samples were prepared by applying an equivalent volume of water to the flesh surfaces.
After allowing an interval of 30-45 minutes after applica-tion of the protease-containing extracts, the sealed cans were placed in an autoclave, sterilized at 250F (120C) for 75 minutes, then stored overnight at room temperature. The canned products were usually examined for curd the following day.
Quantitation of curd on the superior and inferior surfaces of canned salmon was accomplished by manually scraping off the curd carefully with a spatula and drying the collected curd overnight at 103C. The "curd scrapers"
were kept ignorant of the dosage applied to any of the samples being scraped in order to maintain objectivity.
B. PLANT TRIAL NO. 1 The first trial under commercial canning conditions was done on sockeye salmon at a commerical cannery in Vancouver, British Columbia. Aqueous extracts of crude papaya latex powder were prepared in the laboratory in the morning of the trial run and transported in ice to the plant. The dosages applied (per "1/2-lb" can) to the superior surfaces were 15, 25, 35, and 45 mg of extract protein in volumes of 1.0 ml. A total of 200 canned salmon samples were processed, including 40 untreated samples which served as controls.
The application of the enzyme solutions with pipets to all samples (randomly chosen from the regular production line), were completed in about 15 mlnutes, and .3 ~`'`
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the cans reintroduced into the canning line for vacuum-closing, rinsing and retorting. About 30 minutes elapsed between the application of papaya latex extract to the last experimental sample -5a-and the introduction of all samples into the retort. Retorting conditions were according to standard commercial practice;
that is, 30 minutes for "come-up" time, 74 minutes cooking at 245F (116C) and 20 minutes "come-down" time.
The sockeye salmon canned during the first experimental plant tria1 originated in waters off the north coast of B.C.
and had been kept in ice for 4-5 days.
Collection and estimation of curd formed under various experimental conditions were performed as described previously.
C. PLANT TRIAL NO. 2 The second plant trial was carried out at the same cannery about one month later. The experimental protocol was the same as for Plant Trial 1, except that (i) the dosages of water extract of papaya latex applied to each sample were reduced, (ii) a hand-held sprayer, modified and calibrated to deliver 0.8 ml of aqueous extract per squeeze of the trigger, was employed for some of the experimental series, (iii) 10 mg of ascorbic acid was added to each sample of an experimental series, in addition to aqueous extracts of papaya latex, (iv) a series of pink salmon was treated with various doses of papaya latex extract.
A total of 710 "1/2-lb" cans were obtained, including 40 cans each of untreated sockeyes and pinks which served as reference controls.
D. EVALUATION
Organoleptic assessment of the experimentally treated samples was performed. Each sitting consisted of 12 experienced tasters who were subjected to a standard "Triangle Taste Test"
as described by Roessler et al. 1948 Food Research 13, 503.
1~3~20 Presented with three samples, one of which was different from the other two, the panelists were asked to identify the two that were similar. Further, they were asked to indicate which had an off-flavour or odour. Experimentally treated and untreated canned salmon, obtained from Plant Trials 1 and 2, were presented to the taste panels in a mashed form under subdued light. The entire contents of each can, including the free liquid, were used to prepare these samples for presentation to the panelists.
Volumetric measurements of oil and aqueous phases of canned salmon samples were carried out by allowing the liquid contents of the cans to drain for at least 10 minutes into cylindrical graduates. After the aqueous phases were measured directly from the graduates, the oil phases were carefully transferred into graduated conical glass centrifuge tubes and centrifuged for at least 5 minutes. The volume of the oil was then estimated directly from the graduated tubes.
Aliquots of oil were removed from these tubes, diluted in appropriate volumes of n-hexane (25-fold dilution for sockeye salmon oil, 5-fold for coho salmon oil) and read aga;nst an n-hexane blank in l-cm cells at 470 nm. It had been previously established that the spectrum of the oil from canned sockeye salmon showed maximum absorption between 465 and 475 nm, with a peak near 470 nm and that a direct relationship existed between the amount of coloured oil and absorbance at 470 nm in the range .040 to .270 optical density units. The spectrum for oil from pink salmon, however, did not possess the same absorption profile, exhibiting a flat plateau in the region 420 to 480 nm.
Measurement of the solids in the aqueous phase was i9Z~
accomplished by collecting the solids on a Whatman (Trade Mark) No. 1 filter paper and drying the samples overnight at 103C. Rinsing the filtered residue with 10% w/v sodium chloride solution, then with water, before drying overnight in an oven resulted in 50-70% reduction in sediment recovery.
The data for residues given in this report represents the obsexved weights of unrinsed residues recovered.
The drawings illustrate certain results achieved.
In these drawings:
Figure 1 illustrates the effect of papaya latex extract on curd recovery from the superior and inferior surfaces of experimentally canned coho salmon;
Figure 2 illustrates the effect of papaya latex extract on curd reduction in canned coho salmon, expressed on the basis of total curd recovered per can and per 100 grams of flesh;
Figure 3 shows the effect of papaya latex extract on curd recovery from the superior and inferior surfaces of experimentally canned sockeye salmon; and Figure 4 shows the effect of papaya latex extract on curd reduction in canned salmon, expressed on the basis of total curd recovered per can and per 100 grams of flesh.
In Figure 1 five examples each of control and experimentally treated cans were prepared from two salmon as shown. The amounts of curd recovered from the top and bottom surfaces of untreated samples are represented by the unmarked bars, the treated samples are indicated by the cross hatched bars. The total amount of papaya latex extract (expressed as milligrams of extract protein) applied ~13~920 to each sample and the approximate anatomical source of the flesh samples are as indicated in the Figures.
In Figure 2 the data obtained and expressed in Figure 1 were calculated and expressed on a common weight basis to account -8a-1136~ZO
for variability in sample weights.
In Figure 3 steaks prepared from one side of each fish served as reference controls for the opposite and corresponding extract-treated sides. Experimental samples from sockeye I were treated with 1.0 ml of extract on each surface of the flesh.
Similarly samples from sockeye II and III were treated with 2.5 rnilligrams per side and 5.0 mg per side respectively.
In Figure 4 the data obtained and presented in Figure 3 were calculated and expressed on common weight bases to account for variability in sample weights.
RESULTS
A. PRELIMINARY LABORATORY EXPERIMENTS
Initial results obtained under carefully controlled laboratory conditions revealed that the aqueous extract of papaya latex has a significant effect on curd reduction. Quantitation of curd collected from both top and bottom surfaces of canned coho flesh confirmed that the samples treated with the extract contained much less curd than the control samples treated with water only.
The results with coho salmon, over a range of extract protein dosages ranging from 10 to 100 mg per sample, are shown in Figure 1, which also illustrates the anatomical areas of the salmon from which the samples were derived. Results obtained at higher dosages tend to be inconsistent with respect to the overall pattern of curd reduction. This anomaly was attributed to the probability that excess amounts of proteases applied to the flesh surface hydrolyzed the flesh itself, resulting in the mixing of much degraded flesh with the scraped curd samples.
There was slightly more curd recovered from the inferior surfaces of untreated canned salmon than from the top surfaces (Figure lB), but the degree of curd reduction was much greater ~L 3t;9 Z O
than that obtained for the top surfaces (Figure lA).
The data from these experiments, expressed in terms of the total amounts of curd recovered per experimental can, and curd recovered per 100 9 of flesh, are shown in Figures 2A and 2B, respectively, to illustrate the consistency of the results regard-less of the basis on which the data are presented.
These initial results with coho salmon dictated the need for confirmation using sockeye salmon, a specie which is canned commercially in much larger quantities than coho. Moreover, it was decided to examine the possibility that aqueous extracts prepared from crude pancreatic protease powder, and from highly purified papainase would prove even more effective than that prepared from crude papaya latex powder.
Application of papaya latex extracts, in amounts ranging from 2.5 mg to 7.5 mg of protein, to both top and bottom sides of sockeye segments resulted in substantial curd reduction. Figures 3A and 3B illustrate the amount of curd recovered from the top and bottom surfaces. The same data, expressed in terms of total curd recovered per can, and curd recovered per 100 9 flesh, are given in Figures 4A and 4B, respec-tively and are consistent with those shown in Figure 3.
Results using crude pancreatic protease applied to both surfaces of sockeye salmon segments were not as visually impressive as those obtained with extracts of papaya latex. Nevertheless, analysis of curd weights indicated appreciable reduction in curd formation, as shown in Table 1. The data also indicates that the amount of curd recovered from the bottom surfaces of the untreated samples is consistently less than that recovered from the top surfaces of the same untreated samples. It is seen also that the treatment is most effective in reducing curd formation at the bottom of canned salmon segments.
Data from the same experiment, calculated on the basis of curd recovered per 100 g flesh are given in Table 2. The data are consistent with those presented in Table 1 with respect to the % reduction achieved. For this reason subsequent calculat;ons with respect to curd reduction were based on total curd recovered per canned sample.
Prior to actual plant trials, the final laboratory experiment performed was to compare the effect of twice-crystallized papainase with the water extract of crude papaya latex powder that was used in earlier experiments. It was reasoned that the latter preparation, being a crude extract, would contain many extraneous proteins which themselves would coagulate upon heating and con-tribute towards total curd formed. Use of highly purified papainase therefore, with its higher specific activity was expected to provide even better results with respect to curd reduction.
Experimental trials using 1, 2.5 and 5 mg of twice-crystallized papainase yielded equivocal results. Only the highest dosage appeared to be effective. Considering the relatively unimpressive results obtained and the high cost of the purified papainase, further experiments with this product were terminated.
A number of other enzyme preparations were also tested for their effect on curd reduction. These included the following proteases, trypsin (a, Cat. No. 22705) ficin (b, Cat. No. 15770) bromelain (c, Cat. No. 12380) proteinase (d, Cat. No. 20815) pronase (e, Cat. No. 20724) pronase ~-chymotrypain (f, Cat. No. 13680) chymopapain (9, Cat. No. 13675) and pepsin (h, Cat. No. 20010).
All were purchased from U.S. Biochemicals Corp., Cleveland, Ohio, except for pronase, Type IV, which was purchased from Sigma Chemical Co., St. Louis, Missouri. Moreover, three lipases 113692~
(Lipase 448, Cat. No. 18480; Lipase, Cat. No. 18416, and wheat germ Lipase, Cat. No. 18495) all purchased from U.S. Biochemical Corp. were tried individually and in combination with a number of proteases. The results of these trials are given in Table 2a.
In addition to its application to coho, sockeye and pink salmon, water extracts of papaya latex were applied to chum, spring (chinook), and steelhead. The effect on curd reduction for these species are given in Table 2b.
In summary, laboratory experiments with extracts of crude papaya latex powder, crude pancreatic protease, and several other enzymes including purified papainase revealed that the most effective and least costly of these protease preparations was the plain water extract of crude papaya latex.
B. PLANT TRIAL N0. 1 Laboratory experiments, in which 5 to 15 mg of crude papaya latex protein extract were applied, had demonstrated clearly that curd formation in canned sockeye salmon was appre-ciably reduced. For the first plant trial, however, a higher dosage range of 15 to 45 mg per can was chosen since it was believed that the ideal conditions employed in a laboratory setting could not be practised or duplicated in an actual commercial salmon canning operation. Papaya latex extract was spread over the randomly selected unsealed cans of sockeye salmon using 1.0 ml volumetric pipets and the cans re-inserted as soon as possible into the canning line, vacuum-closed, and placed into the retort along with that day's commercial production of canned salmon.
Table 3 shows the effect of added extract upon total curd recovered for each extract dosage. Large standard deviations were expected, since no two canned salmon samples are ever identical.
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Moreover, at the high levels of extract protein employed, it is very difficult to clearly separate the curd from the flesh since the physical demarcation between the curd and flesh becomes poorly defined and difficult to discriminate. Nevertheless, the data for the initial cannery trial revealed a definite reduction of curd which appeared to show some effects related to the dosages used.
Of particular interest was the apparent improvement in the general colour of the extract-treated samples, aside from the improvement in the general appearance of canned sockeye salmon as a result of curd reduction.
C. PLANT TRIAL NO. 2 The first plant trial not only confirmed the effective-ness of the papaya extract when tried under industrial conditions, but further revealed that trials using a lower range of enzyme protein concentrations was required in order to establish the least, yet most effective, amount of extract to be used. In addition to measuring curd formation in canned sockeye and pink salmon, other parameters were examined, including volume of free liquid in the aqueous phase, colour of free oil and the amount of suspended solids in the aqueous phases. These parameters were also examined for a set of canned sockeye salmon to which ascorbic acid (Vitamin C) was included. Previous experiments had indicated that the colour of extract treated canned salmon was enhanced, possibly as a result of some natural anti-oxidant present in the papaya latex extract.
(a) Sockeye Salmon i. Effect On Curd Formation Curd formation was appreciably reduced even at the lowest concentration of extract applied, but the optlmum dosage was found to be in the 10 to 15 mg/can range (Table 4), where about 50-75% reduction of curd was obtained. It is noteworthy that the mean curd weight of untreated samples from trial #l was 383 + 189 mg (mean + standard deviation), whereas the curd in the controls from plant trial #2 was 253 + 135 mg. This illustrates the variance in the amounts of curd found in canned salmon obtained from plant productions spaced only two weeks apart.
ii Effect of Extract on oil Colour and Volume Oil recovered from canned sockeye salmon demonstrated some general irnprovement in colour as a result of treatment with papaya latex extract. Table 5 shows that the total number of "colour" units for the oil taken from the experimental samples were greater than in the untreated controls. The relative intensi-ties of the oil colours are also provided in Table 5, which more clearly reveals the increase in the reddish-orange colour of the oil .
The data obtained for the volume of free oil recovered appears to suggest a slight increase at the level of 5 to 10 mg of added extract. However, the large natural variation in the volumes of oil recorded from sample to sample prohibits a definite con-clusion to be made in respect of changes in oil volume.
iii Effect of Extract on Volume and Appearance of Aqueous Phase of Drained Liquid Incorporation of crude papaya latex extract to canned salmon resulted in visible increases in the amount of suspended particulate matter in the aqueous phase of the drained liquid.
The liquid from untreated cans was amber-coloured and quite clear, whereas those obtained from treated samples demonstrated an appreciable amount of suspended matter in them. Quantitation of the solids in the aqueous phase showed that slightly more particulate matter was recovered from those samples which had been treated with extract in the 10 mg range (Table 6), probably as a result of enzyme action disrupting to some extent the integrity of the exposed tissues.
A slight increase in the corrected volume of free water was also noted in experimentally treated samples.
iv Effect of Added Vitamin C
The enrichment in the natural reddish-orange colour of oil recovered from samples which had been treated with papaya latex extract suggested that the crude extract possessed some substance or substances which inhibited, to some extent, the usual bleaching effect of the retorting process of canned salmon flesh.
Since the reddish-orange colour of sockeye salmon flesh is probably derived from one or more of the naturally occurring carotenoid pigments, the addition of some anti-oxidant substance to the experimental samples was thought to favour the retention of the reddish-orange colour in the free oil by inhibiting the oxidation of the natural pigment. Accordingly, an independent set of canned sockeye salmon were treated with varying amounts of papaya latex extract to which were added 10 mg/ml of ascorbic acid. Table 7 shows that the inclusion of 10 mg of ascorbic acid to the extract resulted in no enrichment in the intensity of the oil colour over those samples which were treated with extract only, as shown in Table 5 earlier.
(b) Pink Salmon Since pink salmon were also being canned during Plant Trial 2, a number of samples were treated with various amounts of papaya latex extract to investigate its effect on curd formation, oil colour, oil volume, water volume and on suspended solids in ~1369Zo the water phase.
i. Curd Formation The amount of curd collected from untreated canned pink salmon was considerably less than those obtained from sockeye salmon controls, which probably accounted for the better effect on curd reduction obtained even at the lowest dosage of extract employed. For pink salmon, approximately 70-80% reduction in curd was achieved (Table 8) as compared with 50-75% reduction achieved for sockeye salmon under similar conditions.
ii Colour and Volume of Oil As expected, the intensity of the colour of pink salmon oil was only about 30% of that sockeye salmon oil, and the volumes of oil recovered to be about 40% less than for sockeye salmon.
Analysis of the intensity of the oil colour of experi-mentally treated samples revealed a marked improvement over the controls (Table 9). However, the apparent increase in the total colour units recovered from the treated samples must be attributed largely to the increase in the volumes of oil.
iii Residue and Free Water Volume Treatment with papaya extract resulted in the recovery of more suspended solids from the aqueous phase and a very pro-nounced increase in the corrected volume of the free aqueous phase as shown in Table lO. Compared to canned sockeye salmon (Table 6), pink salmon flesh released about lO% more water after being canned and retorted.
D. TASTE PANEL
Three independent organoleptic trials were conducted on experimentally canned salmon to determine whether taste panelists could differentiate between the untreated and treated samples. They were also asked to identify the treated sample.
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The test samples included sockeye salmon canned in Plant Trial 1, containing 15 to 45 mg of extract per can, and those obtained from Plant Trial 2, treated with 17.4 mg of extract.
The results of the three taste tes~ are summarized in Table 11. The triangle test employed dictates that by chance alone, three correct answers are to be expected from 12 testers, and a mini-mum of eight correct answers are necessary to establish, at the 95%
confidence level, the ability of the tasters to discriminate between the treated and untreated samples. The results given in Table 11 clearly show that the panelists experienced considerable difficulty in differentiating between the treated and untreated samples of salmon, and encountered even more difficulty in correctly identi-fying the treated sample, even for those cans in which 45 mg of papaya latex extract was incorporated.
It is worth noting, however, that of those panelists who correctly distinguished between the 45 mg treated and untreated samples, all three correctly identified the sample (or samples) that had been treated, whereas such was not the case in which 15 and 17.4 mg extract had been used.
E. OTHER RESULTS
i Application of Extract by Spraying In all preliminary work leading to plant trials, known volumes of enzyme extract were spread manually and laboriously over the surfaces of canned salmon with p;pets. However, it was recognized that if the use of papaya latex extract in the commercial canning of salmon should ever be realized, the extract would have to be applied by another method, likely by spraying at rates exceeding 250 cans per minute.
For this reason, trials were performed in which extracts were applied to the exposed top surfaces of a series of ~1369ZO
canned salmon using a hand-held sprayer, modified to deliver 0.8 ml of extract with each squeeze of the plunger. The efficacy of this technique on curd reduction and on other parameters was examined, and subsequent analyses showed that the spray method of application was as effective as pipetting. The data in support of this con-clusion are given in Table 12 (for curd reduction) and in Table 13 (for oil colour oil and water volumes and quantity of residue recovered from the aqueous phase). Although the dosages applied by spraying differ somewhat for the pipetted series, the data in Table 12 can be compared with those given in Table 4 (for the pipetted series). The data given in Table 13 can be compared with those given in Tables 5 and 6. These comparisons clearly show that the application of the extract by spraying was as effective as pipetting.
ii Composition of Curd Curd collected from a number of untreated canned sock-eye salmon were subjected to routine chemical analysis for fat, protein and water content. The results, shown in Table 14, illustrate the lipoprotein nature of curd which forms in canned sockeye salmon.
CONCLUSION AND COMMENTS
It was unequivocally demonstrated in laboratory and plant trials that the application of a water extract of natural papaya latex powder to the surfaces of canned salmon effectively reduced the amount of curd formed. Under the conditions employed, the optimum amount of extract recommended is in the 10-15 mg~can range for sockeye salmon (to achieve approximately 50-75% reductjon), and 2-5 mg for pink salmon (to achieve approxi-mately 70-80% reduction), provided (a) an interval of at least 30 min at ordinary room temperature is allowed between the 1~3~ZO
application of the extract and the heat sterilization process, and (b) the specific activity of the extract is 0.94 optical density units per minute per mg. of protein.
The use of excess papaya latex extract gives canned salmon a "dryish" look and should be avoided.
Concerning proteolytic activity individual proteol-ytic preparations will have a range of specific activities, based upon their state of purity. The relatively impure preparations will have a lower specific activity than the more highly purified preparations. For example, typical specific proteolytic activity values for crystalline papain (highly purified) are about four times greater than those for crude papaya extracts (latex). Under conditions where time and temperature are approximately constant, as in a fish canning line, the desired result according to the invention is brought about by the total amount of proteoly-tic activity which is added. The total activity is repre-sented by the product of the protein concentration (milli-grams per liter) multiplied by the specific activity (rate of protein hydrolysis per milligram of protein). Thus with
The canning of salmon is an important industry in a number of countries. Canned salmon are particularly important to the economy of British Columbia. In 1978 the wholesale value of canned salmon was $116 million dollars which represents 23~ of the wholesale value of fishery products in the province.
That year British Columbia packed 1.1 million 48 lbs cases.
The United States packed 3.3 million cases and Japan 1.7 million.
The production and export of canned salmon has always been an important economy of British Columbia fish processing industry. During the past decade its role has diminished slightly due to the emergence of other markets for other fishery products, such as herring roe, and an increasing trend in recent years towards marketing salmon in fresh and frozen form.
Technological innovations and processing problems relating to salmon canning have been slight. The basic machinery used for steaking, filleting, sealing and retorting has remained virtually unchanged for many decades. One long recognized problem periodically brought to the attention of researchers however is the formation of excess curd on the cut surfaces of canned salmon. The curd, which appears as an offwhite, jelly-like mass, largely results from the heat coagulation of soluble proteins exuded from the cut surfaces of salmon flesh. The curd detracts from the appearance of the canned product.
Attempts have been made to reduce or eliminate this formation of curd. For example brining the salmon segments prior to canning is reported to reduce curd formation by 9~
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virtue of the salt solution diluting most of the soluble proteins from the cut surface of the segments. Similarly the use of disodium dipicolinate and urea solutions have been reported to reduce curd formation. As these procedures require hand filling of individual cans however, the methods are economically unfeasible and are not acceptable to the established canning systems employed. Other steps advocated have been subjecting the surfaces of canned salmon to steam treatment before the lids are placed on the cans. However, this method has not proved successful during a fairly large scale trial by a commercial canning firm in British Columbia.
The present invention has provided a method in which a substantial reduction of curd formation is possible. The invention is based on the idea that if the porteinaceous exudate can by hydrolyzed into small, non-coagulable fragments of polypeptides and peptides then the amount of curd formed would be appreciably reduced or even eliminated completely.
Accordingly, the present invention is a method of reducing curd formation in a salmon canning process. The method comprises application of proteolytic enzymes or a combination of enzymes to a cut surface of the salmon prior to the retorting process.
In a preferred aspect the enzyme is natural papaya latex applied as a water extract. Other proteoloytic enzymes that have proven useful include pancreatic protease,papainase, trypsin, ficin, bromelain, prolase, chymopapain and pepsin. Hog pancreatic lipase, and wheat germ lipase have also proved useful.
Salmon that has been treated includes sockeye salmon, coho salmon, pink salmon, chum salmon and spring (Chinook) salmon. Steelhead has also been treated.
In a preferred aspect in the treating of sockeye salmon ~3~9ZO
the method comprises applying to a cut surface of the salmon, while in the can, a water extract from natural papaya latex powder containing 10 to 15 milligrams of extract protein, or 9.4 to 14.1 units of protease activity, as defined in "Methods in Enzymology" (1970), Vol. XIX, p 227.
In the treatment of pink salmon the preferred method is applying to a cut surface of the salmon two to five milligrams per can of a water extract of natural papaya latex powder containing two to five milligrams of extract protein, or 1.9 to 4.7 units of protease activity, as defined in "Methods in Enzymology" (1970), Vol. XIX, p 227.
It has also been observed that the color of the oil in the can can be improved by adding the water extract of natural papaya latex powder containing two to 45 mg of extract protein.
The following experimental information illustrates the invention:
MATERIALS AND METHODS
A. PRELIMINARY LABORATORY EXPERIMENTS
Proteolytic enzyme products were purchased from Sigma Chemical Co., St. Louis, Mo, and described by them as:
i. "Crude Powder, Type II - purified from papaya latex", ii. "Pancreatic Protease, Type I, crude", iii. "Papainase, twice crystallized".
Other enzymes were obtained from U.S. Biochemical Corp., Cleveland, Ohio.
Preparation of enzyme extract from crude papaya latex powder, The coarse powder was suspended in 10 volumes of cold de-ionized water, stirred for 20 minutes and centrifuged for 20 minutes at 15,000 x 9 in a refrigerated centrifuge. The clear amber supernatant fluid (protein concentration, usually about 45 mg/ml) was further diluted ~13~92~
with water to achieve the required protein concentration for a given experiment.
Aqueous extracts were similarly prepared from purified papainase and from crude pancreatic protease pOwder Porteolytic activities of the extract were esti-mated according to Arnon, 1970 Methods in Enzymology, Aca-demic Press, Vol. XIX, 226. Activity was related to the increase in optical absorbency at 280 nm by trichloroacetic acid-soluble digestion products of casein, under stand-ardized conditions. Protein was measured by the biuret method according to Gornall, et al, J. siOl. Chem. 177,751 (1949) using commercially prepared serum albumin solution as reference, and by the Kjeldahl method. Lipids were extrac-ted with a 3:1 mixture of ethyl alcohol and petroleum ether.Two species of salmon, coho (I. kisutch) and sockeye (0.
nerka) were used in preliminary trials on curd reduction.
Both species were purchased locally in the unfrozen form.
The sockeyes had been transported in a slush ice system from the fishing grounds to a local fish processing plant. Since they appeared to be in excellent condition, they were allowed to "age" from 3 to 7 days in the laboratory cold room before experimental canning trials were undertaken.
This action was taken on the assumption that a longer post-mortem period would enhance curd formation. Some sockeyes were stored at -30C for the same reason.
Salmon were cut into segments, weighed and packed into cylindrical ("1/2 - lb") cans. The amount of flesh in each can ranged from about 180 to 220 g. Common salt 113~gZ0 (sodium chloride), 1.5 g, was added to the bottom of each experimental can.
After the cans were filled, protease-containing extracts~ usually 1.0 ml, were carefully spread over the entixe exposed superior surfaces of the flesh with a volu-metric -4a-1136i9Z~
pipet and the cans vacuum-sealed in a Rooney (Trade Mark) closing machine. Reference control samples were prepared by applying an equivalent volume of water to the flesh surfaces.
After allowing an interval of 30-45 minutes after applica-tion of the protease-containing extracts, the sealed cans were placed in an autoclave, sterilized at 250F (120C) for 75 minutes, then stored overnight at room temperature. The canned products were usually examined for curd the following day.
Quantitation of curd on the superior and inferior surfaces of canned salmon was accomplished by manually scraping off the curd carefully with a spatula and drying the collected curd overnight at 103C. The "curd scrapers"
were kept ignorant of the dosage applied to any of the samples being scraped in order to maintain objectivity.
B. PLANT TRIAL NO. 1 The first trial under commercial canning conditions was done on sockeye salmon at a commerical cannery in Vancouver, British Columbia. Aqueous extracts of crude papaya latex powder were prepared in the laboratory in the morning of the trial run and transported in ice to the plant. The dosages applied (per "1/2-lb" can) to the superior surfaces were 15, 25, 35, and 45 mg of extract protein in volumes of 1.0 ml. A total of 200 canned salmon samples were processed, including 40 untreated samples which served as controls.
The application of the enzyme solutions with pipets to all samples (randomly chosen from the regular production line), were completed in about 15 mlnutes, and .3 ~`'`
~13~ZO
the cans reintroduced into the canning line for vacuum-closing, rinsing and retorting. About 30 minutes elapsed between the application of papaya latex extract to the last experimental sample -5a-and the introduction of all samples into the retort. Retorting conditions were according to standard commercial practice;
that is, 30 minutes for "come-up" time, 74 minutes cooking at 245F (116C) and 20 minutes "come-down" time.
The sockeye salmon canned during the first experimental plant tria1 originated in waters off the north coast of B.C.
and had been kept in ice for 4-5 days.
Collection and estimation of curd formed under various experimental conditions were performed as described previously.
C. PLANT TRIAL NO. 2 The second plant trial was carried out at the same cannery about one month later. The experimental protocol was the same as for Plant Trial 1, except that (i) the dosages of water extract of papaya latex applied to each sample were reduced, (ii) a hand-held sprayer, modified and calibrated to deliver 0.8 ml of aqueous extract per squeeze of the trigger, was employed for some of the experimental series, (iii) 10 mg of ascorbic acid was added to each sample of an experimental series, in addition to aqueous extracts of papaya latex, (iv) a series of pink salmon was treated with various doses of papaya latex extract.
A total of 710 "1/2-lb" cans were obtained, including 40 cans each of untreated sockeyes and pinks which served as reference controls.
D. EVALUATION
Organoleptic assessment of the experimentally treated samples was performed. Each sitting consisted of 12 experienced tasters who were subjected to a standard "Triangle Taste Test"
as described by Roessler et al. 1948 Food Research 13, 503.
1~3~20 Presented with three samples, one of which was different from the other two, the panelists were asked to identify the two that were similar. Further, they were asked to indicate which had an off-flavour or odour. Experimentally treated and untreated canned salmon, obtained from Plant Trials 1 and 2, were presented to the taste panels in a mashed form under subdued light. The entire contents of each can, including the free liquid, were used to prepare these samples for presentation to the panelists.
Volumetric measurements of oil and aqueous phases of canned salmon samples were carried out by allowing the liquid contents of the cans to drain for at least 10 minutes into cylindrical graduates. After the aqueous phases were measured directly from the graduates, the oil phases were carefully transferred into graduated conical glass centrifuge tubes and centrifuged for at least 5 minutes. The volume of the oil was then estimated directly from the graduated tubes.
Aliquots of oil were removed from these tubes, diluted in appropriate volumes of n-hexane (25-fold dilution for sockeye salmon oil, 5-fold for coho salmon oil) and read aga;nst an n-hexane blank in l-cm cells at 470 nm. It had been previously established that the spectrum of the oil from canned sockeye salmon showed maximum absorption between 465 and 475 nm, with a peak near 470 nm and that a direct relationship existed between the amount of coloured oil and absorbance at 470 nm in the range .040 to .270 optical density units. The spectrum for oil from pink salmon, however, did not possess the same absorption profile, exhibiting a flat plateau in the region 420 to 480 nm.
Measurement of the solids in the aqueous phase was i9Z~
accomplished by collecting the solids on a Whatman (Trade Mark) No. 1 filter paper and drying the samples overnight at 103C. Rinsing the filtered residue with 10% w/v sodium chloride solution, then with water, before drying overnight in an oven resulted in 50-70% reduction in sediment recovery.
The data for residues given in this report represents the obsexved weights of unrinsed residues recovered.
The drawings illustrate certain results achieved.
In these drawings:
Figure 1 illustrates the effect of papaya latex extract on curd recovery from the superior and inferior surfaces of experimentally canned coho salmon;
Figure 2 illustrates the effect of papaya latex extract on curd reduction in canned coho salmon, expressed on the basis of total curd recovered per can and per 100 grams of flesh;
Figure 3 shows the effect of papaya latex extract on curd recovery from the superior and inferior surfaces of experimentally canned sockeye salmon; and Figure 4 shows the effect of papaya latex extract on curd reduction in canned salmon, expressed on the basis of total curd recovered per can and per 100 grams of flesh.
In Figure 1 five examples each of control and experimentally treated cans were prepared from two salmon as shown. The amounts of curd recovered from the top and bottom surfaces of untreated samples are represented by the unmarked bars, the treated samples are indicated by the cross hatched bars. The total amount of papaya latex extract (expressed as milligrams of extract protein) applied ~13~920 to each sample and the approximate anatomical source of the flesh samples are as indicated in the Figures.
In Figure 2 the data obtained and expressed in Figure 1 were calculated and expressed on a common weight basis to account -8a-1136~ZO
for variability in sample weights.
In Figure 3 steaks prepared from one side of each fish served as reference controls for the opposite and corresponding extract-treated sides. Experimental samples from sockeye I were treated with 1.0 ml of extract on each surface of the flesh.
Similarly samples from sockeye II and III were treated with 2.5 rnilligrams per side and 5.0 mg per side respectively.
In Figure 4 the data obtained and presented in Figure 3 were calculated and expressed on common weight bases to account for variability in sample weights.
RESULTS
A. PRELIMINARY LABORATORY EXPERIMENTS
Initial results obtained under carefully controlled laboratory conditions revealed that the aqueous extract of papaya latex has a significant effect on curd reduction. Quantitation of curd collected from both top and bottom surfaces of canned coho flesh confirmed that the samples treated with the extract contained much less curd than the control samples treated with water only.
The results with coho salmon, over a range of extract protein dosages ranging from 10 to 100 mg per sample, are shown in Figure 1, which also illustrates the anatomical areas of the salmon from which the samples were derived. Results obtained at higher dosages tend to be inconsistent with respect to the overall pattern of curd reduction. This anomaly was attributed to the probability that excess amounts of proteases applied to the flesh surface hydrolyzed the flesh itself, resulting in the mixing of much degraded flesh with the scraped curd samples.
There was slightly more curd recovered from the inferior surfaces of untreated canned salmon than from the top surfaces (Figure lB), but the degree of curd reduction was much greater ~L 3t;9 Z O
than that obtained for the top surfaces (Figure lA).
The data from these experiments, expressed in terms of the total amounts of curd recovered per experimental can, and curd recovered per 100 9 of flesh, are shown in Figures 2A and 2B, respectively, to illustrate the consistency of the results regard-less of the basis on which the data are presented.
These initial results with coho salmon dictated the need for confirmation using sockeye salmon, a specie which is canned commercially in much larger quantities than coho. Moreover, it was decided to examine the possibility that aqueous extracts prepared from crude pancreatic protease powder, and from highly purified papainase would prove even more effective than that prepared from crude papaya latex powder.
Application of papaya latex extracts, in amounts ranging from 2.5 mg to 7.5 mg of protein, to both top and bottom sides of sockeye segments resulted in substantial curd reduction. Figures 3A and 3B illustrate the amount of curd recovered from the top and bottom surfaces. The same data, expressed in terms of total curd recovered per can, and curd recovered per 100 9 flesh, are given in Figures 4A and 4B, respec-tively and are consistent with those shown in Figure 3.
Results using crude pancreatic protease applied to both surfaces of sockeye salmon segments were not as visually impressive as those obtained with extracts of papaya latex. Nevertheless, analysis of curd weights indicated appreciable reduction in curd formation, as shown in Table 1. The data also indicates that the amount of curd recovered from the bottom surfaces of the untreated samples is consistently less than that recovered from the top surfaces of the same untreated samples. It is seen also that the treatment is most effective in reducing curd formation at the bottom of canned salmon segments.
Data from the same experiment, calculated on the basis of curd recovered per 100 g flesh are given in Table 2. The data are consistent with those presented in Table 1 with respect to the % reduction achieved. For this reason subsequent calculat;ons with respect to curd reduction were based on total curd recovered per canned sample.
Prior to actual plant trials, the final laboratory experiment performed was to compare the effect of twice-crystallized papainase with the water extract of crude papaya latex powder that was used in earlier experiments. It was reasoned that the latter preparation, being a crude extract, would contain many extraneous proteins which themselves would coagulate upon heating and con-tribute towards total curd formed. Use of highly purified papainase therefore, with its higher specific activity was expected to provide even better results with respect to curd reduction.
Experimental trials using 1, 2.5 and 5 mg of twice-crystallized papainase yielded equivocal results. Only the highest dosage appeared to be effective. Considering the relatively unimpressive results obtained and the high cost of the purified papainase, further experiments with this product were terminated.
A number of other enzyme preparations were also tested for their effect on curd reduction. These included the following proteases, trypsin (a, Cat. No. 22705) ficin (b, Cat. No. 15770) bromelain (c, Cat. No. 12380) proteinase (d, Cat. No. 20815) pronase (e, Cat. No. 20724) pronase ~-chymotrypain (f, Cat. No. 13680) chymopapain (9, Cat. No. 13675) and pepsin (h, Cat. No. 20010).
All were purchased from U.S. Biochemicals Corp., Cleveland, Ohio, except for pronase, Type IV, which was purchased from Sigma Chemical Co., St. Louis, Missouri. Moreover, three lipases 113692~
(Lipase 448, Cat. No. 18480; Lipase, Cat. No. 18416, and wheat germ Lipase, Cat. No. 18495) all purchased from U.S. Biochemical Corp. were tried individually and in combination with a number of proteases. The results of these trials are given in Table 2a.
In addition to its application to coho, sockeye and pink salmon, water extracts of papaya latex were applied to chum, spring (chinook), and steelhead. The effect on curd reduction for these species are given in Table 2b.
In summary, laboratory experiments with extracts of crude papaya latex powder, crude pancreatic protease, and several other enzymes including purified papainase revealed that the most effective and least costly of these protease preparations was the plain water extract of crude papaya latex.
B. PLANT TRIAL N0. 1 Laboratory experiments, in which 5 to 15 mg of crude papaya latex protein extract were applied, had demonstrated clearly that curd formation in canned sockeye salmon was appre-ciably reduced. For the first plant trial, however, a higher dosage range of 15 to 45 mg per can was chosen since it was believed that the ideal conditions employed in a laboratory setting could not be practised or duplicated in an actual commercial salmon canning operation. Papaya latex extract was spread over the randomly selected unsealed cans of sockeye salmon using 1.0 ml volumetric pipets and the cans re-inserted as soon as possible into the canning line, vacuum-closed, and placed into the retort along with that day's commercial production of canned salmon.
Table 3 shows the effect of added extract upon total curd recovered for each extract dosage. Large standard deviations were expected, since no two canned salmon samples are ever identical.
13 3~9ZO
Moreover, at the high levels of extract protein employed, it is very difficult to clearly separate the curd from the flesh since the physical demarcation between the curd and flesh becomes poorly defined and difficult to discriminate. Nevertheless, the data for the initial cannery trial revealed a definite reduction of curd which appeared to show some effects related to the dosages used.
Of particular interest was the apparent improvement in the general colour of the extract-treated samples, aside from the improvement in the general appearance of canned sockeye salmon as a result of curd reduction.
C. PLANT TRIAL NO. 2 The first plant trial not only confirmed the effective-ness of the papaya extract when tried under industrial conditions, but further revealed that trials using a lower range of enzyme protein concentrations was required in order to establish the least, yet most effective, amount of extract to be used. In addition to measuring curd formation in canned sockeye and pink salmon, other parameters were examined, including volume of free liquid in the aqueous phase, colour of free oil and the amount of suspended solids in the aqueous phases. These parameters were also examined for a set of canned sockeye salmon to which ascorbic acid (Vitamin C) was included. Previous experiments had indicated that the colour of extract treated canned salmon was enhanced, possibly as a result of some natural anti-oxidant present in the papaya latex extract.
(a) Sockeye Salmon i. Effect On Curd Formation Curd formation was appreciably reduced even at the lowest concentration of extract applied, but the optlmum dosage was found to be in the 10 to 15 mg/can range (Table 4), where about 50-75% reduction of curd was obtained. It is noteworthy that the mean curd weight of untreated samples from trial #l was 383 + 189 mg (mean + standard deviation), whereas the curd in the controls from plant trial #2 was 253 + 135 mg. This illustrates the variance in the amounts of curd found in canned salmon obtained from plant productions spaced only two weeks apart.
ii Effect of Extract on oil Colour and Volume Oil recovered from canned sockeye salmon demonstrated some general irnprovement in colour as a result of treatment with papaya latex extract. Table 5 shows that the total number of "colour" units for the oil taken from the experimental samples were greater than in the untreated controls. The relative intensi-ties of the oil colours are also provided in Table 5, which more clearly reveals the increase in the reddish-orange colour of the oil .
The data obtained for the volume of free oil recovered appears to suggest a slight increase at the level of 5 to 10 mg of added extract. However, the large natural variation in the volumes of oil recorded from sample to sample prohibits a definite con-clusion to be made in respect of changes in oil volume.
iii Effect of Extract on Volume and Appearance of Aqueous Phase of Drained Liquid Incorporation of crude papaya latex extract to canned salmon resulted in visible increases in the amount of suspended particulate matter in the aqueous phase of the drained liquid.
The liquid from untreated cans was amber-coloured and quite clear, whereas those obtained from treated samples demonstrated an appreciable amount of suspended matter in them. Quantitation of the solids in the aqueous phase showed that slightly more particulate matter was recovered from those samples which had been treated with extract in the 10 mg range (Table 6), probably as a result of enzyme action disrupting to some extent the integrity of the exposed tissues.
A slight increase in the corrected volume of free water was also noted in experimentally treated samples.
iv Effect of Added Vitamin C
The enrichment in the natural reddish-orange colour of oil recovered from samples which had been treated with papaya latex extract suggested that the crude extract possessed some substance or substances which inhibited, to some extent, the usual bleaching effect of the retorting process of canned salmon flesh.
Since the reddish-orange colour of sockeye salmon flesh is probably derived from one or more of the naturally occurring carotenoid pigments, the addition of some anti-oxidant substance to the experimental samples was thought to favour the retention of the reddish-orange colour in the free oil by inhibiting the oxidation of the natural pigment. Accordingly, an independent set of canned sockeye salmon were treated with varying amounts of papaya latex extract to which were added 10 mg/ml of ascorbic acid. Table 7 shows that the inclusion of 10 mg of ascorbic acid to the extract resulted in no enrichment in the intensity of the oil colour over those samples which were treated with extract only, as shown in Table 5 earlier.
(b) Pink Salmon Since pink salmon were also being canned during Plant Trial 2, a number of samples were treated with various amounts of papaya latex extract to investigate its effect on curd formation, oil colour, oil volume, water volume and on suspended solids in ~1369Zo the water phase.
i. Curd Formation The amount of curd collected from untreated canned pink salmon was considerably less than those obtained from sockeye salmon controls, which probably accounted for the better effect on curd reduction obtained even at the lowest dosage of extract employed. For pink salmon, approximately 70-80% reduction in curd was achieved (Table 8) as compared with 50-75% reduction achieved for sockeye salmon under similar conditions.
ii Colour and Volume of Oil As expected, the intensity of the colour of pink salmon oil was only about 30% of that sockeye salmon oil, and the volumes of oil recovered to be about 40% less than for sockeye salmon.
Analysis of the intensity of the oil colour of experi-mentally treated samples revealed a marked improvement over the controls (Table 9). However, the apparent increase in the total colour units recovered from the treated samples must be attributed largely to the increase in the volumes of oil.
iii Residue and Free Water Volume Treatment with papaya extract resulted in the recovery of more suspended solids from the aqueous phase and a very pro-nounced increase in the corrected volume of the free aqueous phase as shown in Table lO. Compared to canned sockeye salmon (Table 6), pink salmon flesh released about lO% more water after being canned and retorted.
D. TASTE PANEL
Three independent organoleptic trials were conducted on experimentally canned salmon to determine whether taste panelists could differentiate between the untreated and treated samples. They were also asked to identify the treated sample.
~13~Z(~
The test samples included sockeye salmon canned in Plant Trial 1, containing 15 to 45 mg of extract per can, and those obtained from Plant Trial 2, treated with 17.4 mg of extract.
The results of the three taste tes~ are summarized in Table 11. The triangle test employed dictates that by chance alone, three correct answers are to be expected from 12 testers, and a mini-mum of eight correct answers are necessary to establish, at the 95%
confidence level, the ability of the tasters to discriminate between the treated and untreated samples. The results given in Table 11 clearly show that the panelists experienced considerable difficulty in differentiating between the treated and untreated samples of salmon, and encountered even more difficulty in correctly identi-fying the treated sample, even for those cans in which 45 mg of papaya latex extract was incorporated.
It is worth noting, however, that of those panelists who correctly distinguished between the 45 mg treated and untreated samples, all three correctly identified the sample (or samples) that had been treated, whereas such was not the case in which 15 and 17.4 mg extract had been used.
E. OTHER RESULTS
i Application of Extract by Spraying In all preliminary work leading to plant trials, known volumes of enzyme extract were spread manually and laboriously over the surfaces of canned salmon with p;pets. However, it was recognized that if the use of papaya latex extract in the commercial canning of salmon should ever be realized, the extract would have to be applied by another method, likely by spraying at rates exceeding 250 cans per minute.
For this reason, trials were performed in which extracts were applied to the exposed top surfaces of a series of ~1369ZO
canned salmon using a hand-held sprayer, modified to deliver 0.8 ml of extract with each squeeze of the plunger. The efficacy of this technique on curd reduction and on other parameters was examined, and subsequent analyses showed that the spray method of application was as effective as pipetting. The data in support of this con-clusion are given in Table 12 (for curd reduction) and in Table 13 (for oil colour oil and water volumes and quantity of residue recovered from the aqueous phase). Although the dosages applied by spraying differ somewhat for the pipetted series, the data in Table 12 can be compared with those given in Table 4 (for the pipetted series). The data given in Table 13 can be compared with those given in Tables 5 and 6. These comparisons clearly show that the application of the extract by spraying was as effective as pipetting.
ii Composition of Curd Curd collected from a number of untreated canned sock-eye salmon were subjected to routine chemical analysis for fat, protein and water content. The results, shown in Table 14, illustrate the lipoprotein nature of curd which forms in canned sockeye salmon.
CONCLUSION AND COMMENTS
It was unequivocally demonstrated in laboratory and plant trials that the application of a water extract of natural papaya latex powder to the surfaces of canned salmon effectively reduced the amount of curd formed. Under the conditions employed, the optimum amount of extract recommended is in the 10-15 mg~can range for sockeye salmon (to achieve approximately 50-75% reductjon), and 2-5 mg for pink salmon (to achieve approxi-mately 70-80% reduction), provided (a) an interval of at least 30 min at ordinary room temperature is allowed between the 1~3~ZO
application of the extract and the heat sterilization process, and (b) the specific activity of the extract is 0.94 optical density units per minute per mg. of protein.
The use of excess papaya latex extract gives canned salmon a "dryish" look and should be avoided.
Concerning proteolytic activity individual proteol-ytic preparations will have a range of specific activities, based upon their state of purity. The relatively impure preparations will have a lower specific activity than the more highly purified preparations. For example, typical specific proteolytic activity values for crystalline papain (highly purified) are about four times greater than those for crude papaya extracts (latex). Under conditions where time and temperature are approximately constant, as in a fish canning line, the desired result according to the invention is brought about by the total amount of proteoly-tic activity which is added. The total activity is repre-sented by the product of the protein concentration (milli-grams per liter) multiplied by the specific activity (rate of protein hydrolysis per milligram of protein). Thus with
2 to 40 milligrams of protein multiplied by a specific activity of 0.94 the range of total activity is from 1.8 to 37.6. This is satisfactory according to the invention, that is the range of total activity may be about 1 to about 38.
This range can be made up from proteolytic preparations having specific activity values other than 0.94. For example, assume that the preparation had a specific activity of 1.88, then the milligrams of protein required would be 1 to 20. It is unlikely that even crude extracts, which have 1~3~
been shown to be the most useful, will have a specific activity of exactly 0.94. They could be 0.82, 1.11 or any variety of numbers in the environs of 0.94.
Apart from the general improvement in the appear-ance of canned salmon as a result of curd reduction, improve-ment in the colour of the canned product was also achieved.
Examination of the free oils revealed an increase of approxi-mately 1.5-fold in the intensity of the natural reddish-orange colour of sockeye oil. Similar increases were observed for oils recovered from canned pink salmon. No marked improve-ment, however, was noted in the colour of the flesh intself.
The choice of ascorbic acid (vitamin C) as the antioxidant was predicated largely upon its high acceptance as an additive in many food preparations. Our experiences showed that no improvement in the colour of sockeye salmon oil results beyond that already achieved by the addition of papaya latex extract only.
Unlike many enzyme preparations, the proteolytic activity of the dilute water extracts of papaya latex was stable for at least 8 hours at ordinary room temperature.
This particular property is extremely important from a practical standpoint, since the water extract can be prepared at the beginning of a canning shift and be used for the entire day's canning operation or longer with no need for refrigeration.
-19a-j ~.~
I~ELE I
EFFECT ON NON~Pln~n~rED PA:3o~FIC PF~n~5~5E E~lWCT oN CURD
FCRM~I~oN IN C~D~aD ~ SALMoN
. Total Wbights of Cbra P~ed E~
Fish Nb. No. Cans Tbtal Reduction Tbp Surface 80tbom Surface ~ng dried wt) Achieved (~ dr~ wt) (T~ dried wt) . , . , ._ . 1 Cbntrol (4) 1951 562 2513 Exptl (4) 1710 286 1996 21%
: _ .
2 Ckntrol ~4) 1862 489 2351 ~Xpkl (4) 1671 198 1869 21%
. . _ _
This range can be made up from proteolytic preparations having specific activity values other than 0.94. For example, assume that the preparation had a specific activity of 1.88, then the milligrams of protein required would be 1 to 20. It is unlikely that even crude extracts, which have 1~3~
been shown to be the most useful, will have a specific activity of exactly 0.94. They could be 0.82, 1.11 or any variety of numbers in the environs of 0.94.
Apart from the general improvement in the appear-ance of canned salmon as a result of curd reduction, improve-ment in the colour of the canned product was also achieved.
Examination of the free oils revealed an increase of approxi-mately 1.5-fold in the intensity of the natural reddish-orange colour of sockeye oil. Similar increases were observed for oils recovered from canned pink salmon. No marked improve-ment, however, was noted in the colour of the flesh intself.
The choice of ascorbic acid (vitamin C) as the antioxidant was predicated largely upon its high acceptance as an additive in many food preparations. Our experiences showed that no improvement in the colour of sockeye salmon oil results beyond that already achieved by the addition of papaya latex extract only.
Unlike many enzyme preparations, the proteolytic activity of the dilute water extracts of papaya latex was stable for at least 8 hours at ordinary room temperature.
This particular property is extremely important from a practical standpoint, since the water extract can be prepared at the beginning of a canning shift and be used for the entire day's canning operation or longer with no need for refrigeration.
-19a-j ~.~
I~ELE I
EFFECT ON NON~Pln~n~rED PA:3o~FIC PF~n~5~5E E~lWCT oN CURD
FCRM~I~oN IN C~D~aD ~ SALMoN
. Total Wbights of Cbra P~ed E~
Fish Nb. No. Cans Tbtal Reduction Tbp Surface 80tbom Surface ~ng dried wt) Achieved (~ dr~ wt) (T~ dried wt) . , . , ._ . 1 Cbntrol (4) 1951 562 2513 Exptl (4) 1710 286 1996 21%
: _ .
2 Ckntrol ~4) 1862 489 2351 ~Xpkl (4) 1671 198 1869 21%
. . _ _
3 oontLvl (4) 1780 736 2516 Expkl (4) 1257 385 1642 35%
, . .......................... . . , -,-Sesment~ oktained fron one side of e æ h sa~non were tL~ated with protease pre$ar-ation with the cpposite and correspond~ng ~egment~ serviing as oontrol~. The enzyme was applied to both Lut~ and top surfaces of salmon ses~ents with a hand-held sprayer. Ihe follcwing dosages were applied: Fish #1, 1.0 mg/siae; Fi~h #2,-2.5 n~wide; Fish #3, 5.0 mg/side.
~13~9;~0 ~2 - 100 g E~ USED
. _ ~ . ._ Curd P~ Per 100 g fle~h Fi~;h ~. Sa~ple Total Red~cti~
Ibp Surfaoe Bott~ S~faoe ~ dFied wt) A~hieved (n~ dried wt) (mg dried wt) 1 (~1 231 300 Exptl 200 32 232 23 2 C;~ntrol 230 60 2gO
_ _ E~ 193 24 217 25%
3 (~1~1 245 101 346 E~ 177 53 230 3496 . ._ . _ ._ __ ._ tal pr~ocol as descri~ed far Table 1.
113~'~ZO
IA~LE 2a EFFECT QF SEVER~L PRCr~LYIIC AND LIPOLY~IC ENZYME
PKEPARA~ICNS CN FCRM~IICN CF CURD IN CANMED SCC~YE SiUllo~
_ _ Curd Reocvered ~mg dried weight) Enzymemg Applied/Can Control^ E~qperiment~l~ ~ Reduction _ _ __ Trypsin 12 2887 2198 24 Ficin 14 2763 1703 38 8rcnelain 30 2976 1804 39 Proteinase 14 2537 2093 18 Prolase 4.5 2129 1977 7 Pronase 5.5 2386 2384 O
~-Chymftrypsin 10 2775 2959 O
Chymcpapain23 2476 1449 42 Pepsin 16 2087 1665 20 Lipase 448 3.5 2807 2503 11 Lipase ~12 x NF~ 15 2008 1733 14 Lipase (wheat germ) 40 2789 2565 8 Papaya Latex Extract 35 2638 1004 62 Ficin7 ~ combined 2556 1736 32 Lipase "12 x N F 7 ) Chymopapain11.5~ combined 2556 1496 42 Lipase ~12 x NF- 7 Trypsin6 ~ cc~'oined 2556 2177 15 Lipase ~12 x NF" 7 ~
Papaya Latex Extract 17 ~ csmbined 2556 1787 30 Lipase ~12 x NF~ 7 J
Samples were prepal~d in such a way that seg~ents taken fro~ one side of the fish served as ccntrols for the experi~antal sesments taken fnon the c~x~sita and correspcnding side. Each figure in the control and expe~inl~tal columns represents the average of three samples.
113~5~ZO
TABLE 2b EFPECT OF PAPAYA LATEX EXTRACT CN CURD FORMATION
IN CHUM, SPRING (CHINOOK) AND STEELHEAD
.. _ , mg Papaya Latex SpeciesExtract Protein Added mg Dr ed Weight % ~eduction Control* Exptl.*
_ _ Chum 2 640a 252a 61 808b 396b 51 949b 395b 58 Spring 5 ll87a 437a 63 l079c 509c 53 Steelhead 5 264a llla 58 333a 44a 87 * Samples were taken from fish and canned as described in Table 2a a Average from two sa~ples b ~verage from five sa~ples c Average frcm three samples 113ti920 ~LE 3 .. __ , ~o~age Curd ~ Redlticn ., ~ ~ ~ ~ ) per can ~q dried wt) A ~ieved .. _ .
O (canl~v11 383 + 189 ~11) ._ .. _ 152 + 134 (11) 60%
128 + 113 (11) 67%
. .__ 141 + 109 tll) 63%
. _ 46+ 27 (11) 88%
nunber of ~le~ given in par~ehes~. App~tc~stian of Dunnet's T~BLE 4 ON ~RD REDCC:~ IJ~
. _ . ..
Dosage C~d ~ P~icn ~g extract prctein) per can ~ng dried wt) Achieved . ._ O (control) 253 + 135 (12) _ .
2.9 179 + 128 tl2) 29%
. _ 178 ~ 131 (12) 29%
; 5.8 135 + 88-(12)- 47%
. __ 11.6 60 + 43 ~12) 7S%
- _ _ . ~
17.4 99 + 113 (12) 61%
l~e papa ~ late~c e~act8 were aE~ lg 1.01~ VOlUll~iC
pipets. Cord rex~rnrred is expressed a~ nn3 ~ standard devia-tion, with the nu~ r of samples given in p2rentheses.
113~i9Z~) I~BIE 5 5ECCND PL~NT TRIALs ~w ~L~l~ oF P~PAY~ IAIEX EXTRACT ON Ct~XJR
.__ Dosage 0~1 Volume Cblcur Intensity Col Uhit~
(mg e~tract prokein) ~1) (O.D. 470 units) . .. . _ ___ . __ _ _ . _ _ O (oontrol) 4.6 + 1.7 (18) 2.3 + 0.4 10.6 ~ 0.7 2.9 4.7 + 2.1 (6) 3.4 + 0.6 16.0 + 1.3 ..... ._ . _.
, . .......................... . . , -,-Sesment~ oktained fron one side of e æ h sa~non were tL~ated with protease pre$ar-ation with the cpposite and correspond~ng ~egment~ serviing as oontrol~. The enzyme was applied to both Lut~ and top surfaces of salmon ses~ents with a hand-held sprayer. Ihe follcwing dosages were applied: Fish #1, 1.0 mg/siae; Fi~h #2,-2.5 n~wide; Fish #3, 5.0 mg/side.
~13~9;~0 ~2 - 100 g E~ USED
. _ ~ . ._ Curd P~ Per 100 g fle~h Fi~;h ~. Sa~ple Total Red~cti~
Ibp Surfaoe Bott~ S~faoe ~ dFied wt) A~hieved (n~ dried wt) (mg dried wt) 1 (~1 231 300 Exptl 200 32 232 23 2 C;~ntrol 230 60 2gO
_ _ E~ 193 24 217 25%
3 (~1~1 245 101 346 E~ 177 53 230 3496 . ._ . _ ._ __ ._ tal pr~ocol as descri~ed far Table 1.
113~'~ZO
IA~LE 2a EFFECT QF SEVER~L PRCr~LYIIC AND LIPOLY~IC ENZYME
PKEPARA~ICNS CN FCRM~IICN CF CURD IN CANMED SCC~YE SiUllo~
_ _ Curd Reocvered ~mg dried weight) Enzymemg Applied/Can Control^ E~qperiment~l~ ~ Reduction _ _ __ Trypsin 12 2887 2198 24 Ficin 14 2763 1703 38 8rcnelain 30 2976 1804 39 Proteinase 14 2537 2093 18 Prolase 4.5 2129 1977 7 Pronase 5.5 2386 2384 O
~-Chymftrypsin 10 2775 2959 O
Chymcpapain23 2476 1449 42 Pepsin 16 2087 1665 20 Lipase 448 3.5 2807 2503 11 Lipase ~12 x NF~ 15 2008 1733 14 Lipase (wheat germ) 40 2789 2565 8 Papaya Latex Extract 35 2638 1004 62 Ficin7 ~ combined 2556 1736 32 Lipase "12 x N F 7 ) Chymopapain11.5~ combined 2556 1496 42 Lipase ~12 x NF- 7 Trypsin6 ~ cc~'oined 2556 2177 15 Lipase ~12 x NF" 7 ~
Papaya Latex Extract 17 ~ csmbined 2556 1787 30 Lipase ~12 x NF~ 7 J
Samples were prepal~d in such a way that seg~ents taken fro~ one side of the fish served as ccntrols for the experi~antal sesments taken fnon the c~x~sita and correspcnding side. Each figure in the control and expe~inl~tal columns represents the average of three samples.
113~5~ZO
TABLE 2b EFPECT OF PAPAYA LATEX EXTRACT CN CURD FORMATION
IN CHUM, SPRING (CHINOOK) AND STEELHEAD
.. _ , mg Papaya Latex SpeciesExtract Protein Added mg Dr ed Weight % ~eduction Control* Exptl.*
_ _ Chum 2 640a 252a 61 808b 396b 51 949b 395b 58 Spring 5 ll87a 437a 63 l079c 509c 53 Steelhead 5 264a llla 58 333a 44a 87 * Samples were taken from fish and canned as described in Table 2a a Average from two sa~ples b ~verage from five sa~ples c Average frcm three samples 113ti920 ~LE 3 .. __ , ~o~age Curd ~ Redlticn ., ~ ~ ~ ~ ) per can ~q dried wt) A ~ieved .. _ .
O (canl~v11 383 + 189 ~11) ._ .. _ 152 + 134 (11) 60%
128 + 113 (11) 67%
. .__ 141 + 109 tll) 63%
. _ 46+ 27 (11) 88%
nunber of ~le~ given in par~ehes~. App~tc~stian of Dunnet's T~BLE 4 ON ~RD REDCC:~ IJ~
. _ . ..
Dosage C~d ~ P~icn ~g extract prctein) per can ~ng dried wt) Achieved . ._ O (control) 253 + 135 (12) _ .
2.9 179 + 128 tl2) 29%
. _ 178 ~ 131 (12) 29%
; 5.8 135 + 88-(12)- 47%
. __ 11.6 60 + 43 ~12) 7S%
- _ _ . ~
17.4 99 + 113 (12) 61%
l~e papa ~ late~c e~act8 were aE~ lg 1.01~ VOlUll~iC
pipets. Cord rex~rnrred is expressed a~ nn3 ~ standard devia-tion, with the nu~ r of samples given in p2rentheses.
113~i9Z~) I~BIE 5 5ECCND PL~NT TRIALs ~w ~L~l~ oF P~PAY~ IAIEX EXTRACT ON Ct~XJR
.__ Dosage 0~1 Volume Cblcur Intensity Col Uhit~
(mg e~tract prokein) ~1) (O.D. 470 units) . .. . _ ___ . __ _ _ . _ _ O (oontrol) 4.6 + 1.7 (18) 2.3 + 0.4 10.6 ~ 0.7 2.9 4.7 + 2.1 (6) 3.4 + 0.6 16.0 + 1.3 ..... ._ . _.
4.6 5.6 + 2.6 (6) 3.1 + 0.5 17.4 + 1.3
5.8 5.9 + 3.8 (5) 3.4 + 0.4 20.1 + 1.5 11.6 4.3 + 1.3 (6) 4.1 + 0.4 17.6 + 0.5 .
- 17.4 3.9 + 1.4 (6) 3.1 + 0.6 12.1 + 0.8 nC~l in Pncity" is def~n4~ as the number of cçti~l density (O.D) units for a given canned sa~mon oil whe~ read at 470 nm in a lOl cm cell at 20-23C. "Col units" is the product of ccl intensity and volume.
Extracts were applied to sa~on surface~ with Pipets.
~369ZO
2~E 6 r~ ~ AND E~;~LS
Dosage Free Wa~Pr Vol~me Residue (n~ extract Fr~tein) (ml) ~ dried wt) O (con-L~11 36.5 + 4.3 (12) 968 + 144 (12) .. .... _ . .
2.9 37.7 + 4.1 (12) 728 + 174 (12) 4.6 36.3 + 5.2 (12) 1092 + 235 (12) 5.8 37.3 + 4.9 tll) n 8 + 155 (11) 11.6 38.3 + 3.4 ~12) 1192 + 333 (12) 17.4 44.1 + 5.2 (12) 813 + 200 (12) Extracts were applied with pipet~.
Except for the control group, free water volumes are crl~Y~bDd bo a ~ t Lor the l.0 nl of a ~ s extract added.
Data e~pressed as T##ms + standard deviation, wit~ number of samples shown in parentheses.
~131~9ZO
5ECCND PL~NT TRI~L: EFFECT CF AS~w IC AC m oN
.. .. _ ..
Dosage O~l Volume Colour IntensityColour Units (mg extract protein)(ml) (O.D. 470 units) . __ O (control) 4.6 + 1.7 (18) 2.3 ~ 0.4 10.6 + 0.7 . _ .. ..
4.6 5.7 + 2.5 (6) 3.0 + 0.7 17.1 + 1.7 9.3 5.7 + 1.8 (6) 3.2 + 0.4 18.2 + 0.7 _ ._ ___ 6.0 + 2.2 (6) 3.7 1 0.4 22.2 + 0.9 16.0 5.3 + 2.0 (6) 2.9 + 0.1 15.4 + 0.2 . .
"Cblour mtensity" and "oolour unit" as def m ed in Table 5.
All exper~mental s ~ e~ were treated with 10 mg asccrbic acid. m e data gi~en in this table should be compared with those gi~en in lable 5, althcugh the dosages di ff OE slishtly.
Extracts were applied by spraying.
~136gZO
l~eLE 8 Dosage Curd FbYIJnerod Reducti3n ~ng e~tract Frotein) per can (~g dried w~) Achieved 95 + 69 (1~) _ 4.6 20 + 17 (12) 79%
9.3 17 + 31 (12) 82%
13.9- 30 + 41 (12) 68%
16.0 20 + 22 (12) 79 . . _.
Curd reo~very ~ e~p~essed as nY~ms I standard deviation.
- ' .
113~i~ZO
~[E 9 CN ~ P~ VaU~ E~ OIL ~N CP~NED P~ SPIM~
. . _ DosageO~l VolumeCblcur ~ntensity Cblour Uhits (mg extract protein) ~nl) (O.D. 470 units) 0 2.6 + 1.0 (6) 0.9 + ~.3 2.3 + 0.3 . . .
4.6 3.4 + 1.4 (6) 1.2 + 0.3 4.1 + 0.4 . , 9.3 3.5 1 1.0 (6) 1.2 + 0.2 4.2 + 0.2 ~ . .
13.g 3.9 ~ 2.4 (6) 1.2 + 0.3 4.7 + 0.7 ... .... . . _ 16.n 5.8 + 3.5 ~6) 1.3 + 0.17.5 + 0.3 "Cblour Inten~ity" ~nd nCOaOUr uni~qn aq defined in Table 5.
Papaya latex e~Lr~ct applied by spraying.
Data expressed a_ neans + ~tandard deviation, with nn~ber o~ 5amples shown in parentheses.
11~69ZO
~E 10 l . . _ __ DbsageFree Water Volu~eResidue ~n~ e~tract protein) ~nl) (mg dried wt) O (control)42.5 _ 2.8 (6) 881 + 211 ~9) 4.6 46.2+1.9 (6)1094~345 (9) 9.3 49.3 + 3.7 (6)1300 _ 221 (4) 13.9 49.0 _ 1.8 (6)1132 _ 121 (4) 16.0 51.8 _ 2.8 ~6)1485 + 348 (4) Data shown as-~eans + stanaard deviation, with n~lL~ of samples - in p2rentheses.
Excepk for the c~A,trol group, free water vDl~ne~ were ccn~lx:bel bo acccunt for the water added.
1136~9~0 q3~LE 11 O~C = ~ CE ~rWED SO~E
q~ w~ Ppæ~ ~c ~
~ ----- --si~ng N~ 1 2 3 .
Dosage/ex~i~,~,tal can ~) 17.4 15 45 ... . _ ND. of tasters participating 12 12 12 .
No of tasters ~rrectly picldng out ~e "odd". sample* 6 6 3 ~ . l ~;b. of ta~ters correctly identi~i3lg treat~ s~mple 2 4 3 ~. oE carrect-arlswers needed to e ~ bli~h significa~rt difference between treated and untreated sample~ at 95% ccnfid~nce level ~8) 8 8 3 * S3mples were presented ae: C-C-E, C-E-C, E-C-C, E-E-C, E-C-E, C-~-E, where C = untreated, and E = treated sa~ples. One of the three ~amples in a triangular taste test represent~ the "odd" sample, whlch could he either treated or untreated.
~13~i9ZO
~2 S = S~
..
Dosage Curd Re~ered P~
P~:~) p~r can (~ drl~ed wt) A~
....
O (oontrol) 253 _ 135 ~18) . .
4.6 162 1 172 (12) 36%
9.3 114 _ 80 (12) 5s%
13.9 73 + 66 ~12~ 74%
...... .
16.0 67 + 78 (12) 73%
Mbthod of spraying and volumes dirç~sliod are described ~n the text.
Cord recovered is exçregced A~ n~#~n~ + standard deviation, with nuTber of sa~ples in pYcls~ibeses.
113~920 ~-- ~1 _ _ _~ D
.. ~ ~ ~r ~ _~ ~ ~Y
~ +l +l +l +l +l ~ CD g O _I
~ ~ o ,~ ~ ~ ~ _, ~0 ~ 3 ~ ~ ~3 U~ o i C o # ~ ~ +l +l +l +l +l .
~ d l ~ .~. o o~ ~ o ~ ~
~3 ~ ~ o _, _, ~ ~ ~
~1 ~
~ ¦ ~ D ~o I ~} g +l +l +l ~ol +l 1 o ~ a~ _1 -1 q~
l ~ _ l _ l ~ ~ ' q~l3LE 14 %~t~
~at 3.5 Pr~n 17.4 ~te~ 79.8 100.7 ;
..
- 17.4 3.9 + 1.4 (6) 3.1 + 0.6 12.1 + 0.8 nC~l in Pncity" is def~n4~ as the number of cçti~l density (O.D) units for a given canned sa~mon oil whe~ read at 470 nm in a lOl cm cell at 20-23C. "Col units" is the product of ccl intensity and volume.
Extracts were applied to sa~on surface~ with Pipets.
~369ZO
2~E 6 r~ ~ AND E~;~LS
Dosage Free Wa~Pr Vol~me Residue (n~ extract Fr~tein) (ml) ~ dried wt) O (con-L~11 36.5 + 4.3 (12) 968 + 144 (12) .. .... _ . .
2.9 37.7 + 4.1 (12) 728 + 174 (12) 4.6 36.3 + 5.2 (12) 1092 + 235 (12) 5.8 37.3 + 4.9 tll) n 8 + 155 (11) 11.6 38.3 + 3.4 ~12) 1192 + 333 (12) 17.4 44.1 + 5.2 (12) 813 + 200 (12) Extracts were applied with pipet~.
Except for the control group, free water volumes are crl~Y~bDd bo a ~ t Lor the l.0 nl of a ~ s extract added.
Data e~pressed as T##ms + standard deviation, wit~ number of samples shown in parentheses.
~131~9ZO
5ECCND PL~NT TRI~L: EFFECT CF AS~w IC AC m oN
.. .. _ ..
Dosage O~l Volume Colour IntensityColour Units (mg extract protein)(ml) (O.D. 470 units) . __ O (control) 4.6 + 1.7 (18) 2.3 ~ 0.4 10.6 + 0.7 . _ .. ..
4.6 5.7 + 2.5 (6) 3.0 + 0.7 17.1 + 1.7 9.3 5.7 + 1.8 (6) 3.2 + 0.4 18.2 + 0.7 _ ._ ___ 6.0 + 2.2 (6) 3.7 1 0.4 22.2 + 0.9 16.0 5.3 + 2.0 (6) 2.9 + 0.1 15.4 + 0.2 . .
"Cblour mtensity" and "oolour unit" as def m ed in Table 5.
All exper~mental s ~ e~ were treated with 10 mg asccrbic acid. m e data gi~en in this table should be compared with those gi~en in lable 5, althcugh the dosages di ff OE slishtly.
Extracts were applied by spraying.
~136gZO
l~eLE 8 Dosage Curd FbYIJnerod Reducti3n ~ng e~tract Frotein) per can (~g dried w~) Achieved 95 + 69 (1~) _ 4.6 20 + 17 (12) 79%
9.3 17 + 31 (12) 82%
13.9- 30 + 41 (12) 68%
16.0 20 + 22 (12) 79 . . _.
Curd reo~very ~ e~p~essed as nY~ms I standard deviation.
- ' .
113~i~ZO
~[E 9 CN ~ P~ VaU~ E~ OIL ~N CP~NED P~ SPIM~
. . _ DosageO~l VolumeCblcur ~ntensity Cblour Uhits (mg extract protein) ~nl) (O.D. 470 units) 0 2.6 + 1.0 (6) 0.9 + ~.3 2.3 + 0.3 . . .
4.6 3.4 + 1.4 (6) 1.2 + 0.3 4.1 + 0.4 . , 9.3 3.5 1 1.0 (6) 1.2 + 0.2 4.2 + 0.2 ~ . .
13.g 3.9 ~ 2.4 (6) 1.2 + 0.3 4.7 + 0.7 ... .... . . _ 16.n 5.8 + 3.5 ~6) 1.3 + 0.17.5 + 0.3 "Cblour Inten~ity" ~nd nCOaOUr uni~qn aq defined in Table 5.
Papaya latex e~Lr~ct applied by spraying.
Data expressed a_ neans + ~tandard deviation, with nn~ber o~ 5amples shown in parentheses.
11~69ZO
~E 10 l . . _ __ DbsageFree Water Volu~eResidue ~n~ e~tract protein) ~nl) (mg dried wt) O (control)42.5 _ 2.8 (6) 881 + 211 ~9) 4.6 46.2+1.9 (6)1094~345 (9) 9.3 49.3 + 3.7 (6)1300 _ 221 (4) 13.9 49.0 _ 1.8 (6)1132 _ 121 (4) 16.0 51.8 _ 2.8 ~6)1485 + 348 (4) Data shown as-~eans + stanaard deviation, with n~lL~ of samples - in p2rentheses.
Excepk for the c~A,trol group, free water vDl~ne~ were ccn~lx:bel bo acccunt for the water added.
1136~9~0 q3~LE 11 O~C = ~ CE ~rWED SO~E
q~ w~ Ppæ~ ~c ~
~ ----- --si~ng N~ 1 2 3 .
Dosage/ex~i~,~,tal can ~) 17.4 15 45 ... . _ ND. of tasters participating 12 12 12 .
No of tasters ~rrectly picldng out ~e "odd". sample* 6 6 3 ~ . l ~;b. of ta~ters correctly identi~i3lg treat~ s~mple 2 4 3 ~. oE carrect-arlswers needed to e ~ bli~h significa~rt difference between treated and untreated sample~ at 95% ccnfid~nce level ~8) 8 8 3 * S3mples were presented ae: C-C-E, C-E-C, E-C-C, E-E-C, E-C-E, C-~-E, where C = untreated, and E = treated sa~ples. One of the three ~amples in a triangular taste test represent~ the "odd" sample, whlch could he either treated or untreated.
~13~i9ZO
~2 S = S~
..
Dosage Curd Re~ered P~
P~:~) p~r can (~ drl~ed wt) A~
....
O (oontrol) 253 _ 135 ~18) . .
4.6 162 1 172 (12) 36%
9.3 114 _ 80 (12) 5s%
13.9 73 + 66 ~12~ 74%
...... .
16.0 67 + 78 (12) 73%
Mbthod of spraying and volumes dirç~sliod are described ~n the text.
Cord recovered is exçregced A~ n~#~n~ + standard deviation, with nuTber of sa~ples in pYcls~ibeses.
113~920 ~-- ~1 _ _ _~ D
.. ~ ~ ~r ~ _~ ~ ~Y
~ +l +l +l +l +l ~ CD g O _I
~ ~ o ,~ ~ ~ ~ _, ~0 ~ 3 ~ ~ ~3 U~ o i C o # ~ ~ +l +l +l +l +l .
~ d l ~ .~. o o~ ~ o ~ ~
~3 ~ ~ o _, _, ~ ~ ~
~1 ~
~ ¦ ~ D ~o I ~} g +l +l +l ~ol +l 1 o ~ a~ _1 -1 q~
l ~ _ l _ l ~ ~ ' q~l3LE 14 %~t~
~at 3.5 Pr~n 17.4 ~te~ 79.8 100.7 ;
..
Claims (17)
1. In a fish canning process comprising the steps:
(a) separating the edible and inedible parts of the fish;
(b) placing the edible parts in a container;
(c) sealing a lid on the container;
and (d) heating the container sufficient to cook the fish the improvement that comprises applying to the fish in the container 2 to 50 milligrams per 1/2 pound of fish of a proteoly-tic enzyme having a proteolytic activity of 0.5 to 3.0 as related to the increase brought about per milligram of protein in the optical absorbency at 280 nm by tric-hloroacetic acid-soluble digestion products of casein, under standardized conditions according to Arnon, 1970, Methods of Enzymology, Academic Press, Volume XIX 226, the milligrams of enzyme and the corresponding specific activity to be in combination such that the total proteolytic activity (specific activity multiplied by milligrams of protein) is in the range of 1 to 38 optical absorbency units, and for a time in the range 5 to 90 minutes prior to the cooking step whereby curd formation on the surface of the cooked fish is reduced.
(a) separating the edible and inedible parts of the fish;
(b) placing the edible parts in a container;
(c) sealing a lid on the container;
and (d) heating the container sufficient to cook the fish the improvement that comprises applying to the fish in the container 2 to 50 milligrams per 1/2 pound of fish of a proteoly-tic enzyme having a proteolytic activity of 0.5 to 3.0 as related to the increase brought about per milligram of protein in the optical absorbency at 280 nm by tric-hloroacetic acid-soluble digestion products of casein, under standardized conditions according to Arnon, 1970, Methods of Enzymology, Academic Press, Volume XIX 226, the milligrams of enzyme and the corresponding specific activity to be in combination such that the total proteolytic activity (specific activity multiplied by milligrams of protein) is in the range of 1 to 38 optical absorbency units, and for a time in the range 5 to 90 minutes prior to the cooking step whereby curd formation on the surface of the cooked fish is reduced.
2. A process as claimed in claim 1 in which the fish is salmon.
3. A process as claimed in claim 2 in which the enzyme is derived from natural papaya latex, applied as a water extract.
4. A process as claimed in claim 1 in which the enzyme is selected from pancreatic protease, papainaise, trypsin, ficin, bromelain, prolase, chymopapapain and pepsin.
5. A process as claimed in claim 2 in which the salmon is sockeye salmon.
6. A process as claimed in claim 2 in which the salmon is pink salmon.
7. A process as claimed in claim 2 in which the salmon is chum salmon.
8. A process as claimed in claim 2 in which the salmon is chinook (spring) salmon.
9. A process as claimed in claim 1 in which the fish is steelhead trout.
10. A process as claimed in claim 2 in which the salmon is coho salmon.
11. A process as claimed in claim 5 comprising applying to a cut surface of the sockeye salmon 10 to 15 milligrams per 1/2 pound of sockeye salmon of proteolytic enzyme contained in a water extract of natural papaya latex.
12. A process as claimed in claim 6 comprising the application to a cut surface of the pink salmon of 2 to 5 milligrams per half pound of pink salmon of proteolytic enzyme contained in a water extract of natural papaya latex.
13. A process as claimed in claim 10 comprising the application to a cut surface of the coho salmon of 10 to 50 milligrams per half pound of the coho salmon of proteo-lytic enzyme contained in a water extract of natural papaya latex.
14. A process as claimed in claim 7 comprising the application to a cut surface of the chum salmon of 2 to 10 milligrams per half pound of chum salmon of proteolytic enzyme contained in a water extract of natural papaya latex.
15. A process as claimed in claim 8 comprising the application to a cut surface of the chinook salmon of 5 to 10 milligrams per half pound of chinook salmon of proteo-lytic enzyme contained in a water extract of natural papaya latex.
16. A process as claimed in claim 9 comprising the application to a cut surface of the steelhead trout of 5 to 100 milligrams per half pound of steelhead trout of proteolytic enzyme contained in a water extract of natural papaya latex.
17. A process as claimed in claim 1 comprising the application to a cut surface of sockeye salmon of 6 to 12 milligrams of trypsin, or 7 to 14 milligrams of ficin, or 30 milligrams of bromelain, or 14 milligrams of proteinase, or 4.5 milligrams of prolase, or 11.5 to 23 milligrams of chymopapain, or 20 milligrams of pepsin, per half pound of sockeye salmon.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000341980A CA1136920A (en) | 1979-12-14 | 1979-12-14 | Fish canning process |
| JP4368980A JPS5685239A (en) | 1979-12-14 | 1980-04-04 | Production of fish can |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000341980A CA1136920A (en) | 1979-12-14 | 1979-12-14 | Fish canning process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1136920A true CA1136920A (en) | 1982-12-07 |
Family
ID=4115838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000341980A Expired CA1136920A (en) | 1979-12-14 | 1979-12-14 | Fish canning process |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5685239A (en) |
| CA (1) | CA1136920A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0228486A1 (en) * | 1985-12-19 | 1987-07-15 | Comercial Alimentaria Internacional, S.A. Calinsa | Process for preparing a meat product |
| WO1995010626A1 (en) * | 1993-10-14 | 1995-04-20 | Centre De Cooperation Internationale En Recherche Agronomique Pour Le Developpement | Method for the enzymatic transformation of triglycerides in a fat, in particular dairy fat |
-
1979
- 1979-12-14 CA CA000341980A patent/CA1136920A/en not_active Expired
-
1980
- 1980-04-04 JP JP4368980A patent/JPS5685239A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0228486A1 (en) * | 1985-12-19 | 1987-07-15 | Comercial Alimentaria Internacional, S.A. Calinsa | Process for preparing a meat product |
| WO1995010626A1 (en) * | 1993-10-14 | 1995-04-20 | Centre De Cooperation Internationale En Recherche Agronomique Pour Le Developpement | Method for the enzymatic transformation of triglycerides in a fat, in particular dairy fat |
| FR2711142A1 (en) * | 1993-10-14 | 1995-04-21 | Internale Rech Ag Centre Coop | Process for the enzymatic transformation of triglycerides of a fat, in particular dairy fat. |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5685239A (en) | 1981-07-11 |
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