FR2599048A1 - Method of treating liquid foods of plant origin for the purpose of stabilising them, especially with respect to their colour - Google Patents

Abstract

The invention relates to a method of treating liquid foods of plant origin, such as musts/worts, wines, beers, juices or aqueous or dilute alcoholic extracts or concentrates of fruits, citruses or vegetables. The liquid to be treated is supplemented with chitosan in the form of a powder of the latter or of its salts - malate, tartrate or citrate -, or in the form of a solution of these same salts, in an amount such that there are 10 to 300 grams of chitosan per hectolitre of liquid, this powder having a particle size of less than 250 microns.

Description

 The present invention relates to a treatment method for edible liquids of vegetable origin - such as musts, wines, beers, juices or aqueous or hydro-alcoholic extracts or concentrates of fruits, citrus fruits or vegetables - with a view to achieving their stabilization, especially with regard to their color.

 The modification of the color of red wines, and especially white wines, as well as that of vegetable juices, either natural or concentrated, is a major problem for many companies in the agro-food sector.

 Indeed, it sometimes happens that this change in color is accompanied by a change in the taste and aroma of the drinks. These alterations, which in liquids of plant origin occur over time and in a natural way, are mainly due to oxidation phenomena, densification of more or less oxidized components, as well as polymerization, due to reactions which, in a medium acid medium, are catalyzed by traces of metals (Fe, Cu, Mn) possibly present.

 We are therefore faced with the requirement to produce vegetable drinks, or concentrates, capable of preserving unaltered as long as possible the organoleptic characteristics which are conferred on them by the fruit or the berry from which they come, as well as those having color, without browning and / or forming sediments.

To this end, beverage technology constantly uses different methods which include: adding CO2 or
N2 during the production cycle; once the drink has been obtained, separate from it as much as possible the solid residues (such as the skin of the grape, the berry, or the fruit from which it comes) which are rich in oxidizable substances; adding antioxidants such as ascorbic acid; to use absorbent materials to remove oxidation products or other substances, such as polyphenols or traces of metals, which are in solution in the drink. However, the absorbents used so far are not free from drawbacks and contraindications with regard to their practical use, because carbon has a very effective action, but it deprives drinks of their aroma. Polyvinylpyrrolidone is indicated to eliminate polyphenols, and it is for this reason that in the United States it is used in the manufacture of goat, but in other countries its use is prohibited. In addition, bentonite has no effectiveness on polyphenols, while gelatin which, it would be effective, tends to dissolve in drinks by reducing the pleasure of their taste.

 The aim of the present invention is to provide an industrial method for treating food liquids of plant origin - in particular musts, wines (in particular white wines, rosé wines and sparkling wines), vegetable juices rich in polyphenols (such as grape, cherry, apple, artichoke juice) citrus juice (for example lemon juice, which is then to be concentrated) - and therefore obtain that these same liquids can keep increased stability with regard to their organoleptic characteristics and their color even when stored at room temperature and even exposed to light.

 Another object of the present invention is to provide a method of treatment of great simplicity and very advantageous from the economic point of view.

 These aims are achieved by the method according to the invention, for the treatment of edible liquids of vegetable origin - such as musts, wines, beers, juices, or aqueous, or hydro-alcoholic, or concentrated, fruit, citrus and vegetables -, characterized in that the liquid to be treated, at a temperature up to 450C, is supplemented with chitosan (polyglucosamine), in the form of -powder of this compound or its salts (for example malate, tartrate or citrate), or alternatively in the form of a solution of these same salts, in an amount such that in one hectolitre of liquid there may be from 10 to 300 grams of chitosan, said powder being of a particle size less than 250 microns, is stirred and finally filtered, after a sedimentation period of up to 24 hours.

 The percentage of chitosan and the particle size of the powders will vary in the proportions indicated according to the polyphenol content or the degree of browning of the liquid food.

 The stabilization of the liquid food which has undergone the treatment according to the invention seems to be attributable to the absorption by chitosan of substances such as polyphenols, phenolic amino acids, traces of metals, proteins, enzymes, ketoacids, diketones, aldehydes, substances which; in a medium acid environment can all give rise to browning reactions.

 It can be observed that, for wines, the treatment with chitosan or with a salt thereof can be carried out before the treatment with bentonite and that it can entirely replace the treatment with gelatin or with potassium caseinate.

When the chitosan salts are used, the preparation of these is facilitated by knowing the N titer declared by the chitosan supplier. The chitosan is reduced to a particle size of less than 500 microns, and preferably less than 250 microns. This chitosan powder is then reacted, with stirring, with an acid such as malic, citric or tartaric acid in aqueous solution at a temperature not higher than 600C, the ratio between meq
N2 of chitosan and meq of acid being between 1 / 0.75 and 1 / 1.2 and the amount of chitosan present in solution (weight / volume ratio) being between 0.01% and 4%. waiting for two to four hours, a very viscous solution is obtained, which is optionally discolored with charcoal and which is filtered by means of a glass membrane filtering funnel, by suction, so as to remove the traces of suspended matter. A viscous, almost colorless solution is thus obtained, which can be lyophilized or dried. By using the same chitosan / acid ratios, the preparation of the chitosan salts can be carried out otherwise, in an anhydrous medium such as an ester (methyl, ethyl, butyl, propyl acetate) by heating the whole with fallout for two to four hours. Then filtered and the solvent is removed in vacuo to obtain the anhydrous salt. This salt is then reduced to a powder with a particle size preferably not greater than 100 microns.

 According to particular embodiments of the methods of the invention, the liquid to be treated is supplemented with chitosan or its salt in the form of powder with a particle size of less than 100 microns, in a powder weight / liquid volume ratio between 0.005X and 0.25%; or else said chitosan salt, in an aqueous solution at 0.04% - 4%, is added to the liquid to be treated in a volume ratio of between 0.1% and 1.5%.

 Other details will emerge more clearly from the following description of a few preferred examples of practical implementation of the treatment method according to the invention, these examples being in no way limiting.

Example 1.

Half a liter of Lambrusco wine, vinified in white from black grapes, was treated in a flask with 0.4 g of chitosan powder with a particle size of less than 100 microns. The treatment was carried out at 25 ° C. for two hours. The wine thus treated was then stored for eight months, at 25C, in a transparent glass container and stirred from time to time. The treated wine and the untreated wine, preserved in the same way, were then examined. At 420 nm, and with cuvettes one cm thick, the first and the second wine showed an absorbance of 0.25 and 3 respectively. Furthermore, the untreated wine presented a color tending to brown, like
Marsala, and a smell of maderized wine, while the treated wine had retained a very similar odor to that of the same untreated wine but kept in a dark bottle and presented, compared to the latter, a distinctly less brown color.

Example 2.

 200 ml of Sicilian white wine of the Marsala type were treated with 1.4 ml of an aqueous solution of chitosan tartrate. The content of chitosan in the solution was 2.6% (weight / volume ratio). The treatment was carried out at room temperature, mixing everything well. We immediately noticed the formation of an insoluble chitosan precipitate which absorbed the brown polymerized substances and a large part of the odor of maderized wine. At 420 min and with a 1 cm cup the absorbance of the treated wine was 0.37 against an absorbance of 2.7 for the untreated wine.

 Example 3.

Grapes from the Albana grape variety were vinified after separating the marc from the mill and reaching 80 mg of SO2 per liter. Part of the drop wine thus obtained was subjected to a treatment with
chitosan powder (80 g / hl) with a particle size less than 74
microns. The duration of treatment with chitosan was two hours. We have
then carried out a treatment with bentonite (100 g / hl). A
other part of the same wine was then treated only with
bentonite. After these treatments, they were kept for 20 days at
250C, in two separate flasks, 250 ml of wine treated with chitosan
and 250 ml of wine treated uniauemnt with bentonite. After this ~ period-I ~~ had an absorbance of 0.20 and the second of
0.45, the latter also showing a marked tendency to smell of
Madeira wine.

 Example 4.

One kilo of Golden apples has been sliced, which have been
then pressed to 100 atmospheres in a nylon net with
0.25 mm mesh. We thus obtained 650 ml of juice which we then
added O, lg of pectic enzymes and which we kept for
two hours at 450C. After precipitation of the pectins the juice is
clarified. Filtration was then carried out, after which 300 ml of
filtered juices were treated, at 250C and with stirring, with 1.50 ml of
chitosan malate solution. The chitosan content of the solution
was 2.6Z. Then added to the 300 ml of juice treated with
chitosan and the same amount of untreated juice 0.3 gr of celite 535
(of a particle size not greater than 250 microns). Then the juice
thus "brilliant" was filtered and concentrated in vacuo until
3
each sample - be reduced to 50 cm. The concentrate, at 72 Brix, has
was finally stored at 250C and in indirect light for three months.

After this time, the sample treated with chitosan had a
absorbance of 0.24 and the other an absorbance of 0.55.

 Example 5.

After subjecting lemon juice to centrifugation for 15
minutes at 4000 rpm, this was divided into two samples of
50 ml. One of these samples was added with 0.4 ml of solution
chitosan citrate (2.6% chitosan). We then stirred the
mixing and after 60 minutes a further centrifugation was carried out.

The two samples were then concentrated by evaporation under
vacuum then, to avoid mold, they were respectively
added with 25 mg of sodium benzoate. After a storage of six months at 250C, the concentrate of the sample treated with chitosan had an absorbance of 0.28 and the other concentrated an absorbance of 0.78.

Example 6.

 250 ml of Lambrusco drop wine were treated with 60 mg of chitosan powder with a particle size of less than 74 microns. The treatment was carried out at 200C for a period of two hours. The mixture was then filtered and put in dark glass bottles with crown caps. After a storage of twelve months at 250C, the color of the treated wine appeared redder and less orange than that of the same wine preserved in the same way but not treated. The ratio between the absorbance at 520 nm and that at 420 nm was 0.40 for the treated wine and 0.25 for the untreated wine.

Claims (5)

Claims 1. Treatment method for edible liquids of vetal origin, such as musts, wines, beers, aqueous or hydro-alcoholic juices or extracts or concentrated fruit, citrus or ruma, characterized in that the liquid to be treated, at a temperature of up to 450c, is added with chitosan. (polyglucosamine) in the form of powder of this compass or one of its salts (such as malate, tartrate or citrate), also in the form of a solution of these same salts, in an amount such that in one hectolitre-liquid there is from 10 to 300 g of chitosan, this powder being of a particle size less than 250 microns, said liquid is stirred and finally filtered, after a sedimentation period of up to 24 hours. 2. Treatment method according to claim 1, characterized in that to obtain said chitosan salt, the chitosan is reacted with a particle size not less than 500 microns, at a temperature not greater than 600C, with the chosen acid, in aqueous solution, the ratio between meq N2 of chitosan and meq of acid being between 1 / 0.75 and 1 / 1.2 and the amount of chitosan present in the solution (weight / volume ratio) being between 0, 01% and 4%, after which, after a time ranging from 2 to 4 hours, a very viscous solution is obtained which is then lyophilized or dried. 3. Treatment method according to claim 1, characterized in that to obtain said chitosan salt, the chitosan is reacted with a particle size of not less than 500 microns with the chosen acid in an anhydrous ester medium (acetate of methyl, ethyl, butyl or propyl), the ratio between meq N2 of chitosaze- and meq of acid being between 1 / 0.75 and 1 / 1.2, after which the whole is reheated during fallout 2 to 4 hours and then the solvent is removed in vacuo. 4. Treatment method according to claim 1, characterized in that the liquid to be treated is supplemented with chitosan or its salt in the form of powder with a particle size of less than 100 microns, in a weight ratio of powder / volume of liquid between 0.005Z and 0.25%. 5. Treatment method according to claim 1, characterized in that said chitosan salt, in an aqueous solution of 0.04% to 4% is added to the liquid to be treated according to a volume ratio of between 0.1% and 1, 5%.