CN116098259B - A method for inhibiting yellowing of colorless systems containing sorbitol-glycine - Google Patents

Abstract

The invention discloses a method for inhibiting the yellowing of a colorless system containing sorbitol-glycine. The present invention uses glutathione or cysteine to be mixed with a sorbitol-glycine system before heating, and inhibits reducing sugars in the system through the reducing properties of the inhibitor itself and competition with the reaction substrates in the original system. The generation of the system keeps the components of the system stable, reduces the generation of color-producing substances, and controls the color changes of the relevant systems during heat treatment and long-term storage. Comparing the yellowing of a colorless system containing sorbitol-glycine after heating, the optimal concentration of inhibitor that has the best color inhibition effect and does not cause the solution to become turbid due to inhibitor precipitation after cooling is the optimal amount to inhibit yellowing. The method disclosed in the invention uses glutathione or cysteine as an inhibitor to control the color of colorless liquid food containing sorbitol-glycine, thereby improving its thermal stability and extending its storage time.

Description

A method for inhibiting yellowing of colorless systems containing sorbitol-glycine

Technical field

The invention belongs to the fields of food chemistry and food additives, and in particular relates to a method for inhibiting the yellowing of a colorless system containing sorbitol-glycine.

Background technique

Many foods in daily life contain sorbitol and amino acids. In liquid foods such as beverages, sorbitol is widely used as a sweetener in sugar-free foods. Glycine has a unique sweetness and can alleviate the sour and alkaline taste. As an inherent component and food additive in natural foods, it is used in foods. ubiquitous. During the thermal processing and storage of sugar-free beverages and foods containing sorbitol and amino acids, due to the interaction between the two, the glucose content in the sugar-free products will increase, resulting in a decline in product quality, and the color will change from colorless to yellow. .

In the food field, appearance color has an important impact on product quality and will directly affect consumers' desire to purchase. During thermal processing and storage, color changes in some foods represent deterioration in product quality, so it is of great significance to understand and control the color change mechanism. Foods containing reducing sugars and amino acids are prone to yellowing in color during thermal processing and storage. An important reason for color changes is the Maillard reaction, which is the reaction between reducing sugars and free amino acids or free amino residues of proteins in foods. A series of oxidation, cyclization, dehydration, polymerization and other reactions occur. Therefore, in order to control the Maillard reaction, people use sugar alcohols such as sorbitol without aldehyde groups instead of reducing sugars in food. This is because sorbitol has a sweet taste and does not contain the carbonyl group required for the Maillard reaction. However, during the daily production and storage process, it was found that the system containing sorbitol and glycine still undergoes a certain degree of color change. However, there are no reports on the yellowing and inhibition methods of the sugar alcohol-amino acid system. Therefore, a method to inhibit the yellowing of the sugar alcohol-amino acid system was developed. The method of yellowing the colorless system of sugar alcohols and amino acids is of great significance and has broad application prospects.

Contents of the invention

The present invention provides a method for inhibiting yellowing of the system during heating or long-term storage by adding reduced glutathione or cysteine to a colorless liquid system containing sorbitol-glycine. The present invention inhibits the production of glucose in the system through the reducing properties of added glutathione or cysteine, and uses glutathione or cysteine as a reaction substrate to competitively consume the glucose generated in the system, Thereby controlling the quality of food, improving the flavor and taste of food and inhibiting the yellowing of the system. The preparation method of the invention is simple, safe to operate and low in cost.

The first object of the present invention is to provide a method for inhibiting the color change of a sorbitol-glycine system by adding glutathione or cysteine to the sorbitol-glycine system to inhibit the system from changing from zero to zero. Color changes to yellow.

In one embodiment of the present invention, the added amount of glutathione is 3-50mmol/L, and the added amount of cysteine is 0.01-0.1mol/L.

Preferably, the added amount of glutathione is 6.25-12.5mmol/L, and the added amount of cysteine is 0.01-0.025mol/L.

In one embodiment of the present invention, the reaction conditions are: pH 5-7, temperature 20-120°C.

In one embodiment of the present invention, the sorbitol-glycine system refers to a system containing both sorbitol and glycine.

The second object of the present invention is to provide a method for inhibiting the generation of reducing sugars in the sorbitol-glycine system during thermal processing and storage. The method is to add glutathione or cysteine to the sorbitol-glycine system. acid.

In one embodiment of the present invention, the added amount of glutathione is 3-50mmol/L, and the added amount of cysteine is 0.01-0.1mol/L.

Preferably, the added amount of glutathione is 6.25-12.5mmol/L, and the added amount of cysteine is 0.01-0.025mol/L.

In an embodiment of the present invention, the thermal processing temperature is 60-120°C.

In one embodiment of the present invention, the sorbitol-glycine system refers to a system containing both sorbitol and glycine.

The third object of the present invention is to provide an application of the above method in food.

The fourth object of the present invention is to provide a method for inhibiting the yellowing of colorless sugar-free beverages by adding glutathione or cysteine thereto.

In one embodiment of the present invention, the added amount of glutathione is 3-50mmol/L, and the added amount of cysteine is 0.01-0.1mol/L.

Preferably, the added amount of glutathione is 6.25-12.5mmol/L, and the added amount of cysteine is 0.01-0.025mol/L.

Beneficial effects of the present invention:

(1) The use of food additives glutathione or cysteine as inhibitors significantly inhibits the color change of the sorbitol-glycine system under heating conditions, reduces the glucose concentration in the system after heating, and solves the problem of using sorbitol as an inhibitor. Food systems in which sweeteners replace reducing sugars and contain amino acids will also suffer from a certain degree of yellowing during thermal processing and storage. Optimizing the color of related foods increases the appeal of related products to consumers. At present, there is no research on the causes and mechanisms of yellowing in sugar alcohol-amino acid systems, so there is no research on the inhibition of yellowing of related products with poor color. The inhibition method disclosed in this method is simple to operate, feasible and universal, uses common food additives, is green and harmless, and research has confirmed that its determined inhibition effect is completely consistent with the result of the A _{420 nm} value of the spectrophotometer.

(2) Prepare analytically pure sorbitol and glycine reagents into a simulation system, and use the systems without inhibitors and those with inhibitors as control groups, and heat at an initial pH of 6.8 and 120°C for 2 hours. The degree of color change, colorless intermediate products, glucose concentration, and dicarbonyl compound concentration (glyoxal) in the system were measured using UV-visible spectrophotometer, fluorescence spectrophotometer, high-pressure ion chromatography, and ultra-high performance liquid chromatography tandem quadrupole mass spectrometry. , pyruvic aldehyde, 2,3-butanedione, 3-deoxyglucosone) were measured. Since the sorbitol used in this method is an analytically pure reagent and contains a trace amount of glucose, which was detected by high-pressure ion chromatography to be 84.51 mg/L, and the glucose concentration in the system without adding inhibitors after heating was 168.77 mg/L, it can be seen that during heating Under these conditions, the concentration of glucose in the system increased, and glucose continued to undergo nucleophilic addition reactions with glycine, causing the color of the system to change from colorless to yellow. The A _{420 nm} value increased to 0.183, and a large number of dicarbonyl compounds (ethylene dicarbonate) were detected in the solution. Aldehydes, pyruvic aldehyde, 2,3-butanedione, 3-deoxyglucosone), the fluorescence intensity and A _{294 nm} value of the solution representing the colorless intermediates of the Maillard reaction also increased significantly. When the system added with glutathione (glutathione concentration is 50mmol/L) was heated under the same conditions, the A _{420 nm} value dropped to 0.026 and the glucose concentration dropped to 14.001mg/L; the system with added cysteine When the system (cysteine concentration is 0.1 mol/L) is heated under the same conditions, the A _{420 nm} value drops to 0.027, and the glucose concentration drops to 4.710 mg/L. The concentration of dicarbonyl compounds, fluorescence intensity, and A _{294 nm} value all decreased significantly. It can be seen that this method significantly inhibited the production of glucose in the system, and inhibited the subsequent carbonyl ammonia reaction by directly hindering the generation of reaction substrates for undesirable subsequent reactions. occurrence, effectively preventing the yellowing of the sorbitol-glycine system.

(3) Cysteine has a significant inhibitory effect on the sorbitol-glycine system. This is because cysteine, as a thiol-containing α-amino acid, is more easily oxidized than most amino acids. In a weak oxidizing environment, cysteine forms a disulfide bond-bonded cysteine dimer, namely cystine. Acid; in a strong oxidizing environment, cysteine can be oxidized into monooxidation products, such as cysteine sulfinic acid and sulfonic acid. The degree of oxidation greatly affects the precursors of main products such as pyrazine and furan, as well as other compounds. Due to the reducibility of cysteine, it inhibits the oxidation or dehydration of sorbitol to produce glucose, blocks the subsequent generation of carbonyl ammonia reaction substrates, thereby inhibiting yellowing. For the small amount of glucose produced, due to the poor thermal stability of the disulfide bond of cysteine under weakly acidic pH conditions, intramolecular transformation of the disulfide bond occurs, forming dehydroamine and sulfated cysteamine residues. The dehydroammonium residue further reacts with nucleophiles, mainly the ε-amino group of the lysine residue, to generate new cross-linked products such as lysine-alanine, thus changing the reaction pathway between glycine and glucose, hindering Break the formation of brown material.

(4) Glutathione also has a significant inhibitory effect on the sorbitol-glycine system. The reducing nature of reduced glutathione itself can inhibit the oxidation and dehydration of sorbitol in the presence of glycine, thus hindering the production of glucose; when glutathione is present in large amounts, glutathione can act as a reaction substrate through competitive Glutathione reacts with the glucose in the system, reducing the concentration of glucose in the system, thereby controlling the color; for the remaining small amount of glucose, the presence of glutathione significantly reduces the pH value of the simulated system, thereby inhibiting further reactions between glucose and glycine, inhibiting similar Melanin formation; in addition, when the amount of glutathione is low, glutathione can be thermally degraded to produce cysteine, and the two synergistically inhibit the color change of the system.

Description of the drawings

Figure 1 is a graph showing the relationship between the _{420 nm} absorbance value of each reaction solution A and the corresponding cysteine concentration in Example 1 of the present invention;

Figure 2 is a graph showing the relationship between the _{294 nm} absorbance value of each reaction solution A and the corresponding cysteine concentration in Example 1 of the present invention;

Figure 3 is a graph showing the relationship between the fluorescence intensity of each reaction solution and the corresponding cysteine concentration in Example 1 of the present invention;

Figure 4 is a graph showing the relationship between the dicarbonyl compound concentration and the corresponding cysteine concentration of each reaction solution in Example 1 of the present invention;

Figure 5 is a graph showing the relationship between the glucose concentration and the corresponding cysteine concentration of each reaction solution in Example 1 of the present invention;

Figure 6 is a graph showing the relationship between the _{420 nm} absorbance value of each reaction solution A and the corresponding glutathione concentration in Example 2 of the present invention;

Figure 7 is a graph showing the relationship between the _{294 nm} absorbance value of each reaction solution A and the corresponding glutathione concentration in Example 2 of the present invention;

Figure 8 is a graph showing the relationship between the pH value of each reaction solution and the corresponding glutathione concentration in Example 2 of the present invention;

Figure 9 is a graph showing the relationship between the fluorescence intensity of each reaction solution and the corresponding glutathione concentration in Example 2 of the present invention;

Figure 10 is a graph showing the relationship between the dicarbonyl compound concentration and the corresponding glutathione concentration of each reaction solution in Example 2 of the present invention;

Figure 11 is a graph showing the relationship between the glucose concentration and the corresponding glutathione concentration of each reaction solution in Example 2 of the present invention.

Detailed ways

Preferred embodiments of the present invention are described below. It should be understood that the embodiments are for the purpose of better explaining the present invention and are not intended to limit the present invention.

1. Test method for yellowing degree:

Take the reaction solutions (2mL) of different reaction systems and put them into cuvettes. Measure the absorbance at 420 nm with a visible spectrophotometer.

2. Test method for the amount of colorless intermediate products produced:

Take the reaction solutions (2mL) of different reaction systems and put them into cuvettes. Measure the absorbance at 294 nm with a UV spectrophotometer.

3. Fluorescence intensity test method:

Take the reaction solutions (2mL) of different reaction systems and use a fluorescence spectrometer to measure the fluorescence intensity of the substances in the reaction solution. The excitation wavelength is 347nm and the emission range is 400~500nm.

4. Test method for dicarbonyl compound concentration (glyoxal, 2,3-butanedione, 3-deoxyglucosone):

Dissolve o-phenylenediamine in water to prepare a 1% aqueous solution, mix it thoroughly with the reaction solution in a ratio of 2:1, and place it in a dark environment for 4 hours to fully derivatize the dicarbonyl compound in the reaction solution. The derivatized reaction solution was detected using ultra-high performance liquid chromatography coupled with a quadrupole mass spectrometer. The chromatographic detection conditions are: chromatographic column: Agilent LiChrospherC18 (250mm×4.6mm, 5μm) column; column temperature: 40°C; UV detection wavelength: 320nm; injection volume: 10μL; flow rate: 1mL/min; mobile phase A: acetonitrile, Mobile phase B: 0.1% formic acid aqueous solution, using gradient elution. Multiple reaction monitoring (MRM) in positive ion mode; entrance potential (EP) = 10V, spray voltage = 5500V, collision energy (CE) = 15V, ion source temperature = 600°C, source gas flow = 15L/min, auxiliary gas flow =18L/min, the MS/MS ion information used to analyze three dicarbonyl compounds is as follows: Glyoxal: parent ion (m/z) is 131, product ions (m/z) include 92 (m/z, quantitative ion), 65 (m/z, qualitative ion); 2,3-butanedione: parent ion (m/z) is 159, product ion (m/z) is 117.5 (m/z, quantitative ion), 79 (m/z, qualifier ion); 3-deoxyglucosone: parent ion (m/z) is 235.1, product ion (m/z) is 217.1 (m/z, quantifier ion), 199.1 (m/z, qualifier ion), 181.1 (m/z, qualifier ion).

5. Glucose concentration test method

High-pressure ion chromatography was used to detect the glucose concentration in the reaction solution. The mobile phases of high-pressure ion chromatography were 0.1 mol/L sodium acetate solution and 250 mmol/L NaOH solution. Chromatographic conditions: 0 to 13 minutes is 2% NaOH solution, 13 to 14 minutes is a linear gradient from 2% NaOH to 80% NaOH, and 14 to 23 minutes is 80% NaOH to the end point. The flow rate is 10.5mL/min.

The experimental water in the examples is distilled water, sorbitol and glycine are analytically pure reagents, the chemical reagents used in the high performance liquid chromatography-mass spectrometry analysis experiment are chromatographically pure, and the other chemical reagents are all analytically pure.

Example 1:

(1) Dissolve 40g sorbitol and 3g glycine in 1200mL deionized water, mix evenly, and adjust the pH to 6.8;

(2) Divide the solution obtained in (1) into 6 parts, each part is 200 mL, and add 0.0242g, 0.0606g, 0.1212g, 0.1815g, and 0.2423g cysteine respectively to form cysteine. Mix solutions with concentrations of 0.01mol/L, 0.025mol/L, 0.05mol/L, 0.075mol/L, and 0.1mol/L respectively, and readjust the pH of the system to 6.8;

(3) Transfer each solution to the same temperature- and pressure-resistant bottle, then heat it to 120°C in an oil bath for 2 hours;

(4) Place the above six samples in an ice bath to cool down to terminate the reaction, and measure the corresponding A _{420 nm} value, A _{294 nm} value (diluted 2 times), fluorescence intensity (347nm excitation wavelength, 400-500nm wavelength range), 2 Carbonyl compound concentration (glyoxal, 2,3-butanedione, 3-deoxyglucoseone), glucose concentration; according to the A _{420 nm} value, the degree of yellowing of the sample can be reflected, A _{294 nm} , fluorescence intensity, dicarbonyl compound The concentration can reflect the severity of the reaction, while the glucose concentration indicates the degree of conversion of sorbitol into glucose and can reflect the degree of inhibition of the inhibitor on the conversion of sorbitol into glucose.

(5) Draw a curve graph between the various data obtained and the corresponding inhibitor concentration in step (3) and the data related to Comparative Example 1 to obtain Figures 1 to 5. Determine the optimal inhibitor concentration under the corresponding reaction conditions. Combined with the figure 1 to 5 and Table 1, it can be seen that when the added cysteine concentration is 0.1 mol/L, the best effect on inhibiting yellowing is achieved, with an inhibition rate as high as 85.24%, and the glucose concentration drops to 5.573% of the system without inhibitors. , however, because cysteine is insoluble, when the added amount is too high, cysteine will precipitate out after the heat treatment, and obvious turbidity will appear in the solution. When the added cysteine concentration reaches 0.05mol/L, The reaction solution showed obvious turbidity after cooling, which was unfavorable for the application of beverages and foods. When the added amount of cysteine was 0.01-0.025mol/L, the yellowing inhibition rate was still as high as 67.76%-81.97%. The glucose concentration dropped to 30.69%-19.57% of the blank group, the inhibitory effect was obvious, and the reaction solution did not appear turbid after cooling. Taking into account the effects of inhibiting glucose production, inhibiting yellowing, and solute precipitation after the reaction is stopped, the optimal addition amount of cysteine is 0.025 mol/L.

Table 1

Example 2:

(1) Dissolve 40g sorbitol and 3g glycine in 1200mL deionized water, mix evenly, and adjust the pH to 6.8;

(2) Divide the solution obtained in (1) into 6 parts, each part is 200 mL, and add 0.01921g, 0.0384g, 0.0768g, 0.1537g, and 0.3073g glutathione respectively to form glutathione. Mixed solutions with concentrations of 3.125mmol/L, 6.25mmol/L, 12.5mmol/L, 25mmol/L, and 50mmol/L. Readjust the pH of the system to 6.8;

(3) Transfer each solution to the same temperature- and pressure-resistant bottle, then heat it to 120°C in an oil bath for 2 hours;

(4) Place the above six samples in an ice bath to cool down to terminate the reaction, and measure the corresponding A _{420 nm} value, A _{294 nm} value (diluted 2 times), pH value, and fluorescence intensity (394nm excitation wavelength, 400-500nm wavelength range ), dicarbonyl compound concentration (glyoxal, 2,3-butanedione, 3-deoxyglucosone), glucose concentration;

(5) Draw a curve graph between the various data obtained and the corresponding inhibitor concentration in step (3) and the corresponding data of Comparative Example 1 to obtain Figures 6 to 11. Determine the optimal inhibitor concentration under the corresponding reaction conditions. Combined with the figure 6 to 11 and Table 2, it can be seen that when the added glutathione concentration is 50mmol/L, the yellowing inhibition effect is the best, the yellowing inhibition rate is 85.79%, and the glucose concentration also drops to 16.57% of the blank group. However, since glutathione itself is relatively insoluble, and will decompose into cysteine after the reaction and precipitate, making the solution turbid, it is not conducive to food processing and sales in real life. When the added amount of glutathione is 6.25- At 12.5mmol/L, the yellowing inhibition rate was 70.49%-73.77%, and the glucose concentration dropped to 34.67%-30.07% of the blank group. The inhibitory effect was obvious and the reaction solution did not appear turbid after cooling. Taking into account the effects of inhibiting glucose production, inhibiting yellowing, and solute precipitation after the reaction is stopped, the optimal addition amount of glutathione is 6.25-12.5mmol/L.

Table 2

Comparative example 1:

(1) Dissolve 40g sorbitol and 3g glycine in 1200mL deionized water, mix evenly, and adjust the pH to 6.8;

(2) Transfer 200mL of the solution to a temperature- and pressure-resistant bottle, then heat it to 120°C in an oil bath for 2 hours;

(3) Place the above sample in an ice bath to cool down to terminate the reaction, and measure the corresponding A _{420 nm} value, A _{294 nm} value (diluted 2 times), pH value, fluorescence intensity (394nm excitation wavelength, 400-500nm wavelength range), Dicarbonyl compound concentration (glyoxal, 2,3-butanedione, 3-deoxyglucosone), glucose concentration;

(4) Draw curve graphs between the various types of data obtained and the corresponding data in Examples 1 and 2 to obtain Figures 1 to 11.

Comparative example 2:

(1) Dissolve 40g sorbitol and 3g glycine in 1200mL deionized water, mix evenly, and adjust the pH to 6.8;

(2) Take 200mL, add epigallocatechin acid ester (EGCG) to the concentration to 0.025mmol/L, and readjust the pH to 6.8. Transfer the solution to a temperature-resistant and pressure-resistant bottle, and then place it in an oil bath Raise the temperature in the pot to 120°C and heat for 2 hours;

(3) Place the above sample in an ice bath to cool down to terminate the reaction, and measure the corresponding A _{420 nm} value, A _{294 nm} value (diluted 2 times), pH value, fluorescence intensity (394nm excitation wavelength, 400-500nm wavelength range), Dicarbonyl compound concentration (glyoxal, 2,3-butanedione, 3-deoxyglucosone), glucose concentration.

Examples 1 and 2 simulated the thermal processing of related sugar-free liquid foods containing sorbitol and glycine. By increasing the temperature, the reaction was accelerated and the long-term storage of related sugar-free foods containing sorbitol and glycine at room temperature was simulated. process. From Comparative Example 1, it can be seen that the sorbitol-glycine solution without inhibitors will generate a certain amount of glucose when heated. If it is not inhibited, glucose and glycine in the system will further undergo a nucleophilic addition reaction, causing the system to turn yellow. , and adding a certain amount of cysteine or glutathione can significantly hinder the production of glucose, hinder the occurrence of subsequent discoloration reactions from the source, and have a more obvious inhibitory effect on the yellowing of the system. According to Comparative Example 2, epigallocatechin acid ester (EGCG) was used to inhibit the production of glucose and yellowing of the color of the system, but the desired effect was not achieved. On the contrary, the color of the system deepened and the glucose content did not decrease significantly. This may be due to EGCG is unstable and prone to agglomeration during heat treatment, so the inhibitory effect is not achieved.

Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (3)

1. A method for inhibiting the yellowing of a colorless system containing sorbitol-glycine during thermal processing, characterized in that the method is by adding glutathione or Cysteine is used to inhibit the yellowing of the colorless system containing sorbitol-glycine during thermal processing; the added amount of glutathione is 6.25-12.5 mmol/L, and the added amount of cysteine is 0.01-0.025 mol/L; the thermal processing temperature is 60-120°C. 2. The method according to claim 1, characterized in that the specific conditions of the method are: reaction at a pH of 5-7 and a temperature of 60-120°C. 3. A method for inhibiting the sorbitol-glycine system from generating reducing sugars during thermal processing, characterized in that the method is to add glutathione or cysteine to the sorbitol-glycine system, and the thermal processing The temperature is 60-120°C, the added amount of glutathione is 6.25-12.5 mmol/L, and the added amount of cysteine is 0.01-0.025 mol/L.