Guar gum and carrageenan complex, and preparation method and application thereof

Abstract

The present application relates to the field of food, in particular to a guar gum and carrageenan compound, a preparation method and application thereof, the preparation method is that a solution of guar gum and a solution of carrageenan are mixed to obtain a reaction precursor; the reaction precursor is modified with an alkali solution and a modified reaction acid in sequence to obtain a target product intermediate, the modified reaction acid is a mixed solution of chloroacetic acid and sorbic acid; a salt solution is added to the target product intermediate, after stirring uniformly, the mixed gel is obtained after standing until it is fully gelled; the mixed gel is broken, then repeatedly cleaned with water, then soaked with an ethanol solution, finally, the ethanol is removed by suction filtration, and the guar gum and carrageenan compound is obtained by drying and crushing.The guar gum and carrageenan compound provided by the present application not only greatly improves the whiteness and solubility of the compound, but also improves the antibacterial performance, especially has a good antibacterial effect when added in bread, and has potential in baking applications.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food, in particular to a guar gum and carrageenan compound, a preparation method and application thereof. BACKGROUND

[0002] Guar gum is a natural galactomannan, whose main chain is formed by mannose through β-1, 4-glycosidic bond, and the side chain is composed of a single galactose connected to the main chain through α-1, 6-glycosidic bond, which belongs to a neutral hydrophilic colloid. There is no group with positive or negative charge in its linear macromolecular structure, so its molecular repulsion is small. Guar gum contains a large number of active free hydroxyl groups in its structure chain, among which, 4 hydroxyl groups in the side chain can participate in etherification or esterification reaction, in addition, the hydroxyl groups in the main chain also have certain activity, which can form a thick colloid by hydrogen bonding with water molecules, and also can form hydrogen bonding with other hydrophilic colloids to cause the viscosity of the composite system to increase [Wan Xinxing. Cationic starch / modified guar gum composite reinforcing agent preparation and its application in papermaking [D]. Jiangnan University, 2013.] Guar gum has a wide range of applications in food. Guar gum as a water-retaining agent added to frozen foods, sausages, bread, cakes or flour can prevent water loss and thus prevent product cracking; guar gum can also be added as a thickening agent to beverages to increase their consistency or play a stabilizing role [Huang Yirong. Preparation and performance of temperature-sensitive guar gum hydrogel [D]. Beijing Forestry University, 2020.].

[0003] K-carrageenan is a sulfated polysaccharide extracted from marine red algae, composed of α-(1, 3)-D-4-sulfate-galactose and β-(1-4)-3, 6-endothelial-D-galactose, which dissolves in hot water and forms a gel with high transparency in the presence of potassium ions as the system temperature decreases.

[0004] Unmodified colloids typically exhibit some performance deficiencies due to structural defects, and guar gum is no exception. For example, guar gum aggregates in water, forming difficult-to-dissolve aggregates. Complete hydration and dissolution are only achievable under high temperature and pressure conditions, a time-consuming process. As a natural polymer, guar gum is easily decomposed by enzymes and bacteria, preventing long-term storage. Inhibiting enzymes and bacteria involves adding Na2S2O3 and NaN3 to the solution [Chen Wei. Preparation of Guar Gum Derivatives and Their Application in Papermaking Reconstituted Tobacco [D]. South China University of Technology, 2012.]. Furthermore, whiteness, a sensory indicator of guar gum quality, affects its processing added value. Currently, commercially available guar gum is mostly in the form of pale yellow or brownish-yellow powder, and its poor solubility limits its application range. On the other hand, natural carrageenan gel also suffers from high brittleness and easy dehydration and shrinkage. Carrageenan originally contains sulfate polysaccharides with antibacterial and anti-allergic activities. Therefore, it is meaningful to explore how to combine the properties of both by introducing functional groups into the structure and make up for their performance shortcomings. Summary of the Invention

[0005] To address the problems mentioned in the prior art, the present invention provides a method for preparing a guar gum and carrageenan complex, comprising the following steps:

[0006] The reaction precursor is obtained by mixing guar gum solution and carrageenan solution;

[0007] The reaction precursor is sequentially reacted with an alkaline solution and a modifying acid to obtain the target product intermediate. The alkaline solution is a sodium hydroxide solution or a sodium bicarbonate solution, and the modifying acid is a mixture of chloroacetic acid and sorbic acid.

[0008] A salt solution was added to the target product intermediate, stirred until homogeneous, and allowed to stand until fully gelled to obtain a mixed gel. The salt solution contained K. + Ca 2+ Mg 2+ Fe 3+ At least one of them;

[0009] After the mixed gel is broken up, it is repeatedly washed with water until the pH is 6.0-6.5, then soaked in an ethanol solution with a mass fraction of 45%-75%, and finally filtered to remove the ethanol. After drying and pulverizing, the guar gum and carrageenan complex is obtained.

[0010] It should be noted that the purpose of washing the above-mentioned mixed gel to a pH of 6.0–6.5 is mainly to wash away Cl. - That is, no Cl - Residues can be further detected using test strips or chemical reagents (AgNO3).

[0011] In an embodiment, the salt solution is a potassium chloride solution, a calcium chloride solution or a magnesium chloride solution, but is not limited thereto.

[0012] In an embodiment, the mass fraction of the potassium chloride solution is 10% to 20%, and the added amount of potassium chloride is 0.15% to 0.25% of the mass of the carrageenan.

[0013] In an embodiment, the carrageenan is k-type carrageenan, and the added amount of the carrageenan is 25% to 50% of the weight of the guar gum.

[0014] In an embodiment, the guar gum is mixed with water at a mass ratio of 1:20 to 30 and heated to fully hydrate and dissolve the guar gum to obtain a guar gum solution.

[0015] The proportion of the carrageenan in the carrageenan solution is 3% to 5%.

[0016] In an embodiment, the mass fraction of the sodium hydroxide solution is 15% to 20%, and the added amount of sodium hydroxide is 10% to 30% of the weight of the guar gum.

[0017] The mass fraction of the sodium bicarbonate solution is 15% to 20%, and the added amount of sodium bicarbonate is 20% to 35% of the weight of the guar gum.

[0018] In an embodiment, the added amount of chloroacetic acid is 5% to 18% of the total mass of the guar gum and the carrageenan, and the added amount of sorbic acid is 0.5% to 1% of the total mass of the guar gum and the carrageenan.

[0019] In an embodiment, the modification reaction is carried out at 30 to 60°C.

[0020] In an embodiment, before the salt solution is added, the system pH of the modified glue solution is adjusted to 6.5 to 7.5.

[0021] The present application provides a guar gum and carrageenan compound prepared by any of the above-mentioned preparation methods.

[0022] The present application also provides a use of the guar gum and carrageenan compound as described above in the preparation of a dough, wherein the baking proportion of the guar gum and carrageenan compound in the dough improver is 1.6% to 2.5%.

[0023] It should be noted that the above-mentioned baking proportion is based on 100% of the weight of the flour in the formula, and the baking proportion of the guar gum and carrageenan compound is relative to the weight of the flour.

[0024] Based on the above, compared with the prior art, the preparation method of the guar gum and carrageenan compound provided by the present application has the following technical principles and effects:

[0025] 1. First, react the mixture of guar gum and carrageenan with an alkaline solution to generate substances containing Na. + The modification of guar gum and carrageenan complexes increases nucleophilicity by replacing the hydroxyl groups on the macromolecules with oxygen anions. At the same time, the expansion of the two macromolecules allows a large amount of chloroacetic acid and sorbic acid to enter the interior of the macromolecules and continue to undergo nucleophilic substitution reactions. This can greatly improve the whiteness and solubility of the modified guar gum and carrageenan complexes, and increase their antibacterial groups, thereby improving the antibacterial effect.

[0026] 2. Because guar gum is a high-viscosity, non-gelling colloid soluble in cold water, chemical modification of it in an aqueous system leaves residual chemical reagents that cannot be washed away later. Carrageenan, on the other hand, is an ionic colloid soluble in hot water, especially with positively charged ions (especially K+). + Under the condition that these two substances are present, they can gel when the system temperature is below 35℃, and residual reagents are easy to wash off after the reaction. Therefore, choosing to mix and modify these two substances can effectively solve the above problems and simultaneously modify both substances, resulting in a significant improvement in the properties of the modified colloidal substance.

[0027] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects can be realized and obtained from the description, claims, and drawings. Attached Figure Description

[0028] Figure 1 A schematic diagram of the reaction mechanism of the modification method provided by the present invention;

[0029] Figure 2a The graph shows the effect of different modified reactive acid compositions on the whiteness and solubility of the guar gum and carrageenan complex.

[0030] Figure 2b The graph shows the effect of different amounts of sodium hydroxide on the whiteness and solubility of the guar gum and carrageenan complex.

[0031] Figure 2c The graph shows the results of different modification reaction temperatures on the whiteness and solubility of the guar gum and carrageenan complex.

[0032] Figure 3 Images of carrageenan, guar gum, and guar gum and carrageenan complexes.

[0033] Figure 4 Infrared spectra of the mixture of guar gum and carrageenan before and after modification;

[0034] Figure 5aThe result chart of whiteness and solubility of guar gum and carrageenan mixture in different system pH in the comparative example 1;

[0035] Figure 5b The result chart of whiteness and solubility of guar gum and carrageenan mixture in different system pH in the comparative example 2;

[0036] Figure 6 The result chart of antibacterial effect of guar gum and carrageenan compound provided by the present application;

[0037] Figure 7 The actual picture of bread mildew situation on the 10th day. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application; the technical features designed in different embodiments of the present application can be combined with each other as long as they do not conflict with each other; all other embodiments obtained by those skilled in the art without creative labor on the basis of the embodiments of the present application belong to the protection scope of the present application.

[0039] In the description of the present application, it should be noted that all the terms (including technical terms and scientific terms) used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs, and should not be understood as a limitation on the present application; it should be further understood that the terms used in the present application should be understood as having the same meaning as the terms in the context of the present specification and the related field, and should not be understood in an idealized or overly formal sense, unless defined explicitly in the present application.

[0040] For the convenience of subsequent description, unless otherwise specified, the "original guar gum / carrageenan" mentioned below refers to the compound glue prepared by directly mixing guar gum and carrageenan in a mass ratio of 2.5:1;

[0041] The "modified guar gum / carrageenan" refers to the guar gum and carrageenan compound prepared by using the modification method provided by the present application.

[0042] Reference Figure 1 According to the reaction mechanism schematic diagram shown in the figure, starting from the substitution reaction mechanism, in the synthesis process of the modified guar gum / carrageenan, first, the macromolecular mixture reacts with NaOH to generate Na +The hydroxyl group on the macromolecule is replaced by an oxygen anion, which increases the nucleophilicity. Meanwhile, NaOH causes the volume of the two macromolecules to expand, and a large amount of chloroacetic acid and sorbic acid randomly enters the interior of the macromolecule, thereby containing Na + The macromolecule continues to undergo a nucleophilic substitution reaction with chloroacetic acid, and the covalent bond between the carbon atom and the chlorine atom on the chloroacetic acid is broken, thereby obtaining a free -CH2COOH; the free -CH2COOH and C5H7COOH are combined with the active groups on the macromolecule structure. Therefore, Na + The reaction is significantly affected by the amount of sodium hydroxide added.

[0043] In addition, the reaction temperature can provide energy for the reaction, and the movement rate of chloroacetic acid and sorbic acid in the reaction system is positively correlated with the temperature value, but not unlimited.

[0044] To illustrate the influence of the amount of sodium hydroxide added, the modification reaction temperature, and the amount of chloroacetic acid and sorbic acid added on the modification reaction, the present application provides the following examples:

[0045] Example 1.1

[0046] S100, guar gum is added to 30 times the weight of water, heated to fully hydrate and dissolve, and then mixed with a 5% carrageenan solution (wherein the amount of carrageenan added is 50% of the weight of guar gum) to obtain a mixed glue solution.

[0047] S200, 20% sodium hydroxide solution is added to the above mixed glue solution (the amount of sodium hydroxide added is 30% of the weight of guar gum), and after stirring at 45°C for 30 min, the modified reaction acid diluted with water is added in batches, and the stirring is continued at 45°C for 60 min, and the pH of the system is adjusted to 6.5-7.0 to obtain a modified glue solution.

[0048] S300, 20% KCl solution is added to the above modified glue solution (the amount of KCl added is 0.2% of the mass of carrageenan), and the stirring is continued for 30 min, and the mixed gel is obtained by standing until it is completely gelled.

[0049] S400, the above mixed gel is crushed and repeatedly washed with water until the pH is 6.0-6.5 and there is no Cl - residue, and finally the mixed gel is soaked in a 75% ethanol solution for 60 min, the ethanol is removed by suction filtration, and the gel is dried at 65°C for 120 min, and then crushed through an 80-mesh sieve to obtain the guar gum and carrageenan compound.

[0050] It should be noted that the modified acid mentioned above can be added in three batches, with the amounts added successively at 40%, 30%, and 30%, all within 10 minutes, but this is not a strict limit. The reason for adding it in batches is that if too much is added at once, the probability of acid-base reaction in the system increases, which can easily lead to side reactions.

[0051] Following the method in Example 1.1, eight groups of experiments were set up. The specific composition and amount of the modified reactive acid in these eight groups are shown in the table below:

[0052] Table 1

[0053] A B C D E F G H Chloroacetic acid 18％ 10％ 0 0 10％ 8％ 5％ 0 Sorbic acid 0 0 0.5％ 1％ 1％ 0.5％ 0.5％ 0

[0054] Note: The percentages in the table refer to the percentage of the corresponding component added relative to the total mass of guar gum and carrageenan.

[0055] The whiteness and solubility of the guar gum and carrageenan complexes obtained from these eight groups were then tested. The test results are shown in [Figure number missing]. Figure 2a .like Figure 2a As shown, different amounts and combinations of additives have varying effects on the modification. The more modifier added, the more significant the modification effect. The combination of chloroacetic acid and sorbic acid is beneficial for improving the whiteness and solubility of modified guar gum / carrageenan, and the addition of sorbic acid can achieve higher quality modified guar gum / carrageenan while reducing the amount of chloroacetic acid added.

[0056] It should be noted that the whiteness test methods of this invention all use a whiteness measuring instrument (High Precision, WSB-3) to measure the whiteness of the powder, and the solubility test method is to measure the amount of colloid dissolved in 90°C hot water within 10 minutes.

[0057] Example 1.2

[0058] S100. Add guar gum to water at a concentration of 30 times the weight of guar gum, heat to fully hydrate and dissolve, and then mix with a 5% carrageenan solution (where the amount of carrageenan added is 50% of the weight of guar gum) to obtain a mixed gum solution.

[0059] S200. Add a 20% sodium hydroxide solution to the above mixed adhesive solution. Stir at 45°C for 30 min. Then, add a mixture of chloroacetic acid and sorbic acid diluted with water in batches (chloroacetic acid and sorbic acid content are 10% and 0.5% of the mass of guar gum and carrageenan, respectively, and add within 10 min). Continue to stir and react at 45°C for 60 min. Adjust the pH of the system to 6.5-7.0 to obtain the modified adhesive solution.

[0060] S300, 20% KCl solution is added to the modified glue solution, and stirring is continued for 30 min. The mixed glue is obtained after the glue is completely gelled.

[0061] S400, the mixed glue is crushed and repeatedly washed with water until the pH is 6.0-6.5 and there is no Cl - residue. Finally, the mixed glue is soaked in a 75% ethanol solution for 60 min. The ethanol is removed by suction filtration, and the mixed glue is dried at 65°C for 120 min. The guar gum and carrageenan compound is obtained after the mixed glue is crushed and passed through an 80-mesh sieve.

[0062] According to the method of Example 1.2, five groups of tests are set up, and the amount of sodium hydroxide added to each group is 10%, 15%, 20%, 25%, and 30% of the weight of guar gum, respectively. The whiteness and solubility of the guar gum and carrageenan compound obtained from each group are then tested, and the test results are shown in Table 1. Figure 2b .

[0063] Figure 2 reflects the effect of the amount of sodium hydroxide added (based on the weight of guar gum) on the reaction (the original material in the figure refers to the original guar gum / carrageenan). Specifically, the effect of different amounts of sodium hydroxide on the whiteness and solubility of modified guar gum / carrageenan is shown in Figure 2. Figure 1 As can be seen from the results, when the amount of sodium hydroxide added is 30% of the weight of guar gum, the two properties of modified guar gum / carrageenan are at their optimal values.

[0064] Example 1.3

[0065] S100, guar gum is added to 30 times its weight in water, heated to fully hydrate and dissolve, and then mixed with a 5% carrageenan solution (where the amount of carrageenan added is 50% of the weight of guar gum) to obtain a mixed glue solution.

[0066] S200, a 20% sodium hydroxide solution is added to the mixed glue solution (the amount of sodium hydroxide added is 30% of the weight of guar gum), and stirring is continued for 30 min at the modification reaction temperature T. A mixture of water-diluted chloroacetic acid and sorbic acid is then added in batches (the content of chloroacetic acid and sorbic acid is 15% and 0.5% of the weight of guar gum and carrageenan, respectively, and the addition is completed within 10 min). Stirring is continued at the modification reaction temperature T for 60 min, the pH of the system is adjusted to 6.5-7.0, and a modified glue solution is obtained.

[0067] S300, 20% KCl solution is added to the modified glue solution, and stirring is continued for 30 min. The mixed glue is obtained after the glue is completely gelled.

[0068] S400: After crushing the above mixed gel, wash it repeatedly with water until the pH is 6.0-6.5 and no Cl is present. - The residue was removed by soaking the mixed gel in 75% ethanol solution for 60 minutes, filtration was used to remove the ethanol, drying was carried out at 65°C for 120 minutes, and the gel was then pulverized through an 80-mesh sieve to obtain the guar gum and carrageenan complex.

[0069] Following the method in Example 1.3, four groups of experiments were set up, with modification reaction temperatures T of 30℃, 40℃, 50℃, and 60℃ respectively. The whiteness and solubility of the guar gum and carrageenan composites obtained from these four groups were then tested. The test results are shown below. Figure 2c .

[0070] Figure 2c This reflects the effect of modification reaction temperature on the reaction, specifically the effect of different modification reaction temperatures on the whiteness and solubility of modified guar gum / carrageenan. Figure 2c The results showed that when the reaction temperature reached 60℃, the whiteness and solubility of the modified guar gum / carrageenan tended to stabilize, reaching about 84% and 11% respectively, which were much higher than the whiteness and solubility of the original guar gum / carrageenan without chloroacetic acid and sorbic acid modification (about 51% and 3.2% respectively).

[0071] To illustrate the improved performance of the guar gum and carrageenan composite provided by this invention, the performance of guar gum, carrageenan, virgin guar gum / carrageenan, modified guar gum / carrageenan (without sorbic acid), and modified guar gum / carrageenan was tested as shown in Table 2. In the table below, R, S, T, U, and V represent guar gum, carrageenan, virgin guar gum / carrageenan, modified guar gum / carrageenan (without sorbic acid), and modified guar gum / carrageenan, respectively. Among them, the modified guar gum / carrageenan (without sorbic acid) in group U is the product obtained from group B in Example 1.1; the modified guar gum / carrageenan in group V refers to the product obtained from group F in Example 1.1.

[0072] Table 2

[0073]

[0074] Note:

[0075] Viscosity (cP): The viscosity of a 1% colloidal solution at 65°C was measured using a digital viscometer (Xiamen Baote Technology, DV-C).

[0076] Elasticity (cm): Reference: Chen Huijing. Preparation, properties and microencapsulation application of octenyl succinic acid agar derivatives [D]. Jimei University, 2020. The method described in the article.

[0077] Sulfate content(%) : The method described in the reference: Chen H J. Preparation, properties and microencapsulation application of octenyl succinic anhydride agar derivatives[D]. Jimei University, 2020.

[0078] (1) Preparation of K2SO4 standard solution: 1.088 g of K2SO4 dried to constant weight was accurately weighed and dissolved in 1 mol / L HCl solution (500 mL).

[0079] (2) Preparation of gelatin-barium chloride solution: 0.5% (w / v) gelatin solution was accurately prepared and stored at 4°C overnight as a solvent to prepare 1% gelatin-barium chloride solution, which was stored at 4°C for standby.

[0080] (3) 0, 0.2, 0.4, 0.6, 0.8, 1.0 mL of K2SO4 standard solution was respectively taken into a 10 mL stoppered test tube, and the sample less than 1 mL was supplemented to 1 mL with ultrapure water. Then 3 mL of gelatin-barium chloride solution was added to the test tube, mixed well and placed for 10 min at 360 nm to measure the absorbance of the sample. The standard curve of SO4 2- content was obtained (y = 3.7201x + 0.3563, R 2 = 0.9989).

[0081] (4) Determination of sulfate content: 0.050 g of the sample to be tested was accurately weighed into a 25 mL colorimetric tube, 25 mL of 1 mol / L HCl solution was added, and it was placed in a water bath at 100°C for acid digestion for 5 h. After cooling to room temperature, it was decolorized with activated carbon and filtered to collect the filtrate. 1 mL of the filtrate was taken and mixed well with 3 mL of gelatin-barium chloride solution, and the absorbance of the sample at 360 nm was measured after standing for 10 min. The sulfate content of agar was determined according to the above standard curve.

[0082] Carbonyl content(%) : The method described in the reference: Chen H J, Xiao Q, Weng H F, et al. Extraction of sulfated agar from Gracilaria lemaneiformis using hydrogen peroxide-assisted enzymatic method [J]. Carbohydrate polymers, 2020, 232: 115790.

[0083] Carboxyl content (%): 1.50 g of the sample to be tested was mixed with 25 mL of HCl solution (0.1 mol / L), and after stirring for 30 min, it was suction filtered, and washed until no chloride ion was present. Then agar powder was dissolved in 100 mL of deionized water, and phenolphthalein was used as an indicator, and the sample to be tested was titrated with 0.020 mol / L NaOH solution until the end point, and the volume of the consumed NaOH solution was recorded. The original agar was used as a control group, and the carboxyl content was expressed as the number of carboxyl groups per 100 galactose units (COOH / 100 GA). The calculation formula is as follows:

[0084]

[0085] wherein:

[0086] V a : the volume of NaOH consumed by the sample (mL);

[0087] V b : the volume of NaOH consumed by the blank group (mL);

[0088] M: the molar concentration of NaOH;

[0089] W: the weight of the sample.

[0090] Dehydration rate: 50 mL of 1.5% (w / v) sample solution was poured into a 50 mL graduated centrifuge tube, and their mass (m1) was recorded, the sample was cooled at 25°C for 12 h, and after the gel was completely stored at -18°C for 12 h. Then the gel was balanced and thawed at 25°C for several hours, and then centrifuged at 3000 x g for 10 min, and the separated water was discarded, and the mass was m2. The calculation formula of the dehydration rate is as follows:

[0091]

[0092] The data in Table 2 show that after modification, the hydrophilic property of guar gum and carrageenan is increased, and the dissolution speed is accelerated. Moreover, after the two are compounded, the elasticity of the gel is enhanced, representing that the brittleness is weakened, and the modified colloid compound has the strongest elasticity.

[0093] Figure 3 For the actual pictures of carrageenan, guar gum and modified guar gum / carrageenan, it can be obviously seen that the whiteness of the modified guar gum / carrageenan is obviously improved compared with carrageenan and guar gum.

[0094] The present application also determines the infrared spectrum of the original guar gum / carrageenan and the modified guar gum / carrageenan in group V, and specifically as shown in Figure 4 The infrared spectrum of the guar gum and carrageenan mixture before and after modification is shown in the figure, and it can be seen that after modification, the colloid mixture is 1550-1610 cm -1Originating from RCOO - The characteristic absorption peaks indicate that chloroacetic acid successfully reacted with the mixed colloid, introducing RCOO into the colloidal structure. - This group, through its ability to induce changes in colloidal properties, is consistent with the carboxyl group data in Table 2.

[0095] It should be noted that the above-mentioned infrared spectroscopy determination method involves mixing the dried sample to constant weight with KBr at a mass ratio of 1:100, grinding and pressing it into a pellet, and then placing it in the sample area of ​​an FT-IR (Thermo Fisher Scientific, USA) to measure its spectrum.

[0096] To illustrate that the modification method provided by this invention has a significant improvement over the prior art, this invention also provides the following comparative example 1:

[0097] Comparative Example 1

[0098] Guar gum was added to 20 times its weight of water and heated to fully hydrate and dissolve it. This solution was then mixed with a 5% carrageenan solution (carrageenan at 50% of guar gum weight) to obtain a mixed gel. At different pH values, appropriate amounts of sodium hypochlorite (10% available chlorine by mass) were added. After reacting at a controlled temperature for a period of time, a 20% KCl solution (0.2% of carrageenan by mass) was added to the modified gel, and stirring was continued for 30 minutes. The mixture was allowed to stand until it completely gelled into a mixed gel. The mixed gel was crushed and repeatedly washed with water until the pH reached 6.0–6.5, until a small amount of sodium bisulfite was added until starch-potassium iodide test paper no longer turned blue. The mixture was filtered, the filter cake was dried, and then pulverized to obtain the modified colloidal mixture.

[0099] Following the method of Comparative Example 1, four groups of experiments were set up with pH values ​​of 6, 8, 9 and 11 respectively. The whiteness and solubility of the modified colloidal mixtures obtained from these four groups were then tested. The test results are shown in Figure 5.

[0100] like Figure 5a As shown, the pH of different systems has a certain effect on the whiteness of the mixture of guar gum and carrageenan. It can be seen that under alkaline conditions (pH 11), the whiteness of the modified guar gum and carrageenan complex reaches a maximum of only 74.1%, while it has no significant effect on the solubility of the complex.

[0101] Comparative Example 2

[0102] Guar gum was added to 20 times the weight of water, heated to fully hydrate and dissolve, and then mixed with a 5% carrageenan solution (wherein the amount of carrageenan added was 50% of the weight of the guar gum) to obtain a mixed glue solution. A 20% hydrogen peroxide solution (20% of the weight of the guar gum and carrageenan) was added at different pH values, and then the temperature was controlled at 60°C for 2h of reaction. Then, a 20% KCl solution (0.2% of the mass of the carrageenan) was added to the modified glue solution described above, and stirring was continued for 30min. The mixed glue was crushed and washed repeatedly with water until the pH was 6.0-6.5, and until the reagent residue was detected using hydrogen peroxide test paper. The filter cake was dried and ground to obtain a modified glue mixture.

[0103] According to the method of Comparative Example 2, four groups of tests were set up, and the pH values of the four groups were 8, 9, 10, and 11, respectively. The whiteness and solubility of the modified glue mixtures obtained from the four groups were then detected, and the test results are shown in Table 1. Figure 5b .

[0104] Hydrogen peroxide itself does not have bleaching effect, but after it is in contact with water, it can decompose to produce HOO - groups in the system, which are extremely strong nucleophilic reagents and can react with the conjugated system of lignin and other colored substances to break the chain, thereby achieving the effect of bleaching. However, the groups decomposed by hydrogen peroxide are different at different pH values. Therefore, the bleaching effect at different pH values is involved in the present comparative example, and the whiteness and solubility of guar gum / carrageenan treated with hydrogen peroxide as a modifier are shown in Table 1. It can be seen that the whiteness increases with the increase of the pH value of the system, and the whiteness of the modified guar gum / carrageenan complex reaches a maximum value of only 76.1% under alkaline conditions (pH 11), and the solubility of the complex is not significantly affected. Figure 5b

[0105] Therefore, from the test results of Comparative Example 1 and Comparative Example 2, it can be seen that even if sodium hypochlorite and hydrogen peroxide, which are commonly used bleaching agents, are used to modify guar gum and carrageenan, the degree of improvement of the whiteness and solubility is lower than that of the modification method provided by the present application.

[0106] In order to further illustrate the obvious improvement effect of the modification method provided by the present application in which guar gum and carrageenan are mixed together for modification compared with separate modification, the present application also provides the following Comparative Examples 3-1 and 3-2.

[0107] Comparative Example 3-1

[0108] ​Considering that guar gum is water-soluble colloid, soluble in cold water, but there is a problem: although it can react in the water system, but after the reaction is finished, the target product in the state of aqueous solution is difficult to operate when washing, so it needs to be compounded in other reaction systems or using the gel properties of other colloids to achieve the washing effect, therefore, the guar gum provided in the application is modified in the ethanol system, and the specific operation is as follows:

[0109] 25g of guar gum is weighed and dispersed in 200g of 95% mass fraction ethanol aqueous solution, 20% sodium hydroxide solution (the addition amount of sodium hydroxide is 30% of the weight of guar gum) is added, after stirring at 50℃ for 30min, the modifier diluted with water is added in batches, and the stirring reaction is continued at 60℃ for 60min, the pH of the system is adjusted to 6.5-7.0, and then the filtration is carried out, and the washing with water is repeated until the pH is 6.0-6.5 and there is no Cl - residue. Finally, the guar gum is washed with 95% ethanol solution for 60min, the ethanol is removed by suction filtration, and the guar gum is dried at 65℃ for 120min, and then the modified guar gum is obtained by crushing to 80 mesh.

[0110] According to the method of Comparative Example 3-1, four groups of tests are set, and the addition of the modifiers of the four groups is as follows:

[0111] ① No modifier is added

[0112] ② The modifier is only chloroacetic acid, and the addition amount is 15% of the mass of guar gum;

[0113] ③ The modifier is only sorbic acid, and the addition amount is 1% of the mass of guar gum;

[0114] ④ The modifier is chloroacetic acid + sorbic acid, wherein the addition amount of chloroacetic acid is 10% of the mass of guar gum, and the addition amount of sorbic acid is 1% of the mass of guar gum.

[0115] Then the whiteness and solubility of the modified guar gum of the four groups are detected, and the test results are shown in Table 3:

[0116] Table 3

[0117] Item Dissolving power (g) Viscosity (cP) Carboxyl content (%) Carbonyl content (%) Whiteness (%) ① 3.3±0.1 8.8±0.2 No No 48.8±0.2 ② 7.6±0.6 9.3±0.1 1.9±0.17 0.9±0.03 56.1±0.1 ③ 3.8±0.5 8.9±0.2 0.3±0.12 0.1±0.01 49.3±0.3 ④ 8.30±0.2 10.5±0.1 2.7±0.07 2.2±0.09 73.1±0.1

[0118] The data in Table 3 show that compared with mixed acid, single sorbic acid has no outstanding effect on the modification of guar gum, but can still introduce new groups into the structure. Moreover, the reaction effect in the ethanol solution system is not as remarkable as that in the water system. This is because the guar gum is in a granular state in the ethanol system, and the modifier is difficult to penetrate into the structure, resulting in the above results.

[0119] Comparative Example 3-2

[0120] The carrageenan was added into 20 times of water by weight of carrageenan, heated to fully hydrate and dissolve, 20% sodium hydroxide solution was added (sodium hydroxide was added in an amount of 30% by weight of guar gum), stirred at 50°C for 30 min, then the modified agent was added in batches after dilution with water, and the reaction was continued at 60°C for 60 min, the pH of the system was adjusted to 6.5-7.0, and the modified glue solution was obtained. In the above modified glue solution, 20% KCl solution (KCl added amount is 0.2% of the mass of carrageenan) was added and stirred for 30 min, and then the mixed gel was obtained after standing. The mixed gel was crushed and washed repeatedly with water until the pH was 6.0-6.5, and there was no Cl - residue. Finally, the mixed gel was soaked in 75% ethanol solution for 60 min, filtered to remove ethanol, dried at 65°C for 120 min, and crushed to 80 mesh to obtain the modified carrageenan.

[0121] According to the method of Comparative Example 3-2, four groups of tests were set up respectively, and the addition of the modified agent in the four groups was as follows:

[0122] ① No modified agent was added

[0123] ② The modified agent was only chloroacetic acid, and the addition amount was 15% of the mass of guar gum;

[0124] ③ The modified agent was only sorbic acid, and the addition amount was 1% of the mass of guar gum;

[0125] ④ The modified agent was chloroacetic acid + sorbic acid, wherein the addition amount of chloroacetic acid was 10% of the mass of guar gum, and the addition amount of sorbic acid was 1% of the mass of guar gum.

[0126] Then the whiteness and solubility of the modified carrageenan obtained in the four groups were detected respectively, and the test results are shown in Table 4:

[0127] Table 4

[0128]

[0129] The data in Table 4 shows that compared with mixed acid, single sorbic acid does not have a prominent effect on the modification of carrageenan, but can still introduce new groups into the structure, and the modification effect of sorbic acid and chloroacetic acid is improved. Because carrageenan is dissolved in water and exists in the form of molecules in the solution, the modified agent can better penetrate into the interior of the molecule to modify its structure, resulting in changes in the molecular structure, and the whiteness of the modified carrageenan is significantly improved.

[0130] The test results of Comparative Examples 3-1 and 3-2 show that modifying guar gum and carrageenan individually with the modifying reagent of this invention does not improve whiteness as much as the mixed modification. Therefore, even if the modified components are mixed again, the technical effect of the guar gum and carrageenan composite provided by this invention cannot be achieved. This may be because guar gum is a high-viscosity non-gelling colloid soluble in cold water, and its modification in an aqueous system makes it impossible to wash away residual chemical reagents later. Carrageenan, on the other hand, is an ionic colloid soluble in hot water. + Under suitable conditions, it can gel at temperatures below 30°C, and residual reagents are easy to wash off after the reaction. Therefore, choosing to mix the two for modification can effectively solve the above problems while simultaneously modifying both substances, and the properties of the modified mixture are significantly improved.

[0131] To illustrate the antibacterial effect of the guar gum and carrageenan complex provided by this invention, the present invention further added carrageenan / guar gum complex and modified guar gum / carrageenan to PDA medium at an addition amount of 2% of the medium mass, and used PDA medium without the addition of other substances as a blank group. The preparation method of PDA medium is as follows:

[0132] Take an appropriate amount of Cycloka potato dextrose agar (PDA) medium powder, add water according to the ratio and heat to dissolve, pour into a plate, and after it cools and solidifies, spread it on Aspergillus flavus and incubate at 30℃ for several days to observe the growth of the bacteria.

[0133] Colony growth status as follows Figure 6 As shown, the modified guar gum complex is more effective at inhibiting the growth and reproduction of Aspergillus flavus than the mixture of carrageenan and guar gum without the addition of carrageenan and guar gum.

[0134] Since mold growth on baked goods such as bread is caused by fungal activity, and Aspergillus flavus is a significant contaminant of bread, its aflatoxin can easily cause liver damage in humans. Utilizing the antibacterial effect of the guar gum and carrageenan complex of this invention, the inventors attempted to apply it to baking, as shown in Example 2 below:

[0135] Example 2

[0136] S100. Add guar gum to water at a ratio of 20 times the weight of guar gum, heat to fully hydrate and dissolve, and then mix with a 5% carrageenan solution (where the amount of carrageenan added is 50% of the weight of guar gum) to obtain a mixed gum solution.

[0137] S200, 20% sodium hydroxide solution is added to the mixed glue solution (sodium hydroxide is added in an amount of 30% of the weight of guar gum), stirred at 50°C for 30 min, then a mixture of chloroacetic acid and sorbic acid diluted with water is added in batches (chloroacetic acid and sorbic acid content is 10% and 1% of the mass of guar gum and carrageenan, added within 10 min), continue to stir and react at 60°C for 60 min, adjust the pH of the system to 6.5-7.0, and obtain a modified glue solution.

[0138] S300, 20% KCl solution (KCl is added in an amount of 0.2% of the mass of carrageenan) is added to the modified glue solution, and stirring is continued for 30 min. Let it stand until it completely gels into a mixed gel.

[0139] S400, the mixed gel is crushed and repeatedly washed with water until the pH is 6.0-6.5, and there is no Cl - residue. Finally, immerse the mixed gel in a 75% ethanol solution for 60 min, remove the ethanol by suction filtration, and dry at 65°C for 120 min. Crush to 80 mesh sieve to obtain modified guar gum / carrageenan.

[0140] The modified guar gum / carrageenan prepared in Example 2 is mixed according to the ingredient table of Table 5, and bread is made by the same process, and is stored in a sealed condition at 25°C, 65% RH, and the deterioration condition is observed, and the surface of the bread is observed by visual observation method whether there is mold.

[0141] Table 5 - Basic ingredients of bread

[0142] Raw material A dough (g) B dough (g) C dough (g) D dough (g) E dough (g) High gluten flour 500 500 500 500 500 Milk powder 20 20 20 20 20 White granulated sugar 100 100 100 100 100 Trehalose 20 20 20 20 20 Salt 5 5 5 5 5 Yeast 11 11 11 11 11 Calcium propionate 0.45 0 0 0.2 0 Sodium dehydroacetate 0.4 0 0 0.15 0 High fructose corn syrup 25 25 25 25 25 Sorbitol solution 15 15 15 15 15 Glycerin 10 10 10 10 10 Egg liquid 40 40 40 40 40 Water 185 185 185 185 185 Angel bread improver 10.5 10.5 10.5 10.5 10.5 Butter 70 70 70 70 70 Raw guar gum / carageenan 0 10 0 0 0 Modified guar gum / carageenan 0 0 10 8 0

[0143] Figure 7 To take a picture of the bread mold on the 10th day, the final test results are as follows: the blank group (E) without any preservative and containing bacteriostatic group colloid first molds at 25°C, 65 RH%, and the shelf life is only 4 days. The experimental group (B) which only adds original guar gum / carrageenan without adding preservative appears mold next, and the shelf life is 6 days, indicating that the functional group has certain bacteriostatic effect, followed by the experimental group (C) which only adds modified guar gum / carrageenan without adding preservative, mold appears after 10 days, indicating that the functional group introduced after modification has good bacteriostatic effect. Then is the experimental group (D) which adds both preservative and modified guar gum / carrageenan, mold appears after 73 days; finally is the experimental group (A) which adds all preservatives, mold appears after 81 days.

[0144] The amount of preservative used in the experimental group (D) is only half of that in the experimental group (A), indicating that in the case of adding a small amount of preservative, the modified guar gum / carrageenan can achieve good bacteriostatic effect, and therefore, the addition of modified guar gum / carrageenan in baking can reduce the amount of preservative added.

[0145] Therefore, the guar gum and carrageenan compound provided by the present application has good bacteriostatic effect when added in bread, can reduce the amount of preservative added, and has potential in baking applications.

[0146] In summary, the preparation method of the guar gum and carrageenan compound provided by the present application not only solves the problem of residual chemical reagents after modification of guar gum in water, but also overcomes the defects of large brittleness and easy dehydration and shrinkage of carrageenan, and the whiteness, solubility and bacteriostatic performance of the modified colloid are significantly improved.

[0147] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present application can only be improved in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or background art at the same time. Those skilled in the art should understand that what is not mentioned in a claim should not be regarded as a limitation of the claim.

[0148] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of a guar gum and carrageenan complex, characterized in that, The method comprises the following steps: mixing a guar gum solution and a carrageenan solution to obtain a reaction precursor; modifying the reaction precursor with an alkali solution and a modified reaction acid to obtain a target product intermediate, wherein the alkali solution is a sodium hydroxide solution or a sodium bicarbonate solution, and the modified reaction acid is a mixture of chloroacetic acid and sorbic acid; In the intermediate of the target product, a salt solution is added, and after stirring, a mixed gel is obtained after the gel is fully gelled by standing. The salt solution contains at least one of K + , Ca 2+ , Mg 2+ , Fe 3+ ​ crushing the mixed gel, washing it repeatedly with water until the pH is 6.0-6.5, then soaking it in an ethanol solution with a mass fraction of 45%-75%, finally removing the ethanol by suction filtration, and drying and crushing to obtain the guar gum and carrageenan compound; the modification reaction is carried out at 30-60℃; the mass fraction of the sodium hydroxide solution is 15%-20%, and the added amount of sodium hydroxide is 10%-30% of the weight of the guar gum; the mass fraction of the sodium bicarbonate solution is 15%-20%, and the added amount of sodium bicarbonate is 20%-35% of the weight of the guar gum; the added amount of chloroacetic acid is 5%-18% of the total mass of the guar gum and the carrageenan, and the added amount of sorbic acid is 0.5%-1% of the total mass of the guar gum and the carrageenan.

2. The process for the preparation of guar gum and carrageenan complex as claimed in claim 1 wherein: The guar gum is mixed with water at a mass ratio of 1:20-30 and heated to fully hydrate and dissolve the guar gum to obtain a guar gum solution. The proportion of carrageenan in the carrageenan solution is 3%-5%.

3. The process for the preparation of guar gum and carrageenan complex as claimed in claim 2, wherein: The carrageenan is k-type carrageenan, and the added amount is 25%-50% of the weight of the guar gum.

4. The method of preparing guar gum and carrageenan complex according to claim 1, characterized in that, The salt solution is a potassium chloride solution, a calcium chloride solution or a magnesium chloride solution.

5. The process for the preparation of guar gum and carrageenan complex as claimed in claim 4, wherein: The mass fraction of the potassium chloride solution is 10%-20%, and the added amount of potassium chloride is 0.15%-0.25% of the mass of the carrageenan.

6. The process for preparing guar gum and carrageenan complex according to claim 1, characterized in that: Before the salt solution is added, the system pH of the modified gel solution is adjusted to 6.5-7.

5.

7. A guar gum and carrageenan complex, characterized by: The guar gum and carrageenan compound is prepared by the method of any one of claims 1-6.

8. Use of the guar gum and carrageenan compound of claim 7 in the preparation of dough.

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