Natural antioxidant for prefabricated vegetables and preparation method of natural antioxidant

Abstract

The invention relates to a natural antioxidant for prefabricated vegetables and a preparation method of the natural antioxidant, and belongs to the technical field of food additives. The antioxidant is prepared from rosmarinic acid, carnosic acid, drug-loaded cellulose and double-phase chelating microspheres; the drug-loaded cellulose is prepared by modifying cellulose with quercetin, loading anthocyanin and then wrapping with a trehalose-gamma-polyglutamic acid composite film; the biphase chelating microspheres are phytic acid-citric acid biphase sustained-release microspheres formed by wrapping phytic acid and citric acid with a chitosan and sodium alginate composite film. Through multi-component functional complementation, multi-stage slow release design and physical-chemical synergistic barrier, comprehensive inhibition of the oxidation problem of the prefabricated vegetable is realized, a'free radical scavenging-metal chelating-phase interface stabilization 'triple protection system is constructed, accurate oxidation resistance in different stages of processing, storage and transportation is realized, and the prepared vegetable has good market prospects. The bottlenecks of short action period and single protection dimension of a natural antioxidant are broken through.

Description

Technical Field

[0001] The present invention belongs to the technical field of food additives, and particularly relates to a natural antioxidant for prefabricated dishes and a preparation method thereof. Background Art

[0002] Prefabricated dishes, as a kind of convenient food that has been pre-processed and packaged and can be directly cooked or eaten, have rapidly emerged in the food market in recent years. However, prefabricated dishes face many challenges in the processes of processing, storage and circulation, among which the oxidation problem is particularly prominent. Oil oxidation is one of the common problems in prefabricated dishes. Prefabricated dishes generally use oils such as soybean oil, sunflower oil and rapeseed oil, and these oils are extremely prone to oxidation during processing and storage. Oil oxidation not only reduces the nutritional value of prefabricated dishes, but also produces volatile substances with rancid odors and toxic substances, seriously affecting the quality and safety of prefabricated dishes. A large number of free radicals, peroxides, etc. generated will cause oxidative rancidity of the product fat, endangering the health of consumers. Nutritional components such as pigments and vitamins in prefabricated dishes are also easily oxidized. During the processing process, the ingredients come into contact with air, and the pigment substances therein may undergo oxidation reactions, resulting in color changes, affecting the appearance color of prefabricated dishes, and reducing the purchasing desire of consumers. The oxidation of nutritional components such as vitamins will cause the loss of nutrients in prefabricated dishes and cannot meet the nutritional needs of consumers.

[0003] To solve the oxidation problem of prefabricated dishes, antioxidants have emerged as the times require. An antioxidant is a substance that can inhibit or slow down the oxidation of oils and other components. Adding an appropriate amount of antioxidant during the production process of prefabricated dishes can effectively slow down the oxidation rate and extend the storage time of prefabricated dishes. The action mechanism of antioxidants mainly focuses on several ways of oil oxidation and can capture free radicals and terminate the oxidation reaction. For example, oil-soluble antioxidants such as butylated hydroxyanisole and dibutylhydroxytoluene, as well as water-soluble antioxidants such as ascorbic acid and tea polyphenols, can combine with free radicals through their own chemical structures, thereby preventing the continuation of the oxidation reaction and maintaining the color, flavor and nutritional components of the product.

[0004] At present, there are many types of antioxidants on the market. According to the source, they can be divided into synthetic antioxidants and natural antioxidants. Synthetic antioxidants such as tertiary butylhydroquinone have the advantages of strong antioxidant ability, low price and easy availability, and are widely used in edible oils and fried foods. However, a large number of studies have shown that excessive intake has potential hazards to the human body, including liver damage, DNA damage and even gastric cancer. Natural antioxidants such as rosemary extract and grape seed extract have the advantages of safety, high efficiency and high temperature resistance, and have received more and more attention. Rosemary extract has been authorized as a preservative and antioxidant for use in meat, fish and oil. It can not only effectively inhibit oxidation, but also has an anti-microbial effect, which can not only extend the shelf life but also increase the flavor.

[0005] However, a single antioxidant often has difficulty meeting the complex antioxidant requirements of prefabricated dishes. Due to the complex composition of prefabricated dishes, which include a variety of ingredients and seasonings, it is difficult to achieve the best antioxidant effect with a single antioxidant; moreover, the antioxidant period of natural antioxidants still cannot meet the long-term storage and transportation requirements, and the decline in freshness affects the edible taste. Summary of the Invention

[0006] Aiming at the problem that a single existing antioxidant is difficult to achieve the best antioxidant effect, and the antioxidant period of natural antioxidants still cannot meet the long-term storage and transportation requirements, and the decline in freshness affects the edible taste. The present invention provides a natural antioxidant for prefabricated dishes and a preparation method thereof. Through multi-component functional complementarity, multi-stage sustained release design and physical-chemical synergistic barrier, all-round inhibition of the oxidation problem of prefabricated dishes is achieved, and a "free radical scavenging-metal chelation-phase interface stabilization" triple protection system is constructed to achieve precise antioxidant protection at different stages of processing, storage and transportation, breaking through the bottleneck of the short action period and single protection dimension of natural antioxidants. The specific technical solutions are as follows:

[0007] A natural antioxidant for prefabricated dishes, comprising rosmarinic acid, carnosic acid, drug-loaded cellulose and biphasic chelating microspheres; the drug-loaded cellulose is obtained by modifying cellulose with quercetin, loading anthocyanins, and then wrapping with a trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are phytic acid-citric acid biphasic sustained release microspheres formed by wrapping phytic acid and citric acid with a composite film of chitosan and sodium alginate.

[0008] Further, the preparation method of the drug-loaded cellulose includes: dispersing microcrystalline cellulose in an acetate buffer solution to form a cellulose solution; dissolving quercetin in ethanol to form a quercetin solution; adding the quercetin solution to the cellulose solution, stirring for surface modification, centrifuging to obtain a solid product, washing, and drying to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in water, adding anthocyanins, stirring for a loading reaction, filtering, taking the solid and drying to obtain the loaded cellulose; preparing a composite film solution with water, γ-polyglutamic acid, and trehalose; dispersing the loaded cellulose in the composite film solution, stirring for a coating reaction, centrifuging, and taking the solid and drying to obtain the drug-loaded cellulose.

[0009] Furthermore, the preparation method of the drug-loaded cellulose includes: by mass ratio, acetic acid buffer: microcrystalline cellulose: ethanol: quercetin = (180 - 200):(10 - 12):(50 - 80):(3 - 4); dispersing microcrystalline cellulose in the acetic acid buffer to form a cellulose solution; dissolving quercetin in ethanol to form a quercetin solution; adding the quercetin solution to the cellulose solution under stirring conditions for surface modification, centrifuging to separate the solid product, washing with deionized water, and drying in vacuum to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in deionized water with a mass 15 - 20 times that of the quercetin-modified cellulose, adding anthocyanin with a mass of 5% - 8% of the quercetin-modified cellulose, stirring for the loading reaction, and embedding and loading the anthocyanin onto the quercetin-modified cellulose by π-π stacking interaction and hydrogen bonding, filtering, taking the solid and drying in vacuum to obtain the loaded cellulose; by mass ratio, deionized water: γ-polyglutamic acid: trehalose = (90 - 100):(1 - 2):(0.5 - 0.8), preparing a composite membrane solution; dispersing the loaded cellulose in the composite membrane solution with a mass 10 - 12 times that of the loaded cellulose, stirring for the coating reaction, centrifuging, taking the solid and drying in vacuum to obtain the drug-loaded cellulose.

[0010] In the preparation method of the drug-loaded cellulose, the acetic acid buffer is an acetic acid-sodium acetate buffer with a pH of 4.3 - 4.7.

[0011] In the preparation method of the drug-loaded cellulose, the temperature of the surface modification is 50°C - 55°C, and the time of the surface modification is 4 h - 6 h; the number of times of washing with deionized water is 3 - 5 times; the temperature of the loading reaction is 30°C - 35°C, and the time of the loading reaction is 2 h - 3 h; the time of the stirring coating reaction is 30 min - 90 min.

[0012] In the preparation method of the drug-loaded cellulose, the rotation speed of the stirring is 100 r / min - 200 r / min; the rotation speed of the centrifuging is 5000 r / min - 6000 r / min, and the time of the centrifuging is 15 min - 20 min; the vacuum drying is carried out at 40°C - 50°C until constant weight.

[0013] In the preparation method of the drug-loaded cellulose, the anthocyanin is the anthocyanin extracted from grape seeds.

[0014] Further, the preparation method of the biphasic chelating microspheres includes: by mass ratio, phytic acid: citric acid: chitosan: sodium alginate = (2-3):(1-2):(0.8-1.2):(0.6-1), dissolving phytic acid and citric acid in water to prepare a mixed solution; dissolving chitosan in an acetic acid aqueous solution to prepare a chitosan solution; dissolving sodium alginate in water to prepare a sodium alginate solution; under continuous stirring, first adding the mixed solution into the chitosan solution to form a primary emulsion, then adding the primary emulsion into the sodium alginate solution, stirring for cross-linking reaction to obtain a reaction solution, adding a calcium chloride aqueous solution to solidify the microspheres, filtering, taking the solid, washing with deionized water, and drying to constant weight to obtain phytic acid-citric acid biphasic sustained-release microspheres.

[0015] In the preparation method of the biphasic chelating microspheres, the phytic acid and citric acid are dissolved in water with a mass 5 to 8 times the total mass of phytic acid and citric acid; the chitosan is dissolved in an acetic acid aqueous solution with a mass 50 to 60 times the mass of chitosan, and the concentration of the acetic acid aqueous solution is 1.5 wt% to 2 wt%; the sodium alginate is dissolved in water with a mass 50 to 60 times the mass of sodium alginate.

[0016] In the preparation method of the biphasic chelating microspheres, the stirring speed is 200 r / min to 300 r / min; the stirring cross-linking reaction time is 2 h to 3 h; the dosage of the calcium chloride aqueous solution is 10% to 20% of the volume of the reaction solution, and the concentration of the calcium chloride aqueous solution is 1 mol / L to 2 mol / L; the solidification time of the microspheres is 30 min to 60 min; the number of times of washing with deionized water is 3 to 5 times.

[0017] The preparation method of the above-mentioned natural antioxidant for prefabricated dishes includes the following steps: by mass ratio, rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = (20-25):(10-15):(15-20):(6-10), and uniformly mixing to obtain the antioxidant.

[0018] A natural antioxidant for prefabricated dishes and its preparation method provided by the present invention have the following beneficial effects:

[0019] First, both rosmarinic acid and carnosic acid are natural polyphenolic compounds, having strong free radical scavenging ability (neutralizing free radicals by donating hydrogen or electrons), and inhibiting the lipid oxidation chain reaction. Rosmarinic acid and carnosic acid form a cross-phase antioxidant system, covering the oxidation protection of the aqueous phase and oil phase in prefabricated dishes.

[0020] Second, the hydrophobic group of quercetin binds to the hydroxyl group of cellulose through hydrogen bonds to form a porous structure, which improves the loading rate of anthocyanins. Quercetin itself has antioxidant activity and binds to anthocyanins (grape seed proanthocyanidins) through π-π stacking and hydrogen bonds to form a conjugated antioxidant network. γ-Polyglutamic acid and trehalose form a semipermeable membrane to delay the release of anthocyanins, avoid rapid consumption during initial oxidative stress, and prevent the degradation of anthocyanins caused by a wet oxygen environment. The γ-polyglutamic acid-trehalose composite film technology is used to achieve the stability of the water / oil biphasic interface.

[0021] Third, phytic acid (strong chelating ability) and citric acid (weak chelating ability) synergistically chelate Fe 3+ , Cu 2+ and other pro-oxidant metal ions to inhibit metal-catalyzed oxidation. Citric acid reduces the local pH and inhibits the activity of lipoxygenase, blocking the enzymatic oxidation pathway. Chitosan (cationic) and sodium alginate (anionic) form a stable microsphere structure through electrostatic cross-linking to achieve the gradient release of phytic acid / citric acid and extend the antioxidant cycle. Sodium alginate and Ca 2+ (from CaCl2) form an "egg box" structure to enhance the mechanical strength of the microspheres and adapt to the mechanical vibration during the storage and transportation of prefabricated dishes. Citric acid (small molecule) is preferentially released to inhibit initial oxidation, and phytic acid (macromolecule) is slowly released to maintain long-term chelating ability.

[0022] Fourth, rosmarinic acid / carnosic acid (direct scavenging) + anthocyanins / quercetin (secondary antioxidant). The phytic acid / citric acid biphasic microspheres block metal-catalyzed oxidation. Citric acid reduces the pH to inhibit enzyme activity, and chitosan resists microorganisms to indirectly reduce enzyme contamination. Each component is used in a certain proportion and has a good synergistic effect.

[0023] Fifth, a spatio-temporal synergistic slow-release system: rosmarinic acid / carnosic acid takes effect quickly to cope with the oxidative stress during the initial processing. The drug-loaded cellulose (slow release of anthocyanins) and the biphasic microspheres (gradient release of phytic acid / citric acid) cover the oxidation protection during storage and transportation, solving the problem of the short action period of natural antioxidants.

[0024] Sixth, a physical-chemical combined barrier: trehalose-γ-polyglutamic acid film (moisture-proof and oxygen-barrier) + chitosan-sodium alginate microspheres (mechanical isolation), reducing the penetration of oxygen and moisture and delaying the oxidation reaction kinetics. Anthocyanin color protection: Through antioxidant and direct reduction effects, it inhibits the oxidative browning of pigments and maintains the appearance of prefabricated dishes.

[0025] In summary, through multi-component functional complementarity (free radical scavenging + metal chelation + enzyme inhibition), multi-stage sustained release design (rapid response + long-term maintenance), and physical-chemical synergistic barrier (controlled release embedding + environmental isolation), this composite antioxidant achieves a comprehensive inhibition of the oxidation problem in prefabricated dishes, constructs a triple protection system of "free radical scavenging - metal chelation - phase interface stabilization", develops sustained release microspheres, realizes precise antioxidant protection at different stages of processing, storage, and transportation, breaks through the bottleneck of the short action cycle and single protection dimension of single natural antioxidants, significantly extends the shelf life, and maintains nutritional and sensory qualities.

[0026] Detailed Description of the Invention

[0027] Example 1

[0028] A natural antioxidant for prefabricated dishes, comprising rosmarinic acid, carnosic acid, drug-loaded cellulose, and biphasic chelating microspheres; the drug-loaded cellulose is prepared by modifying cellulose with quercetin, loading anthocyanins, and then wrapping it with a trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are formed by wrapping phytic acid and citric acid with a chitosan and sodium alginate composite film to form phytic acid-citric acid biphasic sustained release microspheres. According to the mass ratio, rosmarinic acid:carnosic acid:drug-loaded cellulose:biphasic chelating microspheres = 23:12:17:8, and they are mixed to obtain the antioxidant.

[0029] Among them, the preparation method of the drug-loaded cellulose includes: according to the mass ratio, acetic acid buffer solution:microcrystalline cellulose:ethanol:quercetin = 190:11:65:3.5; dispersing microcrystalline cellulose in the acetic acid buffer solution to form a cellulose solution, and the acetic acid buffer solution is an acetic acid-sodium acetate buffer solution with a pH of 4.5; dissolving quercetin in ethanol to form a quercetin solution; under the stirring condition of 150 r / min, adding the quercetin solution to the cellulose solution, and performing surface modification by stirring at 52 °C and 150 r / min for 5 h, centrifuging at 5500 r / min for 18 min, separating to obtain a solid product, washing it 4 times with deionized water, and drying it to constant weight in a vacuum at 45 °C to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in deionized water with a mass 18 times that of the quercetin-modified cellulose, adding 6.5% of the mass of the quercetin-modified cellulose of anthocyanins, and the anthocyanins are grape seed proanthocyanidins, and performing a loading reaction by stirring at 32 °C and 150 r / min for 2.5 h, and embedding and loading the anthocyanins into the quercetin-modified cellulose by π-π stacking and hydrogen bonding, filtering, and drying the solid to constant weight in a vacuum at 45 °C to obtain the loaded cellulose; according to the mass ratio, deionized water:γ-polyglutamic acid:trehalose = 95:1.5:0.7, preparing a composite film solution; dispersing the loaded cellulose in a composite film solution with a mass 11 times that of the loaded cellulose, performing a coating reaction by stirring at 150 r / min for 50 min, centrifuging at 5500 r / min for 18 min, and drying the solid to constant weight in a vacuum at 45 °C to obtain the drug-loaded cellulose.

[0030] Among them, the preparation method of the biphasic chelating microspheres includes: by mass ratio, phytic acid: citric acid: chitosan: sodium alginate = 2.5: 1.5: 1: 0.8. Dissolve phytic acid and citric acid in water with a mass 6.5 times the total mass of phytic acid and citric acid to prepare a mixed solution; dissolve chitosan in an acetic acid aqueous solution with a concentration of 1.8 wt% and a mass 55 times that of chitosan to prepare a chitosan solution; dissolve sodium alginate in water with a mass 55 times that of sodium alginate to prepare a sodium alginate solution; under the continuous stirring state of 250 r / min, first add the mixed solution to the chitosan solution to form a primary emulsion, and then add the primary emulsion to the sodium alginate solution, and stir and crosslink for 2.5 h at 250 r / min to obtain a reaction solution. Add a 1.5 mol / L calcium chloride aqueous solution with a volume of 15% of the reaction solution volume to solidify the microspheres for 40 min, filter, wash the solid with deionized water 4 times, and dry to constant weight to obtain phytic acid-citric acid biphasic sustained-release microspheres.

[0031] Example 2

[0032] A natural antioxidant for prefabricated dishes includes rosmarinic acid, carnosic acid, drug-loaded cellulose, and biphasic chelating microspheres; the drug-loaded cellulose is quercetin-modified cellulose loaded with anthocyanins and then wrapped with a trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are phytic acid-citric acid biphasic sustained-release microspheres formed by wrapping phytic acid and citric acid with a chitosan and sodium alginate composite film. By mass ratio, rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = 20: 15: 15: 10, and they are uniformly mixed to obtain the antioxidant.

[0033] Among them, the preparation method of the drug-loaded cellulose includes: by mass ratio, acetic acid buffer: microcrystalline cellulose: ethanol: quercetin = 180:12:50:4; dispersing microcrystalline cellulose in the acetic acid buffer to form a cellulose solution, and the acetic acid buffer is an acetic acid-sodium acetate buffer with a pH of 4.3; dissolving quercetin in ethanol to form a quercetin solution; under the stirring condition of 200 r / min, adding the quercetin solution to the cellulose solution, performing surface modification by stirring at 50 °C and 200 r / min for 4 h, centrifuging at 6000 r / min for 15 min, separating to obtain a solid product, washing with deionized water 5 times, and drying in vacuum at 40 °C to constant weight to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in deionized water with a mass 20 times that of the quercetin-modified cellulose, adding grape seed proanthocyanidin, which is 5% of the mass of the quercetin-modified cellulose, and performing a loading reaction by stirring at 35 °C and 100 r / min for 3 h. The proanthocyanidin is embedded and loaded on the quercetin-modified cellulose by π-π stacking and hydrogen bond binding, filtering, and taking the solid and drying in vacuum at 40 °C to constant weight to obtain the loaded cellulose; by mass ratio, deionized water: γ-polyglutamic acid: trehalose = 100:1:0.8, preparing a composite membrane solution; dispersing the loaded cellulose in a composite membrane solution with a mass 10 times that of the loaded cellulose, performing a coating reaction by stirring at 200 r / min for 30 min, centrifuging at 6000 r / min for 15 min, taking the solid and drying in vacuum at 50 °C to constant weight to obtain the drug-loaded cellulose.

[0034] Among them, the preparation method of the biphasic chelating microspheres includes: by mass ratio, phytic acid: citric acid: chitosan: sodium alginate = 2:2:0.8:1, dissolving phytic acid and citric acid in water with a mass 5 times the total mass of phytic acid and citric acid to prepare a mixed solution; dissolving chitosan in an acetic acid aqueous solution with a concentration of 1.5 wt% and a mass 60 times that of chitosan to prepare a chitosan solution; dissolving sodium alginate in water with a mass 60 times that of sodium alginate to prepare a sodium alginate solution; under the continuous stirring condition of 200 r / min, first adding the mixed solution to the chitosan solution to form a primary emulsion, and then adding the primary emulsion to the sodium alginate solution, and performing a cross-linking reaction by stirring at 300 r / min for 2 h to obtain a reaction solution, adding a 1 mol / L calcium chloride aqueous solution with a volume 20% of the reaction solution volume, curing the microspheres for 60 min, filtering, taking the solid and washing with deionized water 3 times, and drying to constant weight to obtain the phytic acid-citric acid biphasic sustained-release microspheres.

[0035] Example 3

[0036] A natural antioxidant for prefabricated dishes, comprising rosmarinic acid, carnosic acid, drug-loaded cellulose, and biphasic chelating microspheres; the drug-loaded cellulose is prepared by modifying cellulose with quercetin and then loading anthocyanins, and then wrapping it with a trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are prepared by wrapping phytic acid and citric acid with a composite film of chitosan and sodium alginate to form phytic acid-citric acid biphasic sustained-release microspheres. By mass ratio, rosmarinic acid:carnosic acid:drug-loaded cellulose:biphasic chelating microspheres = 25:10:20:6, and they are uniformly mixed to obtain the antioxidant.

[0037] Among them, the preparation method of the drug-loaded cellulose includes: by mass ratio, acetic acid buffer solution:microcrystalline cellulose:ethanol:quercetin = 200:10:80:3; dispersing microcrystalline cellulose in the acetic acid buffer solution to form a cellulose solution, and the acetic acid buffer solution is an acetic acid-sodium acetate buffer solution with a pH of 4.7; dissolving quercetin in ethanol to form a quercetin solution; under the stirring condition of 100 r / min, adding the quercetin solution to the cellulose solution, and performing surface modification at 55 °C and 100 r / min for 6 h, centrifuging at 5000 r / min for 20 min, separating to obtain a solid product, washing it 3 times with deionized water, and drying it in vacuum at 50 °C to constant weight to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in deionized water with a mass 15 times that of the quercetin-modified cellulose, adding anthocyanins with a mass of 8% of the quercetin-modified cellulose, and the anthocyanins are grape seed proanthocyanidins, and performing a loading reaction by stirring at 30 °C and 200 r / min for 2 h, and embedding and loading the anthocyanins into the quercetin-modified cellulose by π-π stacking and hydrogen bond binding, filtering, and taking the solid and drying it in vacuum at 50 °C to constant weight to obtain the loaded cellulose; by mass ratio, deionized water:γ-polyglutamic acid:trehalose = 90:2:0.5, preparing a composite film solution; dispersing the loaded cellulose in a composite film solution with a mass 12 times that of the loaded cellulose, and performing a coating reaction by stirring at 100 r / min for 90 min, centrifuging at 5000 r / min for 20 min, and taking the solid and drying it in vacuum at 40 °C to constant weight to obtain the drug-loaded cellulose.

[0038] Among them, the preparation method of the biphasic chelating microspheres includes: by mass ratio, phytic acid: citric acid: chitosan: sodium alginate = 3:1:1.2:0.6. Dissolve phytic acid and citric acid in water with a total mass 8 times that of phytic acid and citric acid to prepare a mixed solution; dissolve chitosan in an acetic acid aqueous solution with a concentration of 2 wt% and a mass 50 times that of chitosan to prepare a chitosan solution; dissolve sodium alginate in water with a mass 50 times that of sodium alginate to prepare a sodium alginate solution; under the condition of continuous stirring at 300 r / min, first add the mixed solution to the chitosan solution to form a primary emulsion, then add the primary emulsion to the sodium alginate solution, stir and crosslink at 200 r / min for 3 h to obtain a reaction solution, add a 2 mol / L calcium chloride aqueous solution with a volume of 10% of the reaction solution volume, solidify the microspheres for 30 min, filter, wash the solid with deionized water 5 times, and dry to a constant weight to obtain phytic acid-citric acid biphasic sustained-release microspheres.

[0039] In the above-mentioned examples, the raw materials are all food-grade. Rosmarinic acid is from Xi'an Hongtaiyuan Biotechnology Co., Ltd. with a purity of 98%. Carnosic acid is from Shaanxi Zhuotao Biotechnology Co., Ltd. with a purity of 95%. Microcrystalline cellulose is from Guangdong Osmann Biotechnology Co., Ltd. Quercetin is from Xi'an Jiahe Biotechnology Co., Ltd. with a purity of 95%. Grape seed proanthocyanidins are from Peiai Biotechnology Co., Ltd. with an OPC purity of grape seed proanthocyanidins of 95%. γ-Polyglutamic acid is from Shaanxi Yuanshengte Biotechnology Co., Ltd. with a molecular weight below 700,000. Trehalose is from Henan Qinuo Food Ingredients Co., Ltd. Phytic acid is from Jiangsu Changjing Bioengineering Co., Ltd. with a purity of 50%. Citric acid is from Shaanxi Yuanshengte Biotechnology Co., Ltd. with a purity of 99%. Chitosan is low-molecular-weight chitosan from Shanxi Fenlu Biotechnology Co., Ltd. with a molecular weight below 1000 Da. Sodium alginate is from Henan Anrui Biotechnology Co., Ltd., model 01, water-based.

[0040] Comparative Example 1

[0041] Change the mass ratio of the antioxidants to rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = 12:23:17:8; other parameters and methods are the same as in Example 1.

[0042] Comparative Example 2

[0043] Change the mass ratio of the antioxidants to rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = 23:12:8:17; other parameters and methods are the same as in Example 1.

[0044] Comparative Example 3

[0045] Change the mass ratio of the antioxidants to rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = 12:23:8:17; other parameters and methods are the same as in Example 1.

[0046] Comparative Example 4

[0047] In the preparation method of the drug-loaded cellulose, microcrystalline cellulose is not modified with quercetin; other parameters and methods are the same as in Example 1.

[0048] Comparative Example 5

[0049] In the preparation method of the drug-loaded cellulose, trehalose is used to replace γ-polyglutamic acid in the composite membrane solution; other parameters and methods are the same as in Example 1.

[0050] Comparative Example 6

[0051] In the preparation method of the drug-loaded cellulose, γ-polyglutamic acid is used to replace trehalose in the composite membrane solution; other parameters and methods are the same as in Example 1.

[0052] Comparative Example 7

[0053] In the preparation method of the drug-loaded cellulose, the loaded cellulose is not wrapped with the composite membrane solution; other parameters and methods are the same as in Example 1.

[0054] Comparative Example 8

[0055] In the preparation method of the biphasic chelating microspheres, the mass ratio is modified to phytic acid:citric acid:chitosan:sodium alginate = 3.5:0.5:1:0.8; other parameters and methods are the same as in Example 1.

[0056] Comparative Example 9

[0057] In the preparation method of the biphasic chelating microspheres, no chitosan coating is added; other parameters and methods are the same as in Example 1.

[0058] Comparative Example 10

[0059] In the preparation method of the biphasic chelating microspheres, no sodium alginate coating is added; other parameters and methods are the same as in Example 1.

[0060] Comparative Example 11

[0061] The biphasic chelating microspheres are not prepared, and the biphasic chelating microspheres are replaced with a mixture of phytic acid and citric acid with a mass ratio of 2.5:1.5; other parameters and methods are the same as in Example 1.

[0062] Comparative Example 12

[0063] The antioxidant is directly replaced with rosmarinic acid.

[0064] Oxidation stability detection: The accelerated oxidation experiment was used to evaluate the oxidation stability of prefabricated dishes after adding different antioxidants. In the accelerated oxidation experiment, the oxidation process of oils and fats was accelerated by increasing conditions such as temperature and humidity to simulate the oxidation situation of prefabricated dishes during actual storage and circulation. By regularly measuring the peroxide value and acid value, the degree of oil oxidation was judged. The peroxide value is an index to measure the content of peroxides in oils and fats. Peroxides are the primary products of oil oxidation, and the increase in their content reflects the occurrence of oxidation reactions; the acid value represents the content of free fatty acids in oils and fats. As the oil oxidation progresses, fatty acids will gradually decompose, resulting in an increase in the acid value. The slower the growth of the peroxide value and acid value, the better the inhibitory effect of the antioxidant on oil oxidation, and the higher the oxidation stability of the prefabricated dishes.

[0065] Samples of prefabricated chicken added with different antioxidants (each sample had a mass of 100 g and the antioxidant addition amount was 200 mg / kg) were placed in a constant temperature and humidity chamber with the temperature set at 60 °C and the humidity at 75%. Sampling was carried out regularly on the 0th day (before adding the antioxidant) and the 15th day. The peroxide value was determined by the sodium thiosulfate titration method: Accurately weigh 2 g of the sample into an iodine flask, add 30 mL of a chloroform - glacial acetic acid mixture (volume ratio 4:6) to completely dissolve the sample. Add 1.00 mL of saturated potassium iodide solution, quickly stopper the flask, shake gently, and place it in the dark for 5 min. After taking it out, add 100 mL of water and titrate with a 0.01 mol / L sodium thiosulfate standard solution until it turns light yellow. Add 1 mL of starch indicator and continue titrating until the blue color disappears as the end point. At the same time, a blank experiment was done. Peroxide value (mmol / kg) = (V - V0) × c × 1000 / m, where V is the volume of the sodium thiosulfate standard solution consumed by the sample (mL), V0 is the volume of the sodium thiosulfate standard solution consumed by the blank (mL), c is the concentration of the sodium thiosulfate standard solution (mol / L), and m is the sample mass (g). The test results are shown in Table 1 below. The acid value was determined by the potassium hydroxide ethanol solution titration method: Accurately weigh 4 g of the sample into a conical flask, add 50 mL of a neutral ether - ethanol mixture (volume ratio 2:1), shake to dissolve the sample. Add 3 drops of phenolphthalein indicator and titrate with a 0.1 mol / L potassium hydroxide ethanol standard solution until the solution turns slightly red and does not fade within 30 s as the end point. Acid value (mg / g) = (V - V0) × c × 56.11 / m, where V is the volume of the potassium hydroxide ethanol standard solution consumed by the sample (mL), V0 is the volume of the potassium hydroxide ethanol standard solution consumed by the blank (mL), c is the concentration of the potassium hydroxide ethanol standard solution (mol / L), m is the sample mass (g), and 56.11 is the molar mass of potassium hydroxide (g / mol). The test results are shown in Table 1 below.

[0066] Table 1 Test data results

[0067]

[0068]

[0069] Among them, the prefabricated chicken cubes are samples of the same batch, with an initial peroxide value of 0.03 mmol / kg and an acid value of 0.26 mg / g.

[0070] It can be seen from the above results that under the same conditions, the peroxide values and acid values of Examples 1 to 3 increase more slowly; the antioxidants in the examples have a more stable and long-lasting antioxidant effect.

[0071] In Comparative Example 1, the ratio of rosmarinic acid to carnosic acid is different from that in Example 1, with a decrease in rosmarinic acid and an increase in carnosic acid. Rosmarinic acid and carnosic acid can exert a synergistic effect through different action mechanisms during the antioxidant process. The change in the ratio destroys this synergistic effect. Rosmarinic acid has an advantage in capturing specific free radicals. The decrease in its content leads to a weakened ability to scavenge certain free radicals, resulting in a decrease in the free radical scavenging rate. In terms of inhibiting lipid oxidation, the imbalance of the synergistic effect causes the peroxide value and acid value to increase.

[0072] Comparative Example 2 changes the ratio of the drug-loaded cellulose to the biphasic chelating microspheres. Quercetin-modified cellulose in the drug-loaded cellulose loads anthocyanins, and phytic acid and citric acid in the biphasic chelating microspheres inhibit oxidation from different perspectives in the prefabricated food system. The drug-loaded cellulose mainly directly scavenges free radicals through its loaded antioxidant components, while the biphasic chelating microspheres chelate metal ions by slowly releasing phytic acid and citric acid to inhibit the initiation of oxidation reactions. After the ratio is changed, this synergistic ability to inhibit oxidation decreases, resulting in poor antioxidant performance.

[0073] Comparative Example 3 completely changes the ratio of each component, further disrupting the synergistic balance among the antioxidants. The free radical scavenging ability drops significantly, lipid oxidation intensifies, the peroxide value and acid value increase significantly, and the color of the prefabricated food also changes more greatly. This fully demonstrates that the ratio among the components of the antioxidant is crucial for its optimal antioxidant performance.

[0074] Comparative Example 4 (microcrystalline cellulose is not modified with quercetin): Quercetin-modified cellulose is the key basis for the drug-loaded cellulose to exert its antioxidant effect. Quercetin has multiple phenolic hydroxyl groups, which can provide hydrogen atoms to combine with free radicals, thereby scavenging free radicals. When microcrystalline cellulose is not modified with quercetin, these antioxidant-active groups cannot be introduced, resulting in a lack of a stable antioxidant environment for the subsequent loaded anthocyanins. Without quercetin modification, the loading amount and loading stability of cellulose for anthocyanins will be affected, leading to a significant reduction in the overall antioxidant ability of the drug-loaded cellulose. In the free radical scavenging experiment, the scavenging rate drops significantly; in the accelerated oxidation experiment, it cannot effectively inhibit lipid oxidation, and the peroxide value and acid value increase.

[0075] In Comparative Example 5, trehalose was used to completely replace γ-polyglutamic acid in the composite film solution. γ-Polyglutamic acid has good film-forming properties and biocompatibility, and its unique structure can synergistically act with trehalose to effectively encapsulate the cellulose loaded with drugs and protect the antioxidant components inside. When γ-polyglutamic acid was replaced, the structure and properties of the composite film changed, and it could not tightly encapsulate the cellulose loaded with drugs. The cellulose loaded with drugs was more vulnerable to external factors such as moisture and oxygen in the prefabricated food system, and the antioxidant components inside were more likely to be lost or inactivated, resulting in a decrease in antioxidant capacity. This was manifested as a decrease in the free radical scavenging rate and an increase in the peroxide value and acid value.

[0076] In Comparative Example 6, trehalose was replaced by γ-polyglutamic acid, which also destroyed the original properties of the composite film. Trehalose has functions such as moisturizing and stabilizing the structure of biological macromolecules, and it jointly maintains the stability of the cellulose loaded with drugs with γ-polyglutamic acid in the composite film. After trehalose was replaced, the stability of the composite film and its protective ability for the cellulose loaded with drugs decreased, resulting in a weakened antioxidant effect of the antioxidant in the prefabricated food and poorer detection indexes.

[0077] Comparative Example 7 (the cellulose loaded is not wrapped with the composite film solution): The cellulose loaded is not wrapped with the composite film solution and is directly exposed to the prefabricated food system. The moisture, oil, microorganisms, and various chemical reactions in the prefabricated food will all affect the cellulose loaded. Without the protection of the composite film, the anthocyanins in the cellulose loaded are easily oxidized and decomposed, and the quercetin-modified cellulose is also easily damaged, resulting in a rapid decrease in its antioxidant capacity. In the accelerated oxidation experiment, it could not effectively slow down the release and inhibit the oxidation of oil, and the peroxide value and acid value increased rapidly.

[0078] Comparative Example 8 (the mass ratio of the components of the biphasic chelating microspheres is changed): The mass ratio of phytic acid, citric acid, chitosan, and sodium alginate in the biphasic chelating microspheres was changed, which affected the structure and properties of the microspheres. Phytic acid and citric acid are the main antioxidant components, and they inhibit the oxidation of oil by chelating metal ions. The composite film formed by chitosan and sodium alginate controls the slow release rate of phytic acid and citric acid. When the mass ratio was changed to phytic acid:citric acid:chitosan:sodium alginate = 3.5:0.5:1:0.8, the content of phytic acid increased while the content of citric acid decreased, breaking the synergistic chelation between the two. At the same time, the structure of the composite film also changed due to the ratio change, affecting the slow release effect of phytic acid and citric acid. In the prefabricated food system, the antioxidant components could not continuously and effectively play their roles, resulting in a decrease in the free radical scavenging rate and an increase in the peroxide value and acid value.

[0079] In Comparative Example 9, no chitosan coating was added, and the structure of the two-phase chelated microspheres became incomplete. Chitosan not only plays a film-forming role in the composite film, but also can cross-link with sodium alginate to form a stable network structure, controlling the release of phytic acid and citric acid. Without chitosan, the microspheres cannot form an effective sustained-release system, and phytic acid and citric acid will be quickly released into the pre-prepared food system. Although the rapidly released antioxidant components have a certain antioxidant effect in the early stage, they cannot continuously inhibit the oxidation of oils and fats, resulting in a rapid increase in peroxide value and acid value in the later stage, and a decrease in free radical scavenging rate.

[0080] Comparative Example 10, without sodium alginate coating, also destroyed the integrity of the dual-phase chelated microspheres. Sodium alginate and chitosan work together to maintain the microspheres' morphology and function. Without sodium alginate, the microspheres' stability decreased, and phytic acid and citric acid were easily lost, preventing them from maintaining their antioxidant effects during storage. This significantly reduced antioxidant performance and deteriorated various test indicators.

[0081] Comparative Example 11 (replacing the biphasic chelating microspheres with a mixture of phytic acid and citric acid): The biphasic chelating microspheres were replaced with a mixture of phytic acid and citric acid in a mass ratio of 2.5:1.5, which lost the sustained-release effect and synergistic effect of the microspheres. The biphasic chelating microspheres are wrapped in a composite membrane of chitosan and sodium alginate, which can slowly release phytic acid and citric acid and continuously inhibit oil oxidation. However, the phytic acid and citric acid in the mixture will quickly contact and react with the ingredients in the pre-prepared food system, and cannot maintain a stable antioxidant effect for a long time. There is a certain free radical scavenging ability in the early stage, but the scavenging rate decreases significantly over time; in the accelerated oxidation experiment, it cannot effectively inhibit the increase in peroxide value and acid value.

[0082] Comparative Example 12 uses a single antioxidant ingredient (rosmarinic acid), which has a single antioxidant mechanism and lacks the synergistic effect of multiple antioxidants, nor does it have a sustained-release and stable antioxidant effect. Its antioxidant stability effect is the worst.

Claims

1. A natural antioxidant for prefabricated dishes, characterized in that, The antioxidants include rosmarinic acid, carnosic acid, drug-loaded cellulose, and biphasic chelating microspheres; the drug-loaded cellulose is prepared by modifying cellulose with quercetin, loading anthocyanins, and then wrapping with a trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are formed by wrapping phytic acid and citric acid with a composite film of chitosan and sodium alginate to form phytic acid-citric acid biphasic sustained-release microspheres.

2. The natural antioxidant for prefabricated dishes according to claim 1, characterized in that, The preparation method of the drug-loaded cellulose includes: dispersing microcrystalline cellulose in an acetic acid buffer solution to form a cellulose solution; dissolving quercetin in ethanol to form a quercetin solution; adding the quercetin solution to the cellulose solution, stirring for surface modification, centrifuging to obtain a solid product, washing, and drying to obtain quercetin-modified cellulose; dispersing the quercetin-modified cellulose in water, adding anthocyanins, stirring for a loading reaction, filtering, taking the solid and drying to obtain the loaded cellulose; preparing a composite film solution with water, γ-polyglutamic acid, and trehalose; dispersing the loaded cellulose in the composite film solution, stirring for a coating reaction, centrifuging, and taking the solid and drying to obtain the drug-loaded cellulose.

3. The natural antioxidant for prefabricated dishes according to claim 2, characterized in that, The acetic acid buffer solution is an acetic acid-sodium acetate buffer solution with a pH of 4.3 to 4.

7.

4. The natural antioxidant for prefabricated dishes according to claim 2, characterized in that, The temperature of the surface modification is 50°C to 55°C, and the time of the surface modification is 4 h to 6 h; the number of times of washing with deionized water is 3 to 5 times; the temperature of the loading reaction is 30°C to 35°C, and the time of the loading reaction is 2 h to 3 h; the time of the stirring coating reaction is 30 min to 90 min.

5. The natural antioxidant for prefabricated dishes according to claim 2, wherein The rotation speed of the stirring is 100 r / min to 200 r / min; the rotation speed of the centrifuging is 5000 r / min to 6000 r / min, and the time of the centrifuging is 15 min to 20 min; the drying is carried out in a vacuum at 40°C to 50°C until constant weight.

6. The natural antioxidant for prefabricated dishes according to claim 2, characterized in that, The anthocyanins are grape seed proanthocyanidins.

7. A natural antioxidant for prefabricated dishes according to claim 1, characterized in that, The preparation method of the biphasic chelating microspheres includes: according to the mass ratio, phytic acid:citric acid:chitosan:sodium alginate = (2 to 3):(1 to 2):(0.8 to 1.2):(0.6 to 1), dissolving phytic acid and citric acid in water to prepare a mixed solution; dissolving chitosan in an acetic acid aqueous solution to prepare a chitosan solution; dissolving sodium alginate in water to prepare a sodium alginate solution; under continuous stirring, first adding the mixed solution to the chitosan solution to form a primary emulsion, then adding the primary emulsion to the sodium alginate solution, stirring for a cross-linking reaction to obtain a reaction solution, adding a calcium chloride aqueous solution to solidify the microspheres, filtering, taking the solid and washing with deionized water, and drying to constant weight to obtain the phytic acid-citric acid biphasic sustained-release microspheres.

8. A natural antioxidant for prefabricated dishes according to claim 7, characterized in that, The phytic acid and citric acid are dissolved in 5 to 8 times the total mass of phytic acid and citric acid in water; the chitosan is dissolved in 50 to 60 times the mass of chitosan in an acetic acid aqueous solution, and the concentration of the acetic acid aqueous solution is 1.5 wt% to 2 wt%; the sodium alginate is dissolved in 50 to 60 times the mass of sodium alginate in water.

9. The natural antioxidant for prefabricated dishes according to claim 7, characterized in that, The speed of the stirring is 200 r / min to 300 r / min; the time of the stirring cross-linking reaction is 2 h to 3 h; the dosage of the calcium chloride aqueous solution is 10% to 20% of the volume of the reaction solution, and the concentration of the calcium chloride aqueous solution is 1 mol / L to 2 mol / L; the time of curing the microspheres is 30 min to 60 min; the number of times of washing with deionized water is 3 to 5 times.

10. The preparation method of the natural antioxidant for prefabricated dishes according to claim 1, characterized in that, It includes the following steps: according to the mass ratio, rosmarinic acid: carnosic acid: drug-loaded cellulose: biphasic chelating microspheres = (20 - 25):(10 - 15):(15 - 20):(6 - 10), uniformly mix them to obtain the antioxidant.

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