Natural antioxidant for pre-prepared meals and method for its preparation

Abstract

The present application relates to a kind of natural antioxidants for pre-prepared dishes and its preparation method, belong to food additive technical field;Antioxidant includes rosemary acid, salvia acid, drug-loaded cellulose and double-phase chelating microspheres;Drug-loaded cellulose is loaded anthocyanin after quercetin modification cellulose, then be wrapped by trehalose-gamma-polyglutamic acid complex film;Double-phase chelating microspheres are phytic acid and citric acid, and the phytic acid-citric acid double-phase sustained-release microspheres formed by sodium alginate complex film wrapping phytic acid and citric acid.The present application realizes the all-round inhibition to pre-prepared dishes oxidation by multi-component function complementation, multi-level sustained-release design and physical-chemical synergistic barrier, constructs "free radical scavenging-metal chelation-phase interface stability" triple protection system, realizes the accurate antioxidation of different stages of processing, storage and transportation, breaks through the bottleneck of short action period and single protection dimension of natural antioxidant.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food additives, and particularly relates to a natural antioxidant for pre-prepared dishes and a preparation method thereof. BACKGROUND

[0002] Pre-prepared dishes, as a kind of convenient food that has been pre-processed and packaged, can be directly cooked or eaten, and have rapidly risen in the food market in recent years. However, pre-prepared dishes face many challenges in quality deterioration during processing, storage and circulation, among which the problem of oxidation is particularly prominent. Oil oxidation is one of the common problems in pre-prepared dishes. Pre-prepared dishes generally use soybean oil, sunflower oil and rapeseed oil, and these oils are prone to oxidation during processing and storage. Oil oxidation not only reduces the nutritional value of pre-prepared dishes, but also produces volatile substances and toxic substances with rancid smell, seriously affecting the quality and safety of pre-prepared dishes. A large amount of free radicals, peroxides and other substances produced will cause product fat oxidation and rancidity, endangering the health of consumers. The nutrients such as pigments and vitamins in pre-prepared dishes are also prone to oxidation. During processing, the pigments in the food materials may be oxidized, causing color change, affecting the appearance and color of pre-prepared dishes, and reducing the purchase desire of consumers. The oxidation of nutrients such as vitamins will cause the loss of nutrients in pre-prepared dishes, which cannot meet the nutritional needs of consumers.

[0003] In order to solve the problem of oxidation of pre-prepared dishes, antioxidants have emerged as the times require. Antioxidants are substances that can inhibit or slow down the oxidation of oils and other ingredients. Adding an appropriate amount of antioxidant in the production process of pre-prepared dishes can effectively slow down the oxidation rate and prolong the storage time of pre-prepared dishes. The mechanism of action of antioxidants is mainly aimed at the several ways of oil oxidation, which can capture free radicals and terminate the oxidation reaction. For example, oil-soluble antioxidants such as butylated hydroxyanisole and dibutylhydroxytoluene, and water-soluble antioxidants such as ascorbic acid and tea polyphenols, can combine with free radicals through their chemical structure, thereby preventing the continuation of the oxidation reaction and maintaining the color, flavor and nutrient content of the product.

[0004] At present, there are various types of antioxidants on the market, which can be divided into synthetic antioxidants and natural antioxidants according to their sources. Synthetic antioxidants such as tert-butyl hydroquinone have the advantages of strong antioxidant capacity, 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 harm 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 are attracting more and more attention. Rosemary extract has been authorized as a preservative and antioxidant for meat, fish and oil, which can not only effectively inhibit oxidation, but also has antimicrobial effect, prolonging the shelf life and increasing the flavor.

[0005] But a single antioxidant is often difficult to meet the complex antioxidant needs of pre-prepared dishes. Because the ingredients of pre-prepared dishes are complex, containing various food materials and seasonings, it is difficult to achieve the best antioxidant effect by using a single antioxidant; and the antioxidant period of natural antioxidants still cannot meet the long-term storage and transportation needs, and the decline in freshness affects the eating taste. SUMMARY

[0006] In view of the fact that the existing single 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 needs, and the decline in freshness affects the eating taste. The present application provides a natural antioxidant for pre-prepared dishes and a preparation method thereof, which realizes all-round inhibition of the oxidation problem of pre-prepared dishes through multi-component functional complementation, multi-stage slow-release design and physical-chemical synergistic barrier, constructs a "free radical scavenging-metal chelation-phase interface stabilization" triple protection system, realizes precise antioxidant at different stages of processing, storage and transportation, and breaks through the bottleneck of short action period and single protection dimension of natural antioxidants. The specific technical scheme is as follows:

[0007] A natural antioxidant for pre-prepared dishes, comprising rosemary acid, salvia acid, drug-loaded cellulose and double-phase chelating microspheres; the drug-loaded cellulose is loaded with anthocyanin after quercetin modified cellulose, and then wrapped with a trehalose-gamma-polyglutamic acid complex film; the double-phase chelating microspheres are formed by wrapping phytic acid and citric acid with a chitosan and sodium alginate complex film.

[0008] Further, the preparation method of the drug-loaded cellulose comprises: dispersing microcrystalline cellulose in an 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, stirring the surface modification, centrifuging to obtain a solid product, washing, drying to obtain quercetin modified cellulose; dispersing the quercetin modified cellulose in water, adding anthocyanin, stirring the loading reaction, filtering, drying the solid to obtain the loaded cellulose; preparing a complex film solution by mixing water, gamma-polyglutamic acid and trehalose; dispersing the loaded cellulose in the complex film solution, stirring the coating reaction, centrifuging, drying the solid to obtain the drug-loaded cellulose.

[0009] Further, the preparation method of the drug-loaded cellulose comprises: according to the mass ratio, acetic acid buffer:microcrystalline cellulose:ethanol:quercetin=(180-200):(10-12):(50-80):(3-4); the microcrystalline cellulose is dispersed in the acetic acid buffer to form a cellulose liquid; the quercetin is dissolved in the ethanol to form a quercetin liquid; under stirring, the quercetin liquid is added to the cellulose liquid, the surface is modified, centrifugation is performed, and the solid product is separated; the solid product is washed with deionized water, vacuum dried, and the quercetin modified cellulose is obtained; the quercetin modified cellulose is dispersed in 15-20 times the mass of the quercetin modified cellulose of deionized water, 5%-8% of the mass of the quercetin modified cellulose of anthocyanin is added, stirring is performed, and the anthocyanin is embedded in the quercetin modified cellulose by π-π stacking and hydrogen bonding; filtration is performed, the solid is vacuum dried, and the drug-loaded cellulose is obtained; according to the mass ratio, deionized water:γ-polyglutamic acid:trehalose=(90-100):(1-2):(0.5-0.8), a composite film solution is prepared; the drug-loaded cellulose is dispersed in 10-12 times the mass of the drug-loaded cellulose of the composite film solution, stirring is performed, and the drug-loaded cellulose is obtained.

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

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

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

[0014] Further, the preparation method of the dual-phase chelating microspheres comprises the following steps: dissolving phytic acid and citric acid in water according to a mass ratio of phytic acid: citric acid: chitosan: sodium alginate = (2-3):(1-2):(0.8-1.2):(0.6-1) 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 and cross-linking to obtain a reaction solution, adding a calcium chloride aqueous solution, solidifying the microspheres, filtering, washing the solid with deionized water, and drying to constant weight to obtain phytic acid-citric acid dual-phase sustained-release microspheres.

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

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

[0017] The preparation method of the natural antioxidant for the pre-prepared food comprises the following steps: uniformly mixing rosmarinic acid, salvia acid, drug-loaded cellulose and dual-phase chelating microspheres according to a mass ratio of rosmarinic acid: salvia acid: drug-loaded cellulose: dual-phase chelating microspheres = (20-25):(10-15):(15-20):(6-10) to obtain the antioxidant.

[0018] The natural antioxidant for the pre-prepared food and the preparation method thereof have the following beneficial effects:

[0019] I. Both rosmarinic acid and salvia acid are natural polyphenolic compounds, have strong free radical scavenging capacity (neutralize free radicals by hydrogen donation or electron), and inhibit lipid oxidation chain reaction. Rosmarinic acid and salvia acid form a cross-phase antioxidant system to cover the oxidation protection of the water phase and the oil phase in the pre-prepared food.

[0020] II. Hydrophobic group of quercetin combined with hydroxyl group of cellulose through hydrogen bond, forming porous structure, improving the loading rate of anthocyanin. Quercetin itself has antioxidant activity, combined with anthocyanin (grape seed proanthocyanidin) through π-π stacking and hydrogen bond, forming a conjugated antioxidant network. γ-polyglutamic acid and trehalose form a semi-permeable membrane, delaying the release of anthocyanin, avoiding rapid consumption during initial oxidative stress, and preventing anthocyanin degradation caused by wet oxygen environment. Using γ-polyglutamic acid-trehalose composite membrane technology, the water / oil biphasic interface is stabilized.

[0021] III. Phytic acid (strong chelating ability) and citric acid (weak chelating ability) synergistically chelate Fe 3+ , Cu 2+ and other pro-oxidant metal ions, inhibiting metal-catalyzed oxidation. Citric acid reduces local pH, inhibiting lipoxygenase activity and blocking the enzymatic oxidation pathway. Chitosan (cationic) and sodium alginate (anionic) form a stable microsphere structure through electrostatic cross-linking, achieving gradient release of phytic acid / citric acid and extending the antioxidant period. Sodium alginate and Ca 2+ (derived from CaCl2) form an "egg box" structure, enhancing the mechanical strength of the microspheres and adapting to mechanical vibration during pre-prepared food storage and transportation. Citric acid (small molecule) is released preferentially to inhibit initial oxidation, and phytic acid (large molecule) is released slowly to maintain long-term chelating ability.

[0022] IV. Rosmarinic acid / Carvacolic acid (direct scavenging) + Anthocyanin / Quercetin (secondary antioxidant). Phytic acid / citric acid biphasic microspheres block metal-catalyzed oxidation. Citric acid reduces pH to inhibit enzyme activity, and chitosan reduces microbial contamination indirectly. The combination of each component in a certain proportion has good synergistic effect.

[0023] V. Spatiotemporal synergistic release system: Rosmarinic acid / Carvacolic acid for rapid effect to cope with initial processing oxidative stress. Drug-loaded cellulose (anthocyanin slow release) and biphasic microspheres (phytic acid / citric acid gradient release) cover the oxidation protection during storage and transportation period, solving the problem of short action period of natural antioxidants.

[0024] VI. Physical-chemical combined barrier: Trehalose-γ-polyglutamic acid membrane (moisture-proof and oxygen-proof) + Chitosan-sodium alginate microspheres (mechanical isolation), reducing oxygen and moisture penetration, and delaying oxidation reaction kinetics. Anthocyanin color protection: through antioxidant and direct reduction, inhibiting pigment oxidation and browning, maintaining the appearance of pre-prepared food.

[0025] In summary, the composite antioxidant achieves all-round inhibition of oxidation problems of pre-prepared dishes by multi-component functional complementation (radical scavenging + metal chelation + enzyme inhibition), multi-level sustained-release design (rapid response + long-term maintenance) and physical-chemical synergistic barrier (controlled release embedding + environmental isolation), constructs a "radical scavenging-metal chelation-phase interface stabilization" triple protection system, develops sustained-release microspheres, realizes precise antioxidant at different stages of processing, storage and transportation, breaks through the bottleneck of short action period and single protection dimension of single natural antioxidant, significantly prolongs the shelf life and maintains the nutritional and sensory quality.

[0026] DETAILED EMBODIMENT

[0027] Embodiment 1

[0028] A natural antioxidant for pre-prepared dishes, comprising rosmarinic acid, carnosic acid, drug-loaded cellulose and biphasic chelating microspheres; the drug-loaded cellulose is loaded with anthocyanin after quercetin modified cellulose, and then wrapped with trehalose-γ-polyglutamic acid composite film; the biphasic chelating microspheres are phytic acid and citric acid wrapped with chitosan and sodium alginate composite film to form phytic acid-citric acid biphasic sustained-release microspheres. The rosmarinic acid, carnosic acid, drug-loaded cellulose and biphasic chelating microspheres are mixed in a mass ratio of 23:12:17:8 to obtain the antioxidant.

[0029] The preparation method of the drug-loaded cellulose comprises: in a mass ratio, acetic acid buffer solution: microcrystalline cellulose: ethanol: quercetin = 190:11:65:3.5; the microcrystalline cellulose is dispersed 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; the quercetin is dissolved in ethanol to form a quercetin solution; under the condition of stirring at 150 r / min, the quercetin solution is added to the cellulose solution, and the surface is modified at 52°C and 150 r / min for 5 h; centrifugation is performed at 5500 r / min for 18 min to separate the solid product; the solid product is washed with deionized water for 4 times, and vacuum dried at 45°C until the weight is constant to obtain quercetin modified cellulose; the quercetin modified cellulose is dispersed in 18 times the mass of the quercetin modified cellulose of deionized water, 6.5% of the mass of the quercetin modified cellulose of anthocyanin is added, the anthocyanin is grape seed proanthocyanidin, and the loading reaction is performed at 32°C and 150 r / min for 2.5 h; the π-π stacking and hydrogen bonding are used to make the anthocyanin embedded and loaded on the quercetin modified cellulose; filtration is performed, and the solid is vacuum dried at 45°C until the weight is constant to obtain the loaded cellulose; in a mass ratio, deionized water: γ-polyglutamic acid: trehalose = 95:1.5:0.7, a composite film solution is prepared; the loaded cellulose is dispersed in 11 times the mass of the loaded cellulose of the composite film solution, and the coating reaction is performed at 150 r / min for 50 min; centrifugation is performed at 5500 r / min for 18 min, and the solid is vacuum dried at 45°C until the weight is constant to obtain the drug-loaded cellulose.

[0030] The preparation method of the dual-phase chelating microspheres comprises the following steps: dissolving phytic acid and citric acid in water in a mass ratio of phytic acid: citric acid: chitosan: sodium alginate = 2.5:1.5:1:0.8, wherein the amount of water is 6.5 times the total mass of phytic acid and citric acid; dissolving chitosan in an acetic acid aqueous solution with a concentration of 1.8 wt% in an amount of 55 times the mass of chitosan to prepare a chitosan solution; dissolving sodium alginate in water in an amount of 55 times the mass of sodium alginate to prepare a sodium alginate solution; under the condition of continuous stirring at 250 r / min, first adding the mixed solution into the chitosan solution to form a primary emulsion, and then adding the primary emulsion into the sodium alginate solution; stirring at 250 r / min for 2.5 h for cross-linking reaction to obtain a reaction solution; adding 15% of the volume of the reaction solution of a 1.5 mol / L calcium chloride aqueous solution; solidifying the microspheres for 40 min; filtering; washing the solid with deionized water for 4 times; drying to constant weight; and obtaining phytic acid-citric acid dual-phase sustained-release microspheres.

[0031] Example 2

[0032] A natural antioxidant for pre-prepared dishes comprises rosemary acid, salvia acid, drug-loaded cellulose, and dual-phase chelating microspheres; the drug-loaded cellulose is cellulose loaded with anthocyanins after modification by quercetin and then wrapped by a trehalose-gamma-polyglutamic acid complex film; the dual-phase chelating microspheres are phytic acid and citric acid wrapped by a chitosan and sodium alginate complex film to form phytic acid-citric acid dual-phase sustained-release microspheres. The rosemary acid, salvia acid, drug-loaded cellulose, and dual-phase chelating microspheres are uniformly mixed in a mass ratio of rosemary acid: salvia acid: drug-loaded cellulose: dual-phase chelating microspheres = 20:15:15:10 to obtain the antioxidant.

[0033] The preparation method of the drug-loaded cellulose comprises: according to the mass ratio, acetic acid buffer solution:microcrystalline cellulose:ethanol:quercetin = 180:12:50:4; the microcrystalline cellulose is dispersed in the acetic acid buffer solution to form a cellulose liquid, and the acetic acid buffer solution is an acetic acid-sodium acetate buffer solution with pH 4.3; the quercetin is dissolved in ethanol to form a quercetin liquid; under the condition of 200 r / min stirring, the quercetin liquid is added to the cellulose liquid, and surface modification is carried out at 50 DEG C and 200 r / min stirring for 4 h; centrifugation is carried out at 6000 r / min for 15 min to separate the solid product; the solid product is washed with deionized water for 5 times; vacuum drying is carried out at 40 DEG C until the weight is constant to obtain the quercetin modified cellulose; the quercetin modified cellulose is dispersed in 20 times the mass of the quercetin modified cellulose of deionized water, 5% of the mass of the quercetin modified cellulose of anthocyanin is added, the anthocyanin is grape seed proanthocyanidin, and the embedding of the anthocyanin in the quercetin modified cellulose is carried out by using the π-π stacking effect and hydrogen bond combination under the condition of 35 DEG C and 100 r / min stirring for 3 h; filtration is carried out, and the solid is vacuum dried at 40 DEG C until the weight is constant to obtain the loaded cellulose; according to the mass ratio, deionized water: gamma-polyglutamic acid: trehalose = 100:1:0.8, a composite film solution is prepared; the loaded cellulose is dispersed in 10 times the mass of the loaded cellulose of the composite film solution, 200 r / min stirring coating reaction is carried out for 30 min, 6000 r / min centrifugation is carried out for 15 min, the solid is vacuum dried at 50 DEG C until the weight is constant, and the drug-loaded cellulose is obtained.

[0034] The preparation method of the drug-loaded cellulose comprises: according to the mass ratio, acetic acid buffer solution:microcrystalline cellulose:ethanol:quercetin = 180:12:50:4; the microcrystalline cellulose is dispersed in the acetic acid buffer solution to form a cellulose liquid, and the acetic acid buffer solution is an acetic acid-sodium acetate buffer solution with pH 4.3; the quercetin is dissolved in ethanol to form a quercetin liquid; under the condition of 200 r / min stirring, the quercetin liquid is added to the cellulose liquid, and surface modification is carried out at 50 DEG C and 200 r / min stirring for 4 h; centrifugation is carried out at 6000 r / min for 15 min to separate the solid product; the solid product is washed with deionized water for 5 times; vacuum drying is carried out at 40 DEG C until the weight is constant to obtain the quercetin modified cellulose; the quercetin modified cellulose is dispersed in 20 times the mass of the quercetin modified cellulose of deionized water, 5% of the mass of the quercetin modified cellulose of anthocyanin is added, the anthocyanin is grape seed proanthocyanidin, and the embedding of the anthocyanin in the quercetin modified cellulose is carried out by using the π-π stacking effect and hydrogen bond combination under the condition of 35 DEG C and 100 r / min stirring for 3 h; filtration is carried out, and the solid is vacuum dried at 40 DEG C until the weight is constant to obtain the loaded cellulose; according to the mass ratio, deionized water: gamma-polyglutamic acid: trehalose = 100:1:0.8, a composite film solution is prepared; the loaded cellulose is dispersed in 10 times the mass of the loaded cellulose of the composite film solution, 200 r / min stirring coating reaction is carried out for 30 min, 6000 r / min centrifugation is carried out for 15 min, the solid is vacuum dried at 50 DEG C until the weight is constant, and the drug-loaded cellulose is obtained.

[0035] Example 3

[0036] A natural antioxidant for pre-prepared dishes, comprising rosemary acid, salvia acid, drug-loaded cellulose and double-phase chelating microspheres; the drug-loaded cellulose is loaded with anthocyanin after quercetin modified cellulose, and then wrapped with trehalose-gamma-polyglutamic acid complex film; the double-phase chelating microspheres are phytic acid and citric acid wrapped with chitosan and sodium alginate complex film to form phytic acid-citric acid double-phase sustained-release microspheres. The rosemary acid: salvia acid: drug-loaded cellulose: double-phase chelating microspheres are uniformly mixed in a mass ratio of 25:10:20:6 to obtain the antioxidant.

[0037] The preparation method of the drug-loaded cellulose comprises: acetic acid buffer solution: microcrystalline cellulose: ethanol: quercetin = 200:10:80:3 by mass ratio; the microcrystalline cellulose is dispersed 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; quercetin is dissolved in ethanol to form a quercetin solution; under the condition of 100 r / min stirring, the quercetin solution is added to the cellulose solution, and the surface is modified at 55°C and 100 r / min for 6h; centrifugation is performed at 5000 r / min for 20 min to separate the solid product, which is washed with deionized water for 3 times and vacuum dried at 50°C to constant weight to obtain quercetin modified cellulose; the quercetin modified cellulose is dispersed in 15 times the mass of deionized water of the quercetin modified cellulose, and 8% of the mass of the quercetin modified cellulose of anthocyanin is added, wherein the anthocyanin is grape seed proanthocyanidin; the anthocyanin is embedded in the quercetin modified cellulose by π-π stacking and hydrogen bonding under the condition of 30°C and 200 r / min stirring for 2h; filtration is performed, and the solid is vacuum dried at 50°C to constant weight to obtain the loaded cellulose; the complex film solution is prepared by mixing deionized water: gamma-polyglutamic acid: trehalose = 90:2:0.5 by mass ratio; the loaded cellulose is dispersed in 12 times the mass of the complex film solution of the loaded cellulose, and the coating reaction is performed at 100 r / min for 90 min; centrifugation is performed at 5000 r / min for 20 min, and the solid is vacuum dried at 40°C to constant weight to obtain the drug-loaded cellulose.

[0038] The preparation method of the dual-phase chelating microspheres comprises the following steps: dissolving phytic acid and citric acid in water in a mass ratio of phytic acid: citric acid: chitosan: sodium alginate = 3: 1: 1.2: 0.6, and preparing a mixed solution; dissolving chitosan in a 2wt% acetic acid aqueous solution in a mass ratio of chitosan: 50 times, and preparing a chitosan solution; dissolving sodium alginate in water in a mass ratio of sodium alginate: 50 times, and preparing a sodium alginate solution; under the condition of continuous stirring at 300 r / min, first adding the mixed solution into the chitosan solution to form a primary emulsion, and then adding the primary emulsion into the sodium alginate solution, and stirring at 200 r / min for 3h to obtain a reaction solution; adding 10% of the reaction solution by volume of a 2mol / L calcium chloride aqueous solution, and solidifying the microspheres for 30 min; filtering, washing the solid with deionized water for 5 times, and drying to constant weight to obtain the phytic acid-citric acid dual-phase sustained-release microspheres.

[0039] In the above examples, the raw materials are food grade, rosmarinic acid is from Xi'an Hongtaiyuan Biological Technology Co., Ltd., and the purity is 98%. Salicic acid is from Shaanxi Zhuotaobiological Technology Co., Ltd., and the purity is 95%. Microcrystalline cellulose is from Guangdong Ousman Biological Technology Co., Ltd. Quercetin is from Xi'an Jiahe Biological Technology Co., Ltd., and the purity is 95%. Grape seed proanthocyanidin is from Peptide Love Biological Technology Co., Ltd., and the purity of grape seed proanthocyanidin OPC is 95%. Gamma-polyglutamic acid is from Shaanxi Yuanshengte Biological Technology Co., Ltd., and the molecular weight is below 70w. Trehalose is from Henan Qinao Food Ingredients Co., Ltd. Phytic acid is from Jiangsu Changjing Biological Engineering Co., Ltd., and the purity is 50%. Citric acid is from Shaanxi Yuanshengte Biological Technology Co., Ltd., and the purity is 99%. Chitosan is low molecular chitosan, which is from Shanxi Fenlu Biological Technology Co., Ltd., and the molecular weight is below 1000Da. Sodium alginate is from Henan Anrui Biological Technology Co., Ltd., and the type is 01, which is aqueous.

[0040] Comparative Example 1

[0041] The mass ratio of the antioxidants is changed to rosmarinic acid: salicic acid: drug-loaded cellulose: dual-phase chelating microspheres = 12:23:17:8; and other parameters and methods are the same as in Example 1.

[0042] Comparative Example 2

[0043] The mass ratio of the antioxidants is changed to rosmarinic acid: salicic acid: drug-loaded cellulose: dual-phase chelating microspheres = 23:12:8:17; and other parameters and methods are the same as in Example 1.

[0044] Comparative Example 3

[0045] The mass ratio of the antioxidants is changed to rosmarinic acid: salicic acid: drug-loaded cellulose: dual-phase chelating microspheres = 12:23:8:17; and other parameters and methods are the same as in Example 1.

[0046] Comparative Example 4

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

[0048] Comparative Example 5

[0049] In the preparation method of drug-loaded cellulose, trehalose was replaced by γ-polyglutamic acid in the composite film solution; other parameters and methods were the same as in Example 1.

[0050] Comparative Example 6

[0051] In the preparation method of drug-loaded cellulose, trehalose was replaced by γ-polyglutamic acid in the composite film solution; other parameters and methods were the same as in Example 1.

[0052] Comparative Example 7

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

[0054] Comparative Example 8

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

[0056] Comparative Example 9

[0057] In the preparation method of the two-phase chelating microspheres, no chitosan coating was added; other parameters and methods were the same as in Example 1.

[0058] Comparative Example 10

[0059] In the preparation method of the two-phase chelating microspheres, no sodium alginate coating was added; other parameters and methods were the same as in Example 1.

[0060] Comparative Example 11

[0061] No two-phase chelating microspheres were prepared, and the two-phase chelating microspheres were replaced by a mixture of phytic acid and citric acid in a mass ratio of 2.5: 1.5; other parameters and methods were the same as in Example 1.

[0062] Comparative Example 12

[0063] The antioxidant was directly replaced by rosmarinic acid.

[0064] Oxidation stability test: The oxidation stability of the prepared dishes after adding different antioxidants was evaluated by accelerated oxidation experiment. The accelerated oxidation experiment accelerated the oxidation process of oil by increasing the temperature and humidity, etc., to simulate the oxidation conditions of the prepared dishes in actual storage and circulation. The degree of oil oxidation was judged by periodically measuring the peroxide value and acid value. The peroxide value is an index to measure the content of peroxide in oil, and peroxide is the primary product of oil oxidation. The increase of its content reflects the occurrence of oxidation reaction; the acid value represents the content of free fatty acid in oil. With the progress of oil oxidation, fatty acid will gradually decompose, leading to the increase of acid value. The slower the growth of peroxide value and acid value, the better the inhibition effect of antioxidant on oil oxidation, and the higher the oxidation stability of prepared dishes.

[0065] The prepared chicken samples (each sample with a mass of 100 g, and the antioxidant added amount was 200 mg / kg) added with different antioxidants were placed in a constant temperature and humidity box, the temperature was set to 60°C, and the humidity was 75%. Sampling was performed at 0th day (before adding antioxidant) and 15th day, respectively. The peroxide value was determined by sodium thiosulfate titration method: 2 g of sample was accurately weighed in an iodometric flask, 30 mL of chloroform-glacial acetic acid mixture (volume ratio 4:6) was added to dissolve the sample completely. 1.00 mL of saturated potassium iodide solution was added, the stopper was quickly tightened, and the flask was shaken gently and placed in the dark for 5 min. After taking out, 100 mL of water was added, and 0.01 mol / L sodium thiosulfate standard solution was added dropwise until the solution turned light yellow. 1 mL of starch indicator was added, and the titration was continued until the blue color disappeared as the end point. A blank experiment was also performed. The peroxide value (mmol / kg) = (V-V0) x c x 1000 / m, wherein V is the volume of sodium thiosulfate standard solution consumed by the sample (mL), V0 is the volume of sodium thiosulfate standard solution consumed by the blank (mL), c is the concentration of sodium thiosulfate standard solution (mol / L), and m is the mass of the sample (g). The detection results are shown in Table 1 below. The acid value was determined by potassium hydroxide ethanol solution titration method: 4 g of sample was accurately weighed in a conical flask, 50 mL of neutral ether-ethanol mixture (volume ratio 2:1) was added, and the sample was shaken to dissolve. 3 drops of phenolphthalein indicator were added, and 0.1 mol / L potassium hydroxide ethanol standard solution was added dropwise until the solution turned light red and did not fade within 30 s as the end point. The acid value (mg / g) = (V-V0) x c x 56.11 / m, wherein V is the volume of potassium hydroxide ethanol standard solution consumed by the sample (mL), V0 is the volume of potassium hydroxide ethanol standard solution consumed by the blank (mL), c is the concentration of potassium hydroxide ethanol standard solution (mol / L), m is the mass of the sample (g), and 56.11 is the molar mass of potassium hydroxide (g / mol). The detection results are shown in Table 1 below.

[0066] Table 1 detection data results

[0067]

[0068]

[0069] The prepared chicken nuggets are the same batch of samples, and the initial peroxide value is 0.03 mmol / kg; the acid value is 0.26 mg / g.

[0070] From the above results, under the same conditions, the peroxide value and acid value of Examples 1 to 3 increase more slowly; the antioxidant of the example has a more stable and long-lasting antioxidant effect.

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

[0072] Comparative Example 2 changes the ratio of drug-loaded cellulose and double-phase chelating microspheres. Quercetin-modified cellulose in drug-loaded cellulose and phytic acid and citric acid in double-phase chelating microspheres inhibit oxidation from different angles in the prepared vegetable system. Drug-loaded cellulose mainly removes free radicals directly through the antioxidant components it carries, and double-phase chelating microspheres chelate metal ions by releasing phytic acid and citric acid to inhibit the initiation of oxidation reaction. After the ratio is changed, the ability to synergistically inhibit oxidation decreases, resulting in poor antioxidant performance.

[0073] Comparative Example 3 changes the ratio of each component comprehensively, further destroying the synergistic balance between the antioxidants. The free radical scavenging ability decreases significantly, the oil oxidation intensifies, the peroxide value and acid value increase significantly, and the color of the prepared vegetable also changes more, which fully illustrates that the ratio of each component of the antioxidant is crucial to its best antioxidant performance.

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

[0075] In the comparative example 5, trehalose completely replaces γ-polyglutamic acid in the composite film solution. γ-polyglutamic acid has good film-forming property and biocompatibility, and its unique structure can synergize with trehalose to effectively wrap the drug-loaded cellulose and protect the antioxidant components inside. When γ-polyglutamic acid is replaced, the structure and performance of the composite film change, and it cannot tightly wrap the drug-loaded cellulose. The drug-loaded cellulose is more easily affected by external factors such as moisture and oxygen in the pre-prepared vegetable system, and the antioxidant components inside are more easily lost or inactivated, resulting in a decrease in antioxidant capacity. This is manifested as a decrease in free radical scavenging rate, an increase in peroxide value, and an increase in acid value.

[0076] In the comparative example 6, trehalose is replaced by γ-polyglutamic acid, which also destroys the original performance of the composite film. Trehalose has the functions of moisturizing and stabilizing the structure of biological macromolecules, and together with γ-polyglutamic acid, it maintains the stability of the drug-loaded cellulose in the composite film. After trehalose is replaced, the stability of the composite film and its protection of the drug-loaded cellulose decrease, resulting in a decrease in the antioxidant effect of the antioxidant in the pre-prepared vegetable, and a deterioration in various detection indexes.

[0077] Comparative example 7 (loaded cellulose without composite film solution wrapping): The loaded cellulose is not wrapped by the composite film solution and is directly exposed in the pre-prepared vegetable system. Moisture, oil, microorganisms and various chemical reactions in the pre-prepared vegetable will affect the loaded cellulose. Without the protection of the composite film, anthocyanins in the loaded cellulose are easily oxidized and decomposed, and quercetin-modified cellulose is also easily damaged, resulting in a rapid decrease in antioxidant capacity. In the accelerated oxidation experiment, it cannot effectively slow down the release of the inhibition of oil oxidation, and the peroxide value and acid value rapidly increase.

[0078] Comparative example 8 (change of mass ratio of components of the two-phase chelating microspheres): The mass ratio of phytic acid, citric acid, chitosan and sodium alginate in the two-phase chelating microspheres is changed, which affects the structure and performance of the microspheres. Phytic acid and citric acid are the main antioxidant components, which inhibit oil oxidation 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 is changed to phytic acid: citric acid: chitosan: sodium alginate = 3.5:0.5:1:0.8, the content of phytic acid increases and the content of citric acid decreases, breaking the synergistic chelation between the two. At the same time, the structure of the composite film also changes due to the change in the ratio, affecting the slow release effect of phytic acid and citric acid. In the pre-prepared vegetable system, the antioxidant components cannot continuously and effectively play a role, resulting in a decrease in free radical scavenging rate, an increase in peroxide value, and an increase in acid value.

[0079] The structure of the two-phase chelating microspheres in Comparative Example 9 becomes incomplete without chitosan coating. Chitosan not only plays a film-forming role in the composite film, but also crosslinks 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 rapidly released into the prepared food system. Although the rapidly released antioxidant ingredients have a certain antioxidant effect in the early stage, they cannot continuously inhibit oil oxidation, leading to rapid increases in peroxide value and acid value in the later stage and a decrease in free radical scavenging rate.

[0080] Comparative Example 10 does not add sodium alginate coating, which also destroys the complete structure of the two-phase chelating microspheres. Sodium alginate cooperates with chitosan to maintain the morphology and function of the microspheres. Without sodium alginate, the stability of the microspheres decreases, and phytic acid and citric acid are easily lost, which cannot continuously play an antioxidant role during the storage of prepared food, thereby leading to a significant decrease in antioxidant performance and poor detection indicators.

[0081] Comparative Example 11 (using a mixture of phytic acid and citric acid to replace two-phase chelating microspheres): Using a mixture of phytic acid and citric acid in a mass ratio of 2.5:1.5 to replace two-phase chelating microspheres, the slow-release effect and synergistic effect of the microspheres are lost. Two-phase chelating microspheres can slowly release phytic acid and citric acid through the wrapping of the chitosan and sodium alginate composite film, continuously inhibiting oil oxidation. However, the phytic acid and citric acid in the mixture will quickly contact and react with the ingredients in the prepared food system, and cannot maintain a stable antioxidant effect for a long time. They have a certain free radical scavenging capacity in the early stage, but the scavenging rate decreases significantly over time; in the accelerated oxidation experiment, they 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 effect principle and does not have the synergistic effect of multiple antioxidants or the stable antioxidant effect of slow release. The antioxidant stability effect is the worst.

Claims

1. A natural antioxidant for use in pre-prepared meals, characterized in that, The antioxidant comprises rosemary acid, salvia acid, drug-loaded cellulose and double-phase chelating microspheres in a mass ratio of (20-25):(10-15):(15-20):(6-10); the drug-loaded cellulose is prepared by loading grape seed proanthocyanidin on quercetin modified cellulose, and then coating the cellulose with a trehalose-gamma-polyglutamic acid composite film; The double-phase chelating microspheres are prepared by coating phytic acid and citric acid with a chitosan and sodium alginate composite film to form phytic acid-citric acid double-phase sustained-release microspheres; The preparation method of the drug-loaded cellulose comprises the following steps: dispersing microcrystalline cellulose in an acetic acid buffer to form a cellulose solution; dissolving quercetin in ethanol to form a quercetin solution; adding the quercetin solution into the cellulose solution, stirring, surface modification, centrifugation, washing, drying, and obtaining quercetin modified cellulose; dispersing the quercetin modified cellulose in water, adding grape seed proanthocyanidin, stirring, loading reaction, filtration, drying, and obtaining drug-loaded cellulose; preparing a composite film solution by mixing water, gamma-polyglutamic acid and trehalose; dispersing the drug-loaded cellulose in the composite film solution, stirring, coating reaction, centrifugation, drying, and obtaining the drug-loaded cellulose. The preparation method of the double-phase chelating microspheres comprises the following steps: dissolving phytic acid and citric acid in water to prepare a mixed solution according to a mass ratio of phytic acid: citric acid: chitosan: sodium alginate = (2-3):(1-2):(0.8-1.2):(0.6-1); 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, and then adding the primary emulsion into the sodium alginate solution, stirring, crosslinking reaction, obtaining a reaction solution, adding a calcium chloride aqueous solution, solidifying the microspheres, filtration, washing with deionized water, drying to constant weight, and obtaining phytic acid-citric acid double-phase sustained-release microspheres.

2. A natural antioxidant for use in pre-prepared meals according to claim 1, characterized in that, 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.

3. The natural antioxidant for pre-prepared food according to claim 1, wherein In the preparation method of the drug-loaded cellulose, the surface modification temperature is 50-55°C, the surface modification time is 4-6h, the washing time with deionized water is 3-5 times, the loading reaction temperature is 30-35°C, the loading reaction time is 2-3h, and the stirring coating reaction time is 30-90min.

4. The natural antioxidant for pre-prepared food according to claim 1, wherein In the preparation method of the drug-loaded cellulose, the stirring speed is 100-200r / min, the centrifugation speed is 5000-6000r / min, the centrifugation time is 15-20min, and the drying is performed at 40-50°C under vacuum until constant weight.

5. The natural antioxidant for pre-prepared food according to claim 1, wherein In the preparation method of the double-phase chelating microspheres, the phytic acid and citric acid are dissolved in 5-8 times the total mass of the phytic acid and citric acid, the chitosan is dissolved in 50-60 times the mass of the chitosan in an acetic acid aqueous solution with a concentration of 1.5-2wt%, and the sodium alginate is dissolved in 50-60 times the mass of the sodium alginate in water.

6. The natural antioxidant for pre-prepared food according to claim 1, wherein In the preparation method of the dual-phase chelating microspheres, the stirring speed is 200 r / min-300 r / min; the stirring cross-linking reaction time is 2 h-3 h; the amount of the calcium chloride aqueous solution is 10%-20% of the reaction liquid volume, and the concentration of the calcium chloride aqueous solution is 1 mol / L-2 mol / L; the solidification microsphere time is 30 min-60 min; and the deionized water washing times are 3-5 times.

7. A method of preparing the natural antioxidant for pre-prepared meals according to claim 1, characterized by, The method comprises the following steps: uniformly mixing rosmarinic acid, salvinic acid, drug-loaded cellulose and dual-phase chelating microspheres according to a mass ratio of (20-25):(10-15):(15-20):(6-10) to obtain an antioxidant.

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