A fried food coating with controlled release properties and its preparation method and application

Abstract

The present invention discloses a fried food coating with controlled release performance, a preparation method and an application thereof, and belongs to the technical field of fried foods. The preparation of the fried food coating with controlled release performance of the present invention includes: compounding a coagulant polysaccharide with carboxymethyl chitosan to obtain a composite polysaccharide solution; uniformly mixing alcohol-soluble protein with polyphenol to obtain an alcohol-soluble protein-polyphenol blended solution; then dripping the alcohol-soluble protein-polyphenol blended solution into a genipin solution to perform a self-assembly reaction to obtain an alcohol-soluble protein-polyphenol complex solution; then dripping the alcohol-soluble protein-polyphenol complex solution into the complex polysaccharide solution to perform an amino cross-linking reaction, thereby obtaining a fried food coating with controlled release performance. The coating has excellent antioxidant properties at room temperature and can extend the shelf life of fried foods; during high-temperature frying, the rapid release of active ingredients can be achieved, which can better maintain the safety and quality of fried foods.

Description

Technical Field

[0001] The invention relates to a fried food coating with controlled release performance and a preparation method and application thereof, belonging to the technical field of fried foods. Background Art

[0002] Fried foods are a traditional food, including fried spring rolls, fried dough sticks, fried pancakes, French fries, fried chicken wings, and potato chips. With the improvement of living standards and the accelerated pace of life, pre-fried convenience foods are becoming increasingly popular. However, fried foods are prone to oxidation and deterioration during storage, and are prone to producing harmful substances during frying, which has limited their further development.

[0003] To address these issues with fried foods, existing technologies typically involve directly adding substances with antioxidant properties or those that inhibit the production of harmful substances to the fried foods, or coating the fried foods with flour. However, these methods are not only ineffective but also limited in function, failing to simultaneously address issues such as the loss of antioxidant properties during room-temperature storage and the continued lack of antioxidant properties during frying.

[0004] Therefore, there is an urgent need to develop a fried food coating with controlled-release properties. This coating can not only inhibit oxidative deterioration of fried foods during storage through the long-term release of active ingredients, thereby maintaining the sensory quality of fried foods during storage, but also rapidly release the active ingredients during the high-temperature frying process to reduce the formation of fried food hazards. This has important economic and social significance for extending the shelf life of fried foods and addressing the safety and quality issues of fried foods. Summary of the Invention

[0005] [Technical Issues]

[0006] Existing fried foods have the technical problems of being easily oxidized and deteriorated during storage and easily producing harmful substances during the frying process.

[0007] [Technical solution]

[0008] In order to solve the above problems, the present invention provides a fried food coating with controlled-release properties, and a preparation method and application thereof. The coating is prepared by reacting coagulant polysaccharide with carboxymethyl chitosan to form a composite polysaccharide, and then cross-linking the composite polysaccharide with the alcohol-soluble protein-polyphenol self-assembled complex through proteoglycan amino groups to prepare a fried food coating with controlled-release properties. The method is simple, green, pollution-free, and low in energy consumption.

[0009] A first object of the present invention is to provide a method for preparing a fried food coating having controlled release properties, the method comprising the following steps:

[0010] (1) Composite reaction of coagulated polysaccharide and carboxymethyl chitosan

[0011] Dissolving the coagulant polysaccharide and carboxymethyl chitosan in water, stirring to allow the coagulant polysaccharide and carboxymethyl chitosan to react with each other, and obtaining a coagulant polysaccharide and carboxymethyl chitosan composite polysaccharide solution;

[0012] (2) Prolamin-polyphenol self-assembly reaction

[0013] The method comprises the steps of uniformly dispersing prolamin in an ethanol aqueous solution, adding polyphenols thereto and mixing them uniformly to obtain a prolamin-polyphenol blend solution; dissolving genipin in water to obtain a genipin solution; and dripping the prolamin-polyphenol blend solution into the genipin solution to cause a self-assembly reaction, thereby obtaining a prolamin-polyphenol complex solution.

[0014] (3) Amino cross-linking reaction

[0015] The alcohol-soluble protein-polyphenol complex solution obtained in step (2) is dripped into the coagulated polysaccharide and carboxymethyl chitosan complex polysaccharide solution obtained in step (1) to carry out amino cross-linking reaction, thereby obtaining a fried food coating with controlled release performance.

[0016] In one embodiment, the mass ratio of the coagulated polysaccharide to water in step (1) is 1:50-100; the mass ratio of carboxymethyl chitosan to deionized water is 1:50-100.

[0017] In one embodiment, the mass ratio of the coagulated polysaccharide to carboxymethyl chitosan in step (1) is 1-2:2-1; preferably 1:1.

[0018] In one embodiment, the stirring in step (1) is carried out at 60-65° C. for 2-4 hours.

[0019] In one embodiment, the mass ratio of the alcohol-soluble protein to the ethanol aqueous solution in step (2) is 1:50-100.

[0020] In one embodiment, the mass ratio of ethanol to water in the ethanol aqueous solution in step (2) is 2:1 to 3:1.

[0021] In one embodiment, the mass ratio of the polyphenols to the ethanol aqueous solution in step (2) is 1:50-100.

[0022] In one embodiment, the mass ratio of genipin to water in step (2) is 1:500-1000.

[0023] In one embodiment, the mass ratio of genipin to prolamin in step (2) is 1 to 2:100.

[0024] In one embodiment, the polyphenols in step (2) are one or more of rutin, curcumin, quercetin, resveratrol, and tea polyphenols.

[0025] The second object of the present invention is to provide a fried food coating with controlled release properties prepared by the above method.

[0026] The third object of the present invention is to provide the application of the fried food coating with controlled release properties described above in the field of fried foods.

[0027] The effective effects of the present invention are:

[0028] The present invention is based on the synergistic effect of polysaccharide complex reaction, alcohol-soluble protein-polyphenol self-assembly reaction and proteoglycan amino cross-linking reaction, which promotes the formation of composite polysaccharides by coagulating polysaccharides and carboxymethyl chitosan molecules, so that the coating has temperature sensitivity, and the alcohol-soluble protein and the composite polysaccharide form a stable multi-cross-linked nano-reinforced structure through hydrogen bonding and covalent bonding, so that it has the performance of controlled release of active substances; under a room temperature storage environment, the polyphenol cooperates with the alcohol-soluble protein and the composite polysaccharide complex to achieve slow and controlled release, so that the coating has excellent antioxidant performance and can extend the shelf life of fried foods; during the high-temperature frying process, the prepared fried food coating can achieve rapid release of active ingredients due to its temperature-sensitive thermal reversibility, and has better antioxidant effect than a coating to which antioxidants are directly added, so as to better maintain the safety and quality of fried foods. DETAILED DESCRIPTION

[0029] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0030] The test method involved in the present invention is:

[0031] 1. Antioxidant test

[0032] The antioxidant capacity of the composite coating against polyphenols was tested using an ultraviolet spectrophotometer: the specific testing method was as follows: first, 0.002 g of DPPH was weighed and dissolved in 50 mL of anhydrous ethanol to prepare a 0.1 mM DPPH-ethanol solution, which was then stored in the dark; then, the freshly prepared sample and the prepared DPPH-ethanol solution were mixed in equal amounts and reacted in the dark for 30 minutes; and the absorbance at λ = 517 nm was measured using an ultraviolet spectrophotometer.

[0033] The antioxidant capacity was calculated according to the following formula (1):

[0034] (A0-A t ) / A0×100%(1)

[0035] Where: At is the absorbance of the mixed solution of sample and prepared DPPH-ethanol solution; A0 is the absorbance of the mixed solution of deionized water and prepared DPPH-ethanol solution.

[0036] Example 1

[0037] A method for preparing a fried food coating with controlled release properties comprises the following steps:

[0038] (1) Preparation of a composite polysaccharide of coagulant polysaccharide and carboxymethyl chitosan: 1 g of coagulant polysaccharide and 1 g of carboxymethyl chitosan were weighed and dissolved in 100 ml of deionized water. The mixture was stirred at 65°C for 1 h to allow the coagulant polysaccharide and carboxymethyl chitosan to react and form a composite polysaccharide solution of coagulant polysaccharide and carboxymethyl chitosan.

[0039] (2) Preparation of prolamin-polyphenol complex: 1 g of prolamin was weighed and dispersed in 100 ml of 75% ethanol aqueous solution, and then 0.02 g of rutin was added thereto and mixed uniformly to obtain a prolamin-rutin blend solution; 0.01 g of genipin was weighed and dissolved in 100 ml of deionized water to obtain a genipin solution; the prolamin-rutin blend solution was then dropped into the genipin solution to allow the mixture to undergo a self-assembly reaction, and after the reaction, a prolamin-rutin complex solution was obtained;

[0040] (3) Preparation of alcohol-soluble protein-polyphenol-complex polysaccharide complex: the alcohol-soluble protein-rutin complex solution obtained in step (2) is dropped into the coagulated polysaccharide and carboxymethyl chitosan complex polysaccharide solution obtained in step (1) to carry out amino cross-linking reaction to obtain a fried food coating with controlled release properties.

[0041] Example 2

[0042] The amount of coagulated polysaccharide added in step (1) of Example 1 was adjusted to 2 g, and the other parameters and conditions remained consistent with those of Example 1.

[0043] Example 3

[0044] The amount of carboxymethyl chitosan added in step (1) of Example 1 was adjusted to 2 g, and other parameters and conditions remained consistent with those of Example 1.

[0045] Comparative Example 1

[0046] The only difference from Example 1 is that step (2) of Example 1 is omitted, and 0.02 g of rutin is directly added to the complex polysaccharide solution. Other parameters and conditions are consistent with Example 1.

[0047] Comparative Example 2

[0048] The only difference from Example 1 is that the carboxymethyl chitosan in step (1) is replaced by pullulan, and the other parameters and conditions are consistent with Example 1.

[0049] Comparative Example 3

[0050] The only difference from Example 1 is that the carboxymethyl chitosan in step (1) is replaced by carboxymethyl cellulose, and the other parameters and conditions are consistent with Example 1.

[0051] Result determination

[0052] The performance of the fried food coatings obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was measured;

[0053] (1) The fried food coating was stored at room temperature (25°C) for 5 days, and the antioxidant properties were measured every day. The results are shown in Table 1:

[0054] Table 1. Antioxidant properties of fried food coatings

[0055] Antioxidant activity (%) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Day 1 8.79±0.24 7.36±0.14 7.96±0.23 8.23±0.25 6.95±0.25 7.53±0.23 Day 2 7.56±0.19 6.83±0.21 6.61±0.20 6.69±0.28 5.71±0.21 6.84±0.27 Day 3 6.35±0.29 5.46±0.22 5.39±0.17 4.33±0.19 4.32±0.17 5.32±0.19 Day 4 5.39±0.16 4.53±0.22 4.23±0.25 2.11±0.23 3.61±0.23 4.26±0.21 Day 5 4.36±0.24 3.86±0.16 3.66±0.19 1.36±0.20 2.15±0.20 2.64±0.17

[0056] From the results in the table, it can be seen that the antioxidant properties of the coatings prepared in Examples 1-3 decrease slowly over time under room temperature storage conditions, and the antioxidant effect of the coatings is best when the addition ratio of coagulant polysaccharide to carboxymethyl chitosan is 1:1, which indicates that the coatings can achieve a sustained release of polyphenols under room temperature storage conditions, thereby giving them excellent antioxidant properties; the antioxidant properties of the coatings prepared in Comparative Examples 1-3 decrease rapidly over time, and their antioxidant properties under room temperature storage conditions are poor.

[0057] (2) Potato strips were dipped in the fried food coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 3 for 10 seconds, and excess surface water was drained to cover the surface of the potato strips with the fried food coating. The potato strips were then fried in soybean oil at 170° C. for 6 seconds and drained in an aluminum frame for 10 seconds. The antioxidant properties of the potato strips were measured at different frying times. The results are shown in Table 2.

[0058] Table 2. Antioxidant properties at different frying times

[0059] Antioxidant activity (%) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Second 2 2.36±0.19 2.21±0.23 2.01±0.18 2.11±0.20 1.87±0.26 1.65±0.21 4th second 1.20±0.26 0.82±0.16 1.12±0.23 1.02±0.23 0.61±0.20 0.71±0.17 6th second 0.42±0.15 0.35±0.11 0.38±0.13 0.15±0.06 0.10±0.03 0.07±0.02

[0060] It can be seen from the data in the table that the antioxidant properties of the coatings prepared in Examples 1-3 decrease slowly over time during the frying process, and the antioxidant effect of the coating is best when the addition ratio of coagulant polysaccharide to carboxymethyl chitosan is 1:1, which indicates that the coating can achieve rapid release of polyphenols during the frying process. At the same time, the rate of decrease in antioxidant properties of the coatings prepared in Examples 1-3 is slower than that of Comparative Examples 1-3 during the frying process, which indicates that they have better antioxidant properties; the antioxidant properties of the coatings prepared in Comparative Examples 1-3 decrease rapidly over time, and their antioxidant properties are poor.

[0061] In summary, the fried food coatings prepared in Examples 1-3 of the present invention have a relatively slow decrease in antioxidant properties over time under room temperature storage conditions, indicating that the coatings can achieve a controlled release of polyphenols under room temperature storage conditions, thereby providing them with excellent antioxidant properties and extending the shelf life of fried foods. At the same time, the fried food coatings prepared in Examples 1-3 can achieve rapid release of active ingredients during the frying process due to their temperature-sensitive thermoreversibility, and the rate of decrease in antioxidant properties is slower than that of the fried food coatings prepared in Comparative Examples 1-3, indicating that they also have better antioxidant properties during the frying process and can better maintain the safety quality of fried food.

[0062] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a fried food coating with controlled release properties, characterized in that: The preparation method comprises the following steps: (1) Composite reaction of coagulated polysaccharide and carboxymethyl chitosan Dissolving the coagulant polysaccharide and carboxymethyl chitosan in water, stirring to allow the coagulant polysaccharide and carboxymethyl chitosan to react with each other, and obtaining a coagulant polysaccharide and carboxymethyl chitosan composite polysaccharide solution; The mass ratio of the coagulated polysaccharide to water is 1:50-100; the mass ratio of carboxymethyl chitosan to water is 1:50-100; The mass ratio of the coagulated polysaccharide to carboxymethyl chitosan is 1-2:2-1; (2) Prolamin-polyphenol self-assembly reaction The method comprises the steps of uniformly dispersing prolamin in an ethanol aqueous solution, adding polyphenols thereto and mixing them uniformly to obtain a prolamin-polyphenol blend solution; dissolving genipin in water to obtain a genipin solution; and dripping the prolamin-polyphenol blend solution into the genipin solution to cause a self-assembly reaction, thereby obtaining a prolamin-polyphenol complex solution. (3) Amino cross-linking reaction The alcohol-soluble protein-polyphenol complex solution obtained in step (2) is dropped into the coagulated polysaccharide and carboxymethyl chitosan complex polysaccharide solution obtained in step (1) to carry out amino cross-linking reaction, thereby obtaining a fried food coating with controlled release properties.

2. The preparation method according to claim 1, characterized in that The mass ratio of the alcohol-soluble protein to the ethanol aqueous solution in step (2) is 1:50-100.

3. The preparation method according to claim 1, characterized in that The mass ratio of ethanol to water in the ethanol-water solution in step (2) is 2:1 to 3:

1.

4. The preparation method according to claim 1, characterized in that The mass ratio of the polyphenols to the ethanol aqueous solution in step (2) is 1:50-100.

5. The preparation method according to claim 1, characterized in that The mass ratio of genipin to gliadin in step (2) is 1-2:

100.

6. The preparation method according to claim 1, characterized in that The polyphenols in step (2) are one or more of rutin, curcumin, quercetin, resveratrol, and tea polyphenols.

7. A fried food coating with controlled release properties prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the fried food coating with controlled release properties according to claim 7 in the field of fried foods.