Sodium alginate composite coating liquid and preparation method thereof

Abstract

The invention discloses a sodium alginate composite coating liquid and a preparation method thereof, and belongs to the field of fruit and vegetable preservation. The epsilon-polylysine hydrochloride is used as a main antibacterial component, the almond protein peptide is used for assisting in inhibiting bacteria and resisting oxidation, the sodium alginate is used as a film forming mechanism, and the sodium carboxymethyl cellulose and the glycerol are added, so that the film coating agent has good film forming property. The fruit and vegetable preservative can effectively inhibit spoilage of fruits and vegetables, realizes antibacterial and fresh-keeping of the fruits and vegetables, and prolongs the shelf life; the fresh-keeping agent is good in fresh-keeping effect, low in material price and wide in application range.

Description

Technical Field

[0001] The invention belongs to the field of fruit and vegetable preservation and relates to a sodium alginate composite coating liquid and a preparation method thereof. Background Art

[0002] As the living standards of the Chinese people continue to improve, their nutritional awareness and nutritional supply capacity have also improved, the quality of residents' diets has improved, and the intake of fruits and vegetables has increased year by year. However, fruits and vegetables are susceptible to infection by pathogenic microorganisms. Every year, a large number of fruits and vegetables rot and deteriorate during storage, transportation and sales. Therefore, it is necessary to choose a good material to preserve fruits and vegetables. At present, scholars have tried a variety of preservation materials and technologies to preserve fruits and vegetables, among which coating preservation technology has been widely studied.

[0003] Sodium alginate is a linear high molecular weight polysaccharide extracted from brown algae and composed of uronic acid monomers. Therefore, it has good film-forming properties, biodegradability and biocompatibility. However, single sodium alginate film is brittle, has poor water resistance and has no obvious antibacterial effect. Composite blended film is an effective method to improve the performance of edible film materials. The film made by adding sodium carboxymethyl cellulose has the functions of preventing the migration of water, oil and fluid, preventing the escape of oxygen and carbon dioxide, and improving mechanical strength.

[0004] ε-polylysine hydrochloride is a food additive extracted from Streptomyces chromogenicus. It has good antibacterial, antibacterial and safety properties and is widely used in food preservation. Cross-linking with polysaccharides can improve the water absorption of hydrogels. The biofilm system is an important place for the survival of bacteria and other microorganisms. ε-polylysine can act on the biofilm system and combine with ribosomes in the biofilm system to inhibit the synthesis of proteins and enzymes, thereby destroying the structural integrity of the biofilm system membrane. The cells in the biofilm system will be selectively changed, and the material, energy and information transmission in the cells will also be interrupted. The respiration of the cells will be affected, which will destroy the energy metabolism and material metabolism of bacteria, reduce the NADH and energy material ATP, and hinder the anabolism, causing the intracellular lysosomal membrane to rupture, so that the microorganisms will undergo autolysis, and eventually the microbial cells will die.

[0005] Almond protein peptide is a pure natural nutrient extracted from sweet almonds, which has antioxidant, antifungal and anti-aging effects. Almond protein peptide is composed of 4-9 amino acids and is an oligopeptide, also known as oligomeric active peptide. It has extremely strong activity and diversity and is called active peptide. Summary of the invention

[0006] The purpose of the present invention is to solve the existing problems of fruit and vegetable preservation and disclose a sodium alginate composite coating liquid and a preparation method thereof. The coating liquid comprises a film-forming component and an antibacterial component; the film-forming component is sodium alginate, sodium carboxymethyl cellulose, and glycerol; the antibacterial component is ε-polylysine hydrochloride and almond protein peptide; and the remaining components are deionized water. The prepared coating liquid can inhibit the corruption and deterioration of fruits and vegetables and prolong the shelf life.

[0007] The technical scheme adopted by the present invention is: a sodium alginate composite coating comprises an appropriate amount of deionized water, 0.5% to 1.5% sodium alginate, 0.5% to 1.2% sodium carboxymethyl cellulose, 0.03% to 0.08% ε-polylysine hydrochloride, 0.01% to 0.03% almond protein peptide, and 0.3% to 0.5% propylene glycol.

[0008] A sodium alginate composite fresh-keeping coating, the specific preparation of which includes the following steps: (1) Add 0.5% to 1.5% sodium alginate into the prepared deionized water and stir for 10 to 30 minutes; (2) adding 0.5% to 1.2% sodium carboxymethyl cellulose to the coating solution prepared in (1) and stirring for 10 to 30 minutes; (3) Add 0.03% to 0.08% of ε-polylysine hydrochloride to the coating solution prepared in (2), and continue stirring for 10 to 30 minutes; (4) Add 0.01% to 0.03% of almond protein peptide to the coating solution prepared in (3) and stir for 10 to 30 minutes; (5) Add 0.3% to 0.5% propylene glycol to the coating solution prepared in (4), continue stirring for 10 to 30 minutes, and then eliminate bubbles by ultrasonication for 15 to 30 minutes; (6) Cooling the coating liquid prepared in (5) for 5 to 15 minutes to finally obtain a composite coating liquid.

[0009] Compared with the prior art, the advantages of the present invention are: (1) The present invention adopts ε-polylysine hydrochloride as the antibacterial ingredient, which is safe and harmless to the human body, green and environmentally friendly, safe and efficient, and has a broad-spectrum antibacterial property, which can effectively inhibit the growth of various microorganisms and ensure the quality of fruits and vegetables. (2) The sodium alginate and sodium carboxymethyl cellulose used in the present invention are used as membrane matrices to give full play to their biocompatibility and improve the mechanical properties of the membrane. (3) After the composite coating liquid prepared by the present invention is dried, the membrane has high transparency, no pungent odor, and good texture. (4) The preparation operation of the present invention is simple, the ingredients are green and environmentally friendly, safe and efficient, it has a good preservation effect on fruits and vegetables and does not affect the appearance of fruits and vegetables. DETAILED DESCRIPTION

[0010] The present invention is described in detail below in conjunction with specific implementation examples. The present invention and its implementation methods are described below, and this description is not restrictive, and the actual implementation methods are not limited to this. In short, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, a structural method and an embodiment similar to the technical solution can be designed without creativity, which should all belong to the protection scope of the present invention.

[0011] Implementation Example 1 Preparation of sodium alginate composite coating solution: (1) Add 2.5 g of sodium alginate to 500 g of deionized water and stir for 15 min; (2) Add 2.5 g of sodium carboxymethyl cellulose to the coating solution prepared in (1) and stir for 15 min; (3) Add 0.15 g of ε-polylysine hydrochloride to the coating solution prepared in (2) and continue stirring for 15 min; (4) Add 0.05 g of almond protein peptide to the coating solution prepared in (3) and continue stirring for 15 min; (5) Add 1.5 g of propylene glycol to the coating solution prepared in (4), continue stirring for 30 min, and then eliminate bubbles by ultrasonication for 15 min; (6) The coating liquid prepared in (5) was cooled for 10 minutes to finally obtain a composite coating liquid. (7) The composite coating liquid finally prepared by this ratio has low viscosity and forms a very thin film on the surface of fruits and vegetables, which can be used to preserve fruits and vegetables.

[0012] Implementation Example 2 Preparation of sodium alginate composite coating solution: (1) Add 5 g of sodium alginate to 500 g of deionized water and stir for 20 min; (2) Add 4 g of sodium carboxymethyl cellulose to the coating solution prepared in (1) and stir for 20 min; (3) Add 0.25 g of ε-polylysine hydrochloride to the coating solution prepared in (2) and continue stirring for 20 min; (4) Add 0.1 g of almond protein peptide to the coating solution prepared in (3) and continue stirring for 20 min; (5) Add 2 g of propylene glycol to the coating solution prepared in (4), continue stirring for 20 min, and then eliminate bubbles by ultrasonication for 15 min; (6) The coating liquid prepared in (5) was cooled for 10 minutes to finally obtain a composite coating liquid. (7) The composite coating liquid finally prepared by this ratio has good viscosity and forms a thin film on the surface of fruits and vegetables, which is suitable for preserving fruits and vegetables.

[0013] Implementation Example 3 Preparation of sodium alginate composite coating solution: (1) Add 7.5 g of sodium alginate to 500 g of deionized water and stir for 30 min; (2) Add 6 g of sodium carboxymethyl cellulose to the coating solution prepared in (1) and stir for 30 min; (3) Add 0.4 g of ε-polylysine hydrochloride to the coating solution prepared in (2) and continue stirring for 30 min; (4) Add 0.15 g of almond protein peptide to the coating solution prepared in (3) and continue stirring for 30 min; (5) Add 2.5 g of propylene glycol to the coating solution prepared in (4), continue stirring for 30 min, and then eliminate bubbles by ultrasonication for 15 min; (6) The coating liquid prepared in (5) was cooled for 10 minutes to finally obtain a composite coating liquid. (7) The composite coating liquid finally prepared by this ratio has high viscosity and forms a thick film on the surface of fruits and vegetables, which can be used to preserve fruits and vegetables.

Claims

1. A sodium alginate composite fresh-keeping coating liquid, characterized in that: The composite coating liquid comprises raw materials such as sodium alginate, sodium carboxymethyl cellulose, ε-polylysine hydrochloride, almond protein peptide, glycerol, etc. The preparation of the composite coating liquid comprises the following steps: Step 1: Add 0.5% to 1.5% sodium alginate into the prepared deionized water and stir for 10 to 30 minutes; Step 2: Add 0.5% to 1.2% sodium carboxymethyl cellulose to the coating solution prepared in step 1 and stir for 10 to 30 minutes; Step 3: Add 0.03% to 0.08% of ε-polylysine hydrochloride to the coating solution prepared in step 2, and continue stirring for 10 to 30 minutes; Step 4: Add 0.01% to 0.03% of almond protein peptide to the coating solution prepared in step 3, and continue stirring for 10 to 30 minutes; Step 5: Add 0.3% to 0.5% propylene glycol to the coating solution prepared in step 4, continue stirring for 10 to 30 minutes, and then eliminate bubbles by ultrasound for 15 to 30 minutes; Step 6: Cool the coating liquid prepared in step 5 for 5 to 15 minutes to finally obtain a composite coating liquid.

2. The sodium alginate composite fresh-keeping coating liquid according to claim 1, characterized in that: The sodium carboxymethyl cellulose added in step 2 is used to improve the performance of the membrane, and substances with carboxymethyl groups have good compatibility with sodium alginate.

3. The sodium alginate composite fresh-keeping coating liquid according to claim 1, characterized in that: The ε-polylysine hydrochloride added in step 3 is a preservative and exerts an antibacterial effect.

4. The sodium alginate composite fresh-keeping coating liquid according to claim 1, characterized in that: The stirring speed in step 3 is 220-500 r / min.

5. Use of the sodium alginate composite fresh-keeping coating liquid according to any one of claims 1 to 3 in inhibiting the corruption of fruits and vegetables.

6. The sodium alginate composite fresh-keeping coating liquid as claimed in claim 5, characterized in that: The fruits and vegetables are immersed in the prepared coating liquid for 15 to 30 seconds, taken out and naturally dried, and finally a sodium alginate composite film is formed on the surface of the fruits and vegetables.