阅读说明：本技术 一种颜色指示型食品保鲜膜及其制备方法 (Color indicating type food preservative film and preparation method thereof ) 是由 费鹏 庄远红 刘静娜 曾繁森 叶妍琦 张美清 于 2019-10-24 设计创作，主要内容包括：本发明属于食品包装领域,具体涉及到一种以改性花色苷作为食品新鲜度指示剂的食品包装膜。本发明公开的颜色指示型食品保鲜膜由以下重量份数的原料制备而成：苯甲酸改性花色苷10-20份,低甲氧基果胶15-30份,壳聚糖15-30份,甘油5-15份,乙酸3-5份。其中,苯甲酸改性花色苷由以下重量份数的原料制备而成：苯甲酸6-12份,天然花色苷9-18份,二环己基碳二亚胺6-12份。本发明针对天然花色苷在自然环境中易氧化、易分解的问题,将苯甲酸接枝到天然花色苷分子上从而增强其稳定性。并以改性花色苷为颜色指示剂,混合低甲氧基果胶、壳聚糖及甘油,制备一种颜色指示型食品保鲜膜。该保鲜膜的颜色会随着食品新鲜度的变化而发生相应变化。(The invention belongs to the field of food packaging, and particularly relates to a food packaging film taking modified anthocyanin as a food freshness indicator. The invention discloses a color indication type food preservative film which is prepared from the following raw materials in parts by weight: 10-20 parts of benzoic acid modified anthocyanin, 15-30 parts of low methoxyl pectin, 15-30 parts of chitosan, 5-15 parts of glycerol and 3-5 parts of acetic acid. The benzoic acid modified anthocyanin is prepared from the following raw materials in parts by weight: 6-12 parts of benzoic acid, 9-18 parts of natural anthocyanin and 6-12 parts of dicyclohexylcarbodiimide. The invention aims at the problems that natural anthocyanin is easy to oxidize and decompose in natural environment, and the benzoic acid is grafted to natural anthocyanin molecules so as to enhance the stability of the natural anthocyanin molecules. And mixing low methoxyl pectin, chitosan and glycerol by taking the modified anthocyanin as a color indicator to prepare the color indicating type food preservative film. The color of the preservative film can change along with the change of the freshness of the food.)

1. A color-indicating food preservative film and a preparation method thereof are characterized in that benzoic acid is grafted to natural anthocyanin molecules to improve the stability of anthocyanin and prolong the effective acting time of the anthocyanin in the color-indicating food preservative film.

2. The color indicating food preservative film according to claim 1, which is prepared from the following raw materials in parts by weight: 10-20 parts of benzoic acid modified anthocyanin, 15-30 parts of low methoxyl pectin (with the methyl esterification degree of 20-30%), 15-30 parts of chitosan, 5-15 parts of glycerol and 3-5 parts of acetic acid; the benzoic acid modified anthocyanin is prepared from the following raw materials in parts by weight: 6-12 parts of benzoic acid, 9-18 parts of natural anthocyanin and 6-12 parts of dicyclohexylcarbodiimide.

3. The method for preparing a color-indicating food preservative film according to claim 1, wherein the method comprises the following steps: which comprises the following steps:

1) dissolving 6-12 parts of benzoic acid in 80 parts of dichloromethane, and placing the solution in an ice water bath for stirring;

2) dissolving 6-12 parts of dicyclohexylcarbodiimide in 80 parts of dichloromethane, adding the dichloromethane into the solution obtained in the step 1), and stirring in an ice-water bath for 2-4 hours;

3) filtering the mixed solution to remove white solid residues (dicyclohexylurea), and collecting filtrate;

4) adding 9-18 parts of natural anthocyanin into the filtrate collected in the step 3), stirring and heating for 2-4 h at 60-90 ℃ in a water bath, concentrating the filtrate through rotary evaporation, then freeze-drying the concentrated solution, and collecting a powdery substance, namely benzoic acid modified anthocyanin;

5) adding 15-30 parts of chitosan into 400 parts of deionized water, adding 3-5 parts of acetic acid, mixing, stirring for 60 min to obtain a clear and light yellow solution, performing ultrasonic treatment for 5 min to degas, and stirring for 5 min at normal temperature;

6) dispersing 10-20 parts of benzoic acid modified anthocyanin in 200 parts of deionized water, adding 5-15 parts of glycerol, performing ultrasonic oscillation for 30 min, then adding 15-30 parts of low methoxyl pectin, and continuing stirring for 60 min;

7) mixing the chitosan solution prepared in the step 6) with the benzoic acid modified anthocyanin/pectin solution prepared in the step 7), and stirring for 60 min to obtain a mixed membrane solution;

8) and pouring the mixed film solution on a ground glass flat plate which is inclined at 15-20 degrees, uniformly coating the film solution on the flat plate, and then placing the flat plate in a blast oven at 40 ℃ for drying for 12-18 h to obtain the color indication type food preservative film.

Technical Field

The invention belongs to the field of food packaging, and particularly relates to a food preservative film taking modified anthocyanin as a food freshness indicator.

Background

While the food packaging industry in China achieves outstanding achievements, the food packaging industry faces huge challenges in aspects of food packaging safety, resources, environment and the like. For this reason, the development of the packaging industry in China (2016-: the method is oriented to the strategic task of building a packaging strong country, maintains independent innovation, breaks through key technology, comprehensively promotes the integrated development of green packaging, safe packaging and intelligent packaging, and effectively improves the comprehensive competitiveness of key fields such as packaging products, packaging equipment and packaging printing.

Anthocyanin is one of the most important water-soluble pigments in the nature, is a flavonoid compound which connects anthocyanin and glucoside through glycosidic bond, widely exists in roots, stems, leaves, flowers and fruits of plants, has various biological activities of resisting oxidation, removing in-vivo free radicals, resisting inflammation, resisting tumors, inhibiting obesity, regulating blood lipid balance, inhibiting cholesterol and the like, and is an ideal antioxidant and bacteriostatic additive. As natural antioxidant additives, they are not called into question as synthetic antioxidants. When the preservative is added into a food preservative film, the preservative film can slowly diffuse to the surface or even the interior of the wrapped food from the preservative film, so that the oxidation of nutrient substances in the food is prevented, and the shelf life of the food is prolonged.

In addition, the natural plant has many kinds of anthocyanins, and the shapes, the properties and the like of the anthocyanins are different, but most of the anthocyanins can form different configurations according to the acid-base conditions in the environment, so that different color development reactions can be generated. The deterioration of food due to spoilage is accompanied by the generation of volatile nitrogen compounds such as amines and ammonia, which causes the pH environment to change. Therefore, according to the characteristic that the anthocyanin color changes along with the change of the environmental pH value, the anthocyanin can be used as a gas-sensitive material of a food preservative film to reflect the freshness of food.

Scholars at home and abroad add anthocyanin to a food packaging film to prepare the food packaging film with the characteristic of indicating food freshness by utilizing the pH-color response characteristic of the anthocyanin, for example, a preparation process of an anthocyanin active intelligent packaging film is published by Mingke packaging technology, Inc. of Touling city (application No. 201810667474. X). However, natural anthocyanin is easy to oxidize and is easy to degrade in natural environment, so that the color indicating preservative film has poor stability and short shelf life, and therefore, the color indicating preservative film needs to be modified to improve the stability.

Disclosure of Invention

The invention aims at the problems that natural anthocyanin is easy to oxidize and decompose in natural environment, and the benzoic acid is grafted to natural anthocyanin molecules so as to enhance the stability of the natural anthocyanin molecules. And mixing low methoxyl pectin, chitosan and glycerol by taking the modified anthocyanin as a color indicator to prepare the color indicating type food preservative film. As the food can release volatile nitrogen compounds such as amine, ammonia and the like in the storage process and change the pH environment, the color of the preservative film can also change along with the change, thereby playing the role of monitoring the freshness of the food.

In order to achieve the purpose, the invention adopts the following technical scheme:

a color indication type food preservative film is prepared from the following raw materials in parts by weight:

10-20 parts of benzoic acid modified anthocyanin

15-30 parts of low methoxyl pectin (methyl esterification degree is 20-30 percent)

15-30 parts of chitosan

5-15 parts of glycerol

3-5 parts of acetic acid

The benzoic acid modified anthocyanin is prepared from the following raw materials in parts by weight:

6-12 parts of benzoic acid

9-18 parts of natural anthocyanin

6-12 parts of dicyclohexylcarbodiimide

The invention also provides a preparation method of the color indication type food preservative film, which comprises the following steps.

1) 6 to 12 parts of benzoic acid are dissolved in 40 parts of dichloromethane and the solution is stirred in an ice-water bath.

2) 6-12 dicyclohexylcarbodiimide was dissolved in 40 parts of dichloromethane and added to the solution described in step 1) and stirred in an ice-water bath.

3) The mixed solution was filtered to remove a white solid residue (dicyclohexylurea), and the filtrate was collected.

4) Adding 9-18 parts of natural anthocyanin into the filtrate collected in the step 3), stirring and heating in a water bath, concentrating the filtrate through rotary evaporation, and then freeze-drying the concentrated solution to collect a powdery substance, namely the benzoic acid modified anthocyanin.

5) Adding 15-30 parts of chitosan into 400 parts of deionized water, adding 3-5 parts of acetic acid, mixing, stirring for 60 min to obtain a clear and light yellow solution, performing ultrasonic treatment for 5 min to degas, and stirring for 5 min at normal temperature.

6) Dispersing 10-20 parts of benzoic acid modified anthocyanin in 200 parts of deionized water, adding 5-15 parts of glycerol, performing ultrasonic oscillation for 30 min, then adding 15-30 parts of low methoxyl pectin, and continuing stirring for 60 min.

7) Mixing the chitosan solution prepared in the step 6) with the benzoic acid modified anthocyanin/pectin solution prepared in the step 7), and stirring for 60 min to obtain a mixed membrane solution.

8) And pouring the mixed film solution on a glass flat plate which leans obliquely at an angle of 15-20 degrees, uniformly coating the film solution on the flat plate, and then placing the flat plate in a blast oven for drying to obtain the color-indicating food preservative film.

And 2) stirring in an ice-water bath for 2-4 h.

And 4) heating in water bath at 60-80 deg.c for 2-4 hr.

And 9) the glass plate is a ground glass plate.

And step 9), drying at 40 ℃ for 12-18 h.

The invention adopts the technical scheme to graft the benzoic acid onto natural anthocyanin molecules so as to improve the stability of the natural anthocyanin molecules. Simultaneously mixing low methoxyl pectin, chitosan and glycerol to prepare the color indicating type food preservative film.

The invention has the following advantages:

1. the invention uses benzoic acid to carry out acylation modification on natural anthocyanin, obviously enhances the stability of natural anthocyanin, and greatly prolongs the effective service time of natural anthocyanin in a preservative film.

2. According to the invention, the benzoic acid modified anthocyanin is used as the color indicator, and the color of the benzoic acid modified anthocyanin can be continuously changed along with the prolonging of the storage time of the food, so that the preservative film can play a role in monitoring the freshness of the food.

3. The modified anthocyanin has stronger oxidation resistance and can play a role in enhancing the fresh-keeping capability of the preservative film.

Drawings

Fig. 1 is a technical schematic diagram of the present invention.

Wherein, (1) phenylpropionic acid, (2) dicyclohexylcarbodiimide; (3) benzoic anhydride; (4) dicyclohexylurea; (5) anthocyanins (e.g., cyanidin-3-O-glucoside); (6) benzoic acid modified anthocyanins (molecular modifications may also occur at other hydroxyl positions).

Detailed Description

A color indication type food preservative film is prepared from the following raw materials in parts by weight:

10-20 parts of benzoic acid modified anthocyanin

15-30 parts of low methoxyl pectin (methyl esterification degree is 20-30 percent)

15-30 parts of chitosan

5-15 parts of glycerol

3-5 parts of acetic acid

The benzoic acid modified anthocyanin is prepared from the following raw materials in parts by weight:

6-12 parts of benzoic acid

9-18 parts of natural anthocyanin

6-12 parts of dicyclohexylcarbodiimide

The invention also provides a preparation method of the color indication type food preservative film, which comprises the following steps.

1) 6 to 12 parts of benzoic acid are dissolved in 80 parts of dichloromethane and the solution is stirred in an ice-water bath.

2) 6-12 parts of dicyclohexylcarbodiimide are dissolved in 80 parts of dichloromethane, added to the solution in step 1), and stirred in an ice-water bath for 2-4 h.

3) The mixed solution was filtered to remove a white solid residue (dicyclohexylurea), and the filtrate was collected.

4) Adding 9-18 parts of natural anthocyanin into the filtrate collected in the step 3), stirring and heating for 2-4 h at 60-90 ℃ in a water bath, concentrating the filtrate through rotary evaporation, then freeze-drying the concentrated solution, and collecting a powdery substance, namely the benzoic acid modified anthocyanin.

5) Adding 15-30 parts of chitosan into 400 parts of deionized water, adding 3-5 parts of acetic acid, mixing, stirring for 60 min to obtain a clear and light yellow solution, performing ultrasonic treatment for 5 min to degas, and stirring for 5 min at normal temperature.

6) Dispersing 10-20 parts of benzoic acid modified anthocyanin in 200 parts of deionized water, adding 5-15 parts of glycerol, performing ultrasonic oscillation for 30 min, then adding 15-30 parts of low methoxyl pectin, and continuing stirring for 60 min.

7) Mixing the chitosan solution prepared in the step 6) with the benzoic acid modified anthocyanin/pectin solution prepared in the step 7), and stirring for 60 min to obtain a mixed membrane solution.

8) And pouring the mixed film solution on a ground glass flat plate which is inclined at 15-20 degrees, uniformly coating the film solution on the flat plate, and then placing the flat plate in a blast oven at 40 ℃ for drying for 12-18 h to obtain the color indication type food preservative film.