Fruit preservative film based on natural component synergy and preparation method thereof

Abstract

The invention discloses a fruit preservative film based on a synergistic effect of natural components and a preparation method of the fruit preservative film, and belongs to the technical field of food preservation. The preservative film is mainly composed of three natural components including fulvic acid, gelatin and genipin, an effective preservation effect is achieved through a synergistic effect, the preservation period of fruits is remarkably prolonged, and the freshness and taste of the fruits are kept. The preparation method is simple, easy to operate and low in cost. Compared with the prior art, the fresh-keeping film has obvious advantages in the aspects of fresh-keeping effect, environmental protection and mechanical performance, and an efficient and green solution is provided for the field of fruit fresh-keeping.

Description

Technical Field

[0001] The invention relates to the technical field of fruit preservation, in particular to a fruit preservative film based on the synergistic effect of fulvic acid, gelatin and genipin and a preparation method thereof. Background Art

[0002] Fruit, as a natural food rich in vitamins, minerals and dietary fiber, is an indispensable part of people's daily diet. However, fruits still have high physiological activity after picking. Factors such as their respiration, water evaporation and microbial growth will cause the quality of fruits to deteriorate, rot and deteriorate, thereby shortening their shelf life. In order to extend the shelf life of fruits and reduce the loss of fruits during storage and transportation, the research and application of preservation technology has always been an important topic in the field of food science. At present, common fruit preservation methods include refrigeration preservation, modified atmosphere preservation, chemical preservative treatment and plastic wrap packaging. Among them, plastic wrap packaging is widely used in the field of fruit preservation due to its advantages such as simple operation, low cost and wide applicability. Plastic wrap can extend the shelf life of fruits by adjusting the gas environment around fruits, reducing water evaporation and blocking the invasion of microorganisms. However, most traditional plastic wraps are made of plastic as the main component, which has some problems, such as insufficient air permeability and moisture permeability, poor biodegradability and limited preservation effect. In addition, plastic cling film is difficult to degrade after use, which will cause serious white pollution to the environment and does not meet the environmental protection requirements of modern society.

[0003] In recent years, with the increasing attention to environmental protection and food safety, researchers have begun to explore and develop new types of cling film materials to replace traditional plastic cling film. Among them, biodegradable cling film has gradually become a research hotspot due to its good environmental performance and biocompatibility. Biodegradable cling film usually uses natural polymer materials as the main component, and improves the preservation effect by adding other functional substances. However, the existing biodegradable cling film still has some shortcomings in practical applications. For example, chitosan, as a commonly used biodegradable material, has good film-forming and antibacterial properties, but its mechanical properties after film formation are poor, and its ability to regulate the respiration of fruits is limited. Although gelatin has good film-forming and biocompatibility, its strength is insufficient when it is formed alone, it is easily dissolved by moisture, and its antibacterial properties are limited. In addition, although the composite cling film mentioned in some studies has improved the preservation effect to a certain extent, its composition is complex, the preparation process is cumbersome, and its adaptability to different fruits is poor.

[0004] In the relevant patent technology, some studies have used fulvic acid and chitosan in synergistic use for meat preservation. This technology uses the antioxidant properties of fulvic acid and the antibacterial properties of chitosan to achieve a certain preservation effect. However, there are significant differences between meat and fruit in terms of physiological characteristics, preservation requirements and preservation environment. Fruits have stronger respiration, higher moisture content and are more susceptible to microbial invasion. Through comparative tests, we found that the combination of fulvic acid and chitosan directly applied to fruit preservation is not ideal. In addition, some studies have improved the performance of cling film by adding multiple ingredients, but the existing cling film is still difficult to meet the multiple needs of fruit preservation at the same time. For example, although some cling films have good antibacterial properties, they are not breathable and breathable, which makes it easy for fruits to rot or deteriorate during the preservation process. Although other cling films have good mechanical properties, their preservation effect is limited and they cannot effectively extend the shelf life of fruits. In addition, the biodegradability of existing cling films is still a problem that needs to be solved urgently, especially in large-scale applications, how to reduce the impact on the environment while ensuring the preservation effect is still a challenge.

[0005] Based on the above-mentioned deficiencies of the prior art, the present invention aims to develop a new type of fruit preservative film, which overcomes the defects of the existing preservative film and realizes efficient preservation of fruits through the synergistic effect of fulvic acid, gelatin and genipin. Fulvic acid has good antioxidant and antibacterial properties, which can delay the ripening of fruits and inhibit the growth of harmful microorganisms; gelatin has excellent film-forming properties and biocompatibility, which can provide good mechanical properties for the preservative film; genipin, as a natural cross-linking agent, can undergo a cross-linking reaction with gelatin to form a stable network structure, adjust the size of the film pores, and further improve the mechanical properties and durability of the preservative film. The synergistic effect of the three can not only significantly extend the shelf life of fruits, but also maintain the freshness and taste of fruits. At the same time, it has good air permeability, moisture permeability and biodegradability, providing a new solution for the field of fruit preservation. Summary of the invention

[0006] One of the purposes of the present invention is to provide a fruit preservative film formula based on the synergy of natural components, which specifically comprises the following components in parts by weight: 40-80 parts of fulvic acid, 400-600 parts of gelatin, 1-3 parts of genipin, 100-200 parts of ethanol, and 9000-9500 parts of water.

[0007] Another object of the present invention is to provide a method for preparing the cling film, the specific steps comprising the following: (1) Weighing genipin by weight, dissolving it in ethanol, and stirring it evenly at room temperature to prepare a genipin alcohol solution for later use; (2) Weigh fulvic acid by weight, add it to half of the total amount of water, stir evenly at room temperature to prepare a fulvic acid aqueous solution for later use; (3) Weighing gelatin by weight, adding it to the other half of the total amount of water, stirring for 5-10 minutes at a temperature of 45-50° C. and a rotation speed of 200-300 r / min, then slowly adding the genipinol solution drop by drop, continuing to stir for 5-10 minutes, then slowly adding the fulvic acid aqueous solution drop by drop, continuing to stir for another 5-10 minutes, stopping stirring and cooling to room temperature, thereby obtaining a preservative film stock solution; The method of using the fruit preservative film is as follows: soak or spray the preservative film stock solution on the surface of the fruit, and wait for the surface water to evaporate slightly to form a soft solid film; The humic acid is lignite humic acid, which is prepared with lignite as raw material according to the patent CN200810233669.X "Method for producing humic acid and its salt by oxidation and degradation of lignite", and has passed the heavy metal test; Among them, gelatin, genipin and ethanol are commercially available products, and all indicators have been tested and qualified; Among them, fulvic acid, gelatin and genipin are used as synergistic active components for fruit preservation.

[0008] The beneficial effects of the present invention are as follows: (1) The product of the present invention is based on the strong synergistic effect of fulvic acid, gelatin and genipin, which effectively inhibits the respiration of fruits and the growth of microorganisms and prolongs the shelf life.

[0009] (2) The product of the present invention has good air permeability, moisture permeability, mechanical properties and biodegradability, provides a suitable microenvironment for preserving fruits, and is environmentally friendly and pollution-free.

[0010] (3) The product of the present invention can be personalized according to the characteristics of different fruits to meet the diverse preservation needs and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] These and / or other aspects and advantages of the present invention will become more clear and easier to understand from the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, in which: Figure 1 This is a comparison diagram of the experimental effect of the fruit preservative film of the present invention in preserving bananas Figure 2 This is a comparison diagram of the experimental effect of the fruit preservative film of the present invention in preserving cherry tomatoes Figure 3 This is a comparison diagram of the fruit preservative film of the present invention after the gelatin is replaced by chitosan and carboxymethyl chitosan DETAILED DESCRIPTION

[0012] The present invention is further described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited to the described contents. Example 1

[0013] The fruit preservative film of the present embodiment is prepared from the following components, and each component and its weight portion are: 60 parts of fulvic acid, 500 parts of gelatin, 2 parts of genipin, 150 parts of ethanol, and 9200 parts of water.

[0014] The preparation method of the fruit preservative film of the present embodiment comprises the following steps: (1) Weighing genipin by weight, dissolving it in ethanol, and stirring it evenly at room temperature to prepare a genipin alcohol solution for later use; (2) Weigh fulvic acid by weight, add it to half of the total amount of water, stir evenly at room temperature to prepare a fulvic acid aqueous solution for later use; (3) Weigh gelatin by weight and add it to the other half of the total amount of water, stir at a temperature of 48°C and a rotation speed of 250 r / min for 8 minutes, then slowly add the genipinol solution drop by drop, continue stirring for 8 minutes, then slowly add the fulvic acid aqueous solution drop by drop, continue stirring for another 8 minutes, stop stirring and cool to room temperature, and the plastic wrap stock solution can be prepared; The humic acid is lignite humic acid, which is prepared with lignite as raw material according to the patent CN200810233669.X "Method for producing humic acid and its salt by oxidation and degradation of lignite", and has passed the heavy metal test; Among them, gelatin, genipin and ethanol are commercially available products, and all indicators have been tested and qualified; The method for using the fruit cling film is as follows: soak or spray the cling film stock solution on the surface of the fruit, and after the surface water evaporates slightly, a layer of soft solid film is formed. Example 2

[0015] The fruit preservative film of the present embodiment is prepared from the following components, and each component and its weight portion are: 40 parts of fulvic acid, 600 parts of gelatin, 3 parts of genipin, 200 parts of ethanol, and 9500 parts of water.

[0016] The preparation method of the fruit preservative film of the present embodiment comprises the following steps: (1) Weighing genipin by weight, dissolving it in ethanol, and stirring it evenly at room temperature to prepare a genipin alcohol solution for later use; (2) Weigh fulvic acid by weight, add it to half of the total amount of water, stir evenly at room temperature to prepare a fulvic acid aqueous solution for later use; (3) Weigh gelatin by weight and add it to the other half of the total amount of water, stir at a temperature of 45°C and a rotation speed of 300 r / min for 5 minutes, then slowly add the genipinol solution drop by drop, continue stirring for 5 minutes, then slowly add the fulvic acid aqueous solution drop by drop, continue stirring for another 5 minutes, stop stirring and cool to room temperature, and the plastic wrap stock solution can be prepared; The source of raw materials and the method of use are consistent with those in Example 1. Example 3

[0017] The fruit preservative film of the present embodiment is prepared from the following components, and each component and its weight portion are: 80 parts of fulvic acid, 400 parts of gelatin, 1 part of genipin, 100 parts of ethanol, and 9000 parts of water.

[0018] The preparation method of the fruit preservative film of the present embodiment comprises the following steps: (1) Weighing genipin by weight, dissolving it in ethanol, and stirring it evenly at room temperature to prepare a genipin alcohol solution for later use; (2) Weigh fulvic acid by weight, add it to half of the total amount of water, stir evenly at room temperature to prepare a fulvic acid aqueous solution for later use; (3) Weigh gelatin by weight and add it to the other half of the total amount of water, stir for 10 minutes at a temperature of 50°C and a rotation speed of 200 r / min, then slowly add the genipinol solution drop by drop, continue stirring for 10 minutes, then slowly add the fulvic acid aqueous solution drop by drop, continue stirring for another 10 minutes, stop stirring and cool to room temperature, and the plastic wrap stock solution can be prepared; The source of raw materials and the method of use are consistent with those in Example 1.

[0019] Blank control: no preservation treatment was performed.

[0020] Comparative Example 1: The difference from Example 1 is that the components and their weight parts are: 60 parts of fulvic acid and 9200 parts of water, and the other parameters are the same as those of Example 1.

[0021] Comparative Example 2: The difference from Example 1 is that the components and their weight parts are: 60 parts of fulvic acid, 2 parts of genipin, 150 parts of ethanol, and 9200 parts of water. The other parameters are the same as those in Example 1.

[0022] Comparative Example 3: The difference from Example 1 is that the components and their weight portions are: 60 parts of fulvic acid, 500 parts of gelatin, and 9200 parts of water, and the other parameters are the same as those of Example 1.

[0023] Comparative Example 4: The difference from Example 1 is that the components and their weight portions are: 500 parts of gelatin, 2 parts of genipin, 150 parts of ethanol, and 9200 parts of water. The other parameters are the same as those in Example 1.

[0024] Effect Example 1: Longest shelf life, sensory index score and weight loss rate of bananas The longest shelf life judgment standard is the number of days when bananas of the same initial maturity show obvious local corruption and color and taste changes. The sensory score after 12 days of storage at room temperature (out of 10 points): 5 points means obvious color changes and poor taste; weight loss rate = (initial weight - real-time weight) / initial weight. The test results are shown in Table 1 and Figure 1 As shown (the longer the shelf life, the higher the sensory index score and the lower the weight loss rate, the better the preservation effect).

[0025] Table 1 Test results of the fruit preservative film of the present invention in banana preservation

[0026] As can be seen from Table 1, Example 1-3 groups have significant fresh-keeping effects compared to the blank control and Comparative Example 1-4 groups. It is not difficult to find from the results of Comparative Example 1 that when gelatin and genipin in the cling film of the present invention are discarded at the same time, its longest fresh-keeping period and sensory index score are significantly lower than those of Example 1 group, and the weight loss rate is significantly increased, which means that the dosage ratio of gelatin and genipin has a significant effect on the fresh-keeping effect of the cling film of the present invention. Similarly, it can be seen from the results of Comparative Example 2 and Comparative Example 3 that when gelatin or genipin in the cling film of the present invention is discarded alone, its fresh-keeping effect is also significantly lower than that of Example 1 group, and the weight loss rate is significantly increased, which once again proves that gelatin or genipin plays an important role in the cling film of the present invention. It can be seen from the results of the comparative example 4 that when the fulvic acid in the cling film of the present invention is abandoned, its longest shelf life and sensory index score are also lower than those of the embodiment 1 group, and the weight loss rate is increased, which means that the dosage ratio of fulvic acid also has a significant effect on the fresh-keeping effect of the cling film of the present invention. In addition, through the effect comparison, it is found that the fresh-keeping effect of any missing fulvic acid, gelatin and genipin is not as good as the simultaneous presence of the three, indicating that a synergistic effect is produced between the three, and none of the three is indispensable. Therefore, the synergistic fresh-keeping effect produced by the compound combination of fulvic acid, gelatin and genipin in the present invention is an unexpected technical effect.

[0027] Effect Example 2: Longest shelf life, sensory index score and weight loss rate of cherry tomatoes The longest shelf life judgment standard is the number of days when cherry tomatoes of the same initial maturity show obvious local corruption and color and taste changes. The sensory score after 12 days of storage at room temperature (out of 10 points): 5 points means obvious color changes and poor taste; weight loss rate = (initial weight - real-time weight) / initial weight. The test results are shown in Table 2 and Figure 2 As shown (the longer the shelf life, the higher the sensory index score and the lower the weight loss rate, the better the preservation effect).

[0028] Table 2 Test results of the fruit preservative film of the present invention in preserving cherry tomatoes

[0029] As shown in Table 2, Example 1-3 groups have significant fresh-keeping effects compared to the blank control and Comparative Example 1-4 groups. It is not difficult to find from the results of Comparative Example 1 that when gelatin and genipin in the cling film of the present invention are discarded at the same time, its longest fresh-keeping period and sensory index score are significantly lower than those of Example 1 group, and the weight loss rate is significantly increased, which means that the dosage ratio of gelatin and genipin has a significant effect on the fresh-keeping effect of the cling film of the present invention. Similarly, it can be seen from the results of Comparative Example 2 and Comparative Example 3 that when gelatin or genipin in the cling film of the present invention is discarded alone, its fresh-keeping effect is also significantly lower than that of Example 1 group, and the weight loss rate is significantly increased, which once again proves that gelatin or genipin plays an important role in the cling film of the present invention. It can be seen from the results of the comparative example 4 that when the fulvic acid in the cling film of the present invention is abandoned, its longest shelf life and sensory index score are also lower than those of the embodiment 1 group, and the weight loss rate is increased, which means that the dosage ratio of fulvic acid also has a significant effect on the fresh-keeping effect of the cling film of the present invention. In addition, through the effect comparison, it is found that the fresh-keeping effect of any missing fulvic acid, gelatin and genipin is not as good as the simultaneous presence of the three, indicating that a synergistic effect is produced between the three, and none of the three is indispensable. Therefore, the synergistic fresh-keeping effect produced by the compound combination of fulvic acid, gelatin and genipin in the present invention is an unexpected technical effect.

[0030] Effect Example 3: Chitosan or carboxymethyl chitosan is used to replace gelatin to prepare fresh-keeping film Chitosan or carboxymethyl chitosan was used to replace the gelatin in Example 1 of the present invention to prepare the relevant fresh-keeping film. The results are as follows Figure 3 The results show that chitosan cannot be dissolved in it and there is an obvious stratification phenomenon ( Figure 3 Therefore, it cannot be directly sprayed on the surface of fruits for preservation; although carboxymethyl chitosan can be dissolved in it, the prepared complex is too viscous and its coating effect is very poor ( Figure 3 ② The adhesion is not good, and ③ The flatness is very poor), and the mechanical properties are poor and it is easy to break. Relatively speaking, the composite with gelatin added has a good coating effect and better mechanical properties ( Figure 3 ④⑤ have good adhesion and ductility, and the toughness of ⑤ is better after adding fulvic acid). It can be seen that the synergistic effect presented in the embodiments of the present invention is not obvious.

[0031] In summary, the fruit preservative film based on the synergistic effect of three natural components of fulvic acid, gelatin and genipin in the present invention has a good preservative effect, and the active components have an obvious synergistic preservative effect, achieving unexpected technical effects.

Claims

1. A fruit preservative film based on the synergy of natural components, characterized in that The components and weight parts are: 40-80 parts of fulvic acid, 400-600 parts of gelatin, 1-3 parts of genipin, 100-200 parts of ethanol, and 9000-9500 parts of water; The fulvic acid is lignite fulvic acid, which is prepared with lignite as raw material according to the patent CN200810233669.X "Method for producing humic acid and its salts by oxidation and degradation of lignite", and has passed the heavy metal test; The fulvic acid, gelatin and genipin are used as synergistic active components for fruit preservation; The preparation method of the fruit preservative film has the following steps: (1) Weighing genipin by weight, dissolving it in ethanol, and stirring it evenly at room temperature to prepare a genipin alcohol solution for later use; (2) Weigh fulvic acid by weight, add it to half of the total amount of water, stir evenly at room temperature to prepare a fulvic acid aqueous solution for later use; (3) Weighing gelatin by weight, adding it to the other half of the total amount of water, stirring for 5-10 minutes at a temperature of 45-50° C. and a rotation speed of 200-300 r / min, then slowly adding the genipinol solution drop by drop, continuing to stir for 5-10 minutes, then slowly adding the fulvic acid aqueous solution drop by drop, continuing to stir for another 5-10 minutes, stopping stirring and cooling to room temperature, thereby obtaining a preservative film stock solution; The method for using the fruit preservative film is as follows: soaking or spraying the preservative film stock solution on the surface of the fruit, and forming a layer of soft solid film after the surface water evaporates slightly.

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