Biological fresh-keeping agent for fruits and vegetables

Abstract

The invention discloses a fruit and vegetable biological fresh-keeping agent, and belongs to the technical field of fruit and vegetable fresh-keeping, and the fruit and vegetable biological fresh-keeping agent is prepared from the following components: chitosan, a citrus extract, galactomannan, an elaeagnus angustifolia flower fermentation extract and water. The elaeagnus angustifolia flower fermentation extract is prepared by the following steps: crushing elaeagnus angustifolia flowers, adding the crushed elaeagnus angustifolia flowers into a liquid culture medium, uniformly mixing, sterilizing, cooling, inoculating lactobacillus reuteri for anaerobic fermentation, inoculating paenibacillus polymyxa for aerobic fermentation, collecting fermentation liquor after the fermentation is finished, filtering and sterilizing by using a microfiltration membrane, and concentrating under reduced pressure to obtain the elaeagnus angustifolia flower fermentation extract. The components of the fruit and vegetable biological fresh-keeping agent are all from pure natural bio-based raw materials, and the fruit and vegetable biological fresh-keeping agent does not contain any chemical product, so that secondary pollution to fruits and vegetables is effectively avoided, the fruit and vegetable biological fresh-keeping agent has an excellent fresh-keeping effect, can obviously prolong the fresh-keeping time of the fruits and vegetables, does not influence the mouth feel of the fruits and vegetables, and is green, safe and convenient to use.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit and vegetable preservation, and particularly relates to a biological preservative for fruits and vegetables. Background Art

[0002] In the modern agricultural production and circulation system, fruits and vegetables, as important agricultural products, play an indispensable role in ensuring people's daily dietary structure and nutritional intake. However, since fruits and vegetables are perishable products, their post-harvest processing and preservation technology are directly related to the quality, economic benefits and market supply stability of fruits and vegetables. According to statistics, about 80 million tons of vegetables and fruits in my country rot and deteriorate every year due to failure to receive effective preservation treatment, causing economic losses of nearly 80 billion yuan. This not only reflects the huge challenges in the post-production management link, but also highlights the importance of optimizing fruit and vegetable preservation measures. If the loss rate can be reduced, it means that a large amount of economic value can be recovered, while improving resource utilization efficiency and reducing waste.

[0003] Fruit and vegetable preservation not only reduces the post-harvest loss rate, but also has important significance for promoting long-distance transportation and circulation and achieving staggered listing. This helps to form a pattern of "regional concentrated production and national cross-regional circulation" to meet the needs of consumers in different regions for diversified fruits and vegetables at different times. By maintaining the good quality and appearance of fruits and vegetables, the market competitiveness and added value of products can also be improved. The application of fruit and vegetable preservatives plays a key role in this process. The correct use of preservatives can delay the respiration of fruits and vegetables and slow down their aging process, thereby extending the shelf life and ensuring that fruits and vegetables maintain their best condition during transportation and storage. At present, there are many types of preservatives, including chemical synthetic substances and natural extracts, which can achieve the preservation effect by inhibiting the growth of microorganisms, regulating the gas environment or affecting the physiological activities inside fruits and vegetables. With the advancement of science and technology, more and more safe and efficient new preservatives have been developed and gradually applied in actual production, providing strong support for solving the problem of post-harvest preservation of fruits and vegetables.

[0004] For example, Chinese patent CN109169870A discloses a method for preparing a fruit and vegetable preservative, whose raw materials include propolis aqueous solution, onion aqueous solution, star anise extract and water, and are prepared by extract preparation, mixing, filtration and sterilization, and packaging steps; the fruit and vegetable preservative can extend the storage period of fruits and vegetables and maintain the color of fruits and vegetables. Chinese patent CN110810502A discloses a composite biological preservative for fruits and vegetables and a preparation method thereof, whose raw materials include chitosan solution, natamycin, citrus peel extract, propolis extract, microbial fermentation liquid, wintergrass extract and water, and are prepared by fermentation liquid preparation, extract preparation, stirring and mixing; the composite biological preservative uses microbial fermentation liquid and natural plant extracts as main raw materials, is safe and non-toxic, can significantly reduce the decay, dehydration, taste change and other phenomena of various fruits and vegetables, and extend the storage period and shelf life of fruits and vegetables. The fruit and vegetable preservative disclosed in the above patent has solved the problems existing in traditional preservation methods to a certain extent, but the preservation effect still needs to be improved in practical applications, so as to have the advantages of ideal preservation effect, safety and health, and not affecting the taste of fruits and vegetables. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a fruit and vegetable biological preservative, which further improves the fruit and vegetable preservation effect of the preservative by adding a specific Elaeagnus angustifolia flower fermented extract and galactomannan to the traditional formula such as chitosan / citrus extract, thereby extending the preservation time of fruits and vegetables without affecting the taste of fruits and vegetables, being green, safe and easy to use. The present invention also provides a preparation method of the above-mentioned fruit and vegetable biological preservative.

[0006] The technical solution of the present invention is as follows:

[0007] A fruit and vegetable biological preservative, comprising the following components:

[0008] Chitosan, citrus extract, galactomannan, Elaeagnus angustifolia flower fermented extract, water.

[0009] Preferably, a fruit and vegetable biological preservative comprises the following components in parts by weight:

[0010] 2-8 parts by weight of chitosan, 2-8 parts by weight of citrus extract, 4-12 parts by weight of galactomannan, 3-10 parts by weight of Elaeagnus angustifolia flower fermented extract, and 900-1100 parts by weight of water.

[0011] Furthermore, a fruit and vegetable biological preservative is prepared by including the following components in parts by weight:

[0012] 4-6 parts by weight of chitosan, 4-6 parts by weight of citrus extract, 6-10 parts by weight of galactomannan, 5-8 parts by weight of Elaeagnus angustifolia flower fermented extract, and 950-1000 parts by weight of water.

[0013] The fruit and vegetable biological preservative of the present invention comprises effective components such as chitosan, citrus extract, galactomannan and elata flower fermented extract; chitosan is a natural polysaccharide, healthy and environmentally friendly, and can form a transparent and flexible protective film on the surface of fruits and vegetables, which can not only effectively reduce water evaporation, but also prevent the invasion of external microorganisms, inhibit the growth and reproduction of pathogens, and significantly extend the shelf life of fruits and vegetables. Galactomannan is a water-soluble macromolecular polysaccharide, which synergizes with chitosan to enhance the flexibility, elasticity and stability of film formation, making the protective film more uniform and dense, and further improving its barrier function. This combination can not only effectively reduce water evaporation, but also prevent oxygen from entering the inside of the fruit, delay the occurrence of oxidation reaction, and maintain the freshness and nutritional value of fruits and vegetables. Citrus extract is rich in various antioxidant substances, such as vitamins, flavonoids and organic acids, which can delay the oxidation reaction of fruits. The synergistic effect of citrus extract, chitosan and galactomannan makes the preservative not only have excellent film-forming and antibacterial properties, but also provide good antioxidant protection. The fermented extract of Elaeagnus angustifolia flower is prepared by a specific method using Elaeagnus angustifolia flower as raw material. It has excellent antibacterial and antiseptic properties and antioxidant properties, and can significantly improve the preservation and anti-corruption effects of fruits and vegetables. It works synergistically with chitosan, galactomannan and citrus extracts to form a multi-level and multifunctional preservation system, which comprehensively improves the preservation effect of fruits and vegetables and maintains the quality and nutritional value of the fruit.

[0014] Preferably, the Elaeagnus angustifolia flower fermented extract is prepared by the following method:

[0015] The flower of Elaeagnus angustifolia was crushed through a 100-200 mesh sieve, and then added to a liquid culture medium and mixed evenly, wherein the weight ratio of the flower of Elaeagnus angustifolia to the liquid culture medium is 1:5-10, and then sterilized at 120-125°C for 10-20 minutes, cooled to room temperature, inoculated with Lactobacillus reuteri for anaerobic fermentation for 50-70 hours; then inoculated with Paenibacillus polymyxa for aerobic fermentation for 30-40 hours; after completion, centrifuged and collected the fermented liquid, filtered and sterilized with a 0.1-0.45 μm microporous filter membrane, and concentrated under reduced pressure to 15-30% of the original volume to obtain an Elaeagnus angustifolia flower fermentation extract.

[0016] Furthermore, the present invention uses the flower of Elaeagnus angustifolia as a raw material to prepare the fermented extract of the flower of Elaeagnus angustifolia. The flower of Elaeagnus angustifolia is rich in nutrients such as polyphenol compounds, flavonoid compounds, terpene compounds, amino acids, vitamins, organic acids, triterpenes, carotenoids, etc., and a specific combination of fermentation bacteria, 'Lactobacillus reuteri (anaerobic) and Paenibacillus polymyxa (aerobic)', are used for joint fermentation treatment. The two bacteria cooperate with each other to form an efficient fermentation system, which can extract the active substances in the flower of Elaeagnus angustifolia to the maximum extent, and at the same time metabolize to produce rich active metabolites, and finally obtain a highly active fermented extract, which not only has excellent antibacterial and antiseptic properties and antioxidant properties, but also can significantly improve the preservation and anti-corruption effects of fruits and vegetables. During the fermentation process, the synergistic effect of Lactobacillus reuteri and Paenibacillus polymyxa is crucial, which can fully decompose large molecular fibers, proteins, etc., while dissolving and retaining antibacterial and antioxidant active substances, achieving the purpose of removing impurities and enriching active ingredients; among them, Lactobacillus reuteri can secrete a variety of enzymes, which can effectively decompose the complex polysaccharides, fibers and proteins in the flowers of the saxaul, and convert them into small molecules that are more easily utilized, such as oligosaccharides, amino acids and short peptides, and promote the release and enrichment of polyphenols and flavonoids in the flowers of the saxaul. These active ingredients can neutralize free radicals, delay the oxidation reaction of fruits and vegetables, maintain the color, flavor and nutritional content of fruits and vegetables, and can also inhibit enzymatic reactions related to fruit and vegetable aging, such as peroxidase and polyphenol oxidase, and reduce the occurrence of browning and softening. Bacillus polymyxa can also metabolize to produce lipopeptides and polypeptide antibacterial substances, which can inhibit the growth of a variety of pathogenic bacteria and spoilage bacteria. Lipopeptides can also improve the stability of other components, making them easier to be evenly distributed on the surface of fruits and vegetables to form a protective film, further improving the antioxidant and anti-corruption capabilities of fruit and vegetable preservatives.

[0017] Preferably, the conditions for the anaerobic fermentation are: temperature 35-40°C, pH value 6.0-6.5, rotation speed 100-250r / min, and ventilation volume 0L / min.

[0018] Preferably, the inoculation amount of Lactobacillus reuteri is 1×10 10 -5×10 10 cfu / L feed solution.

[0019] Preferably, the conditions for aerobic fermentation are: temperature 27-32°C, pH 6.5-7.0, rotation speed 100-250r / min, and ventilation volume 20-30L / min.

[0020] Preferably, the inoculation amount of the polymyxa bacillus is 1×10 10 -3×10 10 cfu / L feed solution.

[0021] Preferably, the Lactobacillus reuteri is purchased from the China Industrial Microbiological Culture Collection Administration Center (CICC6132); the Paenibacillus polymyxa is purchased from the China Industrial Microbiological Culture Collection Administration Center (No.: CICC21779).

[0022] Preferably, the raw material of Elaeagnus angustifolia flower is dried Elaeagnus angustifolia flower with a water content of 5-10%; wherein the Elaeagnus angustifolia flower is the flower of Elaeagnus angustifolia L. of the family Elaeagnaceae.

[0023] Preferably, the liquid culture medium is composed of the following raw materials: water, glucose, yeast extract, triammonium citrate, sodium chloride, dipotassium hydrogen phosphate, and magnesium sulfate.

[0024] Furthermore, the liquid culture medium is composed of the following raw materials: based on 1L of water, 3-5g of glucose, 2-4g of yeast extract, 0.1-0.5g of triammonium citrate, 0.5-0.8g of sodium chloride, 0.1-0.5g of dipotassium hydrogen phosphate, and 0.02-0.06g of magnesium sulfate.

[0025] The chitosan used in the invention has an average molecular weight of 50,000-80,000 and a deacetylation degree of 80-90%, and is derived from the exoskeleton of marine crustaceans.

[0026] The galactomannan used in the present invention has an average molecular weight of 20,000-50,000 and is derived from carob.

[0027] The citrus extract used in the present invention can be directly purchased from the market, or can be prepared by the following method.

[0028] Preferably, the citrus extract is prepared by the following method:

[0029] The citrus peel is crushed, then added into an ethanol aqueous solution and mixed evenly, heated for extraction, cooled, centrifuged, the supernatant is collected, and concentrated under reduced pressure to obtain the citrus extract.

[0030] Furthermore, the citrus extract is prepared by the following method:

[0031] The citrus peel is crushed and passed through a 100-200 mesh sieve, and then added into a 65-80wt% ethanol aqueous solution and mixed evenly, wherein the weight ratio of the citrus peel to the ethanol aqueous solution is 1:3-5, and the citrus peel is heated and extracted at 80-90°C and 100-200r / min for 1-3h, cooled to room temperature, centrifuged, the supernatant is collected, and reduced pressure concentration is performed to 15-30% of the original volume to obtain a citrus extract.

[0032] Preferably, the raw material citrus peel is dried citrus peel with a water content of 5-10%.

[0033] Preferably, the citrus fruit includes any one of sweet orange, grapefruit, citron, kumquat, tangerine, and lemon.

[0034] The present invention also provides a method for preparing a fruit and vegetable biological preservative, comprising the following steps:

[0035] Weigh each component according to the formula, dissolve chitosan in acetic acid aqueous solution, and then mix it with citrus extract, galactomannan, Elaeagnus angustifolia flower fermented extract and water to obtain the fruit and vegetable biological preservative. Preferably, the concentration of acetic acid aqueous solution is 1-2wt%.

[0036] Beneficial effects of the present invention:

[0037] The fruit and vegetable biological preservative prepared by the present invention has components all derived from pure natural bio-based raw materials, is green and safe, has excellent fresh-keeping effect, and can significantly extend the fresh-keeping time of fruits and vegetables. The present invention can synergize with chitosan and citrus extract by adding galactomannan and a specific elata flower fermentation extract (which uses elata flower as the main raw material and is extracted after being subjected to combined fermentation treatment of Lactobacillus reuteri and Paenibacillus polymyxa), further improving the fruit and vegetable fresh-keeping effect of the preservative, while not adversely affecting the taste of fruits and vegetables. DETAILED DESCRIPTION

[0038] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The chitosan in the embodiment has CAS: 9012-76-4, a deacetylation degree of 85%, an average molecular weight of 50,000, and is derived from the exoskeleton of marine crustaceans.

[0040] The galactomannan in the embodiment has CAS number 11078-30-1 and an average molecular weight of 20,000, and is derived from carob.

[0041] The citrus extract in the embodiment is prepared by the following method:

[0042] The dried citrus peel (specifically sweet orange (Latin name: Citrus sinensis (L.) Osbeck) peel, water content 10%) was crushed through a 200-mesh sieve, and then added to a 70wt% ethanol aqueous solution and mixed evenly, the weight ratio of the citrus peel to the ethanol aqueous solution was 1:4, heated and extracted at 85°C and 150r / min for 2h, cooled to room temperature, centrifuged, the supernatant was collected, and reduced pressure was concentrated to 20% of the original volume to obtain a citrus extract.

[0043] Example 1

[0044] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0045] 5 parts by weight of chitosan, 5.5 parts by weight of citrus extract, 8 parts by weight of galactomannan, 6.5 parts by weight of Elaeagnus angustifolia flower fermented extract, and 975 parts by weight of water.

[0046] The Elaeagnus angustifolia flower fermented extract is prepared by the following method:

[0047] The dried Elaeagnus angustifolia flower (water content 8%) was crushed through a 200-mesh sieve, and then added to the liquid culture medium and mixed evenly, the weight ratio of the Elaeagnus angustifolia flower to the liquid culture medium was 1:7, and then sterilized at 121°C for 15 minutes, cooled to room temperature, and inoculated with Lactobacillus reuteri for anaerobic fermentation for 60 hours; wherein the conditions of the anaerobic fermentation were: temperature 37°C, pH 6.5, rotation speed 200r / min, ventilation volume 0L / min; the inoculation amount of Lactobacillus reuteri was 3.6×10 10 cfu / L liquid; the Lactobacillus reuteri was purchased from China Industrial Microbiological Culture Collection Center (CICC 6132);

[0048] Then, Bacillus polymyxa was inoculated and aerobic fermentation was carried out for 36 hours; wherein the conditions of aerobic fermentation were: temperature 30°C, pH value 7.0, rotation speed 200r / min, ventilation volume 25L / min; the inoculation amount of Bacillus polymyxa was 1.5×10 10 cfu / L liquid; the polymyxa bacillus was purchased from China Industrial Microbiological Culture Collection Center (No.: CICC21779);

[0049] After the reaction was completed, the fermentation liquid was collected by centrifugation, sterilized by filtration using a 0.22 μm microporous filter membrane, and concentrated under reduced pressure to 20% of the original volume to obtain the fermentation extract of Elaeagnus angustifolia flowers.

[0050] The liquid culture medium is composed of the following raw materials: based on 1L of water, 4g of glucose, 3g of yeast extract, 0.3g of triammonium citrate, 0.6g of sodium chloride, 0.3g of dipotassium hydrogen phosphate, and 0.04g of magnesium sulfate.

[0051] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0052] The components are weighed according to the formula, chitosan is dissolved in a 1 wt% acetic acid aqueous solution, and then the chitosan is evenly mixed with citrus extract, galactomannan, angustifolia flower fermented extract and water to obtain the fruit and vegetable biological preservative.

[0053] Example 2

[0054] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0055] 13 parts by weight of chitosan, 5.5 parts by weight of citrus extract, 6.5 parts by weight of Elaeagnus angustifolia flower fermented extract, and 975 parts by weight of water.

[0056] The Elaeagnus angustifolia flower fermented extract is prepared by the following method:

[0057] The dried Elaeagnus angustifolia flower (water content 8%) was crushed through a 200-mesh sieve, and then added to the liquid culture medium and mixed evenly, the weight ratio of the Elaeagnus angustifolia flower to the liquid culture medium was 1:7, and then sterilized at 121°C for 15 minutes, cooled to room temperature, and inoculated with Lactobacillus reuteri for anaerobic fermentation for 60 hours; wherein the conditions of the anaerobic fermentation were: temperature 37°C, pH 6.5, rotation speed 200r / min, ventilation volume 0L / min; the inoculation amount of Lactobacillus reuteri was 3.6×10 10 cfu / L liquid; the Lactobacillus reuteri was purchased from China Industrial Microbiological Culture Collection Center (CICC 6132);

[0058] Then, Bacillus polymyxa was inoculated and aerobic fermentation was carried out for 36 hours; wherein the conditions of aerobic fermentation were: temperature 30°C, pH value 7.0, rotation speed 200r / min, ventilation volume 25L / min; the inoculation amount of Bacillus polymyxa was 1.5×10 10 cfu / L liquid; the polymyxa bacillus was purchased from China Industrial Microbiological Culture Collection Center (No.: CICC21779);

[0059] After the reaction was completed, the fermentation liquid was collected by centrifugation, sterilized by filtration using a 0.22 μm microporous filter membrane, and concentrated under reduced pressure to 20% of the original volume to obtain the fermentation extract of Elaeagnus angustifolia flowers.

[0060] The liquid culture medium is composed of the following raw materials: based on 1L of water, 4g of glucose, 3g of yeast extract, 0.3g of triammonium citrate, 0.6g of sodium chloride, 0.3g of dipotassium hydrogen phosphate, and 0.04g of magnesium sulfate.

[0061] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0062] The components are weighed according to the formula, chitosan is dissolved in a 1 wt % acetic acid aqueous solution, and then the chitosan is evenly mixed with the citrus extract, the fermented extract of the angustifolia flower and water to obtain the fruit and vegetable biological preservative.

[0063] Example 3

[0064] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0065] 5 parts by weight of chitosan, 12 parts by weight of citrus extract, 8 parts by weight of galactomannan, and 975 parts by weight of water.

[0066] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0067] The components are weighed according to the formula, chitosan is dissolved in a 1 wt% acetic acid aqueous solution, and then the chitosan is evenly mixed with the citrus extract, galactomannan and water to obtain the fruit and vegetable biological preservative.

[0068] Example 4

[0069] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0070] 5 parts by weight of chitosan, 5.5 parts by weight of citrus extract, 8 parts by weight of galactomannan, 6.5 parts by weight of Elaeagnus angustifolia flower fermented extract, and 975 parts by weight of water.

[0071] The Elaeagnus angustifolia flower fermented extract is prepared by the following method:

[0072] The dried Elaeagnus angustifolia flower (water content 8%) was crushed through a 200-mesh sieve, and then added to the liquid culture medium and mixed evenly, the weight ratio of the Elaeagnus angustifolia flower to the liquid culture medium was 1:7, and then sterilized at 121°C for 15 minutes, cooled to room temperature, and inoculated with Lactobacillus reuteri for anaerobic fermentation for 96 hours; wherein the conditions of the anaerobic fermentation were: temperature 37°C, pH 6.5, rotation speed 200r / min, ventilation volume 0L / min; the inoculation amount of Lactobacillus reuteri was 3.6×10 10 cfu / L liquid; the Lactobacillus reuteri was purchased from China Industrial Microbiological Culture Collection Center (CICC 6132);

[0073] After the reaction was completed, the fermentation liquid was collected by centrifugation, sterilized by filtration using a 0.22 μm microporous filter membrane, and concentrated under reduced pressure to 20% of the original volume to obtain the fermentation extract of Elaeagnus angustifolia flowers.

[0074] The liquid culture medium is composed of the following raw materials: based on 1L of water, 4g of glucose, 3g of yeast extract, 0.3g of triammonium citrate, 0.6g of sodium chloride, 0.3g of dipotassium hydrogen phosphate, and 0.04g of magnesium sulfate.

[0075] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0076] The components are weighed according to the formula, chitosan is dissolved in a 1 wt% acetic acid aqueous solution, and then the chitosan is evenly mixed with citrus extract, galactomannan, angustifolia flower fermented extract and water to obtain the fruit and vegetable biological preservative.

[0077] Example 5

[0078] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0079] 5 parts by weight of chitosan, 5.5 parts by weight of citrus extract, 8 parts by weight of galactomannan, 6.5 parts by weight of Elaeagnus angustifolia flower fermented extract, and 975 parts by weight of water.

[0080] The Elaeagnus angustifolia flower fermented extract is prepared by the following method:

[0081] The dried Elaeagnus angustifolia flowers (water content 8%) were crushed through a 200-mesh sieve, and then added to the liquid culture medium and mixed evenly. The weight ratio of the Elaeagnus angustifolia flowers to the liquid culture medium was 1:7. The mixture was sterilized at 121°C for 15 minutes, cooled to room temperature, and inoculated with Bacillus polymyxa for aerobic fermentation for 96 hours. The conditions for aerobic fermentation were as follows: temperature 30°C, pH 7.0, rotation speed 200r / min, and ventilation volume 25L / min. The inoculation amount of Bacillus polymyxa was 1.5×10 10 cfu / L liquid; the polymyxa bacillus was purchased from China Industrial Microbiological Culture Collection Center (No.: CICC 21779);

[0082] After the reaction was completed, the fermentation liquid was collected by centrifugation, sterilized by filtration using a 0.22 μm microporous filter membrane, and concentrated under reduced pressure to 20% of the original volume to obtain the fermentation extract of Elaeagnus angustifolia flowers.

[0083] The liquid culture medium is composed of the following raw materials: based on 1L of water, 4g of glucose, 3g of yeast extract, 0.3g of triammonium citrate, 0.6g of sodium chloride, 0.3g of dipotassium hydrogen phosphate, and 0.04g of magnesium sulfate.

[0084] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0085] The components are weighed according to the formula, chitosan is dissolved in a 1 wt% acetic acid aqueous solution, and then the chitosan is evenly mixed with citrus extract, galactomannan, angustifolia flower fermented extract and water to obtain the fruit and vegetable biological preservative.

[0086] Example 6

[0087] A fruit and vegetable biological preservative, comprising the following components in parts by weight:

[0088] 5 parts by weight of chitosan, 5.5 parts by weight of citrus extract, 8 parts by weight of galactomannan, 6.5 parts by weight of Elaeagnus angustifolia flower extract, and 975 parts by weight of water.

[0089] The Elaeagnus angustifolia flower extract is prepared by the following method:

[0090] The dried Elaeagnus angustifolia flower (water content 8%) was crushed through a 200-mesh sieve, and then added into a 70wt% ethanol aqueous solution and mixed evenly, wherein the weight ratio of the Elaeagnus angustifolia flower to the ethanol aqueous solution was 1:7. The mixture was heated and extracted at 85°C and 150r / min for 2h, cooled to room temperature, centrifuged, the supernatant was collected, and concentrated under reduced pressure to 20% of the original volume to obtain an Elaeagnus angustifolia flower extract.

[0091] A method for preparing a fruit and vegetable biological preservative comprises the following steps:

[0092] The components are weighed according to the formula, chitosan is dissolved in a 1 wt% acetic acid aqueous solution, and then the chitosan is evenly mixed with the citrus extract, galactomannan, angustifolia flower extract and water to obtain the fruit and vegetable biological preservative.

[0093] Test Example 1

[0094] Tomatoes of the same batch, with consistent maturity and good development, were picked for storage experiment and randomly divided into 7 groups, each with the same weight. Among them, one group was used as the control group to soak the post-harvest tomatoes in water for 6 minutes, and the other 6 groups were used as experimental groups to soak the post-harvest tomatoes in the fruit and vegetable biological preservatives described in Examples 1-6 for 6 minutes, and the surface moisture was naturally air-dried, and the tomatoes were packaged in 30μm thick polyethylene gas-controlled fresh-keeping bags and stored at low temperature (10℃) for 2 weeks to evaluate the changes in the hardness, weight and VC content of the tomatoes. Reduction rate = (initial value - final value) / initial value × 100%, and the test results are shown in Table 1.

[0095] Table 1: Storage test results

[0096]

[0097] As can be seen from Table 1, the use of the fruit and vegetable biological preservative of Example 1 of the present invention can achieve the best preservation effect, extend the storage time, and retain the nutritional value of fruits and vegetables to the maximum extent. In comparison, Examples 2-6 did not adopt a specific technical solution, and their various test results were significantly worse. Compared with Examples 2-3, Example 1 simultaneously adds the fermented extract of the flower of Elaeagnus angustifolia and galactomannan. Galactomannan can synergize with chitosan to enhance the flexibility, elasticity and stability of the film, making the protective film more uniform and dense, and further improving its barrier function. This combination can not only effectively reduce water evaporation, but also prevent oxygen from entering the interior of the fruit, delay the occurrence of oxidation reactions, and maintain the freshness and nutritional value of fruits and vegetables; the fermented extract of the flower of Elaeagnus angustifolia is prepared from the flower of Elaeagnus angustifolia by specific fermentation bacteria, has excellent antibacterial and antiseptic properties and antioxidant properties, can significantly improve the preservation and anti-corruption effects of fruits and vegetables, and synergizes with chitosan, galactomannan and citrus extract to form a multi-level and multifunctional preservation system, which comprehensively improves the preservation effect of fruits and vegetables and maintains the quality and nutritional value of the fruit. Compared with embodiment 4-6, embodiment 1 carries out joint fermentation treatment by adopting fermentation bacteria of specific combination ' Lactobacillus reuteri mucus (anaerobic) and Paenibacillus polymyxa (aerobic)', and the two cooperate with each other to form an efficient fermentation system, and the active substances in the flower of Elaeagnus angustifolia can be extracted to the greatest extent, and abundant active metabolites are produced by metabolism at the same time, and finally a high-activity fermentation extract is obtained, which not only has excellent antibacterial and antiseptic properties and antioxidant properties, but also can significantly improve the fresh-keeping and anti-corruption effects of fruits and vegetables. In the fermentation process, the synergistic effect of Lactobacillus reuteri mucus and Paenibacillus polymyxa is crucial, and macromolecular fibers, proteins, etc. can be fully decomposed, and antibacterial and antioxidant active substances are dissolved and retained at the same time, so as to achieve the purpose of removing impurities and enriching active ingredients.

[0098] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A biological preservative for fruits and vegetables, characterized in that: The invention comprises the following components in parts by weight: 2-8 parts by weight of chitosan, 2-8 parts by weight of citrus extract, 4-12 parts by weight of galactomannan, 3-10 parts by weight of fermented extract of Elaeagnus angustifolia flowers, and 900-1100 parts by weight of water.

2. The fruit and vegetable biological preservative according to claim 1, characterized in that: The Elaeagnus angustifolia flower fermented extract is prepared by the following method: The flower of Elaeagnus angustifolia was crushed, then added into liquid culture medium and mixed evenly, sterilized, cooled and inoculated with Lactobacillus reuteri for anaerobic fermentation, and then inoculated with Bacillus polymyxa for aerobic fermentation. After completion, the fermentation liquid was centrifuged and collected, filtered and sterilized with a microporous filter membrane, and concentrated under reduced pressure to obtain the fermented extract of Elaeagnus angustifolia.

3. The fruit and vegetable biological preservative according to claim 2, characterized in that: The liquid culture medium is composed of the following raw materials: water, glucose, yeast extract, triammonium citrate, sodium chloride, dipotassium hydrogen phosphate and magnesium sulfate.

4. The fruit and vegetable biological preservative according to claim 2, characterized in that: The weight ratio of the Elaeagnus angustifolia flowers to the liquid culture medium is 1:5-10.

5. The fruit and vegetable biological preservative according to claim 2, characterized in that: The inoculation amount of Lactobacillus reuteri is 1×10 10 -5×10 10 cfu / L feed solution.

6. The fruit and vegetable biological preservative according to claim 2, characterized in that: The inoculum size of the polymyxa bacillus was 1×10 10 -3×10 10 cfu / L feed solution.

7. The fruit and vegetable biological preservative according to claim 2, characterized in that: The conditions of the anaerobic fermentation are: temperature 35-40°C, pH value 6.0-6.5, and rotation speed 100-250r / min.

8. The fruit and vegetable biological preservative according to claim 2, characterized in that: The conditions of aerobic fermentation are: temperature 27-32°C, pH value 6.5-7.0, and rotation speed 100-250r / min.

9. The fruit and vegetable biological preservative according to claim 1, characterized in that: The composition is made of the following components in parts by weight: 4-6 parts by weight of chitosan, 4-6 parts by weight of citrus extract, 6-10 parts by weight of galactomannan, 5-8 parts by weight of Elaeagnus angustifolia flower fermented extract, and 950-1000 parts by weight of water.

10. The method for preparing the fruit and vegetable biological preservative according to any one of claims 1 to 9, characterized in that: The steps include: The components are weighed according to the formula, chitosan is dissolved in an acetic acid aqueous solution, and then the chitosan is evenly mixed with citrus extract, galactomannan, angustifolia flower fermented extract and water to obtain the fruit and vegetable biological preservative.

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