Compound preservative and its application in preservation of postharvest juicy peach

Abstract

This invention discloses a composite preservative and its application in postharvest preservation of peaches. The preservative is formulated from a compound of Pinus sylvestris extract, oat extract, chitosan, olive oil, arginine, calcium glutamate, 1-MCP powder, and a food-grade emulsifier. The invention first prepares Pinus sylvestris extract through ultrasonic ethanol extraction, and then prepares oat extract powder using a microwave-ultrasonic enzymatic hydrolysis process. Next, amino acids, Pinus sylvestris extract, and olive oil are emulsified and homogenized, and then compounded with 1-MCP to obtain a composite emulsion. Finally, the emulsion is cross-linked and mixed with chitosan and oat base liquid to obtain a stable preservative. This preservative is applied by atomized spraying to form a film. The film is highly flexible and does not crack at low temperatures. It simultaneously achieves multiple functions including ethylene inhibition, respiration reduction, antioxidant properties, chilling injury resistance, and broad-spectrum antibacterial activity. It can significantly delay the softening of peach flesh, browning of the peel, and rotting, making it suitable for large-scale postharvest preservation of peaches.

Description

Technical Field

[0001] This invention belongs to the field of postharvest preservation technology for fruits and vegetables, specifically relating to a compound preservative, its preparation method, and its application. Background Technology

[0002] Peaches are typical climacteric drupes with thin skin, soft flesh, high water content, and high post-harvest respiration rate. This makes them highly susceptible to problems such as excessive ethylene accumulation, rapid softening of the flesh, browning of the skin, dehydration and shriveling, and mold infection and rotting. Under normal temperature conditions, peaches have an extremely short shelf life, making them a high-loss and difficult-to-store category in the preservation of fresh fruits and vegetables, severely limiting their long-distance transportation and shelf sales.

[0003] Peaches are highly susceptible to mechanical damage, and due to their cold sensitivity, prolonged exposure to unsuitable low temperatures can easily cause chilling injury. Quality deterioration caused by chilling injury includes: leathery flesh, tissue rot, hardening, browning, and loss of inherent flavor. Peaches are also vulnerable to various diseases during storage, such as blue mold rot, gray mold rot, Rhizopus rot, and brown rot, which can lead to softening and decay. Pathogens can be carried in the field and infect through mechanical wounds, and the rich nutrients in peaches easily attract microbial growth.

[0004] Existing preservation technologies mainly fall into two categories: physical preservation (low-temperature refrigeration, modified atmosphere treatment, heat treatment, etc.) and chemical preservation. While physical preservation technologies have seen some adoption, they also have limitations, such as high equipment investment, high energy consumption, and difficulty in widespread implementation. Chemical preservatives pose a problem of pesticide residues, which may affect human health with long-term consumption. Currently, most commercially available peach bio-preservatives are single antibacterial agents, unable to simultaneously address the multiple aging issues during storage. Therefore, developing a fully natural, edible, highly stable, and multifunctional peach-specific preservative, suitable for both ambient temperature storage and transportation as well as low-temperature cold chain preservation, has significant practical importance and application value. Summary of the Invention

[0005] Technical problems to be solved: This invention addresses the shortcomings of existing peach preservatives, such as limited functionality, lack of inhibition of ethylene synthesis, and susceptibility to chilling injury during cold storage. This invention provides a compound preservative suitable for peaches and its preparation method by optimizing the formula and preparation process.

[0006] Technical solution: A composite preservative, composed of the following components in parts by weight: 5-8 parts chitosan, 5-8 parts oat extract, 12-15 parts pine extract, 15-20 parts olive oil, 2-3 parts arginine, 1.5-2.5 parts calcium glutamate, 0.3-0.5 parts 1-MCP powder, and 0.5-1.0 parts food-grade emulsifier.

[0007] Furthermore, the pine extract is an ethanol extract of pine wood, prepared by the following method: pine wood is crushed and sieved to obtain sawdust raw material, ethanol solution is added, ultrasonic extraction is performed at room temperature, centrifugation and filtration are performed, the filtrate is collected, and the filtrate is concentrated under reduced pressure to obtain the pine extract.

[0008] Furthermore, the concentration of the ethanol solution is 50-60 wt.%; the mass ratio of sawdust raw material to ethanol solution is 1:(10-15); the ultrasonic extraction time is 30-40 min, and the ultrasonic power is 300-400 W; and the volume is concentrated under reduced pressure to 20-30% of the original volume.

[0009] Furthermore, the oat extract is prepared by the following method: oats are dried, pulverized and sieved to obtain oat flour, water is added and microwaved to obtain an oat mixture, amylase and saccharifying enzyme are added for enzymatic hydrolysis, enzymes are inactivated and centrifuged to remove solid residue, the supernatant is concentrated under reduced pressure and spray-dried to obtain oat extract powder.

[0010] Furthermore, the mass ratio of oat flour to water is 1:(10-15); the microwave power is 400-500W, and the processing time is 3-5 minutes; the amount of amylase and saccharifying enzyme added, measured by oat flour, is 1500-2000 U / g and 3000-4000 U / g, respectively; the enzymatic hydrolysis conditions are pH 6.0-6.5, temperature 55-60℃, and hydrolysis time of 2-3 hours; the enzyme inactivation conditions are an 80-90℃ water bath for 10-15 minutes.

[0011] Furthermore, the food-grade emulsifier is one or both of Tween-80 or lecithin.

[0012] The preparation method of the above-described composite preservative is characterized by comprising the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8-10 times the amount of water, add food-grade emulsifier, and stir at room temperature for 10-15 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at high speed, then add 1-MCP powder, homogenize at a reduced speed to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to the acetic acid solution and stir until completely swollen and dissolved to form a base solution; S4. Add the composite emulsion to the base liquid, stir for 30-50 minutes, and let stand for 20-40 minutes to obtain the composite preservative.

[0013] Furthermore, in step S2, the high-speed homogenization speed is 8000-10000 rpm and the time is 5-10 min; the speed is reduced to 3000-5000 rpm and the homogenization time is 2-3 min.

[0014] Furthermore, in step S3, the concentration of the acetic acid solution is 0.8-1.5 wt.%; the mass ratio of acetic acid solution to chitosan is (29-39):1; the stirring speed is 300-500 rpm, and the stirring time is 3-5 h.

[0015] The application method of the compound preservative described above in the postharvest preservation of peaches is as follows: The compound preservative is evenly sprayed onto the surface of the peaches using an atomized spraying method. The spraying amount is 80-120 mL per kilogram of fruit. After spraying, let it stand at room temperature for 15-20 minutes before refrigeration, room temperature storage, or cold chain transportation. Beneficial effects

[0016] This invention utilizes the metal chelating properties of polyphenols in Pinus sylvestris extract to deprive ACC oxidase of its cofactors, thereby inhibiting ACC oxidase activity, blocking the ethylene synthesis pathway, and reducing ethylene secretion; at the same time, the combination of polyphenols with iron ions can further enhance antibacterial and antioxidant capabilities.

[0017] This invention relies on active ingredients in oats (such as spermidine) and 1-MCP powder to further inhibit ethylene synthesis, delay the peak of respiratory climacteric, suppress ineffective endogenous respiration in fruits, and combine with a broad-spectrum antibacterial system constructed from polyphenols and chitosan to achieve multi-dimensional preservation regulation that reduces ethylene synthesis and respiration, resists oxidation, and inhibits mold growth, thus delaying the post-harvest senescence process of peaches.

[0018] This invention utilizes chitosan and polysaccharides from oats to form a film-forming framework, combined with olive oil, arginine, and pine extract for cross-linking and sealing, forming a multi-layered, dense barrier structure that effectively blocks oxygen and water while also providing multiple physical antibacterial barriers. Through polysaccharide molecular chain entanglement, amino acid hydrogen bond cross-linking, and oil filling, it overcomes the shortcomings of traditional membranes, such as being loose, highly permeable to air and water, and prone to cracking and falling off. It can effectively block the invasion of external oxygen, water vapor, and microbial spores, significantly reducing the probability of fruit oxidation browning, dehydration and shriveling, and mold and rot.

[0019] Arginine and calcium glutamate stabilize the cell membrane structure of the pericarp and reduce cell membrane permeability damage under low temperature stress. As a cold-resistant plant, the extract of Pinus sylvestris contains natural resins and other antifreeze substances that may penetrate the pulp tissue to buffer low temperature stress and prevent water stains, pulp rot, and flavor loss during cold chain storage. At the same time, both have plasticizing effects, which improve the problem of low temperature hardening and brittleness failure of the formed membrane and ensure the long-term stability of the membrane barrier performance during cold chain storage.

[0020] The extracts of Pinus sylvestris var. mongolica, oats, olive oil, chitosan, and amino acids in this invention are all natural edible raw materials. They are free of chemical preservatives and toxic drug residues, making them green and healthy. The preservative prepared by this invention is suitable for both room temperature storage and transportation, as well as low-temperature cold chain storage. It can exert excellent preservation effects under different storage conditions, greatly extending the shelf life and storage period of peaches. Attached Figure Description

[0021] Figure 1 Figure showing the effect of different treatments in the embodiments and comparative examples on the respiration rate of peaches during storage; Figure 2 The graph shows the weight loss and decay rate of peaches after 30 days of storage under different embodiments and comparative treatments. Figure 3 The graph shows the results of hardness and soluble solids content of peaches after 30 days of storage under different embodiments and comparative treatments. Figure 4 The graph shows the effect of different embodiments and comparative examples on the ascorbic acid content of peaches during storage. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: Example 1

[0023] The preparation of Pinus sylvestris extract includes the following steps: Fresh pine wood was selected, crushed and passed through a 40-mesh sieve to obtain sawdust raw material. 10 times the weight of 50wt.% ethanol solution was added, and ultrasonic extraction was carried out at 300W for 40 min at room temperature. After centrifugation and filtration, the extract was centrifuged at 5000rpm for 15 min. All the extract filtrate was collected, and the filtrate was concentrated under reduced pressure to 20-30% of the original volume to obtain pine extract. Example 2

[0024] The preparation of Pinus sylvestris extract includes the following steps: Fresh pine wood was selected, crushed and passed through a 40-mesh sieve to obtain sawdust raw material. 10 times its weight of 60wt.% ethanol solution was added, and ultrasonic extraction was carried out at 300W for 40 min at room temperature. After centrifugation and filtration, the extract was centrifuged at 5000rpm for 15 min. All the extract filtrate was collected, and the filtrate was concentrated under reduced pressure to 20-30% of the original volume to obtain pine extract. Example 3

[0025] The preparation of Pinus sylvestris extract includes the following steps: Fresh Pinus sylvestris wood was selected, crushed and passed through a 40-mesh sieve to obtain sawdust raw material, and 15 times its weight of 50wt.% ethanol solution was added. The mixture was ultrasonically extracted at 300W for 40 minutes at room temperature, centrifuged and filtered, and centrifuged at 5000rpm for 15 minutes. All the extract was collected and concentrated under reduced pressure to 20-30% of the original volume to obtain Pinus sylvestris extract. Example 4

[0026] The preparation of oat extract includes the following steps: Oatmeal was dried at 65℃, pulverized through a 60-mesh sieve, and the oatmeal powder was added to water at a mass ratio of 1:10. The mixture was then microwaved for 5 minutes at a power of 500W. Amylase and saccharifying enzyme were added, with the amount of amylase added at 1500 U / g and saccharifying enzyme at 3000 U / g. The pH was 6.5, the temperature was 60℃, and the enzymatic hydrolysis time was 3 hours. After inactivating the enzymes at 90℃ for 10 minutes, the mixture was centrifuged to remove the solid residue. The supernatant was concentrated under reduced pressure and then spray-dried to obtain oat extract powder. Example 5

[0027] The preparation of oat extract includes the following steps: Oatmeal was dried at 65℃, pulverized through a 60-mesh sieve, and the oatmeal powder was added to water at a mass ratio of 1:15. The mixture was then microwaved for 5 minutes at a power of 500W. Amylase and saccharifying enzyme were added, with the amount of amylase added at 1500 U / g and saccharifying enzyme at 3000 U / g. The pH was 6.5, the temperature was 60℃, and the enzymatic hydrolysis time was 3 hours. After inactivating the enzymes at 90℃ for 10 minutes, the mixture was centrifuged to remove the solid residue. The supernatant was concentrated under reduced pressure and then spray-dried to obtain oat extract powder. Example 6

[0028] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80. A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 7

[0029] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 15 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80. A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 8

[0030] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 2, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80; A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 9

[0031] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 5 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80. A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 10

[0032] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 5, 12 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80; A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 11

[0033] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 3, 20 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80; A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 12

[0034] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 1 part lecithin. A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add lecithin, and stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 29:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Example 13

[0035] A composite preservative comprises the following raw materials in parts by weight: 8 parts chitosan, 8 parts oat extract prepared in Example 4, 12 parts pine extract prepared in Example 3, 15 parts olive oil, 2 parts arginine, 2 parts calcium glutamate, 0.3 parts 1-MCP powder, and 0.5 parts Tween-80. A method for preparing a compound preservative includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8 times the amount of water, add Tween-80, stir at room temperature for 10 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at 8000 rpm for 8 min, then add 1-MCP powder, reduce the speed to 3000 rpm and homogenize for 3 min to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to a 1 wt.% acetic acid solution. The mass ratio of acetic acid solution to chitosan is 39:1. Stir at 300 rpm for 4 hours until completely swollen and dissolved to form a base solution. S4. Add the composite emulsion to the base liquid, stir for 30 minutes, and let stand for 40 minutes to obtain the composite preservative. Comparative Example 1

[0036] The difference between this comparative example and Example 6 is that the pine extract was not added, while the other conditions and steps are the same. Comparative Example 2

[0037] The difference between this comparative example and Example 6 is that oat extract was not added, while the other conditions and steps are the same. Comparative Example 3

[0038] The difference between this comparative example and Example 6 is that olive oil is not added, but the other conditions and steps are the same. Comparative Example 4

[0039] The difference between this comparative example and Example 6 is that tea polyphenols are used instead of pine extract, while the other conditions and steps are the same. Comparative Example 5

[0040] The difference between this comparative example and Example 6 is that all raw materials are mixed together, homogenized, and stirred to obtain the composite preservative. The preparation is not done in steps, but other conditions and steps are the same. Performance testing

[0041] After harvesting, the peaches were divided into groups and sprayed with different preservatives by atomization at a dosage of 100 mL / kg of fruit. The groups were then left to stand for 20 minutes. The blank control (CK) group was sprayed with an equal amount of water. The peaches were then packaged separately: the CK group, each example group, and the comparative example group were packaged into polyethylene (LDPE) bags and stored at 0±0.5℃ with a relative humidity of 85%~95% for 30 days.

[0042] 1. Breathing intensity The respiration intensity of peach fruit was measured using a fruit and vegetable respiration intensity analyzer and expressed as mg CO2 / (kg·h).

[0043] The results are as follows Figure 1 As shown, both the CK group and the comparative group reached their peak respiration rate at 20 days, while the peak respiration rate in the examples was delayed and decreased. The comparative group (lacking Pinus sylvestris extract) exhibited a significantly higher respiration rate than the example groups. The respiration rate in all treatment groups initially increased and then decreased with storage time. The preservative of this invention can maintain a low respiration level throughout the storage process, thus delaying fruit senescence.

[0044] 2. Weightlessness rate The weight was measured using a weighing method. The weight of the fruit on day 0 of storage was recorded as W0. After 30 days of storage, samples of the fruit were weighed and recorded as W1. The calculation formula is shown in the following equation:

[0045] The results are as follows Figure 2 As shown, the weight loss rate of the blank group was the highest among all groups. Without the use of preservatives to block the stomata of the fruit peel, moisture was rapidly lost. The weight loss rates of all examples were significantly better than those of the blank and all comparative examples, with the weight loss rates of the examples ranging from 4.05% to 5.41%. Comparative Example 3, lacking hydrophobic liposomes to fill the gaps between polysaccharide molecules, significantly improved the membrane's water and air permeability, resulting in a relatively high weight loss rate.

[0046] 3. Decay rate The degree of rot is determined by the percentage of rotten area relative to the fruit's surface area: Grade 0, no rot; Grade 1, 0-10%; Grade 2, 11%-30%; Grade 3, 31%-50%; Grade 4, 51%-100%. The formula for calculating the rot rate is shown below:

[0047] The results are as follows Figure 2 As shown, the blank group had the highest decay rate among all groups. Lacking the antibacterial system of pine polyphenols, chitosan, and amino acid calcium, the fruit was highly susceptible to infection by gray mold and brown rot fungi, resulting in the fastest decay rate during cold chain storage. The decay rate of the example groups was only 3.20%~4.20%, while the decay rates of all comparative examples differed significantly from those of the example groups. Comparative example 1 showed the most severe decay, not only lacking components such as polyphenol chelation and antibacterial agents but also failing to prevent low-temperature freezing damage, leading to increased decay. Comparative example 4, while containing tea polyphenols, exhibited antibacterial activity, but its antibacterial ability was weaker than that of the pine extract and it lacked antifreeze properties.

[0048] 4. Hardness The hardness of three locations around the equator on a peeled peach was measured using a hardness tester. The results were expressed in kg / cm². 2 express.

[0049] The results are as follows Figure 3As shown, the blank group experienced the most severe pulp softening and the greatest sugar loss; the firmness of all examples was significantly better than that of the blank and all comparative examples. Increased respiratory metabolism accelerates pulp softening, and the ability of Comparative Examples 1 and 2 to inhibit respiration and ethylene production may be weakened, resulting in lower firmness compared to the examples.

[0050] 5. Soluble solids (TSS) content was determined using a saccharimeter.

[0051] Soluble solids play a crucial role in fruit ripening, determining the fruit's texture and flavor. Figure 3 As shown, fruit respiration continuously consumes endogenous sugars during storage, and the TSS content decreases with aging. The degree of decrease directly reflects the ability of the preservation system to inhibit respiratory metabolism. In this experiment, after 30 days of cold chain storage, the TSS content of each group of examples was better than that of the comparative examples and the blank control group, proving that this composite edible coating system can significantly reduce sugar loss. Comparative Example 1 lacked the core components for inhibiting ethylene and antioxidation, resulting in a significant increase in respiration intensity and the lowest TSS among all comparative examples. Although Comparative Example 5 had complete raw materials, the lack of segmented emulsification led to a decrease in the physical barrier function of water spray film formation, and a reduction in the activity of active substances in the system. Therefore, it still showed a decrease compared to the examples.

[0052] 6. The ascorbic acid (Vc) content was determined by the 2,6-dichlorophenolindophenol titration method.

[0053] Ascorbic acid is an important non-enzymatic antioxidant. Increased levels of ascorbic acid not only provide reducing power for maintaining redox balance and reactive oxygen species homeostasis, but also enhance the nutritional value of fruits. For example... Figure 4 As shown, the ascorbic acid content in peaches increased during storage from 0 to 10 days and decreased towards the end of storage. The control group consistently had the lowest vitamin C content throughout the entire storage period, while the peak vitamin C content and the amount retained at the end of the storage period in the examples were significantly higher than those in all comparative groups.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A composite preservative, characterized by comprising: It is composed of the following components in parts by weight: 5-8 parts chitosan, 5-8 parts oat extract, 12-15 parts pine extract, 15-20 parts olive oil, 2-3 parts arginine, 1.5-2.5 parts calcium glutamate, 0.3-0.5 parts 1-MCP powder, and 0.5-1.0 parts food-grade emulsifier.

2. The composite preservative according to claim 1, characterized in that, The pine extract is an ethanol extract of pine wood, prepared by the following method: pine wood is crushed and sieved to obtain sawdust raw material, ethanol solution is added, ultrasonic extraction is performed at room temperature, centrifugation and filtration are carried out, the filtrate is collected, and the filtrate is concentrated under reduced pressure to obtain the pine extract.

3. The composite preservative according to claim 2, characterized in that, The concentration of the ethanol solution is 50-60 wt.%; the mass ratio of wood chips to ethanol solution is 1:(10-15); the ultrasonic extraction time is 30-40 min, and the ultrasonic power is 300-400 W; the volume is concentrated under reduced pressure to 20-30% of the original volume.

4. The composite preservative according to claim 1, characterized in that, The oat extract is prepared by the following method: oats are dried, pulverized and sieved to obtain oat flour, water is added and microwaved to obtain oat mixture, amylase and saccharifying enzyme are added for enzymatic hydrolysis, enzymes are inactivated and centrifuged to remove solid residue, the supernatant is concentrated under reduced pressure and spray-dried to obtain oat extract powder.

5. The composite preservative according to claim 4, characterized in that, The mass ratio of oat flour to water is 1:(10-15); the microwave power is 400-500W, and the processing time is 3-5 minutes; the amount of amylase and saccharifying enzyme added, measured by oat flour, is 1500-2000 U / g and 3000-4000 U / g, respectively; the enzymatic hydrolysis conditions are pH 6.0-6.5, temperature 55-60℃, and hydrolysis time of 2-3 hours; the enzyme inactivation conditions are a water bath at 80-90℃ for 10-15 minutes.

6. The composite preservative according to claim 1, characterized in that, The food-grade emulsifier is one or both of Tween-80 and lecithin.

7. The method for preparing the composite preservative according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Add arginine, calcium glutamate, and pine extract to 8-10 times the amount of water, add food-grade emulsifier, and stir at room temperature for 10-15 minutes to obtain solution A; S2. Slowly add solution A to the olive oil system, homogenize at high speed, then add 1-MCP powder, homogenize at a reduced speed to obtain a composite emulsion; S3. Slowly add chitosan and oat extract powder to the acetic acid solution and stir until completely swollen and dissolved to form a base solution; S4. Add the composite emulsion to the base liquid, stir for 30-50 minutes, and let stand for 20-40 minutes to obtain the composite preservative.

8. The method for preparing a composite preservative according to claim 7, characterized in that: In step S2, the high-speed homogenization speed is 8000-10000 rpm and the time is 5-10 min; the speed is reduced to 3000-5000 rpm and the homogenization time is 2-3 min.

9. The method for preparing a composite preservative according to claim 7, characterized in that: In step S3, the concentration of the acetic acid solution is 0.8-1.5 wt.%; the mass ratio of acetic acid solution to chitosan is (29-39):1; the stirring speed is 300-500 rpm, and the stirring time is 3-5 h.

10. The application of the compound preservative according to any one of claims 1-6 in postharvest preservation of peaches, characterized in that, The application method is as follows: The compound preservative is evenly sprayed onto the surface of the peach using a misting spraying method. The spraying amount is 80-120mL per kilogram of fruit. After spraying, let it stand at room temperature for 15-20 minutes before refrigeration, room temperature storage or cold chain transportation.

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