A method for reducing the amount of chemicals used to preserve the freshness of bayberry after harvest

Abstract

The objective of the present invention is to provide a method for reducing chemicals used to preserve the freshness of bayberry after harvest. The method includes a post-harvest packaging step (1) of picking mature bayberries, placing them in a hollow injection-molded packaging container, and arranging the bayberries evenly at intervals in the hollow injection-molded packaging container, a low-concentration peracetic acid treatment step (2) of spraying 0.1% peracetic acid on the surface of the bayberries, and an atmospheric plasma treatment step (3) of introducing atmospheric plasma into the bayberries that have been treated with low-concentration peracetic acid for 5 minutes, and then temporarily storing them in a refrigerator at 4° C. The present invention can effectively reduce the amount of peracetic acid used and increase its effectiveness by using peracetic acid and atmospheric plasma in combination.

Description

[Technical field]

[0001] The present invention relates to the technical field of freshness preservation of agricultural products, and in particular to a method for reducing the amount of chemicals used to preserve the freshness of bayberry after harvest. [Background technology]

[0002] Bayberry is a subtropical fruit native to China, mainly cultivated in eastern and southern China. The fruit is juicy, rich in nutrients, and known for its attractive red-purple color and unique flavor. Bayberry also contains large amounts of oxidants, such as anthocyanins, flavonoids, and other phenolic compounds, which can inhibit the oxidation of low-density lipoproteins and liposomes in the human body.

[0003] Bayberry fruits generally ripen in the hot, rainy season, and after harvest, they are susceptible to rotting and deterioration due to microbial infection (especially if mechanically damaged), resulting in a very short shelf life. The seasonal and regional characteristics of bayberry fruit production make it difficult to store them for long periods and to transport them north, limiting their shelf life and sales range.

[0004] This meant that finding economical, efficient and non-polluting freshness-preserving technologies was key to the sustainable development of the bayberry industry.

[0005] Non-thermal plasma, an ionized gas composed of charged particles, electric fields, ultraviolet photons, and activated species, has been widely recognized as an effective sterilization method, among which reactive oxygen species (ROS) have been considered as the key agents for plasma inactivation.

[0006] Peracetic acid (PAA) has broad-spectrum antimicrobial activity at low concentrations, exhibits strong bactericidal, virucidal, fungicidal and sporicidal properties, is unaffected by changes in temperature and pH value, is virtually unaffected by protein residues and is effective even after short exposure times.

[0007] Peracetic acid is stable at room temperature, has little effect on organic matter, has no residual toxicity, is reasonably priced and easy to use, and after treatment with peracetic acid, it is quickly decomposed into oxygen, acetic acid, and water, and these substances can be quickly metabolized by microorganisms, so there is almost no impact on the environment. The concentration of peracetic acid generally used during production is 0.5%, but the less it is used, the higher the safety. Therefore, there is an urgent issue of how to reduce the amount of freshness preservation agents used to keep bayberry fresh after harvest. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a method for reducing the amount of peracetic acid used and increasing the effectiveness of a post-harvest freshness-preserving treatment for bayberry by using peracetic acid in combination with atmospheric plasma. [Means for solving the problem]

[0009] In order to solve the above technical problems, the present invention provides the following technical means: A method for reducing the amount of medicine used to preserve the freshness of bayberry after harvest, comprising the steps of: a post-harvest packaging step (1) of picking mature bayberries and placing them in a hollow injection-molded packaging container and distributing the bayberries evenly and at intervals in the hollow injection-molded packaging container; A low-concentration peracetic acid treatment process (2) in which 0.1% peracetic acid is sprayed on the surface of the bayberry; The atmospheric plasma treatment process (3) involves introducing atmospheric plasma into the bayberry fruit treated with low-concentration peracetic acid for 5 minutes, and then temporarily storing the fruit in a refrigerator at 4°C after the treatment is complete. The method includes:

[0010] In step (2), peracetic acid is sprayed a total of six times from six sides of the bayberry: top, bottom, front, back, left and right.

[0011] In step (3), the atmospheric plasma uses air as the working gas, and the gas flow rate is 1.05 m 3 / min and is injected into the electrode tube to generate plasma within a discharge gap of 0.3 mm.

[0012] The atmospheric plasma treatment in step (3) alternates between transporting plasma at room temperature and transporting plasma after low temperature treatment; specifically, for the first minute, plasma after low temperature treatment is transported, for the second minute, plasma after low temperature treatment is transported, for the third minute, plasma after low temperature treatment is transported, for the fourth minute, plasma after low temperature treatment is transported, and for the fifth minute, plasma after low temperature treatment is transported; the transport of the plasma after low temperature treatment is achieved by cooling the generated atmospheric plasma through a mixture of ice and water.

[0013] The conventional atmospheric plasma treatment of bayberry has a problem, that is, after the air is excited to form plasma, the temperature rises, and the temperature of the emitted plasma airflow reaches about 40℃ after reaching the bayberry fruit through the pipeline at room temperature, the plasma airflow treatment of bayberry at such a temperature has a good sterilization effect, but the flesh is easily deformed, and when the temperature drops, the plasma becomes inactive and the sterilization effect is not ideal. Therefore, in order to solve the shortcomings of the conventional atmospheric plasma treatment of bayberry, the present invention improves the atmospheric plasma treatment method, and adopts a mode of alternately transporting plasma at room temperature and transporting plasma after low temperature treatment, transporting plasma at room temperature, and ensuring good sterilization effect at about 40℃ of plasma airflow temperature, and also adopts a mode of transporting plasma after low temperature treatment in order to reduce the impact of high temperature on the quality of the bayberry, and although the sterilization effect is weakened at low temperature, the impact on the quality of the bayberry is also reduced at the same time, so that both sterilization effect and quality assurance can be taken into consideration. The present invention adopts a method of alternating between transporting plasma at room temperature and transporting plasma after low temperature treatment because the last transport of plasma must be after low temperature treatment, and this is because after atmospheric plasma treatment, the bayberry needs to be refrigerated in a refrigerator. After plasma treatment at about 40°C, the temperature difference is large, so the quality and texture of the flesh are easily damaged and frostbite occurs. The final transport of plasma after low temperature treatment has a low plasma treatment temperature for bayberry, and the difference with the refrigeration temperature is small, so the quality and texture are more guaranteed. The present invention uses a method of alternating between transporting plasma at room temperature and transporting plasma after low temperature treatment, and the alternating time is not long, so there is no sudden change in fruit temperature. Effect of the Invention

[0014] The advantageous effect of the present invention is that the use of peracetic acid in combination with atmospheric plasma can effectively reduce the amount of peracetic acid used and increase its effectiveness. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The technical solutions of the present invention will be described in more detail below through specific embodiments.

[0017] In the present invention, the raw materials and equipment used are commercially available or generally used in the art unless otherwise specified. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0018] (First embodiment) A method for reducing the amount of chemicals used to preserve freshness after harvesting bayberry, comprising the following steps:

[0019] (1) Post-harvest packaging process: After the mature bayberry is picked, it is put into a hollow injection-molded packaging container, and the bayberry is evenly arranged with intervals in the hollow injection-molded packaging container. The hollow injection-molded packaging container is shown in Figure 1.

[0020] (2) Low-concentration peracetic acid treatment process: 0.1% peracetic acid is sprayed onto the surface of the bayberry. Peracetic acid is sprayed onto the six sides of the bayberry (top, bottom, front, back, left and right) a total of six times.

[0021] (3) Atmospheric plasma treatment process: The low-concentration peracetic acid-treated bayberry is treated with atmospheric plasma for 5 minutes, and after the treatment is completed, it is temporarily stored in a refrigerator at 4°C. The atmospheric plasma system was composed of a function generator (Nanjing Suman Electronics Co., Ltd., China), a chamber, and an AC power supply (CTP 2000 K, Nanjing Suman Electronics Co., Ltd., China). The function generator had nine electrode tubes. Each electrode tube was hollow and consisted of an inner stainless steel electrode and an outer quartz electrode. A high voltage (up to 30 kV) generated by an AC power supply (220 V, 50 Hz) was coupled to the electrodes. The size of the container was 30 × 25 × 15 cm, made of polypropylene, and tightly sealed. Plasma was generated by the DBD method. Air was used as the working gas, and the gas flow rate was 1.05 m / s. 3 / min, and the plasma was generated in a discharge gap of 0.3 mm, and then transported into the chamber for processing. The atmospheric plasma processing alternates between transporting plasma at room temperature and transporting plasma after low temperature processing, specifically, the plasma after low temperature processing is transported for the first minute, the plasma after low temperature processing is transported for the second minute, the plasma after low temperature processing is transported for the third minute, the plasma after low temperature processing is transported for the fourth minute, and the plasma after low temperature processing is transported for the fifth minute, and the transport of the plasma after low temperature processing is achieved by cooling the generated atmospheric plasma through a mixture of ice and water.

[0022] The method of transporting plasma at room temperature and after low-temperature treatment is as follows: after plasma is generated, it is transported through two pipes, one pipeline is in a room temperature environment to transport plasma at room temperature, and the other pipeline passes through a mixture of ice and water, so that the plasma airflow in the pipeline can be cooled before processing the bayberry.

[0023] <Freshness retention test> method In the morning, we went to Xianju, Zhejiang, to transport freshly picked Dongkui bayberry fruits to the laboratory, and in the afternoon we sorted and divided the fruits into groups (selecting bayberry fruits without mechanical damage, without mold hyphae on the surface, and with approximately the same size and maturity), and processed each experimental group in the evening. CK: No processing is performed.

[0024] Group A: atmospheric plasma treatment for 5 minutes (the generated atmospheric plasma was introduced into a large sealed box, two pipes were connected to the front end of the box and one pipe was connected to the rear end. Both of the two pipes at the front end were connected to a generator that generated atmospheric plasma, one of the two pipes at the front end was exposed to a room temperature environment, and the other pipe was partially immersed in a mixture of ice and water, and the rear pipe was placed outside the room to eliminate the generated ozone. The atmospheric plasma treatment alternated between transporting plasma at room temperature and transporting plasma after low temperature treatment. Specifically, the first minute was transporting plasma after low temperature treatment, the second minute was transporting plasma at room temperature, the third minute was transporting plasma after low temperature treatment, the fourth minute was transporting plasma at room temperature, and the fifth minute was transporting plasma after low temperature treatment. The total treatment time was 5 minutes).

[0025] Group B: 0.5% peracetic acid was sprayed six times, once on each side of the bayberry (in the experiment, the bayberry was placed in a hollow injection-molded packaging container with 15 cells (the packaging form is shown in Figure 1), the top half of the packaging container was first removed, and peracetic acid was sprayed once each on the top, front, back, left and right of the container, then the top half of the packaging container was placed over the bayberry, and the top half of the packaging container was removed again, and peracetic acid was sprayed once more on the top of the container. This was to allow peracetic acid to be sprayed on the six sides of each bayberry.

[0026] Group C: Bayberry was sprayed with 0.5% peracetic acid six times and then treated with atmospheric plasma for 5 min, and the atmospheric plasma treatment was the same as that of Group A.

[0027] Group D: 0.1% peracetic acid was sprayed six times, once on each side of the bayberry.

[0028] Group E: Bayberry was sprayed with 0.1% peracetic acid six times and then treated with atmospheric plasma for 5 min, and the atmospheric plasma treatment was the same as that of Group A.

[0029] In all combination treatments, peracetic acid was sprayed first and then atmospheric plasma was introduced. There were two main purposes for doing this: (1) when peracetic acid was sprayed first to wet the surface of the bayberry and then atmospheric plasma was introduced, the surface was not dried out, and (2) when peracetic acid was sprayed first and then atmospheric plasma was introduced, the remaining peracetic acid could be decomposed after the action of peracetic acid on the bayberry.

[0030] All treated bayberries were stored in a refrigerator at 4°C and bacterial colony counts were performed by microbial smears and counts on days 0, 3, 6, 9 and 12, respectively.

[0031] (2) Results 2.1 Broad spectrum disinfection of natural microorganisms (non-inoculated, fungi or yeasts originally present on the fruit surface) During the storage period, the colony count of each treatment group was significantly reduced when compared with the control group. As shown in Table 1, the combination of plasma and peracetic acid was better than the combination of plasma alone when comparing groups A and C or A and E, the combination of plasma and peracetic acid was better than the combination of peracetic acid alone when comparing groups B and C or D and E, and the combination of plasma and peracetic acid was better than the combination of peracetic acid alone when comparing groups B and E. The effects of 0.5% peracetic acid and 0.1% peracetic acid + 5 minutes plasma treatment were almost the same, both of which reduced by about 1.8 Lg, indicating that the drug reduction effect was exerted.

[0032] Table 1 shows the colony counts for each broad spectrum treatment group (CK: untreated bayberry, A: 5 min plasma treatment, B: 0.5% peracetic acid, C: 0.5% peracetic acid + 5 min plasma treatment, D: 0.1% peracetic acid, E: 0.1% peracetic acid + 5 min plasma treatment). The Lg value X is calculated as the colony count of 10 X CFU / g. For example, if the Lg value is 5.7710, 10 5.771 It becomes CFU / g.

[0033] [Table 1]

[0034] 2.2 Changes in weight loss rate During the early storage period, the weight loss rate of each treatment group was almost the same as that of the control group, but during the later storage period, the weight loss rate of each treatment group was lower than that of the control group (Table 2).

[0035] Comparing groups A and C, or A and E, it was found that the combined effect of plasma and peracetic acid was better than using plasma alone (the weight loss of bayberry fruits is not only due to the consumption of their own nutrients through respiration, but can also be caused by microorganisms causing the fruit to rot and lose moisture; plasma and peracetic acid have the effect of suppressing the respiration of microorganisms and fruit, and because peracetic acid is sprayed first during treatment, the surface of the bayberry fruits is kept moist and moisture loss from the surface of the fruit is prevented when plasma is introduced).

[0036] In the later storage period, comparisons between groups B and C or between groups D and E showed that the combined effect of plasma and peracetic acid was better than that of using peracetic acid alone.

[0037] Table 2 shows the weight loss rate for each treatment group (CK: untreated bayberry, A: plasma treatment for 5 minutes, B: 0.5% peracetic acid, C: 0.5% peracetic acid + plasma treatment for 5 minutes, D: 0.1% peracetic acid, E: 0.1% peracetic acid + plasma treatment for 5 minutes), and the weight loss rate is expressed in %.

[0038] [Table 2]

[0039] 2.3 Changes in hardness The reason why bayberry fruits easily soften and lose firmness during storage is mainly because bayberry fruits are susceptible to fungal infection and decay. Both peracetic acid and plasma can inhibit fungal growth, thereby delaying the softening of the fruit and preserving the freshness of bayberry fruits.

[0040] During the storage period, the hardness of each treatment group was higher than that of the control group, and was significantly higher especially in the later stage of storage (Table 3).

[0041] Comparison of groups A and C or A and E showed that the combined effect of plasma and peracetic acid was better than that of plasma alone, especially in the early storage period.

[0042] Comparison of groups B and C or D and E showed that the combined effect of plasma and peracetic acid was better than that of peracetic acid alone, especially in the early storage period.

[0043] Table 3: Changes in hardness in each treatment group [Table 3]

[0044] <Bacterial inoculation test> Bacteria inoculation: In the morning, we went to Xianju, Zhejiang to bring freshly picked Dongkui bayberry to the laboratory, in the afternoon we sorted the fruits and divided them into groups, and in the evening we inoculated all the fruits with bacteria (Penicillium citrinum). The surfaces of the fruits of each treatment group and the control group were sprayed with 75% ethanol for disinfection, the bayberry was naturally ventilated to allow the ethanol to evaporate, and a single-needle wound inoculation method was used in which a sterilized stainless steel needle was used to make a 0.1 mm deep wound on the surface of each bayberry. Each fruit was inoculated with 20 μL of a spore suspension containing Penicillium citrinum via a pipette.

[0045] The inoculated bayberries were allowed to dry on a clean bench for 1 hour and each group was treated after inoculation.

[0046] CK: No processing is performed.

[0047] Group A: atmospheric plasma treatment for 5 minutes (the generated atmospheric plasma was introduced into a large sealed box, two pipes were connected to the front end of the box and one pipe was connected to the rear end. Both of the two pipes at the front end were connected to a generator that generated atmospheric plasma, one of the two pipes at the front end was exposed to a room temperature environment, and the other pipe was partially immersed in a mixture of ice and water, and the rear pipe was placed outside the room to eliminate the generated ozone. The atmospheric plasma treatment alternated between transporting plasma at room temperature and transporting plasma after low temperature treatment. Specifically, the first minute was transporting plasma after low temperature treatment, the second minute was transporting plasma at room temperature, the third minute was transporting plasma after low temperature treatment, the fourth minute was transporting plasma at room temperature, and the fifth minute was transporting plasma after low temperature treatment. The total treatment time was 5 minutes).

[0048] Group B: 0.5% peracetic acid was sprayed six times, once on each side of the bayberry.

[0049] Group C: Bayberry plants were sprayed with 0.5% peracetic acid six times and then treated with atmospheric plasma for 5 min.

[0050] All bayberries were stored in a refrigerator at 20°C, and microbial smears and counts were performed on days 0, 3, 6, 9, and 12 to determine bacterial colony counts and spoilage rates.

[0051] result As shown in Table 4, the number of colonies in each treatment group was significantly reduced compared with the control group. Comparing groups B and C, the effects in the early storage period were almost the same, showing a drug-reducing effect, while the number of colonies in group C in the later storage period decreased more than in group B, showing a drug-reducing and efficacy-improving effect.

[0052] Comparing groups A and C, the storage period had no significance, but the number of colonies in group C was lower than that in group A during the storage period, indicating that the combined effect of plasma and peracetic acid was better than using plasma alone.

[0053] Table 4: Colony counts in each treatment group after inoculation with bacteria (Penicillium citrinum). [Table 4]

[0054] Spoilage rate by inoculation Comparing groups A and C, the spoilage rate of group C during the storage period was lower than that of group A, indicating that the combined effect of plasma and peracetic acid was better than using plasma alone.

[0055] Comparing groups B and C, the spoilage rate of group C during the storage period was lower than that of group B, indicating that it had the effect of reducing the dosage and improving efficacy (Table 5).

[0056] Table 5: Decay rate of each treatment group after inoculation with bacteria (Penicillium citrinum) [Table 5]

[0057] significance The present invention achieves the effect of reducing the amount of medication and improving effectiveness by combining physical technology with chemical freshness-preserving agents, and ensures an effective reduction in microorganisms (mainly fungi and yeasts) on the surface of bayberry, thereby not only lowering the spoilage rate and extending the shelf life of the fruit, but also reducing the amount of chemical freshness-preserving agents used, achieving green freshness-preservation.

[0058] The above-described embodiments are merely preferred solutions of the present invention, and are not intended to limit the present invention in any way, and other modifications and improvements may be made without departing from the technical means described in the claims.

[0059] [Note] [Appendix 1] A post-harvest packaging step (1) of picking mature bayberries and placing them in a hollow injection-molded packaging container and distributing the bayberries evenly and at intervals in the hollow injection-molded packaging container; A low-concentration peracetic acid treatment step (2) of spraying 0.1% peracetic acid on the surface of the bayberry; An atmospheric plasma treatment process (3) in which atmospheric plasma is introduced into the bayberry treated with low-concentration peracetic acid for 5 minutes, and after the treatment is completed, the bayberry is temporarily stored in a refrigerator at 4 ° C. A method for reducing the amount of pesticides used to preserve the freshness of bayberry after harvest, comprising:

[0060] [Appendix 2] In the step (2), the peracetic acid is sprayed a total of six times from six sides of the bayberry (top, bottom, front, back, left and right), in accordance with the reduced-dose treatment method for preserving the freshness of bayberry after harvest, as described in Appendix 1.

[0061] [Appendix 3] In the step (3), the atmospheric plasma uses air as a working gas, and the gas flow rate is 1.05 m 3 / min into an electrode tube to generate plasma within a discharge gap of 0.3 mm.

[0062] [Appendix 4] The atmospheric plasma treatment in step (3) alternates between transporting plasma at room temperature and transporting plasma after low temperature treatment, specifically, transporting plasma after low temperature treatment for the first minute, transporting plasma at room temperature for the second minute, transporting plasma after low temperature treatment for the third minute, transporting plasma at room temperature for the fourth minute, and transporting plasma after low temperature treatment for the fifth minute, and the transport of the plasma after low temperature treatment is achieved by cooling the generated atmospheric plasma through a mixture of ice and water, a method for reducing chemicals to preserve the freshness of post-harvest bayberry described in Appendix 1.

Claims

1. a post-harvest packaging step (1) of picking mature bayberries and placing them in a hollow injection-molded packaging container and distributing the bayberries evenly and at intervals in the hollow injection-molded packaging container; A low-concentration peracetic acid treatment step (2) of spraying 0.1% peracetic acid on the surface of the bayberry; An atmospheric plasma treatment step (3) in which atmospheric plasma is introduced into the bayberry treated with low-concentration peracetic acid for 5 minutes, and after the treatment is completed, the bayberry is temporarily stored in a refrigerator at 4 ° C. Including, The atmospheric plasma treatment in step (3) alternates between transporting plasma at room temperature and transporting plasma after low temperature treatment, specifically transporting plasma after low temperature treatment for the first minute, transporting plasma at room temperature for the second minute, transporting plasma after low temperature treatment for the third minute, transporting plasma at room temperature for the fourth minute, and transporting plasma after low temperature treatment for the fifth minute, and the transport of the plasma after low temperature treatment is achieved by cooling the generated atmospheric plasma through a mixture of ice and water.

2. The method for reducing the amount of peracetic acid used to preserve the freshness of bayberry after harvest as described in claim 1, wherein in the step (2), the peracetic acid is sprayed a total of six times from six sides of the bayberry, namely, top, bottom, front, back, left and right.

3. In the step (3), the atmospheric plasma uses air as a working gas, and the gas flow rate is 1.05 m ３ 2. A method for reducing chemicals to preserve the freshness of post-harvest bayberry as described in claim 1, in which a discharge of 0.3 mm is injected into an electrode tube at a rate of 0.1 MPa / min to generate plasma within a discharge gap of 0.3 mm.

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