Composite waxberry preservation method based on multi-step cooperative treatment

Abstract

The invention discloses a waxberry composite fresh-keeping method based on multi-step cooperative treatment, and belongs to the technical field of postharvest treatment of fruits and vegetables. According to the method, through the synergistic effect of multiple steps of rapid pre-cooling, salt washing and floating fruit removal, surface drying and edible composite nano film spraying, ozone-spontaneous controlled atmosphere in the bag, radio frequency assisted mild heat shock and phase change microenvironment constant-temperature storage, the shelf life of the waxberries is remarkably prolonged, and the intact fruit rate, color, hardness and flavor of the fruits are effectively kept. The core of the method lies in organic combination and parameter optimization of various physical fresh-keeping technologies, radio frequency auxiliary heat shock is adopted to replace traditional hot air / water bath to improve heating uniformity and efficiency, and an anti-fog air-conditioning bag with specific air permeability is combined with low-concentration ozone to create an antibacterial environment; an edible composite nano film is sprayed to realize slow release of active ingredients; and the phase change cold storage plate and the high-voltage electrostatic field are used for maintaining the storage environment to be extremely stable. The waxberry fresh-keeping method is efficient, low in cost, green and safe.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of postharvest processing of fruits and vegetables, and relates to a compound preservation method for waxberries based on multi-step synergistic processing, specifically a compound preservation method for significantly prolonging the shelf life of waxberries and maintaining their sensory quality through multi-step synergistic processes such as precooling, salt washing-screening, surface drying-edible nano film spraying, in-bag ozone-spontaneous modified atmosphere (O3-MAP), radio frequency assisted mild heat shock, and constant temperature storage. BACKGROUND

[0002] Waxberry, belonging to the plant of Myricaceae, has the functions of digesting food, relieving summer-heat, generating fluid to relieve cough, aiding digestion, and diuresis, etc., and is praised as "jade in fruits" and is deeply loved by consumers. Hunan Province is one of the main producing areas of waxberries in China. Hunan waxberries mature in the high-temperature and high-humidity season in mid-June every year, and most of them are sold fresh with large postharvest losses. In addition to fresh consumption, there are also many deep processing products such as waxberry wine, waxberry jam, and dried waxberry, etc.

[0003] Waxberry fruit is columnar without an outer pericarp structure, has a high postharvest respiration intensity, and is extremely prone to spoilage and odor generation in a short period. The shelf life at room temperature is usually only 2-3 days, and it is one of the fruits with extremely high difficulty in storage and preservation.

[0004] Patent CN116114750A discloses a new waxberry preservation process, which is carried out through the steps of waxberry picking and sorting, vehicle frame pretreatment, waxberry precooling and quick freezing, waxberry drying, and waxberry unloading. This process can increase the shelf life of waxberries, keep the integrity of waxberries during the preservation process, completely retain the nutritional components of waxberries, and have a good taste and high retention rate of nutritional components after thawing, thus having good use effect and being beneficial to popularization.

[0005] Patent CN114586838A discloses a waxberry preservation method and application thereof. The waxberry preservation method first freezes the pre-cooled waxberries at an ultra-low temperature of -50 to -80℃, and then stores the frozen waxberries. The frozen waxberries are thawed to 10-20℃ under the conditions of ultrasonic and microwave to obtain thawed waxberries. The above-mentioned waxberry preservation method is beneficial to maintaining the quality of waxberry fruits, has little damage to the internal structure of the fruits, reduces the consumption of internal nutrients, effectively retains water, greatly prolongs the shelf life of waxberries, and has a short thawing time, which is beneficial to timely placing the waxberries on the shelves in the sales area and speeding up the operation of the production and sales chain. The juice loss rate is low, the quality of the waxberry fruits can be well maintained, and the sales value is ensured.

[0006] Although the frozen storage can greatly prolong the shelf life of the waxberry, the quality of the waxberry after thawing is still not comparable to that of the fresh storage. The existing waxberry preservation technologies, such as ordinary cold storage, modified atmosphere preservation, chemical preservative treatment, hot water and hot air treatment, all have different limitations: ① single cold storage: temperature fluctuation is large, humidity is difficult to maintain constant, and preservation effect is limited (usually only a few days); ② conventional CA / MA: high equipment investment, complex operation, and dynamic adjustment of gas ratio is required; ③ ozone open treatment: ozone is easy to decompose, the sterilization is uneven, the effect is limited or the fruit is damaged; ④ hot water or hot air heat shock: easy to cause pulp softening, water loss and surface shrinkage and other problems.

[0007] Therefore, it is of great industrial significance to develop a waxberry preservation method suitable for waxberry production, sales and transportation, which can inhibit fruit respiration, reduce nutrient loss rate, reduce freezing damage and reduce juice loss.

[0008] In view of the above problems, the present application is proposed. SUMMARY

[0009] The present application provides a compound preservation process and a matching packaging system for waxberry, which takes waxberry as the object and takes multi-step synergy as the core, and solves the pain points of the prior art such as short preservation period, rapid quality deterioration and high energy consumption.

[0010] The present application aims to provide a waxberry compound preservation method based on multi-step synergy treatment, comprising the following steps: S1: rapid precooling Freshly picked 8-9 mature waxberry fruits are placed in a cold storage, pre-cooled at 0-4 DEG C for 0.5-1h, so that the fruit temperature is reduced to 2-4 DEG C. In this step, the rapid precooling process inhibits the respiration of the waxberry, reduces the consumption of internal nutrients, slows down the rate of water migration, effectively retains water, maintains fruit hardness, and greatly prolongs the shelf life of the waxberry.

[0011] S2: salt washing and screening The pre-cooled waxberry is placed in a salt solution with an effective chlorine concentration of 30-50ppm and a mass concentration of 0.5%-3% for 1-10min, and the fruits floating on the liquid surface are removed at the same time; S3: surface drying and edible nano-membrane spraying The water on the surface of the washed waxberry is absorbed, and the fruits with mechanical damage or insect damage are removed; then a layer of edible composite nano-membrane with a thickness of 0.03-0.08mm is sprayed on the surface of the fruits by atomization spraying; In this step, the washed waxberries are immediately transferred to the surface of the water-absorbing fiber material to absorb the water on the surface of the waxberries, and the fruits with mechanical damage or insect damage are removed by manual or optical sorting machine.

[0012] S4: ozone-in-bag - spontaneous modified atmosphere packaging (O3-MAP) The sprayed waxberries are placed in a packaging box, then wrapped with a fog-proof and breathable modified atmosphere packaging bag, and then an ozone packaging machine is used to fill 10-80 ppm of ozone into the bag and seal it. S5: radio frequency-assisted mild heat shock (RF-HST) The sealed and packaged waxberries are placed in a radio frequency treatment chamber, and the radio frequency generator parameters are set so that the waxberry fruits are uniformly heated to 40-55°C within 3-10 minutes, and are kept at this target temperature for 5-30 minutes. S6: phase change microenvironment constant temperature storage The heat-shocked waxberries are transferred to a refrigeration box in which a cold storage plate with a phase change temperature of 0-1°C has been placed, and then the refrigeration box is stored in a cold storage room at -0.5-2°C.

[0013] Preferably, the salt solution in step S2 is one or more of sodium chloride, calcium chloride, sodium carbonate, and sodium bicarbonate solution.

[0014] Preferably, based on the total mass of the dry film, the edible composite nanofilm in step S3 includes 1.5%-4% chitosan-ε-polylysine matrix (continuous phase), 1.5%-4% plant essential oil microcapsules (core material), 0.1%-0.8% nanocellulose whiskers (NCC, network reinforcement), 0.05%-0.3% antioxidant-acidity double-buffering microparticles, 0.01%-0.05% radio frequency heat shock post-repair factor, 0.15%-0.8% emulsification-electrostatic atomization aid, and the balance of 1% glacial acetic acid aqueous solution or water; the edible composite nanofilm is a Pickering emulsion formed by high-pressure homogenization-electrostatic atomization spraying of the above components, the dry film thickness is 0.03-0.08 mm, and a 50 μm level nanorelease film is formed on the fruit surface after radio frequency heat shock.

[0015] Preferably, the chitosan-epsilon-polylysine matrix is composed of chitosan and epsilon-polylysine in a mass ratio of 1:0.2-0.5, the chitosan has a degree of deacetylation of ≥85%, and the epsilon-polylysine has a molecular weight of 3-5 kDa; the plant essential oil microcapsules have a wall material of 2% sodium alginate and 0.5% CaCl2 gel or beta-cyclodextrin, the essential oil is selected from at least one of cinnamomum, litsea cubeba, rosemary, origanum, thyme, clove, and eucalyptus, the microcapsule particle size is 200-400 nm, and the essential oil loading is 30%-40%; the antioxidant-acidity double-buffering microparticles are prepared by co-spray drying 0.05%-0.2% calcium ascorbate and 0.02%-0.1% sodium bicarbonate, and the particle size is 50-100 nm; the radio frequency thermal after-repair factor is 0.01%-0.05% phosphatidylcholine-glycerol monostearate complex; and the emulsification-electrostatic atomization aid is Tween 80 and glycerol in a mass ratio of 0.2-1:1.

[0016] By adopting the technical solution, the nanocellulose whiskers are modified by surface carboxylation, and the ζ-potential is below -30 mV to form a dense network; the antioxidant-acidity double-buffering microparticles are prepared by co-spray drying 0.05%-0.2% calcium ascorbate and 0.02%-0.1% sodium bicarbonate, and are used to absorb residual ozone and neutralize excess H2CO3 generated by CO2 dissolution; and the radio frequency thermal after-repair factor migrates by phase transition when heated at 40-55 ℃, fills the microcracks on the fruit surface, and prevents the film from being brittle and cracked.

[0017] During the radio frequency thermal heating stage at 40-55 ℃, the phosphatidylcholine-glycerol monostearate migrates by phase transition to the microcracks on the fruit surface to form an elastic "repair layer"; meanwhile, the NCC three-dimensional network is crosslinked, the essential oil microcapsule wall material micropores are expanded, and the time sequence release of ≤30% within 0-3 d, 50%-70% within 4-10 d, and ≤10% after 11 d is achieved; and the obtained film layer is an edible composite nanoreleased film, which has multiple functions of antibacterial, antioxidant, anti-cracking, and anti-acidification.

[0018] Preferably, the film preparation process in step S3 is as follows: Step one: preparation of continuous phase chitosan-epsilon-polylysine matrix Chitosan is dissolved in 1% ice acetic acid aqueous solution, stirred at 60 ℃ for 30 min to obtain a chitosan solution; and epsilon-polylysine is dissolved in the above solution to form a "chitosan-epsilon-polylysine matrix phase"; Step two: preparation of core material plant essential oil microcapsules Under high-speed shearing, the essential oil is slowly dropped into 1% sodium alginate aqueous phase to form an O / W initial emulsion; then, 0.5% CaCl2 solution is added to induce gelation, or the essential oil is slowly dropped into beta-cyclodextrin saturated liquid to form 200-400 nm microcapsules; Step three: Pickering emulsion construction The plant essential oil microcapsule core material, nanocellulose whisker, antioxidant-acidity double-buffering microparticle and radio frequency thermal repair factor are sequentially added into the above-mentioned matrix phase, and high-pressure homogenization is used to realize nanoscale uniform dispersion, so that a stable Pickering emulsion is obtained. Step four: electrostatic atomization spraying The process parameters are adjusted to spray the waxberries, and the film thickness of a single fruit is 0.03-0.08 mm (wet film 0.15-0.35 mm, shrinks to the target thickness after drying).

[0019] By adopting the technical scheme, the plant essential oil microcapsule releases ≤30% of the total amount within 0-3 days of storage, 50%-70% within 4-10 days, and ≤10% after 11 days, so that the time sequence control of “mildew inhibition in the early stage, bacteria inhibition in the middle stage, and flavor maintenance in the later stage” is realized; the antioxidant-acidity double-buffering microparticle can still control the pH fluctuation range of the fruit surface within ±0.2 under the conditions of an ozone concentration of 10-80 ppm and a CO2 partial pressure increased to 15-25 kPa, and inhibit acidification and browning; and the phosphatidylcholine-glycerol monostearate complex migrates to the membrane-fruit interface within 5 minutes after radio frequency thermal stimulation, reduces the surface energy, and increases the breaking elongation rate of the film at-0.5-2 ℃ by ≥40%.

[0020] Preferably, the modified atmosphere bag in step S4 is made of polyethylene, functional resin or polypropylene as a base material.

[0021] Preferably, the oxygen transmission rate of the modified atmosphere bag in step S4 is 4000-15000 cm³ / (m²·day·atm), and the carbon dioxide transmission rate is 12000-100000 cm³ / (m²·day·atm).

[0022] Preferably, the radio frequency generator used in step S5 has a frequency of 27.12 MHz, a plate spacing of 5-30 cm, and a power density dynamically adjusted according to the fruit load.

[0023] Preferably, the cold storage in step S6 is equipped with a high-voltage electrostatic field device, and the cold storage is equipped with an ozone automatic sterilization device, which automatically adjusts the ozone concentration to 20-50 ppm every 12 hours and sterilizes in the storage for 10-60 minutes.

[0024] Preferably, the cold storage box in step S6 is made of polyurethane, foamed polypropylene or foamed polystyrene material; and the cold storage board can absorb the heat transmitted from the outside, and cooperates with the cold storage to maintain the stable state of the temperature in the box at 0-1 ℃.

[0025] The beneficial effects of the present application are: (1) The preservation effect of the method adopted by the present application is outstanding: through the cooperation of multiple technologies, the preservation period of waxberries can be extended to more than 15 days, and the good fruit rate can be increased to more than 90%.

[0026] (2) The method adopted by the present application keeps the quality of waxberries good: it can effectively slow down the weight loss and hardness reduction of waxberries, and better maintain their original color and flavor.

[0027] (3) The method adopted by the present application is highly safe: it mainly uses physical technology, reducing the use of chemical preservatives.

[0028] (4) The method adopted by the present application has relatively low energy consumption and cost: the process energy consumption is 30-40% lower than that of traditional hot air and hot water heat shock, no large CA library is needed, and it is suitable for pre-cooling in production areas and e-commerce logistics. The use of radio frequency assisted heating has high efficiency; the use of self-generating modified atmosphere bags reduces the dependence on high-cost modified atmosphere storage; the use of cold storage plates enhances temperature stability and may reduce the energy consumption of cold storage.

[0029] (5) The parameters of the present application are optimized: the key parameters (such as concentration, time, temperature, gas permeability, etc.) in each step are verified by experiments, providing an optimal range to ensure the effectiveness and operability of the method.

[0030] (6) Based on the ternary coupling regulation mechanism of "microenvironment-fruit-microorganism", the present application first integrates radio frequency (RF) precise heat shock, edible composite nanometer film, ozone-self-generating modified atmosphere (O3-MAP) in a bag, and phase change cold storage microenvironment, realizes complementary functions and effect superposition in each step, and realizes stable extension of shelf life to 15-20d, good fruit rate ≥90%, and simple process, low cost, suitable for large-scale promotion. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The physical map of the waxberry composite preservation package of the present application. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative characteristics, purposes and effects achieved by the present application easy to understand, the present application will be further described below in combination with specific embodiments.

[0033] A waxberry composite preservation method based on multi-step cooperative treatment, comprising the following steps: S1: rapid pre-cooling Rapidly reduce the temperature of the fruit, inhibit postharvest respiration intensity, and prepare for subsequent treatment.

[0034] S2: salt washing and fruit floating removal Use a salt solution of a specific concentration to clean, remove surface impurities, and simultaneously remove floating fruits and surface microorganisms, reducing the initial total number of colonies by 1-2 orders of magnitude.

[0035] In some embodiments, the salt solution in step S2 is one or more of sodium chloride, calcium chloride, sodium carbonate, and sodium bicarbonate solution.

[0036] S3: Surface drying and edible composite nanofilm spraying Absorb surface moisture in time, screen out defective products, and evenly cover the fruit surface with a 0.03-0.08mm thick edible Pickering nanofilm through atomization spraying device.

[0037] In some embodiments, the edible composite nanofilm in step S3 includes 1.5%, 2%, 2.5%, 3%, 3.5%, 4% chitosan-ε-polylysine matrix (continuous phase), 1.5%, 2%, 2.5%, 3%, 3.5%, 4% plant essential oil microcapsules (core material), 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% nanocellulose whiskers (NCC, network reinforcement), 0.05%-0.3% antioxidant-acidity double-buffering microparticles, 0.01%, 0.02%, 0.03%, 0.04%, 0.05% radio frequency thermal activation post-repair factor, 0.15%, 0.2%, 0.4%, 0.6%, 0.8% emulsification-electrostatic atomization aid, and the balance of 1% ice acetic acid aqueous solution or water, based on the total mass of the dry film. The edible composite nanofilm is formed by Pickering emulsion of the above components through high-pressure homogenization-electrostatic atomization spraying, with a dry film thickness of 0.03-0.08mm, and a 50μm level nanorelease film is formed on the fruit surface after radio frequency thermal activation.

[0038] In some embodiments, the chitosan-ε-polylysine matrix is composed of chitosan and ε-polylysine with a mass ratio of 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, the chitosan has a degree of deacetylation ≥85%, and the ε-polylysine has a molecular weight of 3kDa, 3.5kDa, 4kDa, 4.5kDa, or 5kDa; the plant essential oil microcapsules have 2% sodium alginate and 0.5% CaCl2 gel or β-cyclodextrin as wall material, the essential oil is selected from at least one of cinnamon, litsea cubeba, rosemary, oregano, thyme, clove, and eucalyptus, the microcapsule particle size is 200-400nm, and the essential oil loading is 30%-40%; the antioxidant-acidity double-buffering microparticles are co-spray dried from 0.05%, 0.1%, 0.15%, 0.2% calcium ascorbate and 0.02%, 0.05%, 0.08%, 0.1% sodium bicarbonate, with a particle size of 50-100nm; the radio frequency thermal activation post-repair factor is 0.01%, 0.02%, 0.03%, 0.04%, 0.05% phosphatidylcholine-glycerol monostearate complex; and the emulsification-electrostatic atomization aid is Tween 80 and glycerol with a mass ratio of 0.2-1:1.

[0039] S4: Ozone-MAP (O3-MAP) in bag After the fruits are packed into the packaging box, the whole is packed into a anti-fog and breathable modified atmosphere bag with specific gas permeability, forming a dynamic atmosphere of "initial high O3 sterilization-low O2 and high CO2 spontaneous modified atmosphere in the middle and later stages".

[0040] S5: Radio frequency assisted mild heat shock (RF-HST) The fruits are rapidly and uniformly heated to a set temperature and short-term incubated by radio frequency heating method, so as to activate the resistance of the fruits, inactivate the enzyme activity and surface microorganisms.

[0041] S6: Phase change microenvironment constant temperature storage The treated fruits are stored in a refrigeration box provided with a cold storage plate in a low temperature and stable environment. When the cold storage is temporarily malfunctioning, the temperature fluctuation in the box can be reduced, realizing the function of "mobile cold chain".

[0042] Example 1 Take "Dongkui" waxberries, and operate according to the steps S1-S6. The salt solution is 2% NaCO3+2% CaCl2 during salt washing, and the washing time is 1 min. After drying, edible composite nanometer film of 0.3% concentration of cinnamon essential oil is sprayed. The modified atmosphere bag has an OTR of 4000 cm³ / (m²·day·atm) and a CTR of 12000 cm³ / (m²·day·atm). The ozone concentration is 10 ppm. The radio frequency is heated to 45℃ within 3 min, and incubated at the target temperature for 15 min. The refrigeration is 0.5±1℃, and the phase change temperature of the cold storage plate is 0℃. The storage time is 15 days.

[0043] Comparative Example 1 No salt solution is used for washing, and the other steps are the same as those in Example 1.

[0044] Comparative Example 2 The salt solution in step S2 is washed for 30 min, and the other steps are the same as those in Example 1.

[0045] Comparative Example 3 The salt solution in step S2 is 5% NaCO3+5% CaCl2, and the other steps are the same as those in Example 1.

[0046] Comparative Example 4 Pure water is used for washing in step S2, and the other steps are the same as those in Example 1.

[0047] The good fruit rate, hardness reduction rate and weight loss rate of Example 1 and Comparative Examples 1-4 after 15 days of storage are compared, and the details are shown in Table 1.

[0048] Table 1 Referring to Table 1, by comparing the comparative examples 1-4 and the example 1, it can be seen that the good fruit rate of the example 1 is the highest, the hardness reduction rate and the weight loss rate are the lowest, and the total number of colonies is the most reduced; the good fruit rate of the comparative example 2 is the lowest, which may be because the salt solution cleaning time is too long to damage the surface of the bayberry pulp, so that the good fruit rate is reduced; the hardness reduction rate of the comparative example 4 is the highest, which may be because the comparative example 4 uses pure water for cleaning and sterilization operation, which cannot well sterilize the fruit, so that the hardness reduction rate is high; the weight loss rate of the comparative example 3 is the highest, because the salt solution concentration of the comparative example 3 is the highest, which causes the water loss of the fruit in the cleaning process, and thus the weight loss rate of the fruit is high.

[0049] Example 2 Take “Dongkui” bayberry, and operate according to the steps S1-S6. The salt solution is 0.5% NaCO3+3% NaHCO3 during salt washing, and the cleaning time is 3 min. After drying, edible composite nanometer film of 0.5% concentration of Litsea cubeba essential oil is sprayed. The OTR is 8000 cm3 / (m2·day·atm), the CTR is 24000 cm3 / (m2·day·atm), the ozone concentration is 20 ppm, the radio frequency is heated to 55℃ within 10 min, and the target temperature is kept for 10 min. The refrigerator is 0±1℃, the phase change temperature of the cold storage plate is 0℃, and the storage time is 15 days.

[0050] Comparative Example 5 After cleaning in step S3, the water-absorbing fiber material is not used for drying, and the fan is blown at 25℃ for drying, and the other steps are the same as those in example 2.

[0051] Comparative Example 6 After cleaning in step S3, the water-absorbing fiber material is not used for drying, and the fan is blown at 4℃ for drying, and the other steps are the same as those in example 2.

[0052] Comparative Example 7 After cleaning in step S3, the surface is not dried, and the other steps are the same as those in example 2.

[0053] Comparative Example 8 After cleaning in step S3, the water-absorbing fiber material is used for surface drying after 1 h, and the other steps are the same as those in example 2.

[0054] The good fruit rate, the hardness reduction rate and the weight loss rate of example 2 and comparative examples 5-8 after 15 days of storage are compared, and the details are shown in Table 2.

[0055] Table 2 Referring to Table 2, by comparing Comparative Examples 5-6 and Example 2, it can be seen that the good fruit rate of the waxberry in Example 2 is the highest, and the hardness reduction rate and the weight loss rate are the lowest. The good fruit rate of Comparative Example 8 is the lowest, which may be because the washed waxberry is not dried in time, which accelerates the mold of the fruit, resulting in a decrease in the good fruit rate. The hardness reduction rate of Comparative Example 7 is the highest, which may be because Comparative Example 7 is not dried, which further accelerates the decay of the fruit, thereby causing the hardness reduction rate to be relatively high. The weight loss rate of Comparative Example 5 is the highest, because Comparative Example 5 is dried in an environment with a relatively high relative temperature, and the blowing drying time is relatively long, which accelerates the reproduction of microorganisms and the water loss of the fruit, thereby causing the fruit to rot. The blowing drying time required by Comparative Example 6 is the longest, which accelerates the mold of the fruit, resulting in a decrease in the good fruit rate.

[0056] Example 3 Take “Wumei” waxberry, and operate according to steps S1-S6. The salt solution is 1% NaCO3+1% NaHCO3+1% CaCl2 during salt washing, and the washing time is 7 min. After drying, edible composite nanometer film of eucalyptus essential oil with a concentration of 0.8% is sprayed. The OTR is 20000 cm³ / (m²·day·atm), and the CTR is 80000 cm³ / (m²·day·atm). The ozone concentration is 80 ppm. The radio frequency is raised to 40℃ within 5 min, and the target temperature is maintained for 30 min. The refrigerator is at 1±1℃, the phase change temperature of the cold storage plate is 1℃, and the storage time is 15 days.

[0057] Comparative Example 9 In step S4, a PE vacuum packaging bag {OTR 1500 cm³ / (m²·day·atm), CTR 7000 cm³ / (m²·day·atm)} is used, and the other steps are the same as in Example 3.

[0058] Comparative Example 10 In step S4, a PE vacuum packaging bag {OTR 1500 cm³ / (m²·day·atm), CTR 7000 cm³ / (m²·day·atm)} is used, and no ozone is used, and the other steps are the same as in Example 3.

[0059] Comparative Example 11 In step S4, no ozone is used, and the other steps are the same as in Example 3.

[0060] Comparative Example 12 In step S4, no ozone is used, and the other steps are the same as in Example 3.

[0061] The good fruit rate, hardness reduction rate, and weight loss rate of Example 3 and Comparative Examples 9-12 after 15 days of storage are compared, and the details are shown in Table 3.

[0062] Table 3 Referring to Table 3, it can be seen from the comparison of Comparative Examples 9-12 and Example 3 that the good fruit rate of the waxberry in Example 3 is the highest, and the hardness reduction rate and the weight loss rate are the lowest. The good fruit rate of Comparative Example 11 is the lowest because the waxberry fruits are not subjected to ozone sterilization, so that the number of molds in the packaging bag is relatively large, which accelerates the mold of the fruits and reduces the good fruit rate. The hardness reduction rates of Comparative Examples 9 and 10 are the highest, which may be because Comparative Examples 9-10 use vacuum packaging, which affects the respiration of the waxberry, thereby causing the hardness reduction rate to be relatively high. The weight loss rate of Comparative Example 11 is the highest because Comparative Example 11 does not use a gas regulating bag and no ozone, which affects the respiration of the waxberry, causes the fruits to lose water seriously, and further causes the weight loss rate of the fruits to be relatively high.

[0063] Example 4 Take "Taimei" waxberry, and operate according to steps S1-S6. The salt solution is 1.5% NaCO3+1.5% NaHCO3+0.5% NaCl during salt washing, and the washing time is 10 min. After drying, spray edible composite nanometer film of eucalyptus / cinnamon essential oil with a concentration of 1.0%; the OTR of the gas regulating bag is 12000 cm³ / (m²·day·atm), and the CTR is 40000 cm³ / (m²·day·atm); the ozone concentration is 50 ppm; the radio frequency is heated to 50℃ within 5 min, and the target temperature is maintained for 20 min; the cold storage temperature is 0±1℃, the phase change temperature of the cold storage plate is 0℃, and the storage time is 15 days.

[0064] Comparative Example 13 In step S5, no radio frequency heating treatment is used, and the other steps are the same as those in Example 4.

[0065] Comparative Example 14 In step S5, the radio frequency is heated to 50℃ and maintained for 4 h, and the other steps are the same as those in Example 4.

[0066] Comparative Example 15 In step S5, the radio frequency is heated to 30℃ and maintained for treatment, and the other steps are the same as those in Example 4.

[0067] Comparative Example 16 In step S5, the radio frequency is heated to 70℃ and maintained for treatment, and the other steps are the same as those in Example 4.

[0068] The good fruit rate, hardness reduction rate, and weight loss rate of Example 4 and Comparative Examples 13-16 after 15 days of storage are compared, and the details are shown in Table 4.

[0069] Table 4 Referring to Table 4, by comparing Comparative Examples 13-16 and Example 4, it can be seen that the good fruit rate of Example 4 is the highest, and the hardness reduction rate and the weight loss rate are slightly low. The good fruit rate of Comparative Example 16 is the lowest because the radio frequency temperature is too high to damage the surface structure of the waxberry, accelerate the corruption of the waxberry, and reduce the good fruit rate. The hardness reduction rate of Comparative Example 14 is slightly high, which may be because the holding time is too long, accelerating the softening of the waxberry. Comparative Example 15 is too low in radio frequency temperature, so it cannot play a role in heat shock enzyme inactivation and bacteriostasis, accelerating the corruption of the waxberry. Although the weight loss rate of Comparative Example 13 is the lowest, in combination with the good fruit rate and the hardness reduction rate, the conditions of Comparative Example 13 are still not conducive to the storage of the waxberry.

[0070] Example 5 Take "Taimei" waxberry, and operate according to steps S1-S6. The salt solution is 1.5% NaCO3+1.5% NaHCO3+0.5% NaCl during salt washing, and the cleaning time is 10 min. After drying, spray edible composite nanometer film of 1.5% concentration of oregano / berberidodendron essential oil. The modified atmosphere packaging OTR is 12000 cm³ / (m²·day·atm), and the CTR is 40000 cm³ / (m²·day·atm). The ozone concentration is 50 ppm. The radio frequency is heated to 50℃ within 5 min, and the target temperature is maintained for 20 min. The cold storage is 0.5±1℃, the phase change temperature of the cold storage plate is 0.5℃, and the storage time is 15 days.

[0071] Comparative Example 17 In step S3, no edible composite nanometer film is sprayed, and the other steps are the same as those in Example 5.

[0072] Comparative Example 18 In step S3, spray edible composite nanometer film of 0.1% concentration of oregano / berberidodendron essential oil, and the other steps are the same as those in Example 5.

[0073] Comparative Example 19 In step S3, spray edible composite nanometer film of 3% concentration of oregano / berberidodendron essential oil, and the other steps are the same as those in Example 5.

[0074] Compare the good fruit rate, hardness reduction rate, and weight loss rate of Example 5 and Comparative Examples 17-19 after 15 days of storage. See Table 5 for details.

[0075] Table 5 Referring to Table 5, by comparing Examples 5 and Comparative Examples 17-19, it can be seen that the good fruit rate of the waxberry in Example 5 is the highest, and the hardness reduction rate and the weight loss rate are relatively low. The good fruit rate of Comparative Example 17 is the lowest because the waxberry fruits are not sprayed with the edible composite nanometer film, so that the protective film cannot be formed on the surface of the fruits, which accelerates the mold of the fruits and reduces the good fruit rate. Although the hardness reduction rate and the weight loss rate of Comparative Examples 17-19 are similar to those of Example 5, and even the hardness reduction rate of Comparative Example 19 and the weight loss rate of Comparative Example 17 are lower than those of Example 5, but considering the other two indicators, the conditions of Example 5 are more conducive to the storage of waxberry.

[0076] Example 6 Take "Wumei" waxberry, and operate according to steps S1-S6. The salt solution is 1.5% NaCO3+1.5% NaHCO3+0.5% NaCl during salt washing, and the washing time is 10 min. After drying, spray the waxberry with edible composite nanometer film of rosemary essential oil with a concentration of 1.2%. The modified atmosphere packaging OTR is 12000 cm3 / (m2·day·atm), and the CTR is 40000 cm3 / (m2·day·atm). The ozone concentration is 50 ppm. The radio frequency is heated to 50℃ within 5 min, and the target temperature is maintained for 20 min. The refrigerator is stored at 0.5±1℃, the phase change temperature of the cold storage board is 0℃, and the storage time is 15 days. The refrigerator is simulated to be out of operation for 12 h at night on the 10th day.

[0077] Comparative Example 20 In step S6, the waxberry is directly stored in the refrigerator without being put into the cold storage box, and there is no phase change cold storage board. The other steps are the same as those in Example 6.

[0078] The good fruit rate, hardness reduction rate and weight loss rate of the waxberry stored for 15 days in Example 6 and Comparative Example 20 are compared, and the details are shown in Table 6.

[0079] Table 6 Referring to Table 6, by comparing Example 6 and Comparative Example 20, it can be seen that the good fruit rate, hardness reduction rate and weight loss rate of the waxberry in Example 6 are all better than those in Comparative Example 20 because the temperature rises greatly during the out-of-operation process of the refrigerator without the low-temperature buffering effect of the phase change cold storage board in Comparative Example 20, which reduces the good fruit rate, hardness and weight loss rate.

[0080] The data in the above examples are obtained by repeated experiments, and the calculation method is as follows: Good fruit of waxberry It refers to the waxberry fruits without signs of rot such as mold, fermentation, juice leakage, dehydration and cracking, and with normal color, aroma and taste. The good fruit rate is calculated by the following formula: The weight loss rate of the waxberry is calculated by the following formula: % wherein m0 is the initial average value of the weight of the arbutus; and m is the average value of the weight of the arbutus at the time of measurement.

[0081] The rate of decrease of the hardness of the arbutus is calculated by the following formula: % wherein N0 is the initial average value of the hardness of the arbutus; and N is the average value of the hardness of the arbutus at the time of measurement.

[0082] The above shows and describes the basic principles and main features of the present application and the advantages thereof, and it is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present application.

[0083] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A compound preservation method of waxberry based on multi-step synergistic treatment, characterized in that, The method comprises the following steps: S1: rapid precooling Freshly picked 8-9 mature waxberry fruits are placed in a cold storage, pre-cooled at 0-4℃ for 0.5-1h, so that the fruit temperature is reduced to 2-4℃; S2: salt washing-screening The pre-cooled waxberries are washed in a salt solution with an effective chlorine concentration of 30-50ppm and a mass concentration of 0.5%-3% for 1-10min, while removing the fruits floating on the liquid surface; S3: surface drying-edible nano film spraying The water on the surface of the washed waxberries is absorbed, and the fruits with mechanical damage or insect damage are removed; then a layer of edible composite nano film with a thickness of 0.03-0.08mm is sprayed on the surface of the fruits by atomization spraying; S4: ozone in bag-self-generated modified atmosphere The film-sprayed waxberries are packed into a packaging box, then wrapped with a moisture-proof and breathable modified atmosphere bag, and then 10-80ppm of ozone is filled into the bag and sealed; S5: radio frequency assisted mild heat shock The sealed and packaged waxberries are placed in a radio frequency treatment chamber, and the radio frequency generator parameters are set so that the waxberry fruits are uniformly heated to 40-55℃ within 3-10min, and are kept at this target temperature for 5-30min; S6: phase change microenvironment constant temperature storage The heat-shocked waxberries are transferred to a cold storage box in which a cold storage plate with a phase change temperature of 0-1℃ has been placed, and then the cold storage box is stored in a cold storage at-0.5-2℃.

2. The compound preservation method of waxberry based on multi-step synergistic treatment according to claim 1, characterized in that, The salt solution in step S2 is one or more of sodium chloride, calcium chloride, sodium carbonate and sodium bicarbonate solution.

3. A multi-step synergistic processing based method for preserving waxberry as claimed in claim 1, wherein, Based on the total mass of 100g of dry film, the edible composite nano film in step S3 comprises 1.5%-4% chitosan-ε-polylysine matrix, 1.5%-4% plant essential oil microcapsules, 0.1%-0.8% nanocellulose whiskers, 0.05%-0.3% antioxidant-acidity double-buffering microparticles, 0.01%-0.05% radio frequency heat shock repair factor, 0.15%-0.8% emulsification-electrostatic atomization aid, and the balance of 1% ice acetic acid aqueous solution or water; the edible composite nano film is a Pickering emulsion formed by high-pressure homogenization-electrostatic atomization spraying of the above components, the dry film thickness is 0.03-0.08mm, and a nano slow-release film of 50μm is formed on the fruit surface after radio frequency heat shock.

4. The compound preservation method of waxberry based on multi-step synergistic treatment according to claim 3, characterized in that, The chitosan-epsilon-polylysine matrix is composed of chitosan and epsilon-polylysine with a mass ratio of 1:0.2-0.5, the chitosan has a degree of deacetylation of greater than or equal to 85%, and the epsilon-polylysine has a molecular weight of 3-5 kDa; the plant essential oil microcapsules have a wall material of 2% sodium alginate and 0.5% CaCl2 gel or beta-cyclodextrin, the essential oil is selected from at least one of cinnamomum, litsea cubeba, rosemary, origanum, thyme, clove, and eucalyptus, the microcapsule particle size is 200-400 nm, and the essential oil loading capacity is 30%-40%; the antioxidant-acidity double-buffering microparticles are prepared by co-spray drying 0.05%-0.2% calcium ascorbate and 0.02%-0.1% sodium bicarbonate, and the particle size is 50-100 nm; the radio frequency thermal after-repair factor is 0.01%-0.05% phosphatidylcholine-glycerol monostearate complex; and the emulsification-electrostatic atomization aid is Tween 80 and glycerol with a mass ratio of 0.2-1:

1.

5. The compound preservation method of waxberry based on multi-step synergistic treatment according to claim 3, characterized in that, The film preparation process in step S3 is as follows: Step one: preparation of the continuous phase chitosan-epsilon-polylysine matrix Chitosan is dissolved in 1% ice acetic acid aqueous solution, stirred at 60°C for 30 min to obtain a chitosan solution; and epsilon-polylysine is dissolved in the above solution to form a "chitosan-epsilon-polylysine matrix phase"; Step two: preparation of the core material plant essential oil microcapsules Under high shear, the essential oil is slowly dropped into the 1% sodium alginate aqueous phase to form an O / W primary emulsion; then, 0.5% CaCl2 solution is added to initiate gelation, or the essential oil is slowly dropped into beta-cyclodextrin saturated liquid to form 200-400 nm microcapsules; Step three: Pickering emulsion construction The plant essential oil microcapsule core material, nanocellulose whiskers, antioxidant-acidity double-buffering microparticles, and radio frequency thermal after-repair factor are sequentially added to the above matrix phase, and high-pressure homogenization is used to achieve uniform dispersion at the nanoscale to obtain a stable Pickering emulsion; Step four: electrostatic atomization spraying Yangmei is sprayed by adjusting the process parameters, and the single fruit film thickness is 0.03-0.08 mm.

6. A multi-step synergistic processing based method for preserving waxberry as claimed in claim 1, wherein, The modified atmosphere bag in step S4 is made of polyethylene, functional resin, or polypropylene as a base material.

7. A multi-step synergistic processing based method for preserving waxberry as claimed in claim 6, wherein the said method comprises the steps of: The oxygen transmission rate of the modified atmosphere bag in step S4 is 4000-15000 cm³ / (m²·day·atm), and the carbon dioxide transmission rate is 12000-100000 cm³ / (m²·day·atm).

8. A multi-step synergistic treatment-based red bayberry composite fresh-keeping method according to claim 1, characterized in that, The parameters of the radio frequency generator used in step S5 are as follows: frequency 27.12 MHz, plate spacing 5-30 cm, and power density dynamically adjusted according to the fruit load.

9. The compound preservation method of waxberry based on multi-step synergistic treatment according to claim 1, characterized in that, The cold storage in step S6 is equipped with a high-voltage electrostatic field device, and the cold storage is equipped with an ozone automatic sterilization device, which automatically adjusts the ozone concentration to 20-50 ppmm every 12 h, and sterilizes in the storage for 10-60 min.

10. The compound preservation method of waxberry based on multi-step synergistic treatment according to claim 1, characterized in that, The cold storage box body in step S6 is made of polyurethane, foamed polypropylene, or foamed polystyrene material; and the cold storage board can absorb the heat transmitted from the outside, and cooperates with the cold storage to maintain the temperature in the box at a stable state of 0-1°C.

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