Method for inhibiting flavor loss of zanthoxylum bungeanum during storage through electricity-membrane-gas coupling

Abstract

The invention discloses a method for inhibiting flavor loss of zanthoxylum bungeanum during storage through electricity-film-gas coupling, and belongs to the technical field of seasoning preservation. According to the method, gradient coating is performed on the pepper by adopting a pulsed electric field auxiliary film solution, and then pepper flavor substances are protected in a low-temperature environment by using a blue-violet light LED and modified atmosphere packaging co-processing technology. According to the method, the loss of active substances and flavor substances in the storage process of the Chinese prickly ash can be effectively controlled, and the degradation of a spicy substance OH-alpha-sanshool is delayed; the original sensory quality and nutritional value are maintained to the maximum extent, the retention rate of linalool is increased by about 70%, and degradation of about 79% of a spicy substance OH-alpha-sanshool in the storage process of the Chinese prickly ash can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of flavoring preservation, and particularly relates to a method for inhibiting the loss of the flavor of stored Chinese prickly ash by electro-membrane-gas coupling. Background Art

[0002] As an aroma-enhancing substance, Chinese prickly ash is deeply favored by consumers in daily life and is also an economic crop with both medicinal and edible uses. Chinese prickly ash is rich in active substances, such as flavonoids, polyphenols, anthocyanins, etc. In pharmacology, Chinese prickly ash has anti-inflammatory, anti-aging, antibacterial, and anti-tumor effects. However, during storage, the flavor substances of Chinese prickly ash are extremely volatile, and the numbing substance hydroxy-α-sanshool is easily degraded by light, oxygen, and lipoxygenase. These factors not only cause a decline in the quality of Chinese prickly ash but also lead to economic losses. Therefore, there is an urgent need to explore a method to reduce the loss of flavor substances during the storage of Chinese prickly ash.

[0003] Zhang Zhiqing (2023) disclosed "A food and its preparation method for slowly releasing fat-soluble flavor substances using food gel" (Publication No.: CN 116616427 A). In this method, sucrose fatty acid ester is dissolved in Chinese prickly ash oil to obtain emulsified oil; then the emulsified oil is mixed with sodium alginate hydrocolloid solution and homogenized to obtain a core liquid mixture of popping beads; it is dropped into a calcium lactate aqueous solution, the coagulated beads are collected, and the calcium lactate on the surface is washed off to obtain the food. This invention can form the shape of coagulated beads, which is convenient for storage and consumption. The product obtained by this invention has the aroma of Chinese prickly ash. After the coagulated beads are broken, a milky white emulsified liquid of Chinese prickly ash oil can flow out, and the flavor of Chinese prickly ash can be well released during eating; while during storage, it can play a role in slowly releasing the flavor of Chinese prickly ash oil and avoid the loss of flavor. However, this method is for the extract of Chinese prickly ash oil and cannot achieve the reduction of the flavor loss of Chinese prickly ash raw materials.

[0004] Zhang Kaiyan et al. (2020) disclosed "A storage and preservation method for fresh Chinese prickly ash" (Application No.: CN202011282584.8). In this method, fresh Chinese prickly ash is blanched at a steam temperature of 110 - 110°C for 5 - 10 min, then sterilized at a steam temperature of 110 - 120°C for 30 - 60 s, and finally stored under the cold storage conditions of 2 - 4°C. The fresh Chinese prickly ash is subjected to enzyme inactivation treatment with high-temperature steam, and the fresh Chinese prickly ash after enzyme inactivation treatment is subjected to sterilization treatment with high-temperature steam. By carrying out enzyme inactivation and sterilization treatment on Chinese prickly ash with high-temperature steam, the occurrence of browning can be effectively prevented and good color can be ensured; after vacuum cooling and packaging, the problem of Chinese prickly ash being contaminated by microorganisms and bacteria can be effectively avoided, and finally it is stored in a low-temperature cold storage. This method only has a certain effect on the spoilage problem of fresh Chinese prickly ash and has a great destructive effect on the flavor of Chinese prickly ash.

[0005] Zhou Tianjin et al. (2021) disclosed "A method for preserving the freshness of green prickly ash" (Publication No.: CN 112314834A). In this method, 1-methylcyclopropene is introduced into the prickly ash, and after being sealed and treated for 4 to 6 hours, thymol is then placed in the sealed environment, with 1 g of thymol placed per cubic meter of space, and after continuing the sealed treatment for 3 to 4 hours, the preservation treatment of the green prickly ash is completed; steam enzyme inactivation: The green prickly ash is evenly spread on a stainless steel mesh, placed in a tunnel, and steam is introduced to quickly reduce the protease activity, and steam is used for enzyme inactivation. This method can effectively inhibit the enzymes and microorganisms of the green prickly ash, thereby achieving the protection of the quality of the prickly ash. However, there are no active microorganisms in the dry prickly ash, and this method cannot obtain the expected effect for the dry prickly ash. Summary of the Invention

[0006] The object of the present invention is to reduce the loss of flavor component substances of prickly ash raw materials during storage through an electro-membrane-gas ternary coupling method, adopt pulsed electric field-assisted membrane solution to perform gradient coating on the prickly ash, and then use the cooperative treatment technology of blue-violet LED and modified atmosphere packaging to protect the flavor substances of the prickly ash in a low-temperature environment. Through this combined technology, the loss of flavor substances and the degradation of numbing substances of the prickly ash during storage can be reduced, the quality of the prickly ash during storage can be maintained for a longer time, and the antioxidant capacity can be improved.

[0007] The technical solution of the present invention:

[0008] A method for electro-membrane-gas coupling to inhibit the flavor loss of prickly ash during storage, the main steps are:

[0009] (1) Selection of prickly ash: Select prickly ash with uniform size, no damage and no microbial infection;

[0010] (2) Preparation of the coating solution: Dissolve chitosan in water, add nano-ZnO and glycerol, and use ultrasound for dispersion to prepare the aqueous phase of the emulsion; Mix prickly ash essential oil, soybean oil and Tween 80 to prepare the oil phase of the emulsion; Add the oil phase of the emulsion to the aqueous phase and accelerate emulsification by ultrasound to obtain a chitosan-prickly ash essential oil-nano-ZnO composite emulsion;

[0011] (3) Electric field-assisted coating: Place the prickly ash selected in step (1) in the chitosan-prickly ash essential oil-nano-ZnO composite emulsion prepared in step (2) to form a gradient film under a pulsed electric field; The gradient film includes three layers: the anode layer is nano-zinc oxide, the middle transition layer is a chitosan-nano-zinc oxide complex, and the cathode layer is a chitosan-essential oil complex. After the coating is completed, remove the excess membrane solution in a sieve;

[0012] (4) Drying: Evenly disperse the prickly ash after coating in step (3) in an oven for drying;

[0013] (5) Modified atmosphere packaging: Put the dried Chinese prickly ash after step (4) into a polyester fiber plastic bag, first evacuate the air, and then use a modified atmosphere packaging machine to fill it with CO2 and O2 gases so that the CO2 concentration ranges from 50% to 70% and the O2 concentration ranges from 30% to 50%. Seal the polyester fiber plastic bag with a heat sealer;

[0014] (6) LED irradiation and dynamic modified atmosphere storage: Store the Chinese prickly ash packaged in modified atmosphere in step (5) by pulsed blue-violet light LED radiation; During the storage period from 21 to 40 days, replace the polyester fiber plastic bag, and use a modified atmosphere packaging machine to fill it with CO2 and O2 gases so that the CO2 concentration ranges from 30% to 50% and the O2 concentration ranges from 70% to 50%. Seal the polyester fiber plastic bag with a heat sealer and store it by LED radiation; During the storage period from 40 to 60 days, replace the polyester fiber plastic bag again, and use a modified atmosphere packaging machine to fill it with CO2 and O2 gases so that the CO2 concentration ranges from 10% to 30% and the O2 concentration ranges from 90% to 70%. Seal the polyester fiber plastic bag with a heat sealer and store it by LED radiation.

[0015] Further, in step (2), in the preparation of the aqueous phase, dissolve chitosan in water with a pH of 4 - 6, the concentration of chitosan is 1% - 3%, add 1% - 2% of glycerol and 0.01% - 0.03% of ZnO for mixing; In the preparation of the oil phase, mix 8% - 15% of soybean oil with 0.1% - 0.3% of Chinese prickly ash essential oil, add 75% - 85% of Tween 80 and heat to 40 - 60 °C until complete emulsification; The concentration of the chitosan solution is 10 - 20 g / L; The mass ratio of chitosan - Chinese prickly ash essential oil - nano ZnO is 10:1:0.1.

[0016] Further, in step (2), the power of the ultrasonic wave is 200 - 500 W and the time is 10 - 20 min.

[0017] Further, in step (3), mix 500 g of dry Chinese prickly ash with 1.5 - 2 L of the composite emulsion and form a gradient film under a pulsed electric field of 20 - 30 kV / cm.

[0018] Further, in step (4), during the drying process, the temperature is 25 - 40 °C and the time is 7 - 10 h.

[0019] Further, in step (5), during the packaging process with polyester fiber plastic bags, the weight of Chinese prickly ash in each packaging bag is 200 - 500 g.

[0020] Furthermore, during the LED storage process in step (6), the LED emits blue-violet light with a wavelength of 380 - 500 nm, a light intensity of 80 - 120 μmol·m-2·s-1, a pulse frequency of 2 - 5 Hz, a temperature of 5 ± 1 °C, and a humidity of 85 ± 5% RH.

[0021] The method for reducing the loss of flavor substances during the storage of Chinese prickly ash provided by the present invention. The pulsed electric field-assisted chitosan-Chinese prickly ash essential oil-nano-ZnO composite emulsion coating will form three dense layers of film on the surface of Chinese prickly ash, which can prevent the volatilization of flavor substances in Chinese prickly ash. The role of modified atmosphere is to reduce the oxidation of flavor substances and numbing substances in the storage environment. Blue-violet light can irradiate nano-ZnO to generate reactive oxygen species, resulting in a decrease in the activity of lipoxygenase, and Chinese prickly ash essential oil can also reduce the activity of lipoxygenase, thereby further reducing the flavor loss of Chinese prickly ash during storage. The blue-violet light LED can reduce the light-induced decomposition of hydroxy-α-sanshool during the storage of Chinese prickly ash. In addition, in a low-temperature environment, the volatilization of flavor substances in Chinese prickly ash can be further reduced. Therefore, the present invention combines film coating-LED-modified atmosphere synergistic treatment to reduce the volatilization of flavor substances and the degradation of numbing substances in Chinese prickly ash during storage, and also protects the sensory quality and nutritional value of Chinese prickly ash during storage.

[0022] The beneficial effects of the present invention compared with the prior art are as follows:

[0023] (1) Chitosan is rich in resources and has a low price, which will not significantly increase the cost. The present invention uses pulsed electric field-assisted chitosan-Chinese prickly ash essential oil-nano-ZnO composite emulsion for gradient coating of Chinese prickly ash, which adds three dense layers of thin films to Chinese prickly ash. The structure of these films is tight, thus restricting the entry of external oxygen. It can not only reduce the volatilization of flavor-active substances during the storage of Chinese prickly ash, but also reduce the oxidation of active substances and flavor substances. At the same time, Chinese prickly ash essential oil and nano-ZnO can destroy the cell walls of microorganisms, thereby reducing the activity of lipoxygenase and further reducing the flavor loss of Chinese prickly ash during storage. These films can also prevent the oxidative degradation of the numbing substance hydroxy-α-sanshool in Chinese prickly ash during storage. This film material is not only simple to obtain but also has the advantage of low price.

[0024] (2) When pulsed electric field-assisted emulsion gradient coating is carried out, through the ingenious combination of transient high field strength and intermittent recovery period, the balance of high efficiency - low damage - high precision is achieved. The pulsed electric field can increase the particle size uniformity of the emulsion particles, improve their surface activity, and enhance the stability of the emulsion. Through the auxiliary action of the pulsed electric field, the particles in the emulsion can be better coated on the surface of the substrate, reducing the waste of the coating and improving the adhesion of the coating. It improves the rheological properties of the emulsion, makes the coating process smoother, forms a smoother coating, and avoids the appearance of coating cracks or unevenness. The pulsed electric field is simple to operate, does not require professional knowledge, and also has a great price advantage.

[0025] (3) The present invention can significantly reduce the loss of flavor substances and numbing substances during the storage of Chinese prickly ash through the synergistic effect of blue-violet LED combined with coating technology. The blue-violet pulsed irradiation can reduce the oxygen permeability of the film by more than 30%. This can further reduce the degradation of the numbing substance hydroxy-α-sanshool in Chinese prickly ash due to oxygen during storage. Moreover, the pulsed LED has relatively low energy consumption and simple operation. The synergistic effect of modified atmosphere prolongs the slow-release time of Chinese prickly ash essential oil by more than 2 times. In addition, storing at a low temperature environment can further reduce the volatilization of flavor substances during the storage of Chinese prickly ash.

[0026] (4) The present invention uses the ternary coupling of electricity-membrane-gas for treatment, with short treatment time and low energy consumption. It can not only reduce the volatilization of flavor substances and the degradation of numbing substances during the storage of Chinese prickly ash, but also protect the sensory quality and nutritional value of Chinese prickly ash during storage. Description of the Drawings

[0027] Figure 1 Effects of different treatment methods on the contents of total polyphenols and total flavonoids in Chinese prickly ash during storage;

[0028] Figure 2 Effects of different treatment methods on the scavenging rates of DPPH and ABTS free radicals in Chinese prickly ash during storage; Detailed Embodiments

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] In the following embodiments of the present invention, the blue-violet LED is implemented using a light strip. The wavelength of the blue-violet LED light strip is 380 - 500 nm, the light intensity is 80 - 120 μmol·m-2·s-1, the pulse frequency is 2 - 5 Hz, and the color temperature is 1500 - 2500 K.

[0031] Embodiment 1

[0032] A method for inhibiting the flavor loss of Chinese prickly ash during storage by electricity-membrane-gas coupling mainly includes the following steps:

[0033] (1) Select Chinese prickly ash with uniform size, no damage and no microbial infection;

[0034] (2) In the preparation of the aqueous phase, 2% chitosan (pH = 5) was prepared, 2% glycerol and 0.02% ZnO were added and mixed, and ultrasonic dispersion was used; in the preparation of the oil phase, 8% soybean oil and 0.2% prickly ash essential oil were mixed, 80% Tween 80 was added and heated to 50 °C to achieve complete emulsification. After emulsification was completed, the oil phase and the aqueous phase were mixed and emulsified at an ultrasonic power of 300 W, and finally a chitosan-prickly ash essential oil-nano ZnO composite emulsion was obtained;

[0035] (3) 500 g of prickly ash was placed in a 40 cm × 60 cm rectangular plastic container and formed a gradient film with 1.5 L of chitosan-prickly ash essential oil-nano ZnO composite emulsion under a pulsed electric field of 25 kV / cm for 20 min. After coating was completed, the excess film solution was removed in a sieve;

[0036] (4) The prickly ash after coating in step (3) was evenly dispersed and dried in an oven at a temperature of 30 °C for 8 h;

[0037] (5) 200 g of the dried prickly ash in step (4) was put into a polyester fiber plastic bag, first evacuated, and then filled with CO2 and O2 gases using a modified atmosphere packaging machine, so that the CO2 concentration range was 50%, and the O2 concentration range was 50%. The polyester fiber plastic bag was sealed with a heat sealer;

[0038] (6) The prickly ash packaged in a modified atmosphere in step (5) was stored by pulsed blue-violet LED radiation, with a pulse frequency of 5 Hz, a humidity of 85 ± 5% RH, and a temperature of 5 ± 1 °C; during the storage period of 21 - 40 days, the polyester fiber plastic bag was replaced, and CO2 and O2 gases were filled using a modified atmosphere packaging machine, so that the CO2 concentration range was 30% and the O2 concentration range was 70%, and the polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation; during the storage period of 40 - 60 days, the polyester fiber plastic bag was replaced again, and CO2 and O2 gases were filled using a modified atmosphere packaging machine, so that the CO2 concentration range was 10% and the O2 concentration range was 90%, and the polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation.

[0039] Samples were taken every 15 days for determination.

[0040] Example 2

[0041] A method for suppressing the loss of flavor during the storage of prickly ash by electro-membrane-gas coupling mainly includes the following steps:

[0042] (1) Select prickly ash with uniform size, no damage and no microbial infection;

[0043] (2) In the preparation of the aqueous phase, 2.5% chitosan (pH = 5) was prepared, 2% glycerol and 0.025% ZnO were added and mixed, and ultrasonic dispersion was used; in the preparation of the oil phase, 8% soybean oil and 0.25% prickly ash essential oil were mixed, 80% Tween 80 was added and heated to 50 °C to achieve complete emulsification. After emulsification, the oil phase and the aqueous phase were mixed and emulsified at an ultrasonic power of 300 W, and finally a chitosan-prickly ash essential oil-nano ZnO composite emulsion was obtained;

[0044] (3) 500 g of prickly ash was placed in a 40 cm × 60 cm rectangular plastic container and formed a gradient film with 1.5 L of chitosan-prickly ash essential oil-nano ZnO composite emulsion under a pulsed electric field of 30 kV / cm for 40 min. After coating, the excess film solution was removed in a sieve;

[0045] (4) The prickly ash after coating in step (3) was evenly dispersed and dried in an oven at a temperature of 40 °C for 8 h;

[0046] (5) 200 g of the dried prickly ash in step (4) was put into a polyester fiber plastic bag. First, it was evacuated, and then CO2 and O2 gases were filled with a modified atmosphere packaging machine so that the CO2 concentration range was 70% and the O2 concentration range was 30%. The polyester fiber plastic bag was sealed with a heat sealer;

[0047] (6) The prickly ash packaged with modified atmosphere in step (5) was stored by pulsed blue-violet LED radiation. The pulse frequency was 5 Hz, the humidity was 85 ± 5% RH, and the temperature was 5 ± 1 °C; during the storage period of 21 - 40 days, the polyester fiber plastic bag was replaced, and CO2 and O2 gases were filled with a modified atmosphere packaging machine so that the CO2 concentration range was 50% and the O2 concentration range was 50%. The polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation; during the storage period of 40 - 60 days, the polyester fiber plastic bag was replaced again, and CO2 and O2 gases were filled with a modified atmosphere packaging machine so that the CO2 concentration range was 30% and the O2 concentration range was 70%. The polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation.

[0048] Samples were taken every 15 days for determination.

[0049] Example 3

[0050] A method for suppressing the flavor loss of prickly ash during storage by electro-membrane-gas coupling mainly includes the following steps:

[0051] (1) Select prickly ash with uniform size, no damage and no microbial infection;

[0052] (2) In the preparation of the aqueous phase, 3% chitosan (pH = 5) was prepared, 2% glycerol and 0.03% ZnO were added and mixed, and ultrasonic dispersion was used; in the preparation of the oil phase, 8% soybean oil and 0.3% prickly ash essential oil were mixed, 80% Tween 80 was added and heated to 50 °C to achieve complete emulsification. After emulsification, the oil phase and the aqueous phase were mixed and emulsified at an ultrasonic power of 300 W, and finally a chitosan-prickly ash essential oil-nano ZnO composite emulsion was obtained;

[0053] (3) 500 g of prickly ash was placed in a 40 cm × 60 cm rectangular plastic container and formed a gradient film with 2 L of chitosan-prickly ash essential oil-nano ZnO composite emulsion under a pulsed electric field of 20 kV / cm for 30 min. After coating, the excess film solution was removed in a sieve;

[0054] (4) The prickly ash after coating in step (3) was evenly dispersed and dried in an oven at a temperature of 33 °C for 8 h;

[0055] (5) 200 g of the dried prickly ash in step (4) was put into a polyester fiber plastic bag, first evacuated, and then filled with CO2 and O2 gases by a modified atmosphere packaging machine so that the CO2 concentration range was 60% and the O2 concentration range was 40%, and the polyester fiber plastic bag was sealed with a heat sealer;

[0056] (6) The prickly ash packaged in a modified atmosphere in step (5) was stored by pulsed blue-violet LED radiation, with a pulse frequency of 5 Hz, a humidity of 85 ± 5% RH, and a temperature of 5 ± 1 °C; during the storage period from 21 to 40 days, the polyester fiber plastic bag was replaced, and CO2 and O2 gases were filled by a modified atmosphere packaging machine so that the CO2 concentration range was 40% and the O2 concentration range was 60%, and the polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation; during the storage period from 40 to 60 days, the polyester fiber plastic bag was replaced again, and CO2 and O2 gases were filled by a modified atmosphere packaging machine so that the CO2 concentration range was 20% and the O2 concentration range was 80%, and the polyester fiber plastic bag was sealed with a heat sealer and stored by LED radiation.

[0057] Samples were taken every 15 days for determination.

[0058] Control Example 1

[0059] (1) Prickly ash with uniform size, no damage and no microbial infection was selected;

[0060] (2) 200 g of the prickly ash in step (1) was put into a polyester fiber plastic bag, first evacuated, and then filled with CO2 and O2 gases by a modified atmosphere packaging machine so that the CO2 concentration range was 50% and the O2 concentration range was 50%, and the polyester fiber plastic bag was sealed with a heat sealer;

[0061] (3) Store the vacuum-packed Chinese prickly ash prepared in step (2) under the conditions of a humidity of 85 ± 5% RH and a temperature of 5 ± 1°C; during the 21st to 40th days of storage, replace the polyester fiber plastic bag, and use a vacuum packaging machine to fill it with CO2 and O2 gases so that the CO2 concentration ranges from 30% and the O2 concentration ranges from 70%, and then seal the polyester fiber plastic bag with a heat sealer; during the 40th to 60th days of storage, replace the polyester fiber plastic bag again, and use a vacuum packaging machine to fill it with CO2 and O2 gases so that the CO2 concentration ranges from 10% and the O2 concentration ranges from 90%, and then seal the polyester fiber plastic bag with a heat sealer.

[0062] (4) Spread the vacuum-packed Chinese prickly ash under a blue-violet LED with a pulse frequency of 5 Hz, a humidity of 85 ± 5% RH, and a temperature of 5 ± 1°C, and take samples for measurement every 15 days.

[0063] Control Example 2

[0064] (1) Select Chinese prickly ash with uniform size, no damage, and no microbial infection.

[0065] (2) In the preparation of the aqueous phase, prepare a solution containing 2% chitosan (pH = 5), add 2% glycerol and 0.02% ZnO, and mix them using ultrasound for dispersion; in the preparation of the oil phase, mix 8% soybean oil with 0.2% Chinese prickly ash essential oil, add 80% Tween 80, and heat to 50°C until complete emulsification. After emulsification, mix the oil phase and the aqueous phase and emulsify them at an ultrasonic power of 300 W to finally obtain a chitosan-Chinese prickly ash essential oil-nano ZnO composite emulsion.

[0066] (3) Place 500 g of Chinese prickly ash in a 40 cm × 60 cm rectangular plastic container and form a gradient film with 1.5 L of the chitosan-Chinese prickly ash essential oil-nano ZnO composite emulsion under a pulsed electric field of 25 kV / cm for 20 min. After coating, remove the excess film solution in a sieve.

[0067] (4) Dry the Chinese prickly ash coated in step (3) evenly in an oven at a temperature of 30°C for 8 h.

[0068] (5) Store the Chinese prickly ash coated in step (4) by irradiating it with a pulsed blue-violet LED, with a pulse frequency of 5 Hz, a humidity of 85 ± 5% RH, and a temperature of 5 ± 1°C.

[0069] Take samples for measurement every 15 days.

[0070] Control Example 3

[0071] (1) Select Chinese prickly ash with uniform size, no damage, and no microbial infection.

[0072] (2) In the preparation of the aqueous phase, 2% chitosan (pH = 5) was prepared, 2% glycerol and 0.02% ZnO were added and mixed, and ultrasonic dispersion was used; in the preparation of the oil phase, 8% soybean oil and 0.2% prickly ash essential oil were mixed, 80% Tween 80 was added and heated to 50 °C to achieve complete emulsification. After emulsification was completed, the oil phase and the aqueous phase were mixed and emulsified at an ultrasonic power of 300 W, and finally a chitosan-prickly ash essential oil-nano ZnO composite emulsion was obtained;

[0073] (3) 500 g of prickly ash was placed in a 40 cm × 60 cm rectangular plastic container and formed a gradient film with 1.5 L of chitosan-prickly ash essential oil-nano ZnO composite emulsion under a pulsed electric field of 25 kV / cm for 20 min. After coating was completed, the excess film solution was removed in a sieve;

[0074] (4) The prickly ash after film coating in step (3) was evenly dispersed and dried in an oven at a temperature of 30 °C for 8 h;

[0075] (5) 200 g of the dried prickly ash in step (4) was put into a polyester fiber plastic bag, first evacuated, and then filled with CO2 and O2 gases by a modified atmosphere packaging machine so that the CO2 concentration range was 50% and the O2 concentration range was 50%, and the polyester fiber plastic bag was sealed with a heat sealer;

[0076] (6) The prickly ash packaged by modified atmosphere in step (5) was stored under the conditions of a humidity of 85 ± 5% RH and a temperature of 5 ± 1 °C; during the 21st to 40th days of storage, the polyester fiber plastic bag was replaced, and CO2 and O2 gases were filled by a modified atmosphere packaging machine so that the CO2 concentration range was 30% and the O2 concentration range was 70%, and the polyester fiber plastic bag was sealed with a heat sealer; during the 40th to 60th days of storage, the polyester fiber plastic bag was replaced again, and CO2 and O2 gases were filled by a modified atmosphere packaging machine so that the CO2 concentration range was 10% and the O2 concentration range was 90%, and the polyester fiber plastic bag was sealed with a heat sealer.

[0077] Samples were taken every 15 days for determination.

[0078] Experimental determination method:

[0079] 1. Determination of total flavonoid and total polyphenol contents

[0080] Prickly ash powder (1 g) was mixed with 20 mL of ethanol (70%, v / v), ultrasonically extracted for 1 h, and centrifuged at 8000 rpm for 10 min at 25 °C to obtain the supernatant.

[0081] Determination of total polyphenol content: Take the supernatant (1 mL) and mix it with 1 mL of Folin-ciocalteu reagent (1 M) solution. After 5 min, add 5 mL of NaCO3 (1 M) solution, fix it to 10 mL with ethanol solution (70%, v / v), react for 30 min at room temperature, and then measure the absorbance value at 760 nm using a UV spectrophotometer. Using gallic acid as the equivalent (mg GAE / g), calculate the total phenol content concentration using the standard curve equation.

[0082] Determination of total flavonoid content: Take the supernatant (1 mL) and mix it with 1 mL of Folin-ciocalteu reagent (1 M) solution. After 5 min, add 5 mL of NaCO3 (1 M) solution, fix it to 10 mL with ethanol solution (70%, v / v), react for 30 min at room temperature, and then measure the absorbance value at 760 nm using a UV spectrophotometer. Using gallic acid as the equivalent (mg GAE / g), calculate the total phenol content concentration using the standard curve equation. Dilute the supernatant (1 mL) to 12.5 mL with 70% ethanol (v / v), and react with 1 mL of NaNO2 (5%, m / v) for 5 min. Add 1 mL of Al(NO3)3·6H2O solution (10%, m / v) to the mixed solution and react for 6 min. Add 5 mL of NaOH solution (1 M), dilute it to 25 mL with 70% ethanol solution (v / v), and react for 10 min at room temperature. Measure the absorbance at 510 nm using a UV spectrophotometer. Using gallic acid as the equivalent (mg RE / g), calculate the total phenol content concentration using the standard curve equation.

[0083] 2. Determination of antioxidant capacity

[0084] Mix 1 g of Zanthoxylum powder with 20 mL of ethanol (70%, v / v), extract it ultrasonically (500 W) for 1 h, centrifuge it at 8000 rpm for 10 min at 25 °C to obtain the supernatant.

[0085] (1) Determination of DPPH free radical scavenging ability

[0086] Mix 200 μL of the supernatant with 2 mL of DPPH (0.25 mM), react in the dark for 30 min, and measure the absorbance at 517 nm using a UV spectrophotometer. Calculate the scavenging rate of Zanthoxylum to DPPH free radicals during storage as:

[0087] Free radical scavenging rate = 100% × (A0 - (A - A x )) / A0 (1)

[0088] Where A0: Absorbance of DPPH solution, A: Absorbance of the sample after reacting with DPPH, A x : Absorbance of the sample.

[0089] (2) Determination of ABTS free radical scavenging ability

[0090] Mix 500 μL of the supernatant with 2 mL of ABTS ·+ Mix for 6 min, and measure the absorbance at 734 nm using a UV-visible spectrophotometer. Calculate the ABTS free radical scavenging rate of Zanthoxylum bungeanum during storage according to the above formula (1).

[0091] 3. Determination of hydroxy-α-sanshool

[0092] Extract hydroxy-α-sanshool from Zanthoxylum bungeanum powder (1 g) with ethanol (20 mL) under ultrasonic conditions (500 W, 1 h). After extraction, centrifuge the mixed solution at 8000 rpm for 15 min to obtain the supernatant. The supernatant is filtered through an organic filter membrane (0.22 μm). Determine the change of OH-α-sanshool in Zanthoxylum bungeanum during storage using a high performance liquid chromatography system (Thermo Fisher Scientific, Santa Clara, CA, USA). Use a Thermo Fisher C 18 chromatographic column (4.6 mm × 75 mm, 5 μm), with a temperature of 30 °C, to separate OH-α-sanshool. The mobile phase is ultrapure water (A) and methanol (B), with a flow rate of 0.8 mL / min. The injection volume is 20 μL, the ultraviolet absorption wavelength is 270 nm, and the column temperature is 40 °C. The elution gradient is as follows: 0 - 15 min, 50 - 70% B; 15 - 25 min, 70% B; 25 - 26 min, 70 - 50% B.

[0093] 4. Determination of flavor substances

[0094] Determine the change of flavor components in Zanthoxylum bungeanum during storage using headspace-gas-phase-mass spectrometry (Agilent 8890-5977B, Agilent Technologies, Santa Clara, USA). Weigh 1 g of Zanthoxylum bungeanum powder and put it into a 10 mL headspace vial. Use an HP-5MS fused silica capillary column (30 mm × 0.25 mm, 0.25 μm), with helium as the carrier gas, a flow rate of 1 mL / min, an extraction time of 5 min, to analyze the flavor compounds in Zanthoxylum bungeanum. The temperature increase process is described as follows: the initial temperature is 50 °C, increase to 70 °C at a rate of 2 °C / min, then increase to 120 °C at a rate of 5 °C / min. Finally, increase to 250 °C at a rate of 10 °C / min and hold for 3 min.

[0095] Compare the indexes of the effects of different treatment methods on the quality of Zanthoxylum bungeanum during storage, and a control for each sample test was conducted. Figure 1 and Figure 2To show the effects of different treatment methods on the active substances (total polyphenol and total flavonoid contents) and antioxidant activity of Chinese prickly ash during storage; Tables 1 and 2 show the effects of different treatment methods on the flavor substances and numbing substances of Chinese prickly ash during storage. Different from the examples, Comparative Example 1 uses the method of dynamic modified atmosphere combined with LED irradiation, Comparative Example 2 uses coating combined with LED irradiation to treat Chinese prickly ash, and Comparative Example 3 uses the method of coating combined with dynamic modified atmosphere for treatment. Examples 1-3 use the combined method of coating, LED and dynamic modified atmosphere to store Chinese prickly ash. The final storage indicators are tested and compared as follows:

[0096] The effects of different treatment methods on the numbing substances of Chinese prickly ash during storage are shown in Table 1 specifically:

[0097] Table 1 Effects of different treatment methods on hydroxy-α-sanshool of Chinese prickly ash during storage

[0098]

[0099]

[0100] The effects of different treatment methods on the flavor substances of Chinese prickly ash during storage are shown in Table 2 specifically:

[0101] Table 2 Effects of different treatment methods on the flavor substances of Chinese prickly ash during storage

[0102]

[0103] Note: Changes in flavor substances stored for 60 days.

[0104] From Figure 1 、 Figure 2、It can be seen from the contents of Table 1 and Table 2 that all three treatments can reduce the loss of flavor substances during the storage of Chinese prickly ash. Compared with the individual control groups 1, 2, and 3, the electro-membrane-gas ternary coupling storage effectively reduces the loss of active substances during the storage of Chinese prickly ash. For example, the loss degrees of the total polyphenol content and the total flavonoid content are significantly reduced, and the antioxidant activity during the storage of Chinese prickly ash can be retained. This may be because pulsed electric field-assisted coating can form multiple layers of tight films on the surface of Chinese prickly ash to reduce the contact between Chinese prickly ash and oxygen. On the other hand, the controlled atmosphere treatment can reduce the oxygen content in the storage environment of Chinese prickly ash, thereby reducing the oxidative degradation during the storage of Chinese prickly ash. This method can not only reduce the oxidation of flavor substances in Chinese prickly ash with oxygen but also prevent the entry of oxygen. In addition, the numbing substance hydroxy-α-sanshool in Chinese prickly ash during storage is also easily degraded under the action of light and oxygen, and the electro-membrane-gas ternary coupling can effectively reduce the degradation of the numbing substance hydroxy-α-sanshool during the storage of Chinese prickly ash. Therefore, the electro-membrane-gas ternary coupling synergistic treatment can maximize the nutritional value and antioxidant capacity of Chinese prickly ash during storage, and reduce the degradation of flavor substances and numbing substances.

Claims

1. A method for suppressing the loss of flavor of pepper during storage by using electric-membrane-gas coupling, characterized in that: The main steps include: (1) Selection of peppercorns: Choose peppercorns that are uniform in size, undamaged, and free of microbial contamination. (2) Preparation of coating solution: dissolving chitosan in water, adding nano ZnO and glycerol, and dispersing by ultrasound to prepare the water phase of the emulsion; mixing Zanthoxylum essential oil, soybean oil and Tween 80 to prepare the oil phase of the emulsion; adding the oil phase of the emulsion to the water phase and emulsifying by ultrasound to obtain the chitosan-Zanthoxylum essential oil-nano ZnO composite emulsion; (3) Electric field assisted coating: placing the pepper selected in step (1) in the chitosan-pepper essential oil-nano ZnO composite emulsion prepared in step (2) to form a gradient film under a pulsed electric field; the gradient film comprises three layers: an anode layer of nano zinc oxide, an intermediate transition layer of chitosan-nano zinc oxide complex, and a cathode layer of chitosan-essential oil complex; after coating, placing the pepper in a sieve to remove excess film solution; (4) Drying: The peppers coated in step (3) are evenly dispersed in an oven and dried; (5) Modified atmosphere packaging: the dried peppers in step (4) are placed in a polyester fiber plastic bag, which is first vacuumized, and then filled with CO2 and O2 gases using a modified atmosphere packaging machine so that the CO2 concentration ranges from 50% to 70%, and the O2 concentration ranges from 30% to 50%, and the polyester fiber plastic bag is sealed using a heat sealer; (6) LED irradiation and dynamic controlled atmosphere storage: The pepper packed in the controlled atmosphere of step (5) is stored by pulsed blue-violet LED irradiation; on the 21st to 40th day of storage, the polyester fiber plastic bag is replaced, and CO2 and O2 gases are filled into the bag using a controlled atmosphere packaging machine to make the CO2 concentration range of 30% to 50% and the O2 concentration range of 70% to 50%, and the polyester fiber plastic bag is sealed with a heat sealer, and then the LED irradiation storage is carried out; on the 40th to 60th day of storage, the polyester fiber plastic bag is replaced again, and CO2 and O2 gases are filled into the bag using a controlled atmosphere packaging machine to make the CO2 concentration range of 10% to 30% and the O2 concentration range of 90% to 70%, and the polyester fiber plastic bag is sealed with a heat sealer, and then the LED irradiation storage is carried out.

2. The method for suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: In step (2), in the preparation of the aqueous phase, chitosan is dissolved in water with a pH of 4 to 6, the concentration of chitosan is 1% to 3%, 1% to 2% of glycerol and 0.01% to 0.03% of ZnO are added and mixed; in the preparation of the oil phase, 8% to 15% of soybean oil and 0.1% to 0.3% of prickly ash essential oil are mixed, 75% to 85% of Tween 80 is added and heated to 40 to 60° C. to achieve complete emulsification; the mass ratio of chitosan-prickly ash essential oil-nano ZnO is 10:1:0.

1.

3. The method for suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: In step (2), the power of ultrasound is 200 to 500 W, and the time is 10 to 20 minutes.

4. The method for suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: Step (3) 500 g of dried prickly ash is mixed with 1.5 to 2 L of the composite emulsion, and a gradient film is formed under a pulse electric field of 20 to 30 kV / cm.

5. The method for suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: The temperature during the drying process in step (4) is 25 to 40° C. and the time is 7 to 10 hours.

6. The method for suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: During the polyester fiber plastic bag packaging process in step (5), the amount of pepper in each packaging bag is 200 to 500 g.

7. The method of suppressing the loss of flavor of pepper during storage by using an electric-membrane-gas coupling method according to claim 1, characterized in that: During the LED irradiation storage process in step (6), the LED is blue-violet light with a wavelength of 380 to 500 nm, a light intensity of 80 to 120 μmol·m-2·s-1, and a pulse frequency of 2 to 5 Hz; the temperature is 5±1°C, and the humidity is 85±5% RH.

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