A method for reducing the loss of flavor components of zanthoxylum during storage

Abstract

The application discloses a method for reducing the loss of flavor components of pepper during storage, and adopts high-voltage electrostatic field pretreatment on pepper, and then uses high static pressure combined with pectin-carboxymethyl cellulose sodium-vitamin C to coat the pepper pretreated by the high-voltage electrostatic field. The pepper is placed in a pectin-carboxymethyl cellulose sodium-vitamin C solution, treated by high static pressure, dried, and stored at room temperature. The application can effectively reduce the loss of flavor of the pepper during storage, and also reduces the loss of active substances of the pepper during storage, so that the original sensory quality and nutritional value are maintained to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for reducing the loss of flavor components of Zanthoxylum bungeanum during storage, in particular to a method for reducing the loss of flavor of Zanthoxylum bungeanum during storage by high static pressure, high voltage electrostatic field and coating film. BACKGROUND

[0002] Zanthoxylum bungeanum is a traditional economic crop of medicine and food. Zanthoxylum bungeanum is favored by consumers in China because of its unique flavor. Zanthoxylum bungeanum contains rich active substances such as flavonoids, polyphenols, and anthocyanins, and also has antioxidant, antibacterial, and anti-inflammatory effects. However, the flavor substances of Zanthoxylum bungeanum are easily oxidized during storage, resulting in loss of flavor substances. And with the passage of storage time, all active substances (polyphenols) and pungent substances hydroxy-α-sansho substances will gradually decompose, reducing the nutritional value of Zanthoxylum bungeanum. Therefore, effective storage techniques must be explored as much as possible to reduce the loss of flavor substances of Zanthoxylum bungeanum during storage.

[0003] Zhang Yan et al. (2020) disclosed a method for storing and preserving fresh Zanthoxylum bungeanum (publication number: CN CN202011282584.8), which blanched fresh Zanthoxylum bungeanum 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 in a cold storage at 2-4°C. The enzyme inactivation treatment of fresh Zanthoxylum bungeanum was carried out by high-temperature steam, and the enzyme inactivation and sterilization treatment of fresh Zanthoxylum bungeanum was carried out by high-temperature steam. The enzyme inactivation and sterilization treatment of fresh Zanthoxylum bungeanum by high-temperature steam can effectively prevent browning and ensure good color. After vacuum cooling and packaging, the problem of contamination of Zanthoxylum bungeanum by microorganisms and bacteria can be effectively avoided, and finally stored in a low-temperature cold storage. This method only has a certain effect on the spoilage of fresh Zanthoxylum bungeanum, and has a great destructive effect on the flavor of Zanthoxylum bungeanum.

[0004] Jiang et al. (2022) disclosed a method for improving the flavor characteristics and storage stability of pre-steaming processed mutton pies (publication number: CN 114847443 A). The method adds 0.05-0.5% natural plant extract to the processed mutton pie, which can effectively improve the fishy smell, rancid and irritating flavor of the mutton pie during storage, improve the sensory acceptability of the product, and significantly delay the oxidative damage of fat and protein in the mutton pie during cold storage, inhibit the growth of microorganisms, and prolong the shelf life of the product. This method can be used in the field of food processing, but it cannot be applied to the reduction of the flavor of some plant raw materials.

[0005] Liang L et al. (2021) disclosed a "storage and preservation method of shelled fresh hazelnut" (publication number: CN115553335 A). The method pre-cools the sorted shelled fresh hazelnut at 2±1℃ for 3-4 days, and finally packs, stores, and stacks at a temperature of -1-0℃ and a relative humidity of 80-85%. The storage and preservation method of the present invention can store shelled fresh hazelnut for more than 180 days, with good appearance of the shell, crisp and tender taste of the hazelnut, and basic aroma flavor. The appearance and eating quality are good; the shell and hazelnut have no water loss and shrinkage, and the water content has no significant change compared with that at harvest; the main nutritional substances of hazelnut, such as fat content, protein content, sugar content and Vc content, have no significant change compared with those at harvest. However, this method only temporarily delays the flavor substances of Sichuan pepper under low temperature conditions and does not protect them.

[0006] Zhang M et al. (2020) disclosed a "method for controlling characteristic flavor substances of sterilized vacuum-packed dried eggs" (publication number: CN112544908 A). The method uses 120℃ for sterilization for 30min, and then applies 20 silk RCP / PA composite packaging vacuum packaging bag for storage, which not only prolongs the shelf life of dried eggs during storage, but also effectively maintains the concentration of flavor substances of dried eggs during the shelf life. However, this method only reduces the loss of flavor of dried eggs from the perspective of microorganisms during storage. Sichuan pepper has strong bacteriostatic ability, so this patent is not suitable for reducing the loss of flavor of Sichuan pepper during storage. SUMMARY

[0007] The purpose of the present invention is to provide a method for reducing the loss of flavor components of Sichuan pepper raw materials during storage. The present invention first ionizes oxygen and kills microorganisms by high-voltage electrostatic field, and then applies high static pressure combined with pectin-sodium carboxymethyl cellulose-vitamin C to coat Sichuan pepper to remove oxygen in the film solution and isolate oxygen and improve antioxidant effect. This combined technology can improve the antioxidant effect of Sichuan pepper during storage, inhibit the growth of microorganisms, maintain the nutritional substances and sensory quality for a longer time, and reduce the loss of flavor substances.

[0008] Technical solutions of the present invention:

[0009] A method for reducing the loss of flavor components of Sichuan pepper raw materials during storage, the steps of which are:

[0010] (1) Sorting of Sichuan pepper: selecting intact, uniform in color and size, free of microbial infection, and dry Sichuan pepper;

[0011] (2) Preparation of pectin-sodium carboxymethyl cellulose-vitamin C solution: dissolving pectin, sodium carboxymethyl cellulose, vitamins and glycerol in water, and preparing a film solution mixed with pectin, sodium carboxymethyl cellulose and vitamin C after ultrasonic treatment;

[0012] (3) High-voltage electrostatic field pretreatment: the Zanthoxylum bungeanum selected in step (1) is placed on the upper and lower positions of the two polar plates of the high-voltage electrostatic field for pretreatment;

[0013] (4) Coating: the Zanthoxylum bungeanum treated in step (3) is immersed in the pectin-sodium carboxymethyl cellulose-vitamin C solution prepared in step (2);

[0014] (5) High static pressure treatment: the Zanthoxylum bungeanum and the pectin-sodium carboxymethyl cellulose-vitamin C solution in step (4) are subjected to high static pressure treatment in a high static pressure device;

[0015] (6) Drying: the Zanthoxylum bungeanum after coating in step (5) is removed from the solution and dried in an oven;

[0016] (7) Storage: the Zanthoxylum bungeanum obtained in step (6) is stored in a constant temperature and humidity incubator;

[0017] In step (2), the concentration of pectin is 1-2%, the concentration of sodium carboxymethyl cellulose is 0.5-1%, the concentration of vitamin is 0.01-0.04%, and the concentration of glycerol is 0.5-1%.

[0018] In step (2), the temperature during the preparation of the pectin-sodium carboxymethyl cellulose-vitamin C solution is 60-80°C.

[0019] In step (2), the vitamin C needs to be added after the solution is cooled to room temperature during the preparation of the pectin-sodium carboxymethyl cellulose-vitamin C solution.

[0020] In step (2), the power of the ultrasonic is 100-300W and the time is 20-40min during the preparation of the pectin-sodium carboxymethyl cellulose-vitamin C solution.

[0021] In step (3), the Zanthoxylum bungeanum is uniformly dispersed in the two polar plates, the distance between the two polar plates is 10-20cm, the voltage is 20-35kV, and the treatment time is 1-2h.

[0022] In step (4), during the coating process, 500-800g of Zanthoxylum bungeanum is mixed and immersed in 1-2L of the coating solution for 0.5-1.5h.

[0023] In step (5), the high static pressure treatment, the pressure is 600-800Mpa and the time is 10-30s.

[0024] In step (6), during the drying process, the temperature is not higher than 50°C and the time is 8-12h.

[0025] The application provides a method for reducing the flavor loss of Zanthoxylum bungeanum during storage, wherein the high-voltage electrostatic field removes the oxygen in Zanthoxylum bungeanum, thereby reducing the oxidation of flavor substances in Zanthoxylum bungeanum during storage. On the other hand, hydroxy-alpha-sanshool is the main pungent substance in Zanthoxylum bungeanum, and is prone to oxidation due to the action of oxygen during storage. Therefore, the high-voltage electrostatic field can reduce the oxidation of flavor substances in Zanthoxylum bungeanum during storage. Meanwhile, oxygen still exists in Zanthoxylum bungeanum after the electrostatic field pretreatment, and the electrostatic field pretreated Zanthoxylum bungeanum is coated with a pectin-sodium carboxymethyl cellulose-vitamin C solution, so that the flavor oxidation loss of Zanthoxylum bungeanum during storage is further prevented. In addition, the pectin-sodium carboxymethyl cellulose-vitamin C solution has strong ultraviolet blocking ability, so that the ultraviolet irradiation degradation ability of hydroxy-alpha-sanshool during storage is reduced. In addition, oxygen still exists in the film solution, and high static pressure can remove the oxygen in the film solution. The high-voltage electrostatic field, the pectin-sodium carboxymethyl cellulose-vitamin C coating and the high static pressure are used in combination to treat Zanthoxylum bungeanum, so that the flavor substances of Zanthoxylum bungeanum during storage are reduced, and the sensory quality and nutritional value of Zanthoxylum bungeanum during storage are improved.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] (1) The application uses high-voltage electrostatic field pretreatment, which is simple in operation and suitable for industrial application. The high-voltage electrostatic field can quickly remove the oxygen in Zanthoxylum bungeanum, produce some active substances, and protect the active substances of Zanthoxylum bungeanum during storage. Compared with other methods of adding chemical reagents, the physical field does not cause safety problems to food, and the high-voltage electrostatic field can also play a sterilization role and prevent microbial contamination of Zanthoxylum bungeanum during storage.

[0028] (2) Pectin, carboxymethyl cellulose sodium and vitamin C are abundant resources, and the pectin-sodium carboxymethyl cellulose-vitamin C film solution is used for coating Zanthoxylum bungeanum in the application, which is equivalent to giving Zanthoxylum bungeanum a natural film, limiting the entry of external gas, reducing the oxidation of flavor substances and active substances, and the pectin-sodium carboxymethyl cellulose-vitamin C film has strong ultraviolet blocking ability, thereby reducing the degradation of hydroxy-alpha-sanshool. The coating material is simple to obtain and low in price.

[0029] (3) High-voltage electrostatic field and pectin-sodium carboxymethyl cellulose-vitamin C solution coating film synergistic treatment, the use of high-voltage electrostatic field pretreatment before coating film, this process ensures the removal of internal oxygen and sterilization effect, after pretreatment, coating film can ensure further isolation from external oxygen and ultraviolet, not only amplifies the role of high-voltage electrostatic field pretreatment to remove internal oxygen, but also ensures the oxygen and ultraviolet blocking ability of the coating film after the subsequent storage of the pepper, further reducing the loss of flavor substances and pungent substances. The synergistic effect of the two treatments can maximize the nutritional value and antioxidant capacity of the pepper during storage, and reduce the degradation of flavor substances and pungent substances.

[0030] (4) High static pressure treatment can remove oxygen in the film solution, further ensuring that the film solution contains less oxygen, reducing the loss of flavor substances due to the presence of oxygen during the storage of the pepper. High static pressure also has low energy consumption, low cost, and no adverse effect on the appearance of the pepper.

[0031] (5) The present application uses high-voltage electrostatic field to pretreat the pepper, which has short treatment time, low energy consumption, and less effect on flavor substances and active substances. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1(A) is the effect of different treatment methods on the total polyphenol content of the pepper during storage;

[0033] Figure 1(B) is the effect of different treatment methods on the total flavonoid content of the pepper during storage;

[0034] Figure 2(A) is the effect of different treatment methods on the DPPH free radical scavenging rate of the pepper during storage;

[0035] Figure 2(B) is the effect of different treatment methods on the ABTS free radical scavenging rate of the pepper during storage;

[0036] Note: CK represents pepper without any treatment, CF, HVEFCF, HVEFHHP-CF and HVEFHHPCF represent coating film (comparative example 1), high-voltage electrostatic field coating film (comparative example 2), high-voltage electrostatic field / high static pressure / coating film (film solution does not contain vitamin C, comparative example 3) and high-voltage electrostatic field / high static pressure / coating film treatment (example 1) of the pepper. The column chart of each example sample from left to right represents the 0th, 15th, 30th, 40th, 60th day. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0038] Example 1

[0039] A method for reducing the loss of flavor components of Zanthoxylum bungeanum Maxim during storage, comprising the following steps:

[0040] (1) Selecting intact, uniform in color and size, non-microbial infection, dry Zanthoxylum bungeanum Maxim;

[0041] (2) Respectively, 1.5 g of pectin and 1 g of carboxymethyl sodium cellulose are dissolved in 100 mL of water, stirred on a magnetic stirrer at 60°C and 800 rpm for 2 h to dissolve, after cooling, 1% glycerol and 0.02 g of vitamin C are added to the above system, continue to stir for 0.7 h, and ultrasonic (100 W) treatment for 20 min to obtain a film solution containing pectin, carboxymethyl sodium cellulose and vitamin C;

[0042] (3) The Zanthoxylum bungeanum Maxim selected in step (1) is placed on the upper and lower positions of the high-voltage electrostatic field two-pole plate (the distance between the two-pole plate is 15 cm) for pretreatment at 30 kV voltage for 1 h;

[0043] (4) 500 g of Zanthoxylum bungeanum Maxim treated in step (3) is placed in a 40 cm x 60 cm rectangular plastic solvent and soaked in 1 L of pectin-carboxymethyl sodium cellulose-vitamin C solution for 1 h;

[0044] (5) The film solution and Zanthoxylum bungeanum Maxim are placed in a high static pressure device, the pressure is 600 Mpa, and the treatment is 10 s, and the excess film solution is removed after the treatment is completed;

[0045] (6) The Zanthoxylum bungeanum Maxim treated by high static pressure in step (5) is taken out from the film solution and evenly dispersed in an oven for drying, the temperature is 40°C, and the time is 8 h;

[0046] (7) The Zanthoxylum bungeanum Maxim sample dried in step (6) is stored in a constant temperature and humidity incubator, the storage temperature is 25°C, and the sample is taken every 15 days for determination;

[0047] Example 2

[0048] (1) Selecting intact, uniform in color and size, non-microbial infection, dry Zanthoxylum bungeanum Maxim;

[0049] (2) Respectively, 1 g of pectin and 0.5 g of carboxymethyl sodium cellulose are dissolved in 100 mL of water, stirred on a magnetic stirrer at 70°C and 800 rpm for 2 h to dissolve, cooled to room temperature, 0.5% glycerol and 0.02 g of vitamin C are added to the above system, continue to stir for 0.7 h, and ultrasonic (150 W) treatment for 25 min to obtain a film solution containing pectin, carboxymethyl sodium cellulose and vitamin C

[0050] (3) The Zanthoxylum bungeanum selected in step (1) is placed on the upper and lower positions of the high-voltage electrostatic field electrode plate (the distance between the electrode plates is 10 cm) for pretreatment at 30 kV voltage for 1 h;

[0051] (4) 500 g of the Zanthoxylum bungeanum treated in step (3) is placed in a 40 cm x 60 cm cuboid plastic solvent and soaked in 1.2 L of a pectin-sodium carboxymethyl cellulose-vitamin C solution for 0.8 h.

[0052] (5) The film solution and the Zanthoxylum bungeanum are placed in a high static pressure device, the pressure is 700 Mpa, and the treatment is performed for 20 s, and after the treatment is completed, the excess film solution is removed;

[0053] (6) The Zanthoxylum bungeanum treated by high static pressure in step (5) is taken out from the film solution and placed in an oven for uniform dispersion and drying, the temperature is 40℃, and the time is 9 h;

[0054] (7) The Zanthoxylum bungeanum sample dried in step (6) is stored in a constant temperature and humidity incubator, the storage temperature is 28℃, and the sample is taken out for determination at intervals of 15 days;

[0055] Example 3

[0056] (1) Select intact, uniform in color and size, free of microbial infection, and dry Zanthoxylum bungeanum;

[0057] (2) 1.5 g of pectin and 1 g of sodium carboxymethyl cellulose are respectively dissolved in 100 mL of water, dissolved on a magnetic stirrer at 80℃ and 800 rpm for 2 h, after cooling, 0.7% glycerol and 0.02 g of vitamin C are added to the above system, continue to stir for 0.7 h, and ultrasonic (200 W) treatment for 30 min to obtain a film solution containing pectin, sodium carboxymethyl cellulose and vitamin C

[0058] (3) The Zanthoxylum bungeanum selected in step (1) is placed on the upper and lower positions of the high-voltage electrostatic field electrode plate (the distance between the electrode plates is 20 cm) for pretreatment at 30 kV voltage for 1 h;

[0059] (4) 500 g of the Zanthoxylum bungeanum treated in step (3) is placed in a 40 cm x 60 cm cuboid plastic solvent and soaked in 1.2 L of a pectin-sodium carboxymethyl cellulose-vitamin C solution for 0.8 h.

[0060] (5) The film solution and the Zanthoxylum bungeanum are placed in a high static pressure device, the pressure is 700 Mpa, and the treatment is performed for 20 s, and after the treatment is completed, the excess film solution is removed;

[0061] (6) The Zanthoxylum bungeanum treated by high static pressure in step (5) is taken out from the film solution and placed in an oven for uniform dispersion and drying, the temperature is 40℃, and the time is 9 h;

[0062] (7) The Zanthoxylum bungeanum Mille after drying in step (6) is stored in a constant temperature and humidity incubator, the storage temperature is 22°C, and the sample is taken every 15 days for determination;

[0063] Comparative Example 1

[0064] (1) Select intact, uniform in color and size, no microbial infection, dry Zanthoxylum bungeanum Mille;

[0065] (2) 1.5 g of pectin and 1 g of carboxymethyl sodium cellulose are respectively dissolved in 100 mL of water, stirred on a magnetic stirrer at 60°C and 800 rpm for 2 h for dissolution, after cooling, 1% glycerol and 0.02 g of vitamin C of the above system are added, and stirring is continued for 0.7 h, and ultrasonic (100 W) treatment is performed for 20 min to obtain a film solution containing pectin, carboxymethyl sodium cellulose and vitamin C;

[0066] (3) 500 g of Zanthoxylum bungeanum Mille is placed in a 40 cm x 60 cm rectangular plastic solvent and soaked in 1 L of pectin-carboxymethyl sodium cellulose-vitamin C solution for 1 h;

[0067] (4) The Zanthoxylum bungeanum Mille after treatment in step (3) is taken out of the film solution and evenly dispersed in an oven for drying, the temperature is 40°C, and the time is 8 h;

[0068] (5) The Zanthoxylum bungeanum Mille sample after drying in step (4) is stored in a constant temperature and humidity incubator, the storage temperature is 25°C, and the sample is taken every 15 days for determination;

[0069] Comparative Example 2

[0070] (1) Select intact, uniform in color and size, no microbial infection, dry Zanthoxylum bungeanum Mille;

[0071] (2) 1.5 g of pectin and 1 g of carboxymethyl sodium cellulose are respectively dissolved in 100 mL of water, stirred on a magnetic stirrer at 60°C and 800 rpm for 2 h for dissolution, after cooling, 1% glycerol and 0.02 g of vitamin C of the above system are added, and stirring is continued for 0.7 h, and ultrasonic (100 W) treatment is performed for 20 min to obtain a film solution containing pectin, carboxymethyl sodium cellulose and vitamin C;

[0072] (3) The Zanthoxylum bungeanum Mille selected in step (1) is placed in the upper and lower positions of the two electrode plates of the high-voltage electrostatic field (the distance between the two electrode plates is 15 cm) for pretreatment at a voltage of 30 kV for 1 h;

[0073] (4) 500 g of Zanthoxylum bungeanum Mille after treatment in step (3) is placed in a 40 cm x 60 cm rectangular plastic solvent and soaked in 1 L of pectin-carboxymethyl sodium cellulose-vitamin C solution for 1 h;

[0074] (5) The Zanthoxylum bungeanum Mille after step (4) is taken out from the film solution and evenly dispersed in an oven for drying, with a temperature of 40°C and a time of 8h;

[0075] (7) The Zanthoxylum bungeanum Mille after step (6) is stored in a constant temperature and humidity incubator, with a storage temperature of 25°C, and samples are taken for determination at intervals of 15 days;

[0076] Comparative Example 3

[0077] (1) Select intact, uniform in color and size, free of microbial infection, dry Zanthoxylum bungeanum Mille;

[0078] (2) 1.5g of pectin and 1g of carboxymethyl cellulose sodium are respectively weighed and dissolved in 100mL of water, stirred on a magnetic stirrer at 60°C and 800rpm for 2h to dissolve, after cooling, 1% glycerol of the above system is added, and stirring is continued for 0.7h, and ultrasonic (100W) treatment is performed for 20min to obtain a film solution containing pectin and carboxymethyl cellulose sodium;

[0079] (3) The Zanthoxylum bungeanum Mille selected in step (1) is placed on the upper and lower positions of the high-voltage electrostatic field electrode plate (the distance between the electrode plates is 15cm) for pretreatment at a voltage of 30kV for 1h;

[0080] (4) 500g of the Zanthoxylum bungeanum Mille after step (3) is placed in a 40cm x 60cm rectangular plastic solvent and soaked in 1L of pectin-carboxymethyl cellulose sodium solution for 1h;

[0081] (5) The film solution and the Zanthoxylum bungeanum Mille are placed in a high static pressure device, with a pressure of 600Mpa and a treatment time of 10s, and after treatment, the excess film solution is removed;

[0082] (6) The Zanthoxylum bungeanum Mille after step (5) is taken out from the film solution and evenly dispersed in an oven for drying, with a temperature of 40°C and a time of 8h;

[0083] (7) The Zanthoxylum bungeanum Mille after step (6) is stored in a constant temperature and humidity incubator, with a storage temperature of 25°C, and samples are taken for determination at intervals of 15 days;

[0084] The effects of different treatment methods on the quality of Zanthoxylum bungeanum during storage were compared by indicators, and the control of each sample test was performed, as shown in the accompanying drawings. Tables 1 and 2 show the effects of different treatment methods on the flavor substances and pungent substances of Zanthoxylum bungeanum during storage. Unlike the examples, the control example 1 was only treated by coating, the control example 2 was treated by high-voltage electrostatic field combined with coating, and the control example 3 was treated by high-voltage electrostatic field combined with high-pressure static and coating (without vitamin C). The examples 1-3 were treated by high-voltage electrostatic field, high-pressure static and coating. The final storage indicators were tested and compared as follows:

[0085] Experimental method:

[0086] 1. Determination of total flavonoid and total polyphenol content

[0087] Zanthoxylum bungeanum powder (1 g) was mixed with 20 mL of ethanol (70%, v / v) and ultrasonically extracted for 1 h, and then centrifuged at 8000 rpm for 10 min at 25°C to obtain the supernatant.

[0088] Determination of total polyphenol content: The supernatant (1 mL) was mixed with 1 mL of Folin-ciocalteu reagent (1 M) solution, 5 min later, 5 mL of NaCO3 (1 M) solution was added, and the volume was fixed to 10 mL with ethanol solution (70%, v / v), and the reaction was carried out at room temperature for 30 min. The absorbance value was measured at 760 nm by ultraviolet spectrophotometer. The total phenol content concentration was calculated by using the standard curve equation with gallic acid as the equivalent (mg GAE / g).

[0089] Determination of total flavonoid content: The supernatant (1 mL) was mixed with 1 mL of Folin-ciocalteu reagent (1 M) solution, 5 min later, 5 mL of NaCO3 (1 M) solution was added, and the volume was fixed to 10 mL with ethanol solution (70%, v / v), and the reaction was carried out at room temperature for 30 min. The absorbance value was measured at 760 nm by ultraviolet spectrophotometer. The total phenol content concentration was calculated by using the standard curve equation with gallic acid as the equivalent (mg GAE / g). The supernatant (1 mL) was fixed to 12.5 mL with 70% ethanol (v / v), reacted with 1 mL of NaNO2 (5%, m / v) for 5 min. 1 mL of Al(NO3)3.6H2O solution (10%, m / v) was added to the mixed solution and reacted for 6 min. 5 mL of NaOH solution (1 M) was added, and the volume was fixed to 25 mL with 70% ethanol solution (v / v), and the reaction was carried out at room temperature for 10 min. The absorbance was measured at 510 nm by ultraviolet spectrophotometer. The total phenol content concentration was calculated by using the standard curve equation with gallic acid as the equivalent (mg RE / g).

[0090] 2. Determination of antioxidant capacity

[0091] Zanthoxylum bungeanum powder (1 g) was mixed with 20 mL of ethanol (70%, v / v) and extracted thoroughly under ultrasonication (500 W) for 1 h. The mixture was centrifuged at 8000 rpm for 10 min at 25 °C to obtain the supernatant.

[0092] (1) Determination of DPPH radical scavenging capacity

[0093] The supernatant 200 μL was mixed with 2 mL of DPPH (0.25 mM) and reacted for 30 min in the dark. The absorbance at 517 nm was measured using a UV spectrophotometer. The DPPH radical scavenging rate of Zanthoxylum bungeanum during storage was calculated as follows:

[0094] Radical scavenging rate = 100% x (A0- (A-A x )) / A0 (1)

[0095] where A0: absorbance of DPPH solution, A: absorbance of sample after reaction with DPPH, and A x : absorbance of sample.

[0096] (2) Determination of ABTS radical scavenging capacity

[0097] The supernatant 500 μL was mixed with 2 mL of ABTS ·+ for 6 min, and the absorbance at 734 nm was measured using a UV spectrophotometer. The ABTS radical scavenging rate of Zanthoxylum bungeanum during storage was calculated according to the above formula (1).

[0098] 3. Determination of hydroxy-α-sanshool

[0099] Zanthoxylum bungeanum powder (1 g) was thoroughly extracted with ethanol (20 mL) under ultrasonication (500 W, 1 h) to extract hydroxy-α-sanshool. After extraction, the mixture was centrifuged at 8000 rpm for 15 min to obtain the supernatant. The supernatant was filtered using an organic filter membrane (0.22 μm). The change in OH-α-sanshool of Zanthoxylum bungeanum during storage was determined using a high-performance liquid chromatography system (Thermo Fisher Scientific, Santa Clara, CA, USA). A Thermo Fisher C 18 chromatographic column (4.6 mm x 75 mm, 5 μm) was used to separate OH-α-sanshool at a temperature of 30 °C. The mobile phase was ultrapure water (A) and methanol (B) at a flow rate of 0.8 mL / min. The injection volume was 20 μL, the UV absorption wavelength was 270 nm, and the column temperature was 40 °C. The elution gradient was as follows: 0-15 min, 50-70% B, 15-25 min, 70% B, 25-26 min, 70-50% B.

[0100] 4. Determination of flavor substances

[0101] The changes of flavor substances in Zanthoxylum bungeanum during storage were determined by headspace-gas chromatography-mass spectrometry (Agilent 8890-5977B, Agilent Technologies, Santa Clara, USA). 1 gram of Zanthoxylum bungeanum powder was placed in a 10-milliliter headspace bottle. The HP-5MS fused silica capillary column (30 mm x 0.25 mm, 0.25 μm) was used with helium as the carrier gas at a flow rate of 1 mL / min, and the extraction time was 5 min. The temperature ramp was described as follows: the initial temperature was 50 °C, increased to 70 °C at 2 °C / min, and then increased to 120 °C at 5 °C / min. Finally, it was increased to 250 °C at 10 °C / min and maintained for 3 min.

[0102] (1) The effects of different treatments on the active substances (total polyphenol and total flavonoid content) of Zanthoxylum bungeanum during storage are shown in Figure 1 (A) and Figure 1 (B):

[0103] (2) The effects of different treatments on the antioxidant activity of Zanthoxylum bungeanum during storage are shown in Figure 2 (A) and Figure 2 (B):

[0104] (3) The effects of different treatments on the pungent substances of Zanthoxylum bungeanum during storage are shown in Table 1:

[0105] Table 1: Effects of different treatments on the hydroxy-α-sanshool of Zanthoxylum bungeanum during storage

[0106]

[0107] (4) The effects of different treatments on the flavor substances of Zanthoxylum bungeanum during storage are shown in Table 2:

[0108] Table 2: Effects of different treatments on the flavor substances of Zanthoxylum bungeanum during storage

[0109]

[0110]

[0111] Note: CK60 represents the flavor substances of the 60th day without any treatment, CF60, HVEFCF60, HVEFHHP-CF60, HVEFHHPCF60 represent the 60th day of storage with coating, high-voltage electrostatic field coating, high-voltage electrostatic field / high static pressure / coating (without vitamin C), and high-voltage electrostatic field / high static pressure / coating, respectively.

[0112] As can be seen from the content of the accompanying drawings, the four treatments can reduce the loss of flavor substances of Zanthoxylum bungeanum during storage. Compared with the coating alone, the high-voltage electrostatic field combined with coating treatment effectively reduces the loss of active substances of Zanthoxylum bungeanum during storage, such as the loss of total polyphenol content and total flavonoid content is significantly reduced, and the antioxidant activity of Zanthoxylum bungeanum during storage can be preserved; this may be that the high-voltage electrostatic field can remove the oxygen inside Zanthoxylum bungeanum and the coating prevents the oxidation of active substances by isolating oxygen. This point can also be concluded from the HVEFHHP-CF treatment. When vitamin C is not added to the film solution, the active substances inside Zanthoxylum bungeanum during storage are oxidized due to the lack of antioxidant effect of the film. At the same time, the addition of high static pressure more effectively reduces the loss of flavor of Zanthoxylum bungeanum during storage, because high static pressure treatment can further reduce the oxygen in the film solution, thereby reducing the loss of flavor of Zanthoxylum bungeanum during storage. In addition, as can be seen from the content of Table 1 and Table 2, high-voltage electrostatic field / high static pressure / coating treatment is also more effective in reducing the change of flavor substances of Zanthoxylum bungeanum during storage; hydroxy-α-sanshool is easily oxidized and decomposed by light and oxygen, however, the high-voltage electrostatic field can remove the oxygen inside Zanthoxylum bungeanum, the high static pressure can reduce the oxygen inside the coating solution, and the coating treatment can prevent the oxygen from isolating; on the other hand, the coating can effectively prevent the irradiation of ultraviolet light, thereby further reducing the degradation of the pungent substance hydroxy-α-sanshool of Zanthoxylum bungeanum. Therefore, the high-voltage electrostatic field, high static pressure and coating technology synergistic treatment can maximize the ability to improve the nutritional value and antioxidant capacity of Zanthoxylum bungeanum during storage, and reduce the degradation of flavor substances and pungent substances.

Claims

1. A method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage, characterized in that, It comprises the following steps: (1) The sorting of Zanthoxylum bungeanum: selecting intact, uniform color and size, no microbial infection, dry Zanthoxylum bungeanum; (2) The preparation of pectin-sodium carboxymethyl cellulose-vitamin C film solution: dissolving pectin, sodium carboxymethyl cellulose, vitamin C and glycerol in water, and then preparing the film solution mixed with pectin, sodium carboxymethyl cellulose and vitamin C after ultrasonic treatment; (3) High-voltage electrostatic field pretreatment: placing the Zanthoxylum bungeanum sorted in step (1) on the upper and lower positions of the two electrode plates of the high-voltage electrostatic field for pretreatment; (4) Film coating: placing the Zanthoxylum bungeanum pretreated in step (3) in the film solution prepared in step (2) for soaking; (5) High static pressure treatment: placing the Zanthoxylum bungeanum and the film solution in step (4) in a high static pressure device for high static pressure treatment; (6) Drying: taking out the Zanthoxylum bungeanum after high static pressure treatment in step (5) from the film solution and drying it in an oven; (7) Storage: storing the Zanthoxylum bungeanum dried in step (6) in a constant temperature and humidity incubator; In step (2), the mass concentration of pectin in the film solution is 1-2%, the mass concentration of sodium carboxymethyl cellulose is 0.5-1%, the mass concentration of vitamin C is 0.01-0.04%, and the mass concentration of glycerol is 0.5-1%; In step (3), the Zanthoxylum bungeanum is uniformly dispersed in the two electrode plates, and the distance between the two electrode plates is 10-20 cm; In step (3), the pretreatment parameters of the high-voltage electrostatic field are: voltage 20-35 kV, and treatment time 1-2 h; In step (5), the pressure of the high static pressure is 600-800 MPa, and the time is 10-30 s.

2. The method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage according to claim 1, characterized in that, In step (2), during the preparation of the film solution, the temperature of pectin and sodium carboxymethyl cellulose is 60-80 ℃ when they are added and mixed.

3. The method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage according to claim 1, characterized in that, In step (2), during the preparation of the film solution, vitamin C and glycerol need to be added after the solution is cooled to room temperature.

4. The method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage according to claim 1, characterized in that, In step (2), during the preparation of the film solution, the power of ultrasonic is 100-300 W, and the time is 20-40 min.

5. The method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage according to claim 1, characterized in that, In step (4), the mixing ratio of Zanthoxylum bungeanum and film solution is: 500-800 g of Zanthoxylum bungeanum is mixed with 1-2 L of film solution for 0.5-1.5 h.

6. The method of reducing the loss of flavor components of Zanthoxylum bungeanum during storage according to claim 1, characterized in that, In step (6), the temperature is not higher than 50 ℃, and the time is 8-12 h; in step (7), the storage temperature is 25 ± 4 ℃.

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