Method for inhibiting quality degradation of pickles using ultrasonic treatment combined with calcium ascorbate sustained-release technique

Abstract

A method for inhibiting the quality degradation of pickles using an ultrasonic treatment combined with a calcium ascorbate sustained-release technique, which method comprises the following steps: blanching pretreated fresh vegetables, soaking same in calcium ascorbate and pectin methylesterase, performing an ultrasonic treatment, and performing a soaking and fermenting treatment using calcium ascorbate microcapsules. The above treatment method can inhibit the softening and blackening of pickles during storage, improve the crispness of pickles, and inhibit the browning of pickles, thereby improving the quality of pickles.

Description

A method for inhibiting kimchi quality deterioration by combining ultrasound with calcium ascorbate sustained-release technology Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology. Background Art

[0002] As a traditional Chinese fermented vegetable product, kimchi, thanks to its simple processing methods and low temperatures, retains most of the nutrients and texture of the vegetables. This makes kimchi rich in nutrients, with a sour and crisp taste and attractive color, a key reason for its popularity among consumers. Furthermore, with economic development and rising urbanization, consumers are becoming more aware of healthy eating and are increasingly choosing specialty green agricultural products. Besides consuming staple foods, they are also paying more attention to the intake of vegetable products containing essential trace elements, vitamins, and amino acids. Due to kimchi's excellent sensory qualities and high nutritional value, market demand will continue to grow, driving increased kimchi production, indicating a promising market prospect for the kimchi industry. However, prolonged processing or storage of kimchi can lead to quality degradation, seriously affecting its sensory quality and commercial value.

[0003] The main manifestations of kimchi quality deterioration during storage are softening and darkening. While kimchi softening is related to a variety of factors, it is primarily due to the gradual breakdown of protopectin, a key component of kimchi's fiber-binding properties, into soluble pectin by protopectinase, which in turn reduces its firmness. The darkening of kimchi during storage is caused by browning, a process that is similarly complex and includes both enzymatic and non-enzymatic browning. Enzymatic browning during kimchi storage is primarily caused by polyphenol oxidase and peroxidase, while non-enzymatic browning is primarily due to ascorbic acid degradation. To address these existing issues, pretreatment with calcium chloride or pectin methylesterase is currently the primary method to increase kimchi firmness before processing, thereby minimizing firmness loss. Current methods for inhibiting kimchi browning primarily rely on the addition of colorants and preservatives, such as citric acid and sodium metabisulfite. However, these methods fail to address the softening of kimchi's texture. Furthermore, the use of preservatives can compromise kimchi's quality and nutritional value. However, the current methods for improving the deterioration of kimchi quality still have the following shortcomings: (1) The pectin methylesterase remaining in the pectin methylesterase treatment operation before pickling will continue to decompose the original pectin during storage, resulting in a further decrease in the hardness of kimchi; (2) The calcium chloride generally added can only inhibit the decrease in kimchi hardness to a certain extent in the early stage of storage. As the storage time increases, the calcium ions are rapidly consumed and cannot be replenished, and cannot continuously provide a calcium source; (3) The current methods for inhibiting kimchi browning cannot solve the problem of kimchi texture softening. In addition, the use of preservatives will also damage the quality and nutritional value of kimchi; (4) Existing research mainly focuses on reducing kimchi softening. There are few solutions to kimchi browning during storage. There is no method to comprehensively solve the softening and browning problems that occur during kimchi storage. Therefore, for the product status and market prospects of the kimchi industry, if the deterioration phenomena such as softening and browning that occur during kimchi storage can be effectively reduced, the deterioration of kimchi sensory properties and the corresponding economic losses can be reduced to a large extent, and the rapid development of the kimchi industry can also be greatly promoted.

[0004] Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology.

[0006] The method of the present invention can effectively solve the shortcomings of existing methods for inhibiting the deterioration of kimchi quality, such as low effect, additives affecting the health properties of kimchi, inability to simultaneously inhibit the browning and softening of kimchi, and inability to exert the inhibitory effect for a long time.

[0007] The purpose of the present invention is achieved through the following solutions:

[0008] A method for inhibiting the quality deterioration of kimchi by combining ultrasound with calcium ascorbate sustained-release technology, comprising the following steps: subjecting pretreated fresh vegetables to blanching, soaking, ultrasound treatment, and pickling and fermentation treatment to obtain the kimchi; wherein the soaking treatment comprises soaking the blanched vegetables in a soaking solution containing calcium ascorbate and pectin methylesterase; and the pickling and fermentation treatment comprises fermenting the sonicated vegetables in a fermentation soaking solution containing calcium ascorbate microcapsules.

[0009] A method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology, specifically comprising the following steps:

[0010] (1) Pretreatment of raw materials: screening and washing fresh vegetables to obtain vegetables with complete shape and cleanliness;

[0011] (2) blanching: blanching the vegetables obtained in step (1), removing them, washing them, draining them and setting them aside;

[0012] (3) Soaking in calcium ascorbate and pectin methylesterase: The blanched vegetables obtained in step (2) are soaked in a soaking solution containing calcium ascorbate and pectin methylesterase, removed, washed, and drained for later use;

[0013] (4) Ultrasonic treatment: ultrasonically treat the soaked vegetables obtained in step (3), remove them, wash them, drain them and set them aside;

[0014] (5) Putting into the fermentation jar: Screening the ultrasonically treated vegetables obtained in step (4), and orderly placing the vegetables with intact morphology into a clean and sanitary fermentation jar for later use;

[0015] (6) Brewing and fermentation: Add the fermentation brewing liquid of calcium ascorbate microcapsules into the jar containing the vegetables to be fermented in step (5), seal it, and place it in a cool place for fermentation.

[0016] The fresh vegetables in step (1) include at least one of cowpea, radish, chili pepper, mustard greens, and ginger.

[0017] The temperature of the blanching treatment in step (2) is 40-60° C., and the treatment time is 10-30 minutes.

[0018] The mass of the calcium ascorbate in step (3) is 0.01% to 0.1% of the mass of the soaking liquid, and the mass of the pectin methylesterase is 0.05% to 0.2% of the mass of the soaking liquid.

[0019] The amount of the soaking liquid used in step (3) is based on the amount of the vegetables that have not been blanched.

[0020] The soaking treatment temperature in step (3) is 20-40° C., the treatment time is 30-60 min, and the pH value is 3-6.

[0021] The ultrasonic treatment in step (4) has an ultrasonic frequency of 28 to 80 kHz, an ultrasonic power of 300 to 600 W, an ultrasonic time of 10 to 30 min, and an ultrasonic temperature of 25 to 35° C.

[0022] The amount of the calcium ascorbate fermentation soaking liquid in step (6) satisfies the following requirement: the mass ratio of the ultrasonically treated vegetables to the calcium ascorbate fermentation soaking liquid is 1:1.2 to 1:2.

[0023] The fermentation environment temperature of step (6) is 20-30° C. and the fermentation time is 10-20 days.

[0024] The calcium ascorbate fermentation brewing liquid in step (6) is prepared by the following steps:

[0025] S1. The oil and emulsifier are thoroughly mixed to obtain an oil phase;

[0026] S2. Add water and calcium ascorbate to the oil phase, mix, and shear homogenize;

[0027] S3. The resulting calcium ascorbate emulsion was spray dried to obtain calcium ascorbate microcapsules;

[0028] S4. Adding calcium ascorbate microcapsules to the fermentation broth to obtain calcium ascorbate fermentation brewing broth.

[0029] The oil in step S1 includes at least one of palm oil, soybean oil, sunflower oil, corn oil, rapeseed oil, and peanut oil; and the emulsifier includes at least one of Tween 20, Tween 40, Tween 60, and Tween 80.

[0030] The amount of the emulsifier used in step S1 is 0.3% to 0.5% of the mass of the oil.

[0031] The amount of calcium ascorbate used in step S2 is 4% to 8% of the mass of water.

[0032] The thorough mixing in step S1 is mixing in a water bath at a temperature of 30° C. to 50° C.

[0033] The amount of the oil phase in step S2 satisfies the requirement that the mass proportion of the oil phase in the oil-water mixture is 5% to 15%.

[0034] The shear homogenization conditions in step S2 are a rotation speed of 10,000 to 14,000 rpm, a processing time of 4 to 8 minutes, and a processing temperature of 30 to 50°C.

[0035] The amount of calcium ascorbate microcapsules added in step S4 is 0.1% to 0.6% of the mass of the fermentation liquid.

[0036] Mechanism of the present invention:

[0037] The present invention utilizes endogenous and exogenous pectin methylesterase to degrade proto-pectin in vegetables, while calcium ascorbate provides calcium ions to form insoluble calcium pectinate, thereby increasing the hardness of kimchi. Calcium ascorbate has strong antioxidant properties, and the ascorbic acid therein can inhibit the oxidative degradation of ascorbic acid during kimchi storage, thereby inhibiting the occurrence of non-enzymatic browning. Furthermore, microcapsules prepared based on calcium ascorbate can be slowly released during kimchi storage, continuously replenishing calcium ions and ascorbic acid, and can continuously and effectively inhibit the softening and browning of kimchi during storage, thereby inhibiting the deterioration of kimchi quality over a long period of time. Furthermore, ultrasonic treatment has an inactivating effect on multiple enzymes and microorganisms in pre-pickled kimchi, effectively inhibiting phenomena such as softening of kimchi texture and darkening of color caused by microorganisms and enzymes, further inhibiting the deterioration of kimchi quality, and protecting the sensory quality and commercial value of kimchi.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) The present invention utilizes calcium ascorbate and its microcapsules in combination with pectin methylesterase and ultrasonic post-treatment to inhibit the softening and blackening of kimchi during storage, thereby increasing the crispness of the kimchi, inhibiting its browning, and improving its quality. Pectin methylesterase promotes the degradation of protopectin in kimchi into pectic acid. Pectic acid combines with calcium ions to form calcium pectate with a certain hardness. As the content of calcium pectate increases, the crispness and hardness of the kimchi also increase.

[0040] (2) The calcium ascorbate used in the present invention has a strong antioxidant function. Compared with other calcium salts that introduce calcium ions, calcium ascorbate not only provides the calcium ions necessary to maintain the crispness of kimchi, but also ascorbic acid. The strong antioxidant function of calcium ascorbate can protect the ascorbic acid in kimchi through its own reaction, thereby reducing the occurrence of browning reactions caused by the oxidative degradation of ascorbic acid. In summary, the combined treatment of calcium ascorbate and pectin methylesterase not only improves the crispness of kimchi but also inhibits the occurrence of kimchi browning.

[0041] (3) The calcium ascorbate microcapsules added to the pickling liquid will be slowly released during the storage process, which can continuously provide a calcium source for the pectin acid that may be produced during the pickling and storage process of kimchi, converting it into calcium pectinate that increases the hardness, and can provide a secondary protection effect for the crispness of kimchi; at the same time, the slowly released ascorbic acid can also continuously replenish the ascorbic acid consumed in the browning inhibition process, which can achieve a continuous and long-term browning inhibition effect.

[0042] (4) The ultrasonic treatment adopted by the present invention can inactivate enzymes such as pectin methylesterase, peroxidase and polyphenol oxidase while ensuring the quality of kimchi. The enzyme inactivation effect of ultrasonic treatment can effectively prevent the continued action of endogenous and exogenous pectin methylesterase during the pickle brewing and storage period, greatly reducing the secondary occurrence of kimchi softening caused by the degradation of original pectin. At the same time, the occurrence of enzymatic browning caused by peroxidase and polyphenol oxidase is also suppressed to a high degree. In addition, ultrasonic treatment can also inactivate microorganisms and other enzyme substances in kimchi before it is put into the jar for brewing, which can effectively avoid the occurrence of quality deterioration caused by microorganisms and enzyme substances brought into the kimchi during the brewing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a comparison chart of the browning index (BI) values ​​of Examples 4, 5, and 6 of the present invention and Comparative Examples 1, 2, and 3.

[0044] FIG2 is a comparison diagram of the physical images of Examples 4, 5, and 6 of the present invention and Comparative Examples 1, 2, and 3. DETAILED DESCRIPTION

[0045] The present invention will be described in further detail below with reference to the Examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. Where specific conditions are not specified in the Examples, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used, where the manufacturer is not specified, are commercially available conventional products.

[0046] Unless otherwise specified, all reagents used in the examples can be purchased from the market.

[0047] Example 1

[0048] A preparation method based on calcium ascorbate microcapsules, the steps are as follows:

[0049] (1) Preparation of oil phase: Weigh 10 g of soybean oil, add 0.3% Tween 20 by weight of soybean oil, heat in a water bath at 30°C and stir until the mixture is uniform, to prepare the oil phase, which is set aside;

[0050] (2) Preparation of aqueous phase: 4% by weight of calcium ascorbate was fully dissolved in deionized water at room temperature to prepare an aqueous phase for later use;

[0051] (3) Premixing the oil phase and the water phase: Add the prepared water phase dropwise to the oil phase for premixing, with the mass proportion of the oil phase in the oil-water mixture being 5%, and set aside;

[0052] (4) Homogenization: The premixed emulsion obtained in step (3) was homogenized using a high-speed shearing machine at 10,000 rpm in a 30°C water bath for 8 minutes, and then cooled to room temperature for later use;

[0053] (5) Spray drying: The homogenized emulsion obtained in step (4) is spray dried to obtain calcium ascorbate microcapsules.

[0054] The encapsulation efficiency of the calcium ascorbate microcapsules prepared in Example 1 was determined to be 48.1%.

[0055] Example 2

[0056] A preparation method based on calcium ascorbate microcapsules, the steps are as follows:

[0057] (1) Preparation of oil phase: Weigh 10 g corn oil, add 0.4% Tween 60 by weight of corn oil, heat in a water bath at 40°C and stir until the mixture is uniformly mixed to prepare the oil phase, which is set aside;

[0058] (2) Preparation of aqueous phase: 6% by weight of calcium ascorbate was fully dissolved in deionized water at room temperature to prepare an aqueous phase for later use;

[0059] (3) Premixing the oil phase and the water phase: Add the prepared water phase dropwise to the oil phase for premixing, with the mass proportion of the oil phase in the oil-water mixture being 10%, and set aside;

[0060] (4) Homogenization: The premixed emulsion obtained in step (3) was homogenized using a high-speed shearing machine at 12,000 rpm in a 40°C water bath for 6 minutes, and then cooled to room temperature for later use;

[0061] (5) Spray drying: The homogenized emulsion obtained in step (4) is spray dried to obtain calcium ascorbate microcapsules.

[0062] The encapsulation efficiency of the calcium ascorbate microcapsules prepared in Example 2 was determined to be 51.8%.

[0063] Example 3

[0064] A preparation method based on calcium ascorbate microcapsules, the steps are as follows:

[0065] (1) Preparation of oil phase: Weigh 10 g peanut oil, add 0.5% Tween 80 by weight of peanut oil, heat in a water bath at 50°C and stir until the mixture is uniformly mixed to prepare the oil phase, which is set aside;

[0066] (2) Preparation of aqueous phase: 8% by weight of calcium ascorbate was fully dissolved in deionized water at room temperature to prepare an aqueous phase for later use;

[0067] (3) Premixing the oil phase and the water phase: Add the prepared water phase dropwise to the oil phase for premixing, with the mass proportion of the oil phase in the oil-water mixture being 15%, and set aside;

[0068] (4) Homogenization: The premixed emulsion obtained in step (3) was homogenized using a high-speed shearing machine at 14,000 rpm in a 50° C. water bath for 4 min, and then cooled to room temperature for later use;

[0069] (5) Spray drying: The homogenized emulsion obtained in step (4) is spray dried to obtain calcium ascorbate microcapsules.

[0070] The encapsulation efficiency of the calcium ascorbate microcapsules prepared in Example 3 was determined to be 65.3%.

[0071] The calcium ascorbate microcapsules prepared in the above example are used in the production of pickles. The specific process is as follows:

[0072] Example 4

[0073] A method for inhibiting the quality deterioration of pickled chili peppers by combining ultrasound with calcium ascorbate sustained-release technology, comprising the following steps:

[0074] (1) Pretreatment of raw materials: 500 g of fresh chili peppers were screened and washed to obtain chili peppers with complete shape and cleanliness, and then set aside;

[0075] (2) low-temperature blanching treatment: The chili pepper obtained in step (1) was blanched at 40° C. for 30 min to activate the endogenous pectin methylesterase activity of the chili pepper, then removed, washed again with clean water, removed, drained, and set aside;

[0076] (3) Soaking in calcium ascorbate and pectin methylesterase: The chili peppers obtained in step (2) are placed in a soaking solution containing 0.01% calcium ascorbate and 0.05% pectin methylesterase and a pH of 3, with the amount of soaking solution being such that the chili peppers are not blanched; soaking in the soaking solution at 20° C. for 60 min, then removing, washing, draining, and setting aside;

[0077] (4) Ultrasonic treatment: The chili pepper obtained in step (3) was ultrasonically treated at a frequency of 28 kHz, a power of 300 W, and a temperature of 25° C. for 30 min, and then removed, washed, drained, and set aside;

[0078] (5) Preparation of fermentation broth of calcium ascorbate microcapsules: 0.1% by weight of the calcium ascorbate microcapsules obtained in Example 1 was added to the fermentation broth and set aside;

[0079] (6) Putting into a fermentation jar: Screening the chili peppers treated with ultrasound obtained in step (4), and orderly loading the chili peppers with intact morphology into a clean fermentation jar for later use;

[0080] (7) Brewing and fermentation: The calcium ascorbate microcapsule fermentation brewing liquid obtained in step (5) is added to the jar containing the vegetables to be fermented obtained in step (6) at a mass ratio of 1:1.2 of chili pepper to fermentation brewing liquid, and then sealed and placed in a fermentation environment at a temperature of 20° C. for 10 days.

[0081] The pickled chili peppers obtained in Example 4 were accelerated stored at 45° C. for 3 months, and then their texture characteristics and color difference values ​​were measured to evaluate their quality. As shown in Example 4 and Comparative Example 1 in Table 1 (the steps are the same as those in Example 4, but calcium ascorbate microcapsules and ultrasonic treatment are not added), the hardness, toughness and chewiness of the treated pickled chili peppers under the same environment are increased by approximately 41.2%, 49.0% and 61.0%, respectively; as shown in Table 2, the decrease in L* value and b* value of the treated pickled chili peppers under the same environment is inhibited by approximately 13.4% and 11.2%, respectively, and the increase in a* value and ΔE is inhibited by approximately 33.1% and 23.38%; as shown in Example 4 and Comparative Example 1 in Figure 1, the increase in BI value of the treated pickled chili peppers under the same environment is inhibited by approximately 15.06%; as shown in Example 4 and Comparative Example 1 in Figure 2, under the same environment, the treated pickled chili peppers have a brighter color and a higher sample support, while the sample in the comparative example is dark in color, the sample collapses, and the support is poor, which indicates that the technical means in the embodiments can effectively inhibit the quality deterioration of kimchi.

[0082] Example 5

[0083] A method for inhibiting the quality deterioration of soaked cowpeas by combining ultrasound with calcium ascorbate sustained-release technology, comprising the following steps:

[0084] (1) Pretreatment of raw materials: 500 g of fresh cowpeas were screened and cleaned to obtain clean cowpeas with complete shape and set aside;

[0085] (2) low-temperature blanching treatment: the cowpea obtained in step (1) was blanched at 50° C. for 20 min to activate the endogenous pectin methylesterase activity of the cowpea, then removed, washed again with clean water, removed, drained, and set aside;

[0086] (3) Soaking with calcium ascorbate and pectin methylesterase: The cowpeas obtained in step (2) were placed in a soaking solution containing 0.05% calcium ascorbate and 0.1% pectin methylesterase at a pH of 4.5, with the amount of soaking solution used being sufficient to cover the cowpeas after blanching; soaking was performed at 30° C. for 45 min, followed by removal, washing, draining, and setting aside;

[0087] (4) Ultrasonic treatment: The cowpea obtained in step (3) was ultrasonically treated at a frequency of 80 kHz, a power of 450 W, and a temperature of 30° C. for 20 min, and then removed, washed, drained, and set aside;

[0088] (5) Preparation of fermentation broth of calcium ascorbate microcapsules: 0.3% by weight of the calcium ascorbate microcapsules obtained in Example 2 was added to the fermentation broth and set aside;

[0089] (6) Putting into a fermentation jar: Screening the ultrasonically treated cowpeas obtained in step (4), and orderly placing the cowpeas with intact morphology into a clean and sanitary fermentation jar for later use;

[0090] (7) Brewing and fermentation: The fermentation brewing liquid of calcium ascorbate microcapsules obtained in step (5) is added to the jar containing the vegetables to be fermented obtained in step (6) at a mass ratio of cowpea to fermentation brewing liquid of 1:1.6, and then sealed and placed in a fermentation environment at a temperature of 25° C. for 15 days.

[0091] The soaked cowpeas obtained in Example 5 were subjected to accelerated storage at 45°C for 3 months, and their texture characteristics and color difference values ​​were then measured to evaluate their quality. As shown in Table 1 for Example 5 and Comparative Example 2 (the same steps as Example 5, except that calcium ascorbate microcapsules were not added), the hardness, toughness, and chewiness of the treated cowpeas under the same conditions were increased by approximately 43.5%, 45.9%, and 41.8%, respectively. As shown in Table 2, the decrease in the L* and b* values ​​of the treated cowpeas under the same conditions was suppressed by approximately 45.2% and 42.9%, respectively, and the increase in the a* and ΔE values ​​was suppressed by approximately 32.7% and 29. .03%; as shown in Example 5 and Comparative Example 2 in Figure 1, the increase in the BI value of the treated pickled cowpea under the same environment was inhibited by about 14.51%; as shown in Example 5 and Comparative Example 2 in Figure 2, under the same environment, the treated pickled cowpea had a brighter color and a higher sample support, while the sample in the comparative example had a darker color, collapsed samples, and poor support, which indicates that the sustained-release calcium ascorbate microcapsules have an effective effect on inhibiting the deterioration of kimchi quality.

[0092] Example 6

[0093] A method for inhibiting the quality deterioration of soaked cowpeas by combining ultrasound with calcium ascorbate sustained-release technology, comprising the following steps:

[0094] (1) Pretreatment of raw materials: 500 g of fresh cowpeas were screened and cleaned to obtain clean cowpeas with complete shape and set aside;

[0095] (2) low-temperature blanching treatment: the cowpea obtained in step (1) was blanched at 60° C. for 10 min to activate the endogenous pectin methylesterase activity of the cowpea, then removed, washed again with clean water, removed, drained, and set aside;

[0096] (3) Soaking with calcium ascorbate and pectin methylesterase: The cowpeas obtained in step (2) were placed in a soaking solution containing 0.1% calcium ascorbate and 0.2% pectin methylesterase at a pH of 6, with the amount of soaking solution used being sufficient to cover the cowpeas after blanching; soaking was performed at 40° C. for 30 min, followed by removal, washing, draining, and setting aside;

[0097] (4) Ultrasonic treatment: The cowpea obtained in step (3) was ultrasonically treated at a frequency of 80 kHz, a power of 600 W, and a temperature of 35° C. for 10 min, and then removed, washed, drained, and set aside;

[0098] (5) Preparation of fermentation broth of calcium ascorbate microcapsules: 0.6% by weight of the calcium ascorbate microcapsules obtained in Example 3 was added to the fermentation broth and set aside;

[0099] (6) Putting into a fermentation jar: Screening the ultrasonically treated cowpeas obtained in step (4), and orderly placing the cowpeas with intact morphology into a clean and sanitary fermentation jar for later use;

[0100] (7) Brewing and fermentation: The fermentation brewing liquid of calcium ascorbate microcapsules obtained in step (5) is added to the jar containing the vegetables to be fermented obtained in step (6) at a mass ratio of cowpea to fermentation brewing liquid of 1:2, and then sealed and placed in a fermentation environment at a temperature of 30° C. for 20 days.

[0101] The soaked cowpea obtained in Example 6 was accelerated stored at 45° C. for 3 months, and then its texture characteristics and color difference values ​​were measured to evaluate its quality. As shown in Example 6 and Comparative Example 3 in Table 1 (the steps are the same as those in Example 6, except that ultrasonic treatment is not performed), the hardness, toughness and chewiness of the treated cowpeas under the same environment are increased by approximately 21.8%, 34.9% and 37.9%, respectively; as shown in Table 2, the decrease in the L* value and b* value of the treated cowpeas under the same environment is inhibited by approximately 39.7% and 44.3%, respectively, and the increase in the a* value and ΔE is inhibited by approximately 34.3% and 19.9%; as shown in Example 6 and Comparative Example 3 in Figure 1, the increase in the BI value of the treated cowpeas under the same environment is inhibited by approximately 18.36%; as shown in Example 6 and Comparative Example 3 in Figure 2, under the same environment, the treated cowpeas have a brighter color and a higher sample support, while the samples in the comparative example are darker in color, collapsed, and have poor support, which indicates that ultrasonic treatment has the effect of inhibiting the deterioration of kimchi quality.

[0102] Table 1 Comparison of texture characteristics of Examples 4, 5, and 6 of the present invention and Comparative Examples 1, 2, and 3

[0103] Table 2 Comparison of color difference between Examples 4, 5, and 6 of the present invention and Comparative Examples 1, 2, and 3

[0104] The encapsulation efficiency of the calcium ascorbate microcapsules obtained in Examples 1 to 3, and the texture characteristics and color difference values ​​of the soaked cowpeas obtained in Examples 4 to 6 and Comparative Examples 1 to 3 were measured. The measurement method is as follows:

[0105] (1) Method for testing the encapsulation efficiency of calcium ascorbate microcapsules: 1 g of calcium ascorbate microcapsule powder was dissolved in 65% ethanol solution, and then treated with a probe ultrasonicator at 40% amplitude with an interval of 1 second for 30 minutes. The mixture was then centrifuged at 4°C and 10,000 rpm for 10 minutes. The supernatant was collected and the calcium content was determined by flame atomic spectroscopy. The encapsulation efficiency was calculated using formula (1):

[0106] (2) Method for determining the texture characteristics of kimchi: Take kimchi of 2 cm × 2 cm size for the determination of texture characteristics, and use a P2 / N probe to test the hardness, crispness and chewiness of the kimchi at a test speed of 1 mm / s.

[0107] (3) Method for measuring kimchi color: Take kimchi of 2 cm × 2 cm size and use a handheld colorimeter to measure the L* value, a* value and b* value of the kimchi. Before the measurement, the colorimeter needs to be calibrated with a white standard plate (L0* = 95.00, a0* = 0.06, b0* = 1.35). The ΔE value is calculated by formula (2), and the browning index BI value is calculated by formula (3). BI=(100×((a * +1.75×L * ) / (5.645×L * +a * -3.012×b * )-0.31)) / 0.172(3)

[0108] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology, characterized in that The following steps are involved: The pretreated fresh vegetables are blanched, soaked, ultrasonically treated and fermented to obtain the pickles; wherein the soaking treatment is to soak the blanched vegetables in a soaking solution containing calcium ascorbate and pectin methylesterase; and the soaking and fermentation treatment is to ferment the ultrasonically treated vegetables in a fermentation soaking solution containing calcium ascorbate microcapsules.

2. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The fresh vegetables include at least one of cowpea, radish, chili pepper, mustard greens and ginger.

3. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The blanching treatment temperature is 40-60° C., and the treatment time is 10-30 minutes.

4. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The mass of the calcium ascorbate is 0.01% to 0.1% of the mass of the soaking liquid; the mass of the pectin methylesterase is 0.05% to 0.2% of the mass of the soaking liquid; The amount of the soaking liquid used is based on the amount of vegetables that have not been blanched.

5. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The soaking treatment temperature is 20-40° C., the treatment time is 30-60 min, and the pH value is 3-6.

6. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The ultrasonic treatment has an ultrasonic frequency of 28 to 80 kHz, an ultrasonic power of 300 to 600 W, an ultrasonic time of 10 to 30 min, and an ultrasonic temperature of 25 to 35° C.

7. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The amount of the fermentation brewing liquid is such that the mass ratio of the ultrasonically treated vegetables to the fermentation brewing liquid is 1:1.2 to 1:

2.

8. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The ambient temperature of the brewing and fermentation treatment is 20-30° C. and the fermentation time is 10-20 days.

9. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 1, characterized in that: The fermented brewing liquid containing calcium ascorbate microcapsules is prepared by the following steps: S1. The oil and the emulsifier are fully mixed to obtain an oil phase; S2. Add water and calcium ascorbate to the oil phase, mix, and shear homogenize; S3. The obtained calcium ascorbate emulsion was spray dried to obtain calcium ascorbate microcapsules; S4. Adding calcium ascorbate microcapsules into the fermented brewing liquid to obtain calcium ascorbate fermented brewing liquid.

10. The method for inhibiting the deterioration of kimchi quality by combining ultrasound with calcium ascorbate sustained-release technology according to claim 9, characterized in that: The oil in step S1 includes at least one of palm oil, soybean oil, sunflower oil, corn oil, rapeseed oil and peanut oil; the emulsifier includes at least one of Tween 20, Tween 40, Tween 60 and Tween 80; The amount of the emulsifier in step S1 is 0.3% to 0.5% of the mass of the oil; The amount of calcium ascorbate in step S2 is 4% to 8% of the mass of water; The sufficient mixing in step S1 is mixing under water bath conditions, and the water bath temperature is 30° C. to 50° C.; The amount of the oil phase in step S2 satisfies: the mass proportion of the oil phase in the oil-water mixture is 5% to 15%; The shearing homogenization conditions in step S2 are a rotation speed of 10000-14000 rpm, a processing time of 4-8 min, and a processing temperature of 30-50° C.; The amount of calcium ascorbate microcapsules added in step S4 is 0.1% to 0.6% of the mass of the fermentation liquid.

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