Method for rapidly unfreezing pomegranate seeds through intermittent microwaves

Abstract

The invention discloses a method for rapidly unfreezing pomegranate seeds through intermittent microwaves. The method comprises the following steps: S1, taking a sample from frozen pomegranate seeds to be unfrozen, and determining the water content H% of the frozen pomegranate seeds; s2, uniformly mixing the remaining frozen pomegranate seeds in the S1 with food-grade glass beads or ceramic beads according to a mass ratio of 1: (2-4), and spreading the mixture; s3, setting the ratio of the microwave output time t1 to the intermittent time t2 to be 1: (1-6), and carrying out microwave thawing on the mixture; and S4, screening and separating out the pomegranate seeds in the unfrozen mixture. Wherein the total microwave output time T in the microwave thawing process in the step S3 meets T = AM / P, A is determined according to the water content H and the size of the pomegranate seeds, and the value range is 100-250; the microwave output time t1 is 10 to 40 seconds, and the microwave output power density is 0.75 to 1.50 W / g. Microwave output parameters can be determined according to the water content and the size of the pomegranate seeds, and accurate unfreezing is achieved; the heating is more uniform, local overheating is avoided, the unfreezing time is shortened, the nutrition loss is reduced, and the unfreezing quality of the pomegranate seeds is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of food thawing, and more specifically, to a method for intermittent microwave rapid thawing of pomegranate seeds. Background Art

[0002] In the field of food processing, thawing of frozen ingredients is an extremely critical link. Pomegranate seeds are rich in vitamin C, polyphenol compounds and other nutrients, and are widely used in juice, jam, baked food ingredients, etc.; the traditional method of thawing pomegranate seeds has many disadvantages. Take natural thawing as an example, it is to place the frozen pomegranate seeds at room temperature and let them absorb heat naturally to thaw. Although natural thawing is simple to operate, it takes a long time, often taking several hours or even longer; during the long thawing process, microorganisms in the external environment are very easy to attach and multiply in large numbers, which greatly reduces the quality of pomegranate seeds and destroys the nutrients to a certain extent. The principle of water bath thawing is to use water as a heat transfer medium to transfer heat to frozen pomegranate seeds. Compared with natural thawing, the speed of water bath thawing is improved, but during thawing, the pomegranate seeds will be in direct contact with water, which causes a large amount of nutrients to dissolve in the water, causing serious nutrient loss, greatly reducing the edible value and processing value of pomegranate seeds.

[0003] With the development of technology, microwave thawing technology has gradually attracted attention due to its high efficiency and rapidity. Microwave thawing technology is widely used in ingredients such as meat. Microwave thawing of pomegranate seeds and meat both face some problems, and there are obvious differences between the two.

[0004] Regarding microwave thawing of meat, the invention patent with application number 202010897237.X discloses a method for ultrasonic-assisted microwave thawing of food. It points out that when meat is thawed by microwave, for larger pieces of meat, the edges and surrounding areas heat up faster, while the middle part heats up slowly, making it difficult to thaw and thawing unevenly. Water’s ability to absorb microwaves is much higher than ice. In the later stages of thawing, after the ice in some areas melts into water, the absorption capacity of these thawed areas for microwaves is instantly enhanced, which can easily lead to local overheating or even ripening, while the core area is still not thawed. The problem of uneven heating during microwave thawing also exists in the thawing process of pomegranate seeds, and is more complicated due to the characteristics of the pomegranate seeds themselves.

[0005] Pomegranate seeds are relatively small and irregular in shape, which makes their heating in the microwave field more complicated. Unlike meat, which can be regarded as a relatively uniform block to a certain extent, pomegranate seeds are numerous and have gaps between them. Microwaves will undergo complex reflection and refraction during the penetration process, making it more difficult to heat evenly. At the same time, the water content, sugar content and other components of pomegranate seeds are quite different from those of meat, and these components have different microwave absorption and conversion efficiencies. The water content of pomegranate seeds is not as relatively stable as meat. The water content of pomegranate seeds from different batches and different origins fluctuates greatly, which makes it more difficult to determine the microwave output time and power.

[0006] There are also differences in the adjustment of microwave output time and power when thawing meat and pomegranate seeds. When thawing meat, the main consideration is to avoid local overheating and ensure that the core area is thawed; when thawing pomegranate seeds, in addition to preventing local overheating, it is also necessary to avoid the destruction of the cell structure of the pomegranate seeds due to improper power and time, which affects its taste and the retention of nutrients. At the same time, due to the small size of pomegranate seeds, they are more sensitive to slight changes in microwave output time and power. Even slight adjustment errors may have a significant impact on the thawing effect. For example, if the microwave output time is too long or the power is too high, the surface of the pomegranate seeds may heat up rapidly, resulting in excessive evaporation of water and a poor taste; if the time is too short or the power is too low, the purpose of complete thawing cannot be achieved.

[0007] When using microwaves to defrost pomegranate seeds, there is a close mutual restriction between the microwave output time and the microwave output power. When the microwave output power is too high, the pomegranate seeds absorb a large amount of microwave energy in a short period of time, and the temperature rises rapidly, which is very likely to cause local overheating. Once the local overheating occurs, the nutrients in the pomegranate seeds, such as heat-sensitive vitamin C and some antioxidants, will be severely damaged, which greatly reduces the nutritional value of the pomegranate seeds. Moreover, too high a temperature may also change the taste and texture of the pomegranate seeds, affecting their application effect in subsequent food processing. On the contrary, if the microwave output power is too low, although it can effectively avoid the problem of local overheating, in order to achieve the purpose of thawing, the microwave output time has to be extended. However, too long a microwave output time will not only reduce production efficiency and increase production costs, but also may cause uneven overall temperature distribution of the pomegranate seeds due to long-term energy input, which also affects its quality.

[0008] More importantly, it is difficult to accurately determine the microwave output time and microwave output power. This is because their determination requires comprehensive consideration of multiple complex factors. First, the weight of frozen pomegranate seeds is an important parameter. Pomegranate seeds of different weights need to absorb different amounts of heat, which directly affects the setting of microwave output time and power. Secondly, the initial water content of pomegranate seeds varies greatly. The energy absorption characteristics of pomegranate seeds with high water content and pomegranate seeds with low water content are completely different during microwave thawing. Pomegranate seeds with high water content are more likely to be heated and evaporated under the action of microwaves, and more precise power and time control is required to prevent excessive water loss and local overheating; while pomegranate seeds with low water content need to adjust microwave parameters appropriately to ensure that they can be heated evenly to achieve the thawing effect. In addition, the size of pomegranate seeds cannot be ignored. The heating conditions of large-sized pomegranate seeds and small-sized pomegranate seeds in the microwave field are different. Small-sized pomegranate seeds are heated relatively evenly, and the required microwave energy and time are relatively less; while large-sized pomegranate seeds may have the problem of insufficient internal heating, and the microwave output parameters need to be optimized according to their size characteristics. At present, the industry lacks an accurate and effective method that can comprehensively consider these factors and accurately determine the microwave output time and power. This technical bottleneck greatly limits the widespread application of intermittent microwave thawing pomegranate seed technology in actual production. Therefore, developing a method for intermittent microwave rapid thawing of pomegranate seeds that can reasonably adjust the microwave output time and power has become an important issue that needs to be solved in the current food processing field. Summary of the invention

[0009] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0010] Another object of the present invention is to provide a method for intermittent microwave rapid thawing of pomegranate seeds, which can determine microwave output parameters according to the water content and size of the pomegranate seeds to achieve precise thawing; the heating is more uniform, local overheating is avoided, the thawing time is shortened, the nutrient loss is reduced, and the thawing quality of the pomegranate seeds is effectively improved.

[0011] In order to achieve these purposes and other advantages according to the present invention, a method for intermittent microwave rapid thawing of pomegranate seeds is provided, comprising: S1. Take samples from the frozen pomegranate seeds to be thawed to determine the water content H of the frozen pomegranate seeds; S2, mix the remaining frozen pomegranate seeds in S1 with food-grade glass beads or ceramic beads in a mass ratio of 1:2-4 and spread them on a microwave drying plate; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:1-6, and performing microwave thawing on the mixture on the microwave drying plate in S2; S4, sieving and separating the pomegranate seeds from the thawed mixture in S3; Wherein, the total microwave output time T during the microwave thawing process in S3 satisfies T=AM / P; P is the microwave output power, W; M is the weight of frozen pomegranate seeds on the microwave drying tray, g; A is the pomegranate seed thawing constant, J / g, which is determined according to the water content H measured in S1 and the size of the pomegranate seeds, and the value range is 100~250; The microwave output time t1 is 10~40s, and the microwave output power density is 0.75~1.50W / g.

[0012] Preferably, the method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H.

[0013] Preferably, the microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000).

[0014] Preferably, the microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M.

[0015] Preferably, the diameter of the food-grade glass beads or ceramic beads in S2 is smaller than the diameter of the frozen pomegranate seeds to be thawed, and the aperture of the sieve used for screening in S4 is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads.

[0016] Preferably, the density of the mixture in the microwave drying dish in S2 is 0.8-1.2 g / cm 2 .

[0017] Preferably, the intermittent microwave rapid thawing method for pomegranate seeds further comprises the step of pre-treating the frozen pomegranate seeds to be thawed: A1. taking out the frozen pomegranate seeds to be thawed at a temperature below -18°C from a freezing environment and placing them at room temperature, so that liquid water can be seen on the surface of the pomegranate seeds by naked eye; A2. Place the pomegranate seeds after A1 in a clean container and stir at a speed of 50-80 r / min for 3-5 minutes while shaking the container up and down 10-15 times. A3. Use a silicone rod to process the pomegranate seeds in the container to ensure that there are no clumps of more than 4 pomegranate seeds.

[0018] Preferably, the surface of the food-grade glass beads or ceramic beads in S2 is sandblasted with corundum having a particle size of 100-150 meshes to increase the surface roughness of the glass beads or ceramic beads.

[0019] Preferably, the method for separating the pomegranate seeds from the thawed mixture in S3 by sieving comprises: B1, place the thawed mixture in S3 in an environment with a temperature of 40-42°C and a relative humidity of 30-35% and dry for 10-15 minutes; B2, selecting a first sieve with a pore size between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads, and performing a primary screening on the dried mixture at a shaking amplitude of 5 to 10 cm and a shaking frequency of 20 to 30 times / min to obtain a first screened product; B3, select a second sieve with an aperture between the diameter of the frozen pomegranate seeds to be thawed and the aperture of the first sieve, and perform a second screening on the first screened material with a shaking amplitude of 5-10 cm and a shaking frequency of 15-20 times / min; B4. A weight sensor is arranged below the second sieve, and the weight sensor is used to monitor the weight of the sieved material on the second sieve. The monitoring period is 3 to 5 seconds. If the weight change of the sieved material on the second sieve is less than 0.3 g within four consecutive monitoring periods, it is determined that the pomegranate seeds are completely separated from the first sieved material; otherwise, the shaking frequency of the second sieve is adjusted to 1.1 to 1.3 times the original shaking frequency, and screening is continued.

[0020] Preferably, the frozen pomegranate seeds to be thawed in step S1 weigh 400-600 g and have a temperature below -18°C.

[0021] The present invention has at least the following beneficial effects: First, in the intermittent rapid microwave thawing method of pomegranate seeds provided by the present invention, frozen pomegranate seeds are mixed with food-grade glass beads or ceramic beads, the microwave field distribution is improved, and on this basis, the microwave output power and microwave output time are accurately adjusted, which not only avoids the risk of local overheating, but also prevents the hidden dangers of insufficient or excessive thawing, and ensures the quality of rapid thawing of pomegranate seeds; at the same time, the entire thawing process is made more operable and stable, thereby ensuring the consistency of the thawing effect of pomegranate seeds; Second, in the intermittent rapid microwave thawing method of pomegranate seeds provided by the present invention, the physical properties of pomegranate seeds and the influence of water content on microwave absorption are fully considered, and the thawing constant A is accurately set according to the water content and size of the pomegranate seeds to ensure that microwave energy suitable for thawing the pomegranate seeds is provided, thereby improving the thawing effect and quality of the pomegranate seeds; Third, in the intermittent rapid microwave thawing method of pomegranate seeds provided by the present invention, the microwave output time t1 is determined according to the water content, size and weight of the pomegranate seeds, the parameter adjustment of microwave thawing is further refined, and the precise time control is combined with the adjustment of microwave output power P and total time T to more accurately meet the thawing requirements of different pomegranate seeds and improve the thawing efficiency and quality of pomegranate seeds; Fourthly, in the intermittent rapid thawing method of the present invention, the pomegranate seed clumps are broken up by pretreatment, so that the frozen pomegranate seeds are in a more uniform state, which is conducive to the uniform action of microwaves. The surface of food-grade glass beads or ceramic beads is sandblasted to increase the surface roughness, enhance the heat exchange and microwave absorption synergy between the beads and the frozen pomegranate seeds, and improve the thawing efficiency and uniformity of the pomegranate seeds. Fifth, in the method for intermittent rapid thawing of pomegranate seeds provided by the present invention, specific drying and screening steps are adopted, combined with weight sensor monitoring, to more accurately determine the degree of separation of the pomegranate seeds, ensure the degree of separation of the pomegranate seeds, and ensure the quality of the thawed product.

[0022] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0024] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0025] Example 1 S1. Taking samples from frozen pomegranate seeds to be thawed to determine the moisture content H% of the frozen pomegranate seeds, wherein the frozen pomegranate seeds to be thawed weigh 400-600 g and the temperature is lower than -18°C; S2, mixing the remaining frozen pomegranate seeds in S1 with food-grade glass beads or ceramic beads in a mass ratio of 1:2 and spreading the mixture on a microwave drying plate, wherein the diameter of the food-grade glass beads or ceramic beads is smaller than the diameter of the frozen pomegranate seeds to be thawed; S3, set the microwave output time t1 and intermittent time t2 ratio of the intermittent microwave output mode to 1: 6, and the mixture on the microwave drying plate in S2 was thawed by microwave; the total microwave output time T during microwave thawing satisfies T = AM / P, A is 100 ~ 250 J / g; microwave output time t1 is 10 ~ 40s, and the microwave output power density is 0.75 ~ 1.50W / g; S4. The pomegranate seeds in the thawed mixture in S3 are separated by sieving. The aperture of the sieve used for sieving is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads.

[0026] Example 2 S1, same as in Example 1; S2, same as in Example 1; S3, set the microwave output time t1 and intermittent time t2 ratio of the intermittent microwave output mode is 1: 6, and the mixture on the microwave drying plate in S2 is thawed by microwave; the total microwave output time T during microwave thawing satisfies T = AM / P, the microwave output time t1 is 10 ~ 40s, and the microwave output power density is 0.75 ~ 1.50W / g; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; S4. Same as Example 1.

[0027] Example 3 S1, same as in Example 1; S2, same as in Example 1; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:6, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P, and the microwave output time t1 is 10-40s; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); S4. Same as Example 1.

[0028] Example 4 S1, same as in Example 1; S2, same as in Example 1; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:6, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M; S4. Same as Example 1.

[0029] Example 5 Pretreatment: Take the frozen pomegranate seeds to be thawed at a temperature below -18°C out of the freezing environment and place them at room temperature so that liquid water can be seen on the surface of the pomegranate seeds by naked eye; place the pomegranate seeds in a clean container, stir them at a stirring speed of 80r / min for 5 minutes, and shake the container up and down 5 times; use a silicone rod to handle the pomegranate seeds in the container to ensure that there are no clumps of more than 4 pomegranate seeds; S1, same as in Example 1; S2, same as in Example 1; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:6, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M; S4. Same as Example 1.

[0030] Example 6 Pretreatment: same as Example 5; S1, same as in Example 1; S2, same as in Example 1; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:6, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M; S4, sieving and separating the pomegranate seeds from the thawed mixture in S3, wherein the aperture of the sieve used for sieving is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads; The method for separating the pomegranate seeds from the thawed mixture by screening comprises: B1, placing the thawed mixture in S3 in an environment with a temperature of 40°C and a relative humidity of 35% to dry for 15 minutes; B2, selecting a first sieve with a pore size between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads, and performing a primary screening on the dried mixture at a shaking amplitude of 10 cm and a shaking frequency of 30 times / min to obtain a first screened product; B3, selecting a second sieve with an aperture between the diameter of the frozen pomegranate seeds to be thawed and the aperture of the first sieve, and performing a second screening on the first screened material with a shaking amplitude of 10 cm and a shaking frequency of 20 times / min; B4. A weight sensor is arranged below the second sieve, and the weight sensor is used to monitor the weight of the sieved material on the second sieve. The monitoring period is 5s. If the weight change of the sieved material on the second sieve is less than 0.3g within four consecutive monitoring periods, it is judged that the pomegranate seeds are completely separated from the first sieved material; otherwise, the shaking frequency of the second sieve is adjusted to 1.3 times of the original shaking frequency, and screening is continued.

[0031] Example 7 S1. Taking a sample from the frozen pomegranate seeds to be thawed to determine the moisture content H% of the frozen pomegranate seeds, wherein the frozen pomegranate seeds to be thawed weigh 400 g and the temperature is lower than -18°C; S2, mixing the remaining frozen pomegranate seeds in S1 with food-grade glass beads or ceramic beads in a mass ratio of 1:4 and spreading the mixture on a microwave drying plate, wherein the diameter of the food-grade glass beads or ceramic beads is smaller than the diameter of the frozen pomegranate seeds to be thawed; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1: 1, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M; S4. The pomegranate seeds in the thawed mixture in S3 are separated by sieving. The aperture of the sieve used for sieving is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads.

[0032] Example 8 S1. Taking a sample from the frozen pomegranate seeds to be thawed to determine the moisture content H% of the frozen pomegranate seeds, wherein the frozen pomegranate seeds to be thawed weigh 600 g and the temperature is lower than -18°C; S2, mixing the remaining frozen pomegranate seeds in S1 with food-grade glass beads or ceramic beads in a mass ratio of 1:3 and spreading the mixture on a microwave drying plate, wherein the diameter of the food-grade glass beads or ceramic beads is smaller than the diameter of the frozen pomegranate seeds to be thawed; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:3, and performing microwave thawing on the mixture on the microwave drying plate in S2; the total microwave output time T during the microwave thawing process satisfies T=AM / P; The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H; The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000); The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M; S4. The pomegranate seeds in the thawed mixture in S3 are separated by sieving. The aperture of the sieve used for sieving is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads.

[0033] Comparative Example 1 Frozen pomegranate seeds of the same batch, weight and temperature as those in the example were selected and placed at room temperature (25° C.) for natural thawing. The thawing time was recorded. After thawing, the appearance and taste of the pomegranate seeds were observed, and the nutritional content was detected.

[0034] Comparative Example 2 Frozen pomegranate seeds under the same conditions were selected. No parameter calculation was performed and ordinary microwave continuous output was used for thawing. A fixed power and time were set for thawing. The thawing time was also recorded. After thawing, the appearance and taste of the pomegranate seeds were observed, and the nutritional content was tested.

[0035] Comparative Example 3 Frozen pomegranate seeds under the same conditions were selected, and no parameter calculation was performed. Ordinary microwave intermittent output was used for thawing. The ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output method was set to 1:10. The thawing time was also recorded. After thawing, the appearance and taste of the pomegranate seeds were observed, and the nutritional content was tested.

[0036] The thawing time, appearance, taste and nutrient retention rate of pomegranate seeds after thawing recorded in Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0037] Table 1 Thawing time of pomegranate seeds, appearance and taste evaluation after thawing, and nutrient retention rate Among them, the nutrient retention rate refers to the total retention rate of vitamin C and polyphenol nutrients.

[0038] It can be seen from the data in Table 1 that when the intermittent microwave rapid thawing method provided by the present invention thaws pomegranate seeds, the thawing time is significantly shorter than that of the natural thawing method, the ordinary microwave connection thawing method and the inaccurately designed intermittent microwave thawing method. This is because the present invention can more efficiently apply microwave energy to the pomegranate seeds and achieve rapid thawing of the pomegranate seeds by accurately calculating the microwave output power and time when the pomegranate seeds are thawed.

[0039] It can be further seen from the data in Table 1 that when the intermittent microwave rapid thawing method provided by the present invention thaws pomegranate seeds, the appearance and color are normal, the thawing is uniform, and the taste is delicious and juicy, while the pomegranate seeds thawed naturally in Comparative Example 1 are dull in color and soft in taste, the pomegranate seeds thawed continuously by ordinary microwaves in Comparative Example 2 are partially burnt, thawed unevenly, and have a dry taste, and the pomegranate seeds thawed by undesigned intermittent microwaves in Comparative Example 3 are dull in color, thawed unevenly, and have a soft taste. This shows that the method for intermittent microwave rapid thawing of pomegranate seeds provided by the present invention can better maintain the appearance and taste of the pomegranate seeds, and avoids the quality degradation of the pomegranate seeds thawed due to improper control of thawing parameters.

[0040] Further comparing the nutrient retention rates of the pomegranate seeds after thawing in Examples 1-2 and Comparative Examples 1-2, the nutrient retention rates of the pomegranate seeds after thawing in Examples 1-2 are significantly higher than those of the pomegranate seeds after thawing in Comparative Examples 1-2. This is because the present invention adopts intermittent microwave thawing, combined with precise parameter adjustment, which reduces the damage of microwaves to the nutrients of the pomegranate seeds, and retains the nutritional value of the pomegranate seeds to the greatest extent.

[0041] Further comparison of the data of Example 1 and Example 2 shows that the nutrient retention rate after thawing in Example 2 is higher than that in Example 1. This is because Example 2 fully considers the physical properties of pomegranate seeds and the effect of water content on microwave absorption, and accurately sets the thawing constant A according to the water content and size of the pomegranate seeds, thereby ensuring that microwave energy suitable for thawing the pomegranate seeds is provided, thereby improving the thawing effect and quality of the pomegranate seeds.

[0042] After repeating the test 10 times, the thawing time, the appearance and taste of the pomegranate seeds after thawing, the nutrient retention rate, the internal temperature uniformity and the operational stability recorded in Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Tables 2 to 4.

[0043] Table 2 Experimental data of Examples 1 to 3 Among them, the nutrient retention rate refers to the total retention rate of vitamin C and polyphenol nutrients; Internal temperature uniformity is detected using an infrared thermal imager and expressed as a temperature deviation range; The operational stability was tested by repeating the test 10 times to examine the thawing effect of the waveguide.

[0044] Table 3 Experimental data of Examples 4 to 6 Among them, the nutrient retention rate refers to the total retention rate of vitamin C and polyphenol nutrients; Internal temperature uniformity is detected using an infrared thermal imager and expressed as a temperature deviation range; The operational stability was tested by repeating the test 10 times to examine the thawing effect of the waveguide.

[0045] Table 4 Comparative Examples 1 to 3 Test Data Among them, the nutrient retention rate refers to the total retention rate of vitamin C and polyphenol nutrients; Internal temperature uniformity is detected using an infrared thermal imager and expressed as a temperature deviation range; The operational stability was tested by repeating the test 10 times to examine the thawing effect of the waveguide.

[0046] It can be seen from the data in Tables 2 to 4 that the natural thawing method in Comparative Example 1 takes a very long time, and due to long-term exposure to room temperature, the pomegranate seeds are easily contaminated by microorganisms, resulting in unsatisfactory appearance, taste and nutritional content retention. Although the time for continuous thawing using ordinary microwaves in Comparative Example 2 is shortened, local overheating is very likely to occur due to the inability to accurately control the microwave output, which not only affects the taste, but also seriously damages the nutritional content. In addition, the thawing effect of each experiment varies greatly, and the operational stability is poor. Comparative Example 3 adopts the ordinary microwave intermittent output mode. Although it alleviates the problem of local overheating to a certain extent, the microwave output cannot be accurately adjusted according to the actual situation of the pomegranate seeds due to the lack of parameter calculation, resulting in a long thawing time, and some pomegranate seeds are not fully thawed. In terms of appearance, there are a small amount of ice crystals remaining, and the color is darker; in terms of taste, it is hard and has a sense of ice chips, less juice, and insufficient flavor; the nutrient retention rate is about 75%, which is lower than that of each embodiment; the internal temperature uniformity is not as good as that of each embodiment, and the temperature deviation range is large; in terms of operational stability, due to the fixed intermittent ratio, it is difficult to adapt to the differences between different batches of pomegranate seeds, and the thawing time and effect fluctuate greatly. The thawing time of Examples 1 to 6 is relatively short. Each embodiment effectively avoids the risk of local overheating by accurately measuring the water content, calculating the thawing constant, and reasonably setting the microwave output time and power, thereby ensuring the uniformity of the internal temperature of the pomegranate seeds and controlling the temperature deviation in a very small range, thereby preventing the problem of insufficient or excessive thawing. While ensuring rapid thawing, the nutritional components of the pomegranate seeds are retained to the greatest extent, so that both the taste and appearance reach a high-quality level. Furthermore, repeated experiments show that the thawing effect of the embodiment has minimal fluctuations, high operational stability, and the entire thawing process is more operable and stable, ensuring the consistency of the thawing effect of the pomegranate seeds. In comparison, each embodiment has obvious advantages in terms of thawing time, appearance, taste, nutrient retention, internal temperature uniformity, and operational stability.

[0047] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the specific embodiments shown and described herein.

Claims

1. A method for rapidly thawing pomegranate seeds by intermittent microwave, characterized in that: include: S1. Take samples from the frozen pomegranate seeds to be thawed to determine the water content H of the frozen pomegranate seeds; S2, mix the remaining frozen pomegranate seeds in S1 with food-grade glass beads or ceramic beads in a mass ratio of 1:2-4 and spread them on a microwave drying plate; S3, setting the ratio of microwave output time t1 and intermittent time t2 of the intermittent microwave output mode to 1:1-6, and performing microwave thawing on the mixture on the microwave drying plate in S2; S4, sieving and separating the pomegranate seeds from the thawed mixture in S3; Wherein, the total microwave output time T during the microwave thawing process in S3 satisfies T=AM / P; P is the microwave output power, W; M is the weight of frozen pomegranate seeds on the microwave drying tray, g; A is the pomegranate seed thawing constant, J / g, which is determined according to the water content H measured in S1 and the size of the pomegranate seeds, and the value range is 100~250; The microwave output time t1 is 10~40s, and the microwave output power density is 0.75~1.50W / g.

2. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 1, characterized in that: The method for determining the value of the pomegranate seed thawing constant A is as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, A=100+0.5(70+H); when H≤70, A=100+H; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, A=130+0.5(80+H); when H≤70, A=130+H; When the average diameter of pomegranate seeds D>8mm: When H>70, A=150+0.5(100+H); when H≤70, A=150+H.

3. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 2, characterized in that: The microwave output power P is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, P=0.75M+0.015M(H-70); when H≤70, P=0.00005M(H+15000); 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, 0.75M+0.02M(H-70); when H≤70, P=0.0001M(H+7500); When the average diameter of pomegranate seeds D>8mm: When H>70, 0.75M+0.025M(H-70); when H≤70, P=0.00015M(H+5000).

4. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 3, characterized in that: The microwave output time t1 is determined according to the water content H measured in S1, the size of the pomegranate seeds, and the weight M of the frozen pomegranate seeds on the microwave drying plate, and the value thereof is determined as follows: When the average diameter of pomegranate seeds is D≤5mm: When H>70, t1=10+400(H-70) / M; when H≤70, t1=(4H+10M) / M; 5mm<average diameter of pomegranate seeds D≤8mm: When H>70, t1=10+500(H-70) / M; when H≤70, t1=(5H+10M) / M; When the average diameter of pomegranate seeds D>8mm: When H>70, t1=10+600(H-70) / M; when H≤70, t1=(6H+10M) / M.

5. The method for intermittent microwave rapid thawing of pomegranate seeds as claimed in claim 1, characterized in that: The diameter of the food-grade glass beads or ceramic beads in S2 is smaller than the diameter of the frozen pomegranate seeds to be thawed, and the aperture of the sieve used for screening in S4 is between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads.

6. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 1, characterized in that: The density of the mixture in the microwave drying pan in S2 is 0.8~1.2g / cm 2 .

7. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 1, characterized in that: The steps of pre-treating the frozen pomegranate seeds to be thawed are also included: A1. taking out the frozen pomegranate seeds to be thawed at a temperature below -18°C from a freezing environment and placing them at room temperature, so that liquid water can be seen on the surface of the pomegranate seeds by naked eye; A2. Place the pomegranate seeds after A1 in a clean container and stir at a speed of 50-80 r / min for 3-5 minutes while shaking the container up and down 10-15 times. A3. Use a silicone rod to process the pomegranate seeds in the container to ensure that there are no clumps of more than 4 pomegranate seeds.

8. The method for rapid thawing of pomegranate seeds by intermittent microwave according to claim 1, characterized in that: The surface of the food-grade glass beads or ceramic beads in S2 is sandblasted with corundum having a particle size of 100-150 meshes to increase the surface roughness of the glass beads or ceramic beads.

9. The method for intermittent microwave rapid thawing of pomegranate seeds as claimed in claim 1, characterized in that: The method for separating the pomegranate seeds from the thawed mixture in S3 by sieving comprises: B1, place the thawed mixture in S3 in an environment with a temperature of 40-42°C and a relative humidity of 30-35% and dry for 10-15 minutes; B2, selecting a first sieve with a pore size between the diameter of the frozen pomegranate seeds to be thawed and the diameter of the food-grade glass beads or ceramic beads, and performing a primary screening on the dried mixture at a shaking amplitude of 5 to 10 cm and a shaking frequency of 20 to 30 times / min to obtain a first screened product; B3, select a second sieve with an aperture between the diameter of the frozen pomegranate seeds to be thawed and the aperture of the first sieve, and perform a second screening on the first screened material with a shaking amplitude of 5-10 cm and a shaking frequency of 15-20 times / min; B4. A weight sensor is arranged below the second sieve, and the weight sensor is used to monitor the weight of the sieved material on the second sieve. The monitoring period is 3 to 5 seconds. If the weight change of the sieved material on the second sieve is less than 0.3 g within four consecutive monitoring periods, it is determined that the pomegranate seeds are completely separated from the first sieved material; otherwise, the shaking frequency of the second sieve is adjusted to 1.1 to 1.3 times the original shaking frequency, and screening is continued.

10. The method for intermittent microwave rapid thawing of pomegranate seeds according to claim 4, characterized in that: In step S1, the weight of the frozen pomegranate seeds to be thawed is 400-600 g and the temperature is lower than -18°C.

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