Method for improving digestion characteristic of frozen meat under assistance of ultrasonic waves

Abstract

The invention discloses a method for improving digestion characteristics of frozen meat under assistance of ultrasonic waves, which comprises the following steps: cutting fresh meat blocks, sealing, and refrigerating at 0-4 DEG C for 4-8 hours; and freezing the refrigerated meat blocks, applying ultrasonic waves in the freezing process, setting the ultrasonic waves to be in a circulating intermittent mode when the central temperature of the sample reaches-0.5 DEG C to 0.5 DEG C, and completely immersing the meat blocks into refrigerant industrial alcohol until the geometric central temperature of muscles is reduced to-18 DEG C, thereby completing freezing. According to the present invention, with the treatment method of auxiliary ultrasonic application on the sample during the freezing process, the nutrition damage and the digestion characteristic reduction caused by the freezing of the sample are reduced, such that the sample has the high digestion rate, the protein is completely decomposed into the small peptide or the amino acid, the protein particles are small and do not aggregate, and the sample has the high nutrition value; the ultrasonic-assisted freezing proves that the digestion characteristic of the frozen meat is improved to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a method for improving the digestibility of frozen meat by utilizing ultrasound. Background Art

[0002] Protein is an important component of meat and an indispensable nutrient for the human body. The quality of protein depends not only on the composition of essential amino acids but also on its digestibility. The physicochemical and structural characteristics of protein play a vital role in food processing, storage and digestion. During the freezing process, protein is affected by chemical or physical factors, which changes its spatial structure and leads to the loss of biological properties of protein. Because frozen denatured or oxidized food protein may not be completely degraded by digestive enzymes, undigested protein may remain in the colon for a long time and eventually ferment, affecting human health. Protein is digested into small peptides or free amino acids and can be absorbed into the blood to promote growth and maintain health. The reduction in protein digestibility will reduce the bioavailability of amino acids. Undigested protein is further utilized by intestinal microflora to produce biogenic amines, which may increase the risk of intestinal diseases. Traditional fresh meat not only contains all the essential amino acids, but also has a high protein digestibility. However, traditional freezing methods such as air freezing have low heat transfer coefficients, and the ice crystals formed during freezing are large, which seriously damages the muscle fiber and protein structure and deteriorates the food quality. Therefore, it is necessary to utilize emerging technologies to regulate the formation of ice crystals, reduce the nutritional damage of proteins and the loss of digestibility to maintain good digestibility of food materials.

[0003] Traditional freezing methods, such as air freezing, easily form ice crystals of uneven sizes between muscle cells. The mechanical damage during the freezing process can cause tissue cells to atrophy and deform, myofibrils to twist and break, and proteins to denature, which seriously restricts the development of the meat industry. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for improving the digestibility of frozen meat by using ultrasound.

[0005] The objective of the present invention is achieved through the following technical scheme, and the steps are as follows: a method for improving the digestibility of frozen meat by using ultrasound to assist, comprising cutting fresh meat blocks and sealing them, and refrigerating them at 0-4°C for 4-8 hours; then freezing the refrigerated meat blocks, immersing the whole meat blocks in refrigerant industrial alcohol, applying ultrasound during the freezing process, and setting the ultrasound to a cyclic intermittent mode when the center temperature of the meat blocks reaches -0.5°C~0.5°C, until the geometric center temperature of the muscle drops to -18°C to complete freezing.

[0006] The power of the ultrasonic intensity is 50~2000 W.

[0007] The fresh meat blocks are sealed with polyethylene bags, polypropylene bags or nylon bags after being cut.

[0008] The ultrasonic instrument is an ultrasonic-assisted quick-freezing instrument.

[0009] The mass fraction of the industrial alcohol is 50%-99%.

[0010] The temperature of the industrial alcohol is set to -21°C to -20°C.

[0011] The ultrasound intensity was set to 200-600 W.

[0012] The ultrasound cycle intermittent mode was set to 3-10 s on / 3-10 s off.

[0013] Compared with the prior art, the present invention has the following advantages and effects: The method of the present invention of applying ultrasound to samples during the freezing process reduces the nutritional damage of the samples caused by freezing and the reduction in digestion characteristics, so that the samples have a higher digestibility, the protein is fully decomposed into small peptides or amino acids, the protein particles are smaller and non-aggregated, and the samples have a higher nutritional value, proving that ultrasonic-assisted freezing improves the digestion characteristics of frozen meat to a certain extent.

[0014] Ultrasound is a non-invasive and pollution-free form of mechanical action. Ultrasound-assisted immersion freezing is a new type of rapid freezing technology. Ultrasound generates cavitation bubbles, promotes nucleation, and increases the freezing rate, thereby maintaining a stable protein structure. In addition, ultrasound can induce protein structure unfolding and inhibit the formation of protein aggregates, thereby improving the in vitro digestibility of protein. At present, research on ultrasound-assisted frozen meat products mainly focuses on the texture and sensory properties of frozen meat and the functional properties of protein, but there are few reports on the nutritional digestibility of frozen meat. Therefore, providing a method for improving the digestibility of frozen meat using ultrasound is a technical problem that technicians in this field urgently need to solve. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is a schematic diagram of the ultrasonic assisted freezing equipment; Figure 2 The effect of different powers of ultrasound-assisted immersion freezing on the digestibility of beef protein; Figure 3The effect of different powers of ultrasound-assisted immersion freezing on the particle size of beef protein after digestion; Figure 4 The microstructure of digested beef protein after freezing and immersion with ultrasound assisted at different powers; DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below by way of examples. The following examples are provided to explain the present invention but the present invention is not limited to the following examples.

[0018] The device of the ultrasonic assisted quick freezing apparatus of the embodiment is as follows Figure 1 As shown, it includes 1, ultrasonic power supply; 2, ultrasonic parameter control panel; 3, ultrasonic generator; 4, cold water tank control panel; 5, ultrasonic probe; 6, muscle sample; 7, refrigeration compressor; 8, temperature inspection instrument; 9, refrigerant circulation fan in freezing chamber; 10, ultrasonic generator x, y axis motion track; 11, refrigerant circulation chamber; 12, refrigerant circulation pipe. The ultrasonic assisted quick freezing instrument was purchased from Wuxi Xinshangjia Biotechnology Co., Ltd., model: SJT-I-10L.

[0019] A method for improving the digestibility of frozen meat by using ultrasound to assist. Fresh meat blocks are cut and sealed, and refrigerated at 0-4°C for 4-8 h. The refrigerated meat blocks are then frozen and immersed in refrigerant industrial alcohol. Ultrasound is applied during the freezing process, and the ultrasound intensity is set to 200-600 W. When the center temperature of the sample reaches -0.5°C~0.5°C, the ultrasound is set to a cyclic intermittent mode of 3-10 s on / 3-10 s off until the geometric center temperature of the muscle drops to -18°C and freezing is completed. Example

[0020] Fresh beef was divided into polyethylene sealed bags and placed in a 4 °C refrigerator for 6 h to obtain a stable initial temperature. 3 The meat blocks were divided into 6 groups, and the visible fat and connective tissue were removed. The control group (Control) was fresh meat, and the various indicators were measured directly. The air freezing (AF) group was in a refrigerator freezer (-20 ± 1℃), and the immersion freezing (IF) group was in an immersion freezing tank (-20 ± 1℃). Different power ultrasound-assisted immersion freezing was performed in an ultrasonic-assisted quick freezer 20 kHz, with an adjustable power of 50 ~ 2000 W. The experiment selected 0 W, 200 W, 400 W, and 600 W, and the temperature was -20 ± 1℃, 5 s on and 5 s off. An ultrasonic probe was placed in a 10 L freezing tank, and the sample temperature dropped to 0℃ and ultrasound was applied. The samples in each group were frozen until the center temperature was -18 ± 1℃.

[0021] Specific operations: (1) Remove the fat and connective tissue on the surface of fresh muscle and cut it into 6×6×3 cm 3 Block-shaped, with an average weight of 110 ± 5 g per block; (2) After cutting, the samples were sealed in polyethylene bags (140 × 200 mm, 8-wire) and refrigerated at 4 °C for 6 h to obtain a uniform initial freezing temperature. (3) The meat was completely immersed in industrial alcohol (-20±0.5℃) with a mass fraction of 95%. Ultrasound was applied during the freezing process and the freezing was completed in an ultrasonic-assisted quick freezer. When the center temperature of the sample reached 0℃, ultrasound was started in a 5s on / 5s off cycle intermittent mode. The sample was completely immersed in industrial alcohol and placed in the same position to maintain uniform ultrasonic intensity. The geometric center temperature of the muscle was measured and recorded every 2 seconds for real-time monitoring until the geometric center temperature of the muscle dropped to -18℃, which was considered to be freezing complete. (4) Different treatment groups were set with different ultrasonic intensities of 0-600 W, with an adjustable power of 50-2000 W, an ultrasonic frequency of 20 kHz, and a temperature of -20±1°C; (5) The ultrasonic probe performs cyclic reciprocating motion along the x-axis and y-axis tracks. The ultrasonic probe performs cyclic reciprocating motion along the track at a speed of 2 cm / s. The ultrasonic probe motion working mode is consistent with the ultrasound working mode. (6) All frozen samples were stored in a -18°C refrigerator for 48 h before protein extraction; (7) Thaw meat samples and establish an in vitro simulated digestion model.

[0022] An in vitro simulated digestion model was established for thawed beef samples to test the effect of ultrasound-assisted freezing on the digestion characteristics of beef protein.

[0023] (1) Simulated gastric juice digestion test Accurately weigh 7 g of minced beef hind leg meat into a 50 mL centrifuge tube, add 28 mL of 10 mmol / L PBS solution (pH 7.0) and homogenize in an ice bath for 3 times (13400 r / min, homogenize for 30 s, and rest for 30 s). Then adjust the pH to 2.0 ± 0.1 with 1 M HCl, add 7 mL of pepsin solution (specific activity ≥ 250 U / mg, concentration: 0.48 g: 15 mL 0.1 mol / L HCl) to each sample, and then simulate in vitro gastric juice digestion for 2 h (160 r / min) on a 37 ℃ constant temperature oscillator. Quickly adjust the pH of the enzymatic solution to about 7.0 with 1 mol / L NaOH solution to terminate the enzymatic reaction.

[0024] (2) Simulated intestinal digestion test After the simulated gastric digestion reaction, the pH of the homogenate was adjusted to 7.5 ± 0.1 with 1 mol / L NaOH solution. Then, 7 mL of trypsin solution (specific activity 8 × USP, concentration: 0.288 g: 12 mL 0.01 M pH 7.0 PBS) was added to the reaction system, and the in vitro intestinal digestion was simulated on a 37 °C constant temperature oscillator for 2 h (160 r / min). Finally, the enzymatic reaction was terminated by heating in a 100 °C boiling water bath for 5 min.

[0025] The results of relevant typical indicators show that the digestibility of frozen meat treated with ultrasonic power of 200-600 W is similar to that of fresh meat, proving that it has the best digestibility.

[0026] Conclusion: The present invention discloses a method for improving the digestibility of frozen meat by using ultrasound. During the freezing process, the protein structure will be oxidatively modified, the protein structure will mutate, and the recognition site of protease will change, which will lead to a decrease in protein digestibility. 200-600 W ultrasound-assisted freezing treatment can be used as an effective way to slow down the degree of freezing oxidation and improve digestibility, and on this basis, the meat maintains good digestibility. The results show that ultrasound-assisted immersion freezing is an effective method to improve the digestibility of frozen meat and can develop high-quality meat products.

[0027] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the digestibility of frozen meat using ultrasound, characterized in that: Fresh meat blocks are cut and sealed, and refrigerated at 0-4℃ for 4-8 hours; the refrigerated meat blocks are then frozen and completely immersed in the refrigerant industrial alcohol. Ultrasound is applied during the freezing process. When the center temperature of the meat block reaches -0.5℃~0.5℃, the ultrasound is set to a cyclic intermittent mode until the geometric center temperature of the muscle drops to -18℃ to complete freezing.

2. The method for improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The power of the ultrasonic intensity is 50~2000 W.

3. The method for improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The fresh meat blocks are sealed with polyethylene bags, polypropylene bags or nylon bags after being cut.

4. The method of improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The ultrasonic instrument is an ultrasonic-assisted quick-freezing instrument.

5. The method of improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The mass fraction of the industrial alcohol is 50%-99%.

6. The method for improving the digestibility of frozen meat with the aid of ultrasound according to claim 1 or 5, characterized in that: The temperature of the industrial alcohol is set to -21°C to -20°C.

7. The method of improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The ultrasound intensity was set to 200-600 W.

8. The method of improving the digestibility of frozen meat with the aid of ultrasound according to claim 1, characterized in that: The ultrasound cycle intermittent mode was set to 3-10 s on / 3-10 s off.

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