Ultrasonic processing method for efficiently reducing purine content of beef

Abstract

The application discloses an ultrasonic processing method for efficiently reducing the content of beef purine, and belongs to the technical field of food processing. In view of the problem that traditional water boiling de-purine is easy to cause dry and hard beef, color loss and flavor loss, the application places beef slices in ultrapure water, and carries out combined treatment under the condition of a water bath temperature of 90 DEG C and an ultrasonic power of 100 W for 60 s. The method utilizes the mechanical shearing force generated by ultrasonic cavitation effect to destroy the muscle cell wall and connective tissue barrier, accelerates the dissolution of water-soluble purine into water phase, simultaneously induces the moderate unfolding of protein, exposes the hydrophilic group, reversely increases the residual tissue water holding rate to more than 98%, and maintains good color, flavor and taste. Compared with single heat treatment, the application significantly improves the purine dissolution efficiency, effectively improves the tenderness and juiciness of beef, and is suitable for industrialized production of low-purine healthy beef products.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to an ultrasonic processing method for efficiently reducing the purine content of beef. Background Technology

[0002] Beef is rich in high-quality protein and various trace elements, making it a popular food among consumers. However, it is a medium-to-high purine food, with a total purine content often exceeding 150 mg / 100 g. Long-term excessive intake of purine-rich meats is a significant environmental factor contributing to hyperuricemia and gout. With changes in modern dietary structures, consumer demand for low-purine meat products is increasing. Effectively reducing the purine content of beef while preserving its nutritional value and edibility has become a pressing technical challenge for the food processing industry.

[0003] Currently, the most common method for removing purines in home cooking and pre-processed meat is boiling. Because purines are highly water-soluble, high-temperature heating causes muscle tissue fluid to seep out, carrying free purines into the aqueous medium. However, simply relying on prolonged high-temperature boiling can lead to severe quality deterioration: heat induces violent contraction of myofibril and collagen, resulting in significant water loss, increased shear force, and a dry texture; simultaneously, myoglobin oxidation causes browning, darkening the color, and a large loss of water-soluble umami precursors, significantly reducing flavor and juiciness. Therefore, there is an urgent need to find a gentle, physical-assisted processing technology that can accelerate purine removal while maximizing the preservation of the original quality of the meat.

[0004] Ultrasonic-assisted processing technology, as a green physical field intervention method, has shown unique advantages in the field of food mass transfer and quality control. The strong microjets and acoustic shear forces generated by ultrasonic cavitation can effectively disrupt muscle cell walls and connective tissue barriers, reduce the thickness of the diffusion boundary layer, and significantly improve the mass transfer efficiency of water-soluble solutes. At the same time, the physical abrasion effect of ultrasound can sever some myofibrils, induce proteins to unfold appropriately and expose hydrophilic groups, thereby achieving meat tenderization and improving water-holding capacity. However, current research on the microscopic mechanisms and macroscopic quality evolution of purine removal in beef systems through combined ultrasonic and heat treatment is not systematic, especially lacking in-depth analysis of early dissolution kinetics, moisture state, and microstructure deconstruction. Therefore, this invention provides an optimized ultrasonic processing method, aiming to efficiently reduce the purine content of beef while improving its sensory qualities such as tenderness and juiciness. Summary of the Invention

[0005] This invention provides an efficient ultrasonic processing method for reducing the purine content of beef, comprising placing beef slices in ultrapure water and treating them in a water bath at 90°C and an ultrasonic power of 100 W for 60 seconds. This method utilizes the ultrasonic cavitation effect to accelerate the dissolution of water-soluble purines into the aqueous phase, while simultaneously inducing appropriate protein unfolding, increasing the water retention rate of residual tissue to over 98%, and maintaining good color, flavor, and texture. It is suitable for the industrial production of low-purine, healthy beef products.

[0006] This invention provides an ultrasonic processing method for efficiently reducing the purine content of beef, employing the following technical solution: An ultrasonic processing method for efficiently reducing the purine content of beef, characterized by comprising the following steps: The beef slices were placed in ultrapure water and subjected to ultrasonic-assisted processing while being heated in a water bath.

[0007] Preferably, the water bath heating temperature is 80~100℃, the ultrasonic treatment power is 100~300 W, and the ultrasonic treatment time is 10~60 s.

[0008] Preferably, the water bath heating temperature is 90℃, the ultrasonic treatment power is 100 W, and the ultrasonic treatment time is 60s.

[0009] Preferably, before ultrasonic combined heat treatment, the visible fascia and fat on the surface of the beef slices are removed, and after washing, they are left to stand at room temperature for 10 minutes before being cut into uniform slices with a size of 30 mm × 30 mm × 2 mm.

[0010] Preferably, 50 mL of ultrapure water is added to each slice of beef.

[0011] Preferably, the ultrasonic processing method increases the amount of purines dissolved in beef and improves the centrifugal water retention rate to over 98%.

[0012] Preferably, the ultrasonic processing method employs a water bath constant temperature oscillator for ultrasonic combined heat treatment.

[0013] Preferably, the beef is beef tenderloin.

[0014] In summary, the beneficial effects of the present invention are as follows: This invention provides an efficient ultrasonic processing method for reducing the purine content of beef. On one hand, it combines ultrasonic assistance with water bath heating, utilizing the strong microjets and acoustic shear forces generated by ultrasonic cavitation to effectively disrupt muscle cell walls and connective tissue barriers, significantly reducing the diffusion boundary layer thickness, thereby greatly improving the mass transfer and dissolution efficiency of water-soluble purines into the aqueous medium. Kinetic experiments show that, under conditions of 90℃ and 100 W, the ultrasonic combined heat treatment group exhibits a near-linear rapid increase in mass transfer rate in the initial 0-20s stage, with a significantly better mass transfer rate than the single heat treatment group. Single-factor optimization experiments further confirm that the purine dissolution effect is optimal under the conditions of 100℃, 100 W, and 60 s. Meanwhile, the physical abrasion effect of ultrasound moderately cuts myofibrils, induces protein structural phase transitions and exposes hydrophilic groups, causing the water-holding capacity of the residual tissue to show a continuous upward trend with the ultrasound treatment time. After 60 seconds of treatment, the water-holding capacity after centrifugation reached 98.28%, which is significantly higher than the approximately 92% of the single heat treatment group. This effectively solves the common technical problem of dry meat and loss of juiciness caused by traditional high-temperature boiling.

[0015] On the other hand, this invention processes beef under optimized conditions (90℃, 100 W, 60 s), which effectively maintains the product's overall sensory quality, including color, texture, flavor, mouthfeel, and juiciness. Sensory evaluation radar charts show that samples under these conditions achieve high scores across all indicators, avoiding the adverse effects of 100℃ high-temperature treatment on flavor and mouthfeel, and achieving a good balance between efficient purine removal and edible quality. Furthermore, this invention employs a physical processing method, requiring no chemical reagents, making it simple, environmentally friendly, and safe. The processing time is only 60 seconds, with low energy consumption and high efficiency, facilitating continuous industrial production and making it suitable for large-scale processing of low-purine, healthy beef products. Attached Figure Description

[0016] Figure 1 The effect of ultrasound on the amount of purines dissolved in beef; in, Figure 1 In Figure A, the effect of ultrasonic temperature on the amount of purines dissolved in beef is shown. Figure 1 In Figure B, the effect of ultrasonic power on the amount of purines dissolved in beef is shown. Figure 1 In the middle, C represents the effect of ultrasound time on the amount of purines dissolved in beef; Figure 2 The effect of different treatments at 90℃ on the purine dissolution kinetics of beef; Figure 3 The changes in cooking loss rate and centrifugal water holding capacity of beef in different treatment groups; in, Figure 3 In the middle, A represents the change in cooking loss rate; Figure 3B represents the change in centrifugal water holding capacity; Figure 4 Microstructure of beef from different treatment groups; in, Figure 4 In the middle, A represents the control group (C); Figure 4 B in the middle represents a single heat treatment group (H); Figure 4 In the middle, C represents the ultrasonic combined heat treatment group (UH); Figure 5 Sensory scores for beef under different treatments. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments.

[0018] Example 1 The specific steps of the ultrasonic combined heat treatment process for the samples are as follows: S1. After washing the fresh beef tenderloin (after removing visible fascia and fat), let it stand at room temperature for 10 minutes, then cut it into uniform slices of approximately 30 mm × 30 mm × 2 mm.

[0019] S2. Add 50 mL of ultrapure water to each slice of beef. Place the sample in a water bath constant temperature shaker to investigate the effects of different water bath temperatures (80, 90, 100℃), ultrasonic treatment times (10, 20, 30, 40, 50, 60 s), and ultrasonic power (100, 150, 300 W) on purine dissolution. The control group (Group C) consisted of fresh beef without any treatment; the heat treatment group (Group H) only underwent water bath heating; and the ultrasonic combined heat treatment group (Group H+US) received ultrasonic assistance while in the water bath.

[0020] S3. To investigate the early mass transfer law, under the condition of 90℃ water bath, the ultrasonic power was set to 100 W, and fixed-point sampling analysis was carried out within the time series of 0~180 s.

[0021] Example 2 The amount of purine dissolved in the extract was determined by ultraviolet spectrophotometry. The specific steps are as follows: Accurately pipette 5.0 mL of the broth extract from each treatment group in Example 1 into a centrifuge tube, add an equal volume of 10% (V / V) perchloric acid solution, and heat in a boiling water bath for 60 min to hydrolyze and fully release bound purines. After cooling under running water, centrifuge at 4°C and 10,000 r / min for 15 min, and collect the supernatant. Adjust the pH of the supernatant to neutral using NaOH solution, then add 0.4 mol / L silver nitrate (AgNO3) solution and allow to stand to form a silver salt precipitate of free purines. Centrifuge again and discard the supernatant. Wash the precipitate twice with acidified water at pH 2.0, add 0.5 mol / L hydrochloric acid (HCl) solution, and heat in a boiling water bath for 30 min to dissolve. Cool under running water and bring to volume, then measure the absorbance (A260 value) at 260 nm using a multi-mode microplate reader to characterize the dissolution level of purines into the aqueous medium.

[0022] The UV absorbance of the extract at 260 nm (A260) can objectively reflect the dissolution level of free purines into the aqueous medium. Figure 1 The results of single-factor experiments showed that heating temperature and ultrasonic treatment time had a positive promoting effect on the removal of purines. Figure 1 As shown in Figure A, when the water bath temperature increased from 80℃ to 100℃, the A260 value significantly jumped from 0.80 to 1.18. This is mainly because the high temperature intensifies the thermal contraction of myofibrils and the dissolution of the collagen network. This matrix volume contraction exerts strong physical pressure on the intracellular fluid, making it easier for fluid rich in water-soluble free purines to be expelled into the external environment. Meanwhile, as the treatment time increased to 60 s, the amount of dissolution showed a continuous increasing trend. Figure 1 (C)

[0023] When examining the effect of ultrasonic power, the dissolution effect did not exhibit a simple linear increase with increasing power. For example... Figure 1 As shown in Figure B, the dissolution levels of 100 W and 300 W are roughly equivalent, while the 150 W group, which is at the intermediate power level, exhibits an atypical phenomenon of a significant decrease in dissolution rate. Considering both the stability of mass transfer efficiency and actual engineering energy consumption, the optimal process parameters for the comparative experiment are determined to be: 100℃, 100 W, and 60 s.

[0024] like Figure 2As shown, to more clearly observe and quantify the temporal evolution characteristics of the mass transfer process, this study recorded the dissolution dynamics from 0 to 180 s under a 90℃ water bath. The morphology of the kinetic curves reveals that the introduction of the ultrasonic physical field significantly altered the rate of purine migration. In the first 20 s of treatment, the dissolution rate of the H+US group increased rapidly in an almost linear fashion, showing a significant difference from the single heat treatment (H group). However, after crossing the 20-s inflection point, the dissolution rate of the H+US group began to slow down abruptly, and its growth slope gradually became parallel to that of the H group. Ultimately, both systems tended towards a plateau in dynamic equilibrium.

[0025] Example 3 The specific steps for addressing the cumulative time-dependent effects of moisture loss and water retention in beef are as follows: Cooking loss rate: Accurately weigh the initial mass of fresh meat slices in each group of Example 1 before treatment. After the water bath / ultrasonic treatment is completed, remove the meat slices, gently blot off excess surface moisture with filter paper, cool and stand at room temperature for 30 min, and then weigh the residual mass again. The cooking loss rate is calculated according to formula (1): (1) In the formula: M1 is the initial mass of the fresh meat slices before processing; M2 is the mass of the meat slices after processing.

[0026] Centrifugal water holding capacity: Accurately weigh approximately 2.0 g of the beef treated in Example 1, wrap it in double-layered qualitative filter paper, and place it in a 50 mL centrifuge tube. Centrifuge at 4000 r / min for 10 min at 4℃. Remove the meat slices, remove the filter paper, and weigh the residual mass. The centrifugal water holding capacity is calculated according to formula (2): (2) In the formula: M1 is the processed meat slice; M2 is the mass of the meat slice after centrifugation.

[0027] The ability to retain and lose moisture (hydration dynamics) directly affects the final texture and juiciness of meat products. For example... Figure 3 As shown in Figure A, from a time perspective (10–60 s), the cooking loss rate of both groups of samples showed a nearly linear upward trend. However, the water loss rate and final water loss degree of the H+US group (33.44%) were significantly higher than those of the H group (20.80%). This is consistent with the physical-hydrodynamic characteristics of ultrasound-assisted processing, namely, the strong microcirculation and asymmetric compression effect generated by ultrasonic cavitation, which accelerates the forced outward drainage of the muscle internal tissue fluid (mainly free water) in the early stage. Although this process leads to water loss, it also objectively acts as a carrier for the removal of water-soluble purines.

[0028] However, regarding the core indicator of centrifugal water retention capacity, which reflects the water-holding capacity of residual meat, the two groups showed drastically different evolutionary trajectories. For example... Figure 3 As shown in Figure B, the water retention rate of group H fluctuated only slightly between 90% and 93% throughout the entire treatment cycle from 0 to 60 seconds, indicating that simple short-term heat contraction did not substantially improve the hydration state of proteins within the muscle. In contrast, the water retention rate of group H+US showed a continuous and significant upward trend with increasing ultrasound treatment time, reaching 98.28% at 60 seconds. This phenomenon, where the water retention capacity of the residual tissue is continuously enhanced after significant initial water loss, provides strong evidence for ultrasound-induced structural phase transitions in proteins.

[0029] Example 4 The effects of ultrasonic treatment on the dynamic changes in the color of beef are investigated through the following steps: The surface color of the samples was measured using a colorimeter. The instrument was preheated and calibrated using a standard black and white plate. Measurements were performed in medium aperture reflectance mode. The brightness (L*), redness (a*), and yellowness (b*) values ​​were recorded. Three slices of beef were randomly selected from each treatment group, and three different points were evenly taken from the surface of each slice for measurement. The final result was the average.

[0030] Color is an important and intuitive sensory indicator reflecting changes in pigments during meat processing. As shown in Tables 1 and 2, the color difference index of group H and group H+US exhibited different temporal change trajectories as the processing time increased (10~60 s). In the initial stage of heat treatment (10 s), the brightness (L*) of both groups of samples rapidly increased and remained at a relatively high level of 55~60. This is mainly due to the denaturation of muscle proteins and the large amount of surface free water seeping out due to heat, which greatly enhances the light scattering effect on the sample surface.

[0031] However, there was a significant difference between the two groups in the changes of redness (a*) and yellowness (b*) that determine the core flesh color. During the 10–60 s period, the a* value of group H gradually and slowly decreased due to the thermal oxidation of myoglobin to form metmyoglobin, while the b* value increased and remained in the brownish-yellow range of 16–17. In contrast, the a* value of group H+US showed a significant drop in the early stages (down to around 5–6), and its yellowness (b*) was consistently suppressed and lower than that of group H (maintained at around 14–15). This "double decrease in red and yellow" fading phenomenon is more directly caused by the mechanical scouring effect of ultrasound, which accelerates the loss of a large amount of polar juice.

[0032] Table 1. Effects of single water bath treatment (Group H) on beef color parameters and total color difference.

[0033] Table 2. Effects of combined ultrasonic and water bath treatment (H+US group) on beef color parameters and total color difference.

[0034] Example 5 The specific steps of ultrasonic treatment to deconstruct the microstructure of beef are as follows: Beef from the control group and beef treated with different methods in Example 1 were cut into cubes of approximately 10×10×10 mm and immediately immersed in 2.5% glutaraldehyde solution. The cubes were then fixed overnight at 4°C in the dark to prevent cell autolysis and maintain tissue structure. After fixation, the samples were rinsed three times (10 min each time) with 0.1 mol / L phosphate-buffered saline (PBS) to remove excess fixative. Subsequently, the samples were dehydrated sequentially with 30%, 50%, 70%, 80%, and 90% ethanol solutions (10–15 min each time), and finally dehydrated twice with 100% anhydrous ethanol (10 min each time). After dehydration, the samples were dried at the critical point of carbon dioxide, fixed on a stage, and ion-sputtered with gold. The longitudinal section morphology of beef muscle fibers was observed and images were acquired under a scanning electron microscope at an appropriate accelerating voltage.

[0035] Dramatic changes in macroscopic physicochemical and mass transfer properties can usually be found in the corresponding physical structure at the microscopic morphological level. For example... Figure 4 As shown, scanning electron microscopy allows for direct observation of the degree of damage to the beef muscle fiber matrix caused by different treatment methods. In the control group (C), the muscle fiber surface was relatively smooth, with the fiber bundles arranged in a tightly ordered parallel pattern along their long axis. After a single heat treatment (H), heat-induced collagen denaturation led to a slight expansion of the gaps between fibers, but the overall cellular barrier and muscle bundle network framework maintained good integrity. In contrast, the H+US group exhibited a significant characteristic of strong deconstruction in its microstructure. Not only were the gaps between muscle fibers abnormally magnified, but transverse brittle fractures of some muscle fibers and large-scale fragmentation of the entire tissue network were also clearly observed.

[0036] Example 6 The sensory evaluation of beef follows these steps: Ten students (five men and five women) with professional training in sensory evaluation were invited to form an evaluation panel. Prepared beef samples were placed on clean plates and provided to the panel members for evaluation of the product's color, texture, flavor, mouthfeel, and juiciness. The sensory evaluation criteria for the beef are shown in Table 3.

[0037] Table 3 Sensory Evaluation Criteria for Beef

[0038] Sensory evaluation results of beef treated with different methods, such as Figure 5 As shown in the table, there are significant differences in color, texture, flavor, mouthfeel, and juiciness among the different treatment groups. The sample with the highest radar cross-section (RCS) area (90℃, 100W, 60s) achieved the highest scores in these aspects. While the purine dissolution effect was good under the conditions of 100℃, 100W, and 60s, it had a certain impact on the sensory quality of the beef. The high temperature of 100℃ significantly affected the flavor, mouthfeel, and juiciness of the beef. Considering factors such as purine dissolution, actual engineering energy consumption, and the quality of the treated beef, the optimal ultrasonic processing conditions for reducing purine content were determined to be: 90℃, 100W, and 60s.

[0039] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A highly efficient ultrasonic processing method for reducing the purine content of beef, characterized in that, Includes the following steps: The beef slices were placed in ultrapure water and subjected to ultrasonic-assisted processing while being heated in a water bath.

2. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 1, characterized in that, The water bath heating temperature is 80~100℃, the ultrasonic treatment power is 100~300 W, and the ultrasonic treatment time is 10~60 s.

3. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 2, characterized in that, The water bath heating temperature is 90℃, the ultrasonic treatment power is 100 W, and the ultrasonic treatment time is 60 s.

4. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 1, characterized in that, Before ultrasonic combined heat treatment, the beef slices are first deboned of visible fascia and fat, washed and left to stand at room temperature for 10 minutes, and then cut into uniform slices with a size of 30 mm × 30 mm × 2 mm.

5. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 1, characterized in that, Each slice of beef was mixed with 50 mL of ultrapure water.

6. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 1, characterized in that, The ultrasonic processing method increases the amount of purines dissolved in beef and improves the centrifugal water retention rate to over 98%.

7. The ultrasonic processing method for efficiently reducing the purine content of beef according to claim 1, characterized in that, The ultrasonic processing method employs a water bath constant temperature oscillator for ultrasonic combined heat treatment.

8. The ultrasonic processing method for efficiently reducing the purine content of beef according to any one of claims 1 to 7, characterized in that, The beef in question is beef tenderloin.

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