Highland barley bran protein and application thereof in improving quality of meat products and preparing meat product modifier

Abstract

The invention discloses highland barley bran protein and application thereof in improving meat product quality and preparing a meat product modifier, and belongs to the technical field of food. The highland barley bran protein and the modified product thereof are added into the meat product, so that the color, the water binding capacity, the cooking loss rate, the texture and the sensory characteristics of the meat product can be improved to different degrees. Therefore, when the highland barley bran protein and the modified bran protein thereof are applied to meat product processing, the waste highland barley bran can be utilized, the quality of the meat product can be improved, and meanwhile, the highland barley bran protein and the modified bran protein thereof serving as the meat product modifier have the characteristics of being green, nutritional and safe. Therefore, a new thought can be provided for utilization of the highland barley bran protein, and the economic benefits of the highland barley bran are increased.

Description

Technical Field

[0001] The present invention relates to the field of food technology, and more particularly, to hulless barley bran protein and its application in improving the quality of meat products and preparing meat product improvers. Background Art

[0002] Hulless barley ( Hordeum vulgare var. coeleste Linnaeus), also known as highland barley, hulless barley or naked barley, is a special variety of barley. It is rich in various bioactive compounds and is considered a healthy food with potential functions of preventing or treating cancer, cardiovascular diseases and metabolic syndrome, and is a crop with great economic promise.

[0003] Hulless barley has a relatively thick seed coat, so it needs to be dehulled during the processing and production process. A large amount of by-product hulless barley bran is generated during this process, accounting for more than 30% of the total amount of hulless barley. Due to the relatively rough taste and poor palatability of hulless barley bran, most of the hulless barley bran is still used as animal feed or directly discarded, resulting in waste of resources. However, the contents of natural active substances such as protein and cellulose in hulless barley bran are higher than those of the raw material hulless barley and also higher than those of other grains.

[0004] Compared with the research on other active ingredients, the current research on hulless barley bran protein is relatively less, and compared with hulless barley whole grains, the protein content of hulless barley bran is higher. The current research on plant proteins has received extensive attention, so it is very necessary to study the characteristics and uses of hulless barley bran protein, which can not only provide more sources of high-quality plant proteins, but also provide more ideas for developing more hulless barley bran protein products and increasing the economic benefits of hulless barley bran.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to provide hulless barley bran protein and its application in meat products.

[0007] The present invention is implemented as follows: On the one hand, the present invention provides the application of hulless barley bran protein in improving the quality of meat products.

[0008] In some embodiments, the above-mentioned quality includes: color, water holding capacity, cooking loss rate, texture and sensory characteristics.

[0009] In some embodiments, the above-mentioned meat products include meatballs. Specifically, the meatballs include pork meatballs, beef meatballs, mutton meatballs, chicken meatballs and fish meatballs.

[0010] In some embodiments, the above-mentioned hulled barley bran protein includes white hulled barley bran protein and black hulled barley bran protein.

[0011] In some embodiments, the above-mentioned hulled barley bran protein includes modified hulled barley bran protein. Here, the modified hulled barley bran protein includes modified black hulled barley bran protein and modified white hulled barley bran protein.

[0012] Since the utilization of hulled barley bran is relatively low because the functional properties of hulled barley bran protein, such as extensibility, solubility, foaming activity and stability, water holding capacity, and oil holding capacity, are often poor, which hinders its application in food. To overcome this problem, the present invention modifies the obtained hulled barley bran protein so that the obtained modified bran protein can be better utilized.

[0013] For the modification method, the present invention selects pH shift and / or ultrasonic treatment. Among them, ultrasonic treatment is: through the action of ultrasonic waves, the spatial structure of proteins can be destroyed, making its molecules easier to combine with other substances, thereby improving the functionality of proteins.

[0014] pH shift modification is: when proteins are exposed to extreme alkaline or acidic pH conditions far from the isoelectric point of the protein, the increased repulsive force between proteins will cause partial unfolding of protein molecules. Then the solution is adjusted back to pH 7, and the proteins refold, resulting in a more flexible structure, called the "molten state". This unfolding and refolding process significantly changes the structure and functional properties of proteins.

[0015] In some embodiments, the modified hulled barley bran protein is obtained by modifying the crude product of hulled barley bran protein through pH shift and / or ultrasonic treatment.

[0016] Since the nutrient contents in bran of different colors are different, and some studies have shown that the total phenolic contents such as fiber, protein, flavonoids, and anthocyanins in colored bran are higher than those in white bran. Based on this, the present invention conducts research on hulled barley with different bran colors and finds that there are not only certain differences in protein content between white hulled barley bran protein and black hulled barley bran protein, but also differences in their properties: when the black / white hulled barley bran proteins are modified under the same conditions, the two bran proteins have different effects. From the overall properties, white hulled barley bran protein is more suitable for alkaline treatment during pH shift treatment, and black hulled barley bran protein is more suitable for acidic treatment during pH shift treatment.

[0017] In some embodiments, the pH shift treatment of white hulled barley bran protein includes: adding an alkaline solution to the crude product of the white hulled barley bran protein, adjusting its pH to 9 - 12, and then adjusting it back to neutral after the reaction.

[0018] In some embodiments, the pH shift treatment of black hulless barley bran protein includes: adding an acidic solution to the crude product of the black hulless barley bran protein, adjusting its pH to 2 - 5, and then adjusting it to neutral after the reaction.

[0019] In some embodiments, the conditions for ultrasonic treatment of hulless barley bran protein are: ultrasonic power is 100 - 300W, and ultrasonic time is 10 - 20min.

[0020] On the other hand, the present invention provides a meat product improver, which includes the above-mentioned hulless barley bran protein.

[0021] In some embodiments, the added mass of hulless barley bran protein in the meat product is 1% - 10%.

[0022] The present invention has the following beneficial effects: The present invention extracts bran protein from hulless barley bran with different bran colors and modifies it. The obtained product has improved water - holding capacity, oil - holding capacity, solubility, emulsifying property, foaming property, foam - holding property and gel property, etc. Adding the modified bran protein to the meat product can improve the color, water - holding capacity, cooking loss rate, texture and sensory properties of the meat product to varying degrees. Therefore, applying hulless barley bran protein and its modified bran protein to meat product processing can not only utilize the discarded hulless barley bran, but also improve the quality of meat products. At the same time, using hulless barley bran protein and its modified bran protein as meat product improvers also has the characteristics of green, nutritious and safe. Therefore, the present invention can provide new ideas for the utilization of hulless barley bran protein and increase the economic benefits of hulless barley bran. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0024] Figure 1 For the effect of ultrasonic combined with pH treatment on the water - holding capacity of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; different letters in the figure indicate significant differences (P < 0.05), the same below; Figure 2 For the effect of ultrasonic combined with pH treatment on the oil - holding capacity of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 3 For the effect of ultrasonic combined with pH treatment on the solubility of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 4 To study the effect of ultrasonic combined with pH treatment on the emulsifying activity of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 5 To observe the microscopy of black / white hulless barley bran protein emulsions treated with ultrasonic combined with pH in Experimental Example 1; Figure 6 To study the effect of ultrasonic combined with pH treatment on the foaming stability of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 7 To study the effect of ultrasonic combined with pH treatment on the storage modulus and loss modulus of temperature scanning of black / white hulless barley bran proteins in Experimental Example 1; (A) and (B) are the storage modulus and loss modulus of black hulless barley bran protein, and (C) and (D) are the storage modulus and loss modulus of white hulless barley bran protein; Figure 8 To study the effect of ultrasonic combined with pH treatment on the storage modulus and loss modulus of frequency scanning of black / white hulless barley bran proteins in Experimental Example 1; (A) and (B) are the storage modulus and loss modulus of black hulless barley bran protein, and (C) and (D) are the storage modulus and loss modulus of white hulless barley bran protein; Figure 9 To study the effect of ultrasonic combined with pH treatment on the ultraviolet scanning spectra of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 10 To study the effect of ultrasonic combined with pH treatment on the fluorescence scanning spectra of black hulless barley bran protein (A) / white hulless barley bran protein (B) in Experimental Example 1; Figure 11 To study the effect of adding different hulless barley bran proteins on the chromaticity of pork balls in Experimental Example 2; Figure 12 To study the effect of adding different hulless barley bran proteins on the cooking loss rate of pork balls in Experimental Example 2; Figure 13 To study the effect of adding different hulless barley bran proteins on the texture of pork balls in Experimental Example 2; Figure 14 To study the effect of adding different hulless barley bran proteins on the cross-section of pork balls in Experimental Example 2; Figure 15 Color of black / white hulless barley bran proteins; Figure 16 Results of the thawing juice loss rate of meatballs in Experimental Example 3; Figure 17 Results of the cooking loss of meatballs in Experimental Example 3; Figure 18 Results of the cooking loss rate of meatballs in Experimental Example 4; Figure 19Results of the texture of meatballs in Experimental Example 4; Figure 20 Results of the thawing juice loss rate of meatballs in Experimental Example 4; Figure 21 Results of the chromaticity of meatballs in Experimental Example 4. Detailed implementation manners

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained by purchasing in the market.

[0026] The features and properties of the present invention will be further described in detail below in conjunction with the embodiments.

[0027] Embodiment 1 This embodiment is for the extraction of hulless barley bran protein. The alkali dissolution and acid precipitation method is used to extract black hulless barley bran protein and white hulless barley bran protein respectively. The specific steps are as follows: (1) The black hulless barley bran powder and the white hulless barley bran powder are respectively sieved through a 80-mesh sieve; (2) The bran powder and distilled water are mixed at a ratio of 1:15 (mass ratio) to obtain a mixed solution; (3) Use 1 mol / L sodium hydroxide solution to adjust the pH of the mixed solution to 11.5; (4) React and extract in a water bath at 30 °C for 90 min; (5) Centrifuge at a speed of 8000 r / min for 10 min and take the supernatant; (6) Use 1 mol / L hydrochloric acid solution to adjust the pH of the supernatant to the isoelectric point of 4.5; (7) Centrifuge at a speed of 8000 r / min for 10 min and take the precipitate; (8) Use 1 mol / L sodium hydroxide solution to adjust the pH of the precipitate to neutral; (9) Obtain protein powder after freeze-drying.

[0028] Embodiment 2 This embodiment is for obtaining modified black hulless barley bran protein. The specific steps are as follows: (1) The protein powder obtained by freeze-drying in Embodiment 1 and distilled water are configured into a solution at a ratio of 1:20 (protein powder mass: water mass), and stirred on a magnetic stirrer for 20 min for full fusion; (2) Take an appropriate amount of the prepared protein solution, use 1 mol / L hydrochloric acid solution to adjust the pH of the protein solution to 2, and place it for reaction for 1 h; (3)Then adjust the protein solution to neutral with 1 mol / L sodium hydroxide solution; (4)Then use a cell disruptor to treat it at an ultrasonic power of 300 W for 10 min. To prevent the temperature from rising during the treatment, place the beaker containing the protein solution in crushed ice. The obtained protein solution is freeze-dried to obtain the combined modified protein.

[0029] Example 3 This example is for obtaining modified white hulless barley bran protein, and the specific steps are as follows: (1)The protein powder obtained by freeze-drying in Example 1 and distilled water are configured into a solution according to a ratio of 1:20 (protein powder mass: water mass), and stirred on a magnetic stirrer for 20 min to fully blend; (2)Take an appropriate amount of the prepared protein solution, adjust the pH of the protein solution to 11 with 1 mol / L sodium hydroxide solution, and let it react for 1 h; (3)Then adjust it to neutral with 1 mol / L hydrochloric acid solution; (4)Then use a cell disruptor to treat it at an ultrasonic power of 300 W for 10 min. To prevent the temperature from rising during the treatment, place the beaker containing the protein solution in crushed ice. The obtained protein solution is freeze-dried to obtain the combined modified protein.

[0030] Comparative Example 1 The difference from Example 2 is that the modification treatment only performs pH shift and does not perform ultrasonic treatment.

[0031] Comparative Example 2 The difference from Example 2 is that the modification treatment only performs ultrasonic treatment and does not perform pH shift.

[0032] Comparative Example 3 The difference from Example 3 is that the modification treatment only performs pH shift and does not perform ultrasonic treatment.

[0033] Comparative Example 4 The difference from Example 3 is that the modification treatment only performs ultrasonic treatment and does not perform pH shift.

[0034] Experimental Example 1 Detect the functional properties of the modified protein powders obtained in Examples 2-3 and Comparative Examples 1-4, including: water-holding capacity, oil-holding capacity, solubility, emulsifying property, foaming property, foam stability, gel property, ultraviolet scanning spectrum, and fluorescence scanning spectrum.

[0035] 1. Water-holding capacity Weigh protein powder with a mass of M0 (accurate to four decimal places) and put it into a test tube. Weigh the total weight of the powder and the test tube and record it as M1. Add 5 mL of pure water to the test tube, mix it on a vortex mixer for 10 min, and let it stand at room temperature for reaction for 40 min. Centrifuge it at a speed of 8000 r / min for 10 min, pour out the supernatant, invert the test tube on filter paper and let it stand for 10 min, wipe off the residual water on the inner wall, and weigh the total weight of the precipitate and the test tube as M2. The calculation formula is as follows: Water holding capacity (g / g) = (M2 - M1) / M0 In the formula, M0 is the mass of the weighed protein powder (g), M1 is the total mass of the powder and the test tube (g), and M2 is the total mass of the precipitate and the test tube after centrifugation with water added (g).

[0036] The test results are as Figure 1 shown. Figure 1 It can be seen from A that the water holding capacity of black hulless barley bran protein is better after ultrasonic treatment than that after single pH shift treatment; while the water holding capacity of the protein treated by pH shift combined with ultrasonic treatment has not been significantly improved. Figure 1 B shows that the water holding capacity of white hulless barley bran protein after single pH shift treatment is significantly lower than that of ultrasonic-treated and untreated proteins, but the water holding capacity of the protein treated by pH shift combined with ultrasonic treatment decreases compared with the untreated protein, which may be due to the influence of pH shift treatment that reduces the water holding capacity of the combined-treated protein.

[0037] 2. Oil holding capacity Weigh protein powder with a mass of N0 (accurate to four decimal places) and put it into a test tube. Weigh the total weight of the powder and the test tube and record it as N1. Add 5 mL of soybean oil to the test tube, mix it on a vortex mixer for 10 min, and let it stand at room temperature for reaction for 40 min. Then centrifuge it at a speed of 8000 r / min for 10 min, pour out the supernatant, invert the test tube on filter paper and let it stand for 10 min, wipe off the residual soybean oil on the inner wall, and weigh the total weight of the precipitate and the test tube as N2. The calculation formula is as follows: Oil holding capacity (g / g) = (N2 - N1) / N0 In the formula, N0 is the mass of the weighed protein powder (g), N1 is the total mass of the powder and the test tube (g), and N2 is the total mass of the precipitate and the test tube after centrifugation with soybean oil added (g).

[0038] The test results are as Figure 2 shown. From Figure 2As can be seen from A, the oil-holding capacity of black hulless barley bran protein after ultrasonic treatment alone is 1.44 times that of the protein after pH shift treatment alone, and 3.47 times that of the untreated protein. The oil-holding capacity of the protein after combined treatment is increased by 3.28 times compared with the control group, and 1.36 times compared with that after ultrasonic treatment alone. The results show that the oil-holding capacity of the protein after combined treatment is significantly improved (P<0.05), and the effect is significantly higher than that of pH shift treatment alone (P<0.05), which is consistent with the effect of ultrasonic treatment.

[0039] Figure 2 As shown in B, the oil-holding capacity of white hulless barley bran protein after ultrasonic treatment alone is 1.27 times that of pH shift treatment alone, and 2.07 times that of the untreated protein. The oil-holding capacity of the protein after combined treatment of pH shift and ultrasonic treatment is significantly higher than that of the protein after pH shift treatment alone and ultrasonic treatment alone, with an increase of 1.41 times (pH shift treatment) and 1.11 times (ultrasonic treatment), respectively. The results show that the oil-holding capacity of white hulless barley bran protein after combined treatment is significantly improved (P<0.05), and the improvement degree is significantly higher than that of pH shift treatment alone and ultrasonic treatment alone (P<0.05).

[0040] 3. Solubility Weigh an appropriate amount of protein powder and prepare a 0.1mg / mL solution. Mix it evenly on a vortex mixer for 10 minutes. After mixing, centrifuge it at a speed of 4000r / min for 10 minutes. Take 0.5mL of the supernatant and add it to 2.5mL of Coomassie Brilliant Blue solution. Mix well and react for 5 minutes. Measure the absorbance of the reaction solution at 595nm, and substitute it into the Coomassie Brilliant Blue standard curve to calculate the solubility. The calculation formula is as follows: Solubility (%) = 100% * concentration of protein in supernatant / total protein concentration Figure 3 As shown in A, the solubility of black hulless barley bran protein after combined treatment is significantly improved (P<0.05), but it decreases compared with that after single treatment, from 46.06% (pH shift treatment) and 51.12% (ultrasonic treatment) to 30.31%. This shows that for the solubility of black hulless barley bran protein, the effect of combined treatment is not as good as that of single treatment. This may be because the turbulent force generated by ultrasonic action during the treatment process accelerates the collision and aggregation speed between protein molecules, causing a certain degree of aggregation of the protein. At the same time, when the pH2 treatment is adjusted back to neutral, passing through the isoelectric point also causes the protein to fold and aggregate, resulting in a decrease in the solubility of the protein after combined treatment compared with single treatment.

[0041] From Figure 3As can be seen from B, the solubility of white hulless barley bran protein increased significantly after combined treatment (P<0.05), from 29.66% to 43.54%. There was no significant difference in the protein solubility of the combined treatment compared with that of the individual pH shift treatment and the individual ultrasonic treatment. The results showed that the combined treatment could significantly improve the protein solubility (P<0.05), and there was no significant difference in the improvement effect of protein solubility compared with the individual treatment.

[0042] 4. Emulsifying property (1)Emulsifying activity The protein powder obtained by freeze-drying was prepared into a 10 mg / mL solution. The protein solution and soybean oil were mixed at a ratio of 3:1, and homogenized with a homogenizer at a speed of 20000 r / min for 2 min. Immediately, 50 μL of the emulsion was taken from the bottom and added to 5 mL of 0.1% (mass fraction) SDS solution, mixed well, and the absorbance A0 of the emulsion was measured at a wavelength of 500 nm. The calculation formula for emulsifying activity is as follows:

[0043] In the formula, T is the constant 2.303; A0 represents the absorbance of the obtained emulsion; Φ is the volume fraction of the oil phase.

[0044] (2)Emulsion turbidity Immediately, 50 μL was taken from the bottom of the emulsion homogenized by the homogenizer and added to 5 mL of pure water, shaken and mixed well, and the absorbance A1 was measured at a wavelength of 600 nm. The value of A1 was used as a reference for the emulsion turbidity.

[0045] Figure 4 It was shown that the emulsifying activity and emulsion turbidity of black / white hulless barley bran protein after combined pH shift and ultrasonic treatment were significantly improved compared with those of individual ultrasonic treatment (P<0.05). The emulsifying activities of black / white hulless barley bran protein increased from 26.42 m 2 / g and 25.1 m 2 / g to 31.43 m 2 / g and 31.52 m 2 / g, respectively. The pH shift treatment played a dominant role here. It can be seen that the ultrasonic treatment could not significantly improve the emulsifying activity of the protein. After the combined pH treatment, the pH shift increased the protein solubility and enhanced the exposure of hydrophobic groups, thus enhancing the emulsifying property of the protein.

[0046] (3)Microscopic observation of emulsion Immediately after the prepared emulsion was taken, 100 μL was drawn from the bottom and added to 1 mL of pure water for dilution. After mixing well, a small amount of the emulsion was taken and placed on a glass slide, and observed under an inverted microscope at a magnification.

[0047] From Figure 5It can be seen that without treatment, the particle size distributions of both protein emulsions are uneven, with a large number of aggregates. After single modification by pH offset, the distribution of emulsion particles is more dispersed, and the emulsion droplets become significantly smaller and more uniform; compared with the untreated emulsion, the aggregation and uneven distribution of the emulsion particles after ultrasonic treatment are improved, which may be due to the increased electrostatic repulsion and hydrophobicity between proteins after ultrasonic treatment, which prevent the aggregation of the emulsion; the emulsion particles after combined treatment of pH offset and ultrasonic treatment are the smallest and most evenly distributed. This result shows that the emulsifying effect of hulless barley protein after combined modification of pH offset and ultrasonic treatment is improved, which confirms the results of emulsifying activity and emulsion turbidity. This may be because when ultrasonic treatment and pH offset are combined, the protein unfolds completely to form a stable structure, promoting the formation of a protein film and increasing the interaction between protein and oil.

[0048] 5. Foaming ability and foam stability The protein powder was formulated into a 10 mg / mL solution, mixed and reacted for 20 min. Take 10 mL of the mixed solution and place it in a centrifuge tube. Use a homogenizer to homogenize it at a speed of 10000 r / min for 2 min, and immediately pour it into a 25 mL graduated cylinder. After stabilizing for 2 min, record the foam volume V0, and then record the foam volume V1 every 30 min. The calculation formulas for foaming ability and foam stability are as follows: Foaming ability (%) = 100 × V0 / 10 Foam stability (%) = 100 × V1 / V0 In the formula, V0 represents the volume of protein foam at the end of homogenization (mL); V1 represents the residual volume of protein foam after standing for 30 min (mL).

[0049] As Figure 6 shown in A, the foaming ability of black hulless barley bran protein was significantly improved (P < 0.05) after single pH offset and single ultrasonic treatment, and the improvement effects were similar, increasing by 1.37 times and 1.35 times respectively compared with the control. The foaming ability of the protein was improved the most after combined treatment (P < 0.05), increasing by 2.59 times compared with the control group, and increasing by 1.89 times (pH offset treatment) and 1.91 times (ultrasonic treatment) respectively compared with the two single treatments. The foam stability of the protein decreased significantly under all treatment conditions (P < 0.05). Especially after combined treatment, the foam stability of the protein was lower than that of the two single-modified proteins and the control group protein, decreasing from 59.24% of the control group, 37.34% of the single pH treatment, and 39.88% of the ultrasonic treatment to 24.34%.

[0050] Figure 6Figure B shows that the foaming ability of white hulless barley bran protein did not increase significantly after single pH shift treatment or single ultrasonic treatment compared with the control group. However, after the combined treatment, the foaming ability of white hulless barley bran protein increased significantly, from 60.67% to 116.67%, which was 1.92 times higher. After the combined treatment, the foam stability of the protein decreased significantly, lower than that of the two single modifications and also lower than that of the control group, decreasing from 55.48% (control), 36.93% (pH shift treatment), and 47.57% (ultrasonic treatment) to 32.60%. Ultrasonic waves cause the unfolding of protein molecules at the gas-liquid interface, increasing their ability to diffuse at the air-water interface to encapsulate air, thus producing better foaming ability. At the same time, the change in pH value also leads to the exposure of hydrophobic protein groups. After the combined treatment, the surface hydrophobicity can be improved, enabling the protein to have better solubility and smaller particle size. All these contribute to the improvement of foaming ability. After the combined treatment, the foaming ability of both proteins increased significantly, and the improvement effect was significantly higher than that of the single treatment (P<0.05).

[0051] 6. Gel properties The protein powder was formulated into a 12% solution and dynamic rheological measurements were performed using a rheometer in the linear viscoelastic region. The mixed solution was equilibrated for 60 seconds before each measurement. Glycerol was added to the edge of the parallel plate during the measurement to prevent water evaporation in the sample during the gelation process. First, a temperature scan was performed at a fixed frequency of 1 Hz and a constant strain of 1%. The protein sample solution was heated from 25 °C to 95 °C at a rate of 5 °C / min, then held at 95 °C for 30 min, and subsequently cooled from 95 °C to 25 °C at a rate of 5 °C / min. The storage modulus G' and loss modulus G'' of each sample were recorded. After the temperature scan was completed, a frequency scan was performed by applying an angular frequency of 0.1 - 100 rad / s and a fixed strain of 1%. The rheological parameters G' and G'' of the mixed gel were recorded.

[0052] The intersection temperature of the storage modulus and the loss modulus during the protein gelation process is defined as the gel point, that is, the starting point of gelation. The gelation temperature of untreated black hulless barley bran protein is 86.28 °C. The pH 2 shift treatment fails to reduce the gelation temperature of the protein. After ultrasonic treatment, the gelation temperature drops to 79.48 °C, while after the combined treatment, the gelation temperature of black hulless barley bran protein drops to 56.43 °C. The gelation temperature of white hulless barley bran protein without treatment is 93.04 °C. The pH 11 shift treatment also fails to reduce the gelation temperature of the protein. After the combined treatment, the gelation temperature of white hulless barley bran protein drops to 58.47 °C. Ultrasonic treatment can increase the sensitivity of the protein to heating, thereby causing the protein to aggregate and gel. Research by TongXing et al. has shown that after ultrasonic treatment, the gel point of chicken protein drops from above 65 °C to between 55.30 - 54.50 °C. The decrease in the protein gel point temperature after the combined treatment is more than that of the single ultrasonic treatment. The possible reasons are as follows: on the one hand, cavitation causes the molecules to move rapidly, and the shear force generated by ultrasonic cavitation is sufficient to break the weak protein bindings and thus break the protein chains, resulting in protein dissociation and partial unfolding, exposing hydrophobic groups and disulfide bonds, etc. Under the action of continuously increasing temperature, these unfolded proteins aggregate again to form a new protein network; on the other hand, the pH shift treatment causes the subunits in the protein to denature, and the sulfhydryl groups are oxidized to form disulfide bonds, and the new disulfide bonds further strengthen the covalent interaction between protein molecules and reinforce the gel network structure of the protein.

[0053] Figure 7 A - 7B shows that after the combined treatment of pH shift and ultrasound, the gel storage modulus value of black hulless barley bran protein increases significantly, and the improvement degree is greater than that of the single pH shift treatment and the single ultrasonic treatment. It can be seen that the storage modulus of the protein obtained by the combined treatment is 625.77 Pa at the end of the cooling stage. After the single pH shift treatment and the single ultrasonic treatment, the storage moduli are 371.74 Pa and 330.82 Pa respectively. The gel elasticity of the protein after the combined treatment increases by 1.68 times and 1.89 times compared with the single treatment. And during the constant temperature cooling stage, the storage modulus of the protein treated by combination is always higher than that of the single treatment and the untreated one, indicating that the gel properties of the protein after the combined treatment are higher than those of the single modification treatment. After 56.43 °C, the storage modulus of the protein treated by combination is always higher than the loss modulus, indicating that the protein gel obtained by the combined treatment has strong solid properties and belongs to a strong gel.

[0054] From Figure 7As can be seen from C-7D, the storage modulus value of white hulless barley bran protein after combined treatment is higher than that of single ultrasound treatment and single pH shift treatment. After the cooling stage, the storage modulus of white hulless barley bran protein treated by combination is 1157.66 Pa, while the storage modulus of white hulless barley bran after pH 11 shift treatment and ultrasound treatment are 317.32 Pa and 1113.70 Pa respectively. The gel elasticity of combined treatment is 3.65 times higher than that of single pH shift treatment, significantly improving the gel properties of the protein. After the heating and cooling stages, the storage modulus and loss modulus of the combined treatment protein are always higher than those of the single pH shift treatment, indicating that the gel properties after combined treatment are much greater than those of the single pH shift treatment. During this process, the storage modulus of the protein is always greater than the loss modulus, indicating that the white hulless barley bran protein forms a strong gel after combined treatment, showing strong solid properties. The change of storage modulus at the end point shows that the combined action can maximize the elasticity and strength of the gel and the compactness of the network structure.

[0055] Figure 8 It shows the changes of the storage modulus and loss modulus of black / white hulless barley bran protein with angular frequency after the cooling stage. At the same angular frequency, compared with the untreated protein, the storage modulus of black and white hulless barley bran protein after all treatments is significantly higher than the loss modulus value, indicating that the black / white hulless barley bran protein after treatment has strong solid gel-like properties. As the angular frequency increases, the storage modulus and loss modulus of black and white hulless barley bran protein before and after treatment also increase continuously. The storage modulus and loss modulus have strong angular frequency dependence, indicating that the gel structure is mainly maintained by non-covalent bonds, and the gel belongs to physical gel rather than covalent gel.

[0056] After the combined treatment of pH 2 shift and ultrasound, the storage modulus and loss modulus of black hulless barley bran protein increased from 54.87 Pa and 86.16 Pa to 1072.53 Pa and 359.80 Pa respectively ( Figure 8 A-8B). At any angular frequency after combined treatment, the storage modulus of the protein is significantly higher than that of single treatment, indicating that the gel strength of the protein is the strongest after combined treatment. The storage modulus of untreated black hulless barley bran protein is lower than the loss modulus, showing a weak gel in liquid state. After combined treatment, the storage modulus of black hulless barley bran protein is higher than the loss modulus, realizing the strengthening of black hulless barley bran protein gel and transforming into solid state, which is a strong gel. After the combined treatment of pH 11 shift and ultrasound, the storage modulus and loss modulus of white hulless barley bran protein increased from 369.38 Pa and 213.17 Pa to 2141.41 Pa and 785.90 Pa respectively ( Figure 8C-8D), higher than the storage modulus of the individual treatment, the protein gel strength was improved after the combined treatment. The storage modulus value of the combined treatment protein was always greater than the loss modulus value, and the protein showed strong gel properties. After the combined treatment, compared with the individual pH shift treatment, it was more able to enhance the gel strength and gel properties of white hulless barley bran protein.

[0057] 7. UV scanning spectrum The protein powder was prepared into a solution with a concentration of 0.4 mg / mL, mixed and reacted for 20 min, and centrifuged at 2500 r / min for 5 min in a centrifuge. An appropriate amount of the supernatant was taken and subjected to spectral scanning in the 200 - 400 nm wavelength band in a UV spectrophotometer.

[0058] As can be seen from Figure 9 A, after the combined treatment of pH shift and ultrasonic treatment, the absorption peak of black hulless barley bran protein at 280 nm was much larger than that of the individual treatment and the untreated protein. This may be because the ultrasonic cavitation effect after the combined treatment caused conformational changes in the protein, and the unfolding and refolding of the protein after the pH shift treatment may have disrupted the hydrophobic interactions and van der Waals forces between protein molecules, causing the protein structure to unfold. The combined treatment opened the protein structure to a greater extent, enhanced the exposure of protein residues, and increased the absorption peak. After the combined treatment, the absorption peak of white hulless barley bran protein decreased and was lower than the absorption peak before treatment ( Figure 9 B). This may be due to the increase in temperature during the ultrasonic treatment, and the aggregation of white hulless barley bran protein wrapped the amino acid residues, resulting in a decrease in the absorption peak.

[0059] 8. Fluorescence scanning spectrum The protein powder was prepared into a solution with a concentration of 0.4 mg / mL, mixed and reacted for 20 min, and centrifuged at 2500 r / min for 5 min in a centrifuge. An appropriate amount of the supernatant was taken, and the fluorescence spectrum was recorded using an RF-6000 fluorescence spectrometer with an excitation wavelength of 280 nm and an emission wavelength of 300 - 500 nm at a minimum scanning rate of 2000 nm.

[0060] Figure 10The results showed that after the combined treatment, the maximum absorption wavelength of black / white hulless barley bran protein exhibited a red shift of 1-2 nm, and the fluorescence intensity decreased. The red shift indicates a change in the polarity of the protein solution, which means the protein structure has been affected. The decrease in fluorescence intensity at this time should be due to the fact that when the combined treatment adjusted back to neutrality and the protein unfolded, the fluorescence intensity of tryptophan decreased due to the exposure of tryptophan residues. Moreover, since heat is generated during the ultrasonic treatment, heating enhances the interaction between exposed hydrophobic amino acid residues by forming larger insoluble aggregates through hydrophobic bonds, resulting in fluorescence quenching. Yizhou Sun et al. also found that the fluorescence intensity of coconut milk protein obtained by combined acid pH shift and ultrasonic treatment was lower than that obtained by acid pH shift treatment alone. They believed that the cavitation generated by ultrasound accelerated the formation of large aggregates, promoted the oxidation of sulfhydryl groups to form disulfide bonds, thereby reducing the exposed chromophores and fluorescence intensity.

[0061] The combined treatment can effectively improve the degree of improvement of the oil-holding capacity, foaming property, and gel properties by pH shift treatment, and at the same time improve the degree of improvement of the emulsifying property, foaming property, and gel properties of the protein by ultrasonic treatment. Moreover, after the combined treatment, the foaming and gel properties of the protein were significantly enhanced compared with the individual pH shift or ultrasonic treatment.

[0062] Experimental Example 2 The black and white hulless barley bran proteins obtained in Example 1 and the modified hulless barley bran proteins in Examples 2-3 were respectively added to pork meatballs to detect their effects on the properties of pork meatballs, as follows: Lean pork and fat pork were mixed and minced according to a mass ratio of 3:1, 30% ice water and appropriate amounts of salt, five-spice powder and other seasonings were added and mixed evenly to obtain a mixed meat paste. Then, the black and white hulless barley bran proteins obtained in Example 1 and the modified hulless barley bran proteins in Examples 2-3 were added to the mixed meat paste according to a mass ratio of 5%, and made into meatballs of a certain size and cooked at 95 °C for 30 min to obtain formed meatballs. Among them, BHBBP represents unmodified black hulless barley bran protein, WHBBP represents unmodified white hulless barley bran protein, UpH-BHBBP represents modified black hulless barley bran protein, and UpH-WHBBP represents modified white hulless barley bran protein.

[0063] 1. Color change of meatballs The meatballs were cut open to be flat, and a colorimeter was used to measure the color of the cut surface of the meatballs. Before measurement, it was calibrated with a white board, and the brightness value (L*), redness value (a*), and yellowness value (b*) were recorded.

[0064] Color is associated with the appearance and acceptability of meat products. The color of meat is an important condition for evaluating the freshness of meat. Brightness (L*) and redness (a*) are important indicators reflecting the color of meat. The higher the myoglobin content, that is, the greater the lean meat content, the more vivid red the color appears.

[0065] It can be seen from Figure 11 that after adding protein, the brightness and yellowness of the meatballs decreased significantly, while the redness increased significantly (P<0.05). An excessively high L* value is due to the poor water-holding capacity of the sample and more internal water migration. It can be seen that the brightness of the pork meatballs without added protein is the highest, while the brightness of the pork meatballs after adding protein decreased significantly (P<0.05). Combining the results of the cooking loss rate, it can be known that the water-holding capacity of the meatballs without added protein is poor and the cooking loss rate is high, which will cause the water in the meatballs to lose and the brightness value to increase. After adding protein, the cooking loss rate of the meatballs decreased. The addition of protein makes the meatballs have good water-holding capacity and less water loss, resulting in a decrease in the surface gloss of the sample. At the same time, the brightness of the meatballs added with white hulless barley bran protein before and after modification is lower than that of the meatballs added with black hulless barley bran protein before and after modification. This is probably due to the color of the protein itself. In contrast, the color of black hulless barley bran protein is brighter. After adding protein, the redness value of the meatballs increased significantly, especially in the group added with modified white hulless barley bran protein, and the redness value reached the highest. The reason is that the reddish-brown color of the white hulless barley bran protein itself changed the color of the meatballs, and the increase in the redness value is more likely to attract the attention of consumers.

[0066] 2. Cooking loss rate of meatballs The weight of each portion of meat paste before cooking is recorded as W1. After the cooked meatballs are fished out and cooled to room temperature, the surface moisture is wiped off and the weight is recorded as W2. The calculation formula for the cooking loss rate of the meatballs is: Cooking loss rate (%) = (W1 - W2) / W1 In the formula, W1 is the mass of the raw pork meatballs before cooking (g), and W2 is the mass of the cooked pork meatballs (g).

[0067] The cooking yield is usually measured by the ability of protein to fix water and fat, and is an important indicator for measuring the loss of meat during cooking at high temperature. More cooking loss will reduce the taste, flavor and nutrition of meat. Figure 12It can be seen that the highest cooking loss rate of the control group without added protein was 25.87%. The cooking loss rates of the meatballs with added unmodified black hulless barley bran protein and added white hulless barley bran protein were significantly reduced, from 25.87% to 18.52% and 22.72% (P<0.05). The loss rate of the meatballs with added black hulless barley bran protein was significantly lower than that of the meatballs with added white hulless barley bran protein (P<0.05). Compared with the cooking loss rates of the control and the meatballs with added untreated protein, the cooking loss rates of the meatballs with added combined modified protein reached the lowest, 10.13% (combined treated black hulless barley bran protein) and 11.34% (combined treated white hulless barley bran protein) respectively, and the improvement degrees of the two combined modified hulless barley bran proteins on the cooking loss rate of the meatballs were the same. After adding protein, the protein played the characteristics of holding water and oil during the cooking process, and the protein formed a gel during the heating process, which also locked the juice in the meatballs, making it difficult for the water in the meatballs to flow out. Compared with the unmodified protein, the modified protein had higher water-holding and oil-holding properties and stronger gel properties. During the heating process, a tight gel network was formed, enhancing the binding performance of the pork meatballs with water and locking the water and oil, resulting in a reduction in the juice loss rate of the meatballs and an improvement in the cooking loss.

[0068] 3. Texture of meatballs The cooled pork meatballs were cut into samples of the same size and height and measured using a texture analyzer. Each group was measured three times. Before the measurement, the height and force of the instrument were corrected. The test mode was TPA; the test rate was 5 mm / s; the deformation was 40%; the time interval between two presses was 5 s; the trigger type was automatic; the trigger force was 5 g.

[0069] From Figure 13It can be seen that adding both proteins can significantly improve the hardness of pork balls. The hardness of the pork balls added with unmodified black hulless barley bran protein is higher than that of the pork balls added with unmodified white hulless barley bran protein. For the pork balls added with combined modified black / white hulless barley bran proteins, the hardness increased significantly from 471.12 to 1049.38 and 982.49 respectively (P<0.05). After adding proteins, the protein content of the pork balls increased. During the cooking process, the proteins in the pork balls were fully denatured, forming a more stable structure, which improved the hardness and chewiness of the pork balls. Adding the two unmodified proteins to the pork balls did not significantly improve the elasticity of the pork balls, while adding the combined modified proteins could significantly improve the elasticity of the pork balls (P<0.05), increasing from 0.82 (control group) to 0.95 (group added with modified black hulless barley bran protein) and 0.92 (group added with modified white hulless barley bran protein) respectively. This may be because the modified proteins have better gel properties and form gels during the cooking process, thus enhancing the elasticity of the pork balls. Compared with the control, adding proteins can significantly improve the chewiness of the pork balls (P<0.05). For the pork balls added with the two unmodified proteins, the chewiness increased significantly from 232.39 to 419.99 (black hulless barley bran protein) and 356.58 (white hulless barley bran protein). For the groups added with modified proteins, the chewiness increased to 740.18 (black hulless barley bran protein) and 716.29 (white hulless barley bran protein), which were 3.19 and 3.08 times higher than that of the control group respectively.

[0070] 4. Observation of the cross-section of the pork balls The cooked and cooled pork balls were cut open, and the changes in the cross-section were photographed and recorded for observation.

[0071] From the cross-section Figure 14 It can be seen that adding the two proteins made the pork balls show different colors. The addition of black hulless barley bran protein made the pork balls show a dark brown color, which looked similar to the appearance of beef balls to the naked eye. After adding white hulless barley bran protein, the pork balls showed a light red color, similar to the appearance of red sausage. In contrast, the color of the pork balls without added protein was lighter, and adding proteins could make the color of the pork balls more attractive. The change in the color of the pork balls after adding proteins was due to the color of the proteins themselves. The black hulless barley bran protein was dark gray, and the white hulless barley bran protein was reddish-brown ( Figure 15 ). Adding proteins not only made the appearance of the pork balls more attractive but also improved the chewiness. From the appearance, adding black / white hulless barley bran proteins was beneficial to improving the color perception of the pork balls, making the pork balls have a more appealing appearance to attract consumers to purchase.

[0072] 5. Sensory evaluation of the pork balls Ten students from the School of Food Science were asked to taste and score the pork balls. Before tasting, they rinsed their mouths with clean water. The scoring criteria were as follows: Table 1 Sensory scoring criteria

[0073] The evaluation results are shown in Table 2: Table 2 Sensory evaluation results of meatballs

[0074] Note: Different letters in the same column indicate significant differences (P < 0.05).

[0075] As can be seen from Table 2, adding proteins before and after modification can significantly improve the color score of meatballs. Especially after adding the modified proteins, it increased by 2.27 times and 2.33 times respectively (P < 0.05); adding modified proteins can significantly improve the taste of meatballs (P < 0.05), increasing by 1.59 times and 1.5 times respectively. This may be because the special smell of plant proteins itself masks the fishy smell of some meatballs; the texture of the meatballs in the group adding unmodified proteins is not very different from that of the control group. Maybe the unmodified protein does not improve the elasticity of the meatballs enough to cause a significant texture difference. However, the protein after combined modification can significantly improve the elasticity, hardness and chewiness of the meatballs in terms of texture (P < 0.05), making the meatballs have a better texture; after adding proteins, the tissue state score of the meatballs is higher, especially in the group adding combined modified proteins. This may be because the modified proteins significantly enhance the gel strength of the meatballs, making the meatballs more compact and remaining in a tight state without falling apart when cut; it can be seen that the group adding combined modified proteins has the highest overall score, which is 2.31 times and 2.13 times higher than the control group, and 1.42 times higher than their respective unmodified protein groups. Adding combined modified proteins can significantly enhance the texture, appearance and taste of meatballs, and can significantly improve consumers' preference for meatballs.

[0076] Experimental Example 3 The method of Experimental Example 2 was used to verify the effect of the addition amount of white hulless barley bran protein on the texture properties of beef balls and mutton balls. The texture test results are shown in Table 3: Table 3 Results of the texture of beef and mutton meatballs

[0077] As can be seen from Table 3, an appropriate amount of white hulless barley bran protein can improve the lubricity of meatballs, making the texture more rich; however, too high an addition amount will lead to a rough texture of meatballs, a decrease in lubricity, and the overall taste will be affected. In summary, different addition amounts of white hulless barley bran protein have an impact on the texture, lubricity and taste of meatballs. Appropriate addition can improve the taste and texture of meatballs and enhance the eating experience.

[0078] Figure 16The thawing juice loss rate of beef and mutton meatballs with different contents of white hulless barley bran protein was measured. The results showed that appropriate addition of white hulless barley bran protein could improve the water retention of meatballs, making the meatballs more tender and juicy. However, when the addition amount was too high, it might lead to the meatballs being overly moist, affecting the taste and texture.

[0079] Table 4 shows the chromaticity test results of beef and mutton meatballs: Table 4 Chromaticity Results

[0080] As can be seen from Table 4, adding white hulless barley bran protein can make the surface of the meatballs show a more uniform color, which is beneficial to improving the overall appearance texture. Secondly, appropriate addition of white hulless barley bran protein can also increase the brightness of the meatballs, making them look more attractive and enhancing the appetite. In addition, white hulless barley bran protein can also improve the color stability of the meatballs, reducing color changes during heating or keeping warm, and maintaining the beauty of the product. Moreover, adding white hulless barley bran protein has a significant impact on the chromaticity of beef and mutton meatballs. After comparing the meatball samples of the experimental group and the control group, it was found that the meatballs added with white hulless barley bran protein showed a more uniform and bright color, and the overall color was relatively bright, having a better visual effect compared with traditional meatballs.

[0081] From Figure 17 the results, compared with traditional meat products, the meatballs added with white hulless barley bran protein showed a lower loss rate during steaming. The addition of white hulless barley bran protein not only improved the taste and chewiness of the meatballs, but also reduced the weight loss during steaming to a certain extent, maintaining the original fresh taste of the meat products. Generally speaking, as a functional ingredient, white hulless barley bran protein has a significant impact on the steaming loss in the production of meatballs.

[0082] Table 5 shows the sensory quality test results of beef and mutton meatballs: Table 5 Determination of Sensory Quality

[0083] As the addition amount of white hulless barley bran protein increases, the taste of beef and mutton meatballs will change to a certain extent. A reasonable addition amount can make the meatballs achieve a balance in taste, color and aroma, improving the overall sensory quality, so as to better meet more taste requirements.

[0084] To sum up, when the content of white hulless barley bran protein is 2%, the proportion of thawing water loss rate of beef meatballs is relatively small, which can well maintain the texture of the meatballs and present good soft elasticity; while for mutton meatballs, when the content of white hulless barley bran protein is 4%, the texture of the meatballs is better.

[0085] Experimental Example 4 The method of Experimental Example 2 was used to verify the effect of the addition amount of black hulless barley bran protein on the cooking loss rate of chicken and fish meatballs. The detection results of the cooking loss rate, texture, thawing juice loss rate, and chromaticity are as Figures 18 - 21 shown below: As can be seen from Figure 18 it, the addition of black hulless barley bran protein does help reduce the water loss of meatballs during cooking, thus improving the water retention of meatballs. Specifically, by comparing the changes in the cooking loss rates of fish and chicken meatballs, it can be found that although both benefit from the addition of black hulless barley bran protein, the specific response patterns may be slightly different. The initial loss rate of chicken meatballs is lower, showing a relatively stable downward trend as the protein addition amount increases. For fish meatballs, with a higher initial loss rate, a greater improvement in water retention is achieved by adding black hulless barley bran protein.

[0086] Figure 19 Figure A in

[0087] As can be seen from Figure 20 it, the addition of black hulless barley bran protein has a positive impact on the texture characteristics of both fish and chicken meatballs. By adjusting the protein addition amount, the hardness, elasticity, and chewiness of meatballs can be effectively improved, providing consumers with more delicious and nutritious meat products.

[0088] Figure 21 Figure A in

[0089] Table 6 shows the sensory evaluation results of fish and chicken meatballs: Table 6 Sensory Evaluation Results of Fish and Chicken Meatballs

[0090] As can be seen from the table, when added in an appropriate amount, black hulless barley bran protein can significantly improve the color, taste, texture, and tissue structure / elasticity of meatballs, thereby enhancing the overall quality of meatballs. However, excessive protein addition may lead to an overly firm texture. Therefore, the addition amount should be strictly controlled in actual applications.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Application of highland barley bran protein in improving the quality of meat products.

2. The use according to claim 1, characterized in that: The qualities include: color, water holding capacity, cooking loss, texture and sensory properties.

3. The use according to claim 1, characterized in that: The highland barley bran protein includes white highland barley bran protein and black highland barley bran protein.

4. The use according to claim 3, characterized in that: The highland barley bran protein includes modified highland barley bran protein.

5. The use according to claim 4, characterized in that: The modified highland barley bran protein is obtained by modifying the crude product of highland barley bran protein through pH shift and / or ultrasound.

6. The use according to claim 5, characterized in that: The pH shift treatment of the white highland barley bran protein comprises: adding an alkaline solution to the crude product of the white highland barley bran protein, adjusting the pH thereof to 9-12, and then adjusting the pH thereof to neutral after the reaction.

7. The use according to claim 5, characterized in that: The pH shift treatment of the black barley bran protein comprises: adding an acidic solution to the crude product of the black barley bran protein to adjust the pH thereof to 2-5, and then adjusting the pH thereof to neutral after the reaction.

8. The use according to claim 5, characterized in that: The conditions for ultrasonic treatment of highland barley bran protein are as follows: ultrasonic power is 100-300W, and ultrasonic time is 10-20min.

9. Application of highland barley bran protein in the preparation of meat product improvers.

10. The use according to claim 9, characterized in that: The added mass of the highland barley bran protein in the meat product is 1%-10%.

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