Wet extrusion protein with high juiciness, low beany flavor and high thermal stability and preparation method thereof

Abstract

The invention discloses juicy wet extruded protein with low beany flavor and high thermal stability and a preparation method. The juicy wet extruded protein comprises the following raw materials in parts by weight: 50-90 parts of pea protein isolate, 20-40 parts of yeast protein, 15-25 parts of vital gluten, 10-15 parts of glucose, 6-9 parts of microbial glutamine transaminase, 0.3-0.9 part of sodium alginate and 7-10 parts of tea polyphenol. The yeast protein and the pea protein isolate are mixed for use, so that the problems of extruded protein chromaticity and beany flavor are solved, and the fibrosis degree is improved; microbial glutamine transaminase is added, so that hydrophilic groups in protein are increased by applying an enzyme-linked Maillard technology to improve the water holding capacity of extruded protein, and the juiciness of a terminal product is improved; the modifier is synergistic (tea polyphenol amp; by enhancing protein complexation reaction and hydrophobic interaction and hydrogen bond linkage of amino acid residues, the heat stability of extruded protein is improved, and a hierarchical chemical fiber micro-network is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of plant proteins, and particularly to a wet-extruded protein with high juiciness, low soybean odor and high thermal stability, and a preparation method therefor. Background Art

[0002] At present, it is estimated that the global protein demand will increase by 60% in 2050. However, traditional animal husbandry consumes a large amount of land (70% of the world's arable land is used for feed), water (about 15,000 L of water is required to produce 1 kg of beef), and energy, and its carbon emissions account for 41% of the total agricultural emissions. Obviously, relying solely on traditional animal husbandry to meet the global protein demand will undoubtedly have a great impact on the ecological environment. Plant-based meat, through plant protein conversion technology, can achieve a production efficiency more than 10 times that of traditional animal husbandry, thus greatly reducing resource consumption and carbon footprint, and is an important path to ensure food security.

[0003] Among them, the wet (high-moisture) extrusion technology is an important basic technology in the plant-based meat industry. It recombines plant proteins (such as pea and soy protein isolate) through high temperature and high pressure to form a porous fiber network (with a diameter of about 40 - 80 μm), which can simulate the chewing feeling and elasticity of animal muscle, thus breaking through the "sponge-like" defect of traditional plant protein products (such as tofu). However, the existing wet extrusion process still has the following bottlenecks to be broken through:

[0004] (1) Insufficient degree of fibrosis: A single protein raw material (such as soy protein) is prone to form a uniform but loose structure, lacking the chewing feeling of real meat;

[0005] (2) Single fiber structure: Traditional methods rely only on physical means such as adjusting parameters such as moisture content, temperature, and rotational speed, and it is difficult to form a hierarchical fiber network;

[0006] (3) Insufficient thermal stability: Wet-extruded proteins often need to undergo high-temperature cooking or high-temperature sterilization processes in applications. However, the wet proteins prepared by the current process have insufficient thermal stability: their texture will be significantly reduced after high temperature;

[0007] (4) Poor water holding capacity: The high-moisture extrusion technology can produce a fiber structure similar to meat, but there is a problem of insufficient water holding capacity, resulting in insufficient juiciness in the final plant-based meat product;

[0008] (5) Strong soybean odor: The protein sources commonly used for wet extrusion are mostly soy protein and pea protein, and such proteins all have a certain soybean odor. Summary of the Invention

[0009] The object of the present invention is to provide a wet-extruded protein with high juice content, low soybean odor and high thermal stability, and a preparation method thereof, aiming to improve the problems of insufficient degree of fibrosis, single fiber structure, insufficient thermal stability, poor water-holding capacity and strong soybean odor existing in wet-extruded protein, improve the defects of wet-extruded protein, and promote the healthy development of plant protein products.

[0010] To achieve the above object, the present invention provides a wet-extruded protein with high juice content, low soybean odor and high thermal stability, comprising the following raw materials in parts by weight:

[0011] 50-90 parts of pea protein isolate with a protein content greater than 70%, 20-40 parts of yeast protein with a protein content greater than 75%, 15-25 parts of wheat gluten with a protein content greater than 70%, 10-15 parts of glucose, 6-9 parts of microbial transglutaminase, 0.3-0.9 parts of sodium alginate, 7-10 parts of tea polyphenols with a purity greater than 90%.

[0012] In a preferred embodiment, it comprises the following raw materials in parts by weight:

[0013] 70 parts of pea protein isolate with a protein content greater than 80%, 30 parts of yeast protein with a protein content greater than 82%, 20 parts of wheat gluten with a protein content greater than 80%, 12 parts of glucose, 7.5 parts of microbial transglutaminase, 0.6 parts of sodium alginate, 8.5 parts of tea polyphenols with a purity greater than 96.5%.

[0014] In a preferred embodiment, the enzyme activity of the microbial transglutaminase is 1600 U / g.

[0015] The present invention also provides a preparation method of a wet-extruded protein with high juice content, low soybean odor and high thermal stability, comprising:

[0016] Step S10: Prepare a 40%-50% suspension with 50-90 parts of pea protein isolate, 20-40 parts of yeast protein and 15-25 parts of wheat gluten using a 0.03 mol / L - 0.07 mol / L phosphate buffer solution, then add 10-15 parts of glucose and react at 50°C - 70°C for 15 h - 30 h to obtain reactant A;

[0017] Step S20: Prepare a 35%-45% suspension of the reactant A using a 0.03 mol / L - 0.07 mol / L phosphate buffer solution, add 6-9 parts of microbial transglutaminase, and perform directional stirring enzymolysis at 35°C - 39°C and a pH value of 5.5 - 6.5 for 3 h - 7 h, then pass steam to raise the temperature to 90°C - 100°C and perform high-speed stirring for 3 min - 7 min to terminate the reaction to obtain reactant B;

[0018] Step S30: Add 0.3 - 0.9 parts of sodium alginate and 7 - 10 parts of tea polyphenols to the reactant B, and stir at medium speed for 10 min until uniform to obtain a mixed material C;

[0019] Step S40: Feed the mixed material C into an extruder at a preset constant speed, add water online in the first zone to maintain the final moisture content of the material at 50% - 60%, and keep the barrel temperature at 20°C - 30°C, 50°C - 70°C, 80°C - 100°C, 150°C - 170°C, 150°C - 170°C, and 105°C - 115°C in the first to sixth zones respectively; in the cooling zone at the end, always keep the die temperature at 65°C - 75°C to obtain wet-extruded protein; wherein, the extruder includes six barrel zones and a long cooling die provided at the end, the six barrel zones are respectively defined as the first zone, ……, the sixth zone, and the long cooling die is defined as the cooling zone.

[0020] In a preferred embodiment, the preparation method includes the following steps:

[0021] Prepare a 45% suspension of 70 parts of pea protein isolate, 30 parts of yeast protein, and 20 parts of wheat gluten using 0.05 mol / L phosphate buffer, then add 12 parts of glucose and react at 60°C for 24 h to obtain reactant A;

[0022] Prepare a 40% suspension of the reactant A using 0.05 mol / L phosphate buffer, add 7.5 parts of microbial transglutaminase, and stir enzymatically in a directional manner at 37°C and pH 6.0 for 5 h, then heat with steam to 95°C and stir at high speed for 5 min to terminate the reaction to obtain reactant B;

[0023] Add 0.6 parts of sodium alginate and 8.5 parts of tea polyphenols to the reactant B, and stir at medium speed for 10 min until uniform to obtain a mixed material C;

[0024] Feed the mixed material C into an extruder at a preset constant speed, add water online in the first zone to maintain the final moisture content of the material at 55%, and keep the barrel temperature at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C in the first to sixth zones respectively; in the cooling zone at the end, always keep the die temperature at 70°C to obtain wet-extruded protein.

[0025] The wet-extruded protein provided by the present invention, which is juicy, low in soybean fishy smell, and high in thermal stability, has the following beneficial effects:

[0026] (1) Use new source proteins with higher production efficiency and lower carbon, namely a mixture of yeast protein and pea protein isolate, which improves the chromaticity and soybean fishy smell problems of the extruded protein and enhances the degree of fibrosis;

[0027] (2) By adding microbial transglutaminase, the enzyme-linked Maillard technology is used to increase the hydrophilic groups in the protein, thereby improving the water-holding capacity of the extruded protein and increasing the juiciness of the end product;

[0028] (3) The modifier synergistically (tea polyphenols & sodium alginate) enhances the protein complexation reaction, the hydrophobic interaction of amino acid residues, and hydrogen bond linkage, improving the thermal stability of the extruded protein and forming a hierarchical chemical fiber micro-network. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus 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.

[0030] Figure 1 It is a flowchart of the preparation method of the wet-extruded protein with high juiciness, low soybean fishy smell, and high thermal stability provided by the present invention;

[0031] Figure 2 It is a photo of the extruded protein sample prepared through Example 9

[0032] Figure 3 For Figure 2 It is a photo of the fiber structure of the tear surface of the shown extruded protein sample. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to make the purpose, technical solutions, and beneficial technical effects of the present invention clearer, the following will further describe the present invention in detail with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described in this specification are only for explaining the present invention, not for limiting the present invention.

[0034] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0035] It should be further understood that the term "and / or" used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0036] In an embodiment of the present invention, a juicy, low-beany, high-thermal-stability wet-extruded protein is provided for replacing traditional animal meat with soy protein. Accordingly, there are no risks such as high environmental burden and veterinary drug residues in traditional livestock and poultry farming.

[0037] Specifically, the juicy, low-beany, and high-thermal-stability wet-extruded protein comprises the following raw materials in parts by weight: 50-90 parts of pea protein isolate with a protein content greater than 70%, 20-40 parts of yeast protein with a protein content greater than 75%, 15-25 parts of gluten with a protein content greater than 70%, 10-15 parts of glucose, 6-9 parts of microbial glutamine transaminase, 0.3-0.9 parts of sodium alginate, and 7-10 parts of tea polyphenols with a purity greater than 90%.

[0038] Preferably, the juicy, low-beany, and high-thermal-stability wet-extruded protein comprises the following raw materials in parts by weight: 70 parts of pea protein isolate with a protein content greater than 80%, 30 parts of yeast protein with a protein content greater than 82%, 20 parts of gluten with a protein content greater than 80%, 12 parts of glucose, 7.5 parts of microbial glutamine transaminase, 0.6 parts of sodium alginate, and 8.5 parts of tea polyphenols with a purity greater than 96.5%.

[0039] Among them, the enzyme activity of microbial glutaminase transaminase (MTG) is 1600U / g, which is used to catalyze the transamination reaction between glutamine and α-keto acid in microorganisms.

[0040] The present invention also provides a method for preparing a juicy, low bean smell, high thermal stability wet extruded protein, which is used to prepare the juicy, low bean smell, high thermal stability wet extruded protein by using the above-mentioned raw material ratios.

[0041] like Figure 1 As shown, the wet-extruded protein with juicy, low beany flavor and high thermal stability comprises steps S10-S40.

[0042] Step S10: 50-90 parts of pea protein isolate, 20-40 parts of yeast protein, and 15-25 parts of gluten are prepared into a 40%-50% suspension using 0.03mol / L-0.07mol / L phosphate buffer (pH 8.0), and then 10-15 parts of glucose are added to react at 50°C-70°C for 15h-30h to obtain reactant A.

[0043] Step S20: Reactant A is formulated into a 35%-45% suspension using a 0.03 mol / L - 0.07 mol / L phosphate buffer (pH 8.0). Then, 6 - 9 parts of microbial transglutaminase are added, and the mixture is subjected to directional stirring and enzymatic hydrolysis at 35°C - 39°C and pH 5.5 - 6.5 for 3 h - 7 h. Subsequently, steam is introduced to raise the temperature to 90°C - 100°C, and high-speed stirring (2500 rpm - 3000 rpm) is carried out for 3 min - 7 min to terminate the reaction, obtaining Reactant B.

[0044] Step S30: 0.3 - 0.9 parts of sodium alginate and 7 - 10 parts of tea polyphenols are added to Reactant B, and medium-speed stirring (1500 rmp - 2000 rmp) is carried out for 10 min until uniform, obtaining the mixed material C.

[0045] Step S40: The mixed material C is fed into an extruder (such as a co-rotating intermeshing twin-screw extruder) at a preset constant speed (e.g., 20 kg / h (dry basis)). Water is added online in the first zone (at a speed of 21 kg / h) to maintain the final moisture content of the material at 50% - 60% (w / w). The screw speed is 160 rpm - 190 rpm, and the barrel temperature is maintained at 20°C - 30°C, 50°C - 70°C, 80°C - 100°C, 150°C - 170°C, 150°C - 170°C, and 105°C - 115°C in the first to sixth zones respectively. The temperature of the die in the terminal cooling zone is always maintained at 65°C - 75°C. After stable extrusion, samples are collected to obtain wet-extruded protein. The extruder includes six barrel zones and a long cooling die at the end. The six barrel zones are defined as the first zone, ……, the sixth zone in sequence, and the long cooling die is defined as the cooling zone. The size of the extruder is 70×10×1800 mm (width × height × length).

[0046] Preferably, the preparation method includes the following steps:

[0047] 70 parts of pea protein isolate, 30 parts of yeast protein, and 20 parts of wheat gluten are formulated into a 45% suspension using a 0.05 mol / L phosphate buffer (pH 8.0), and then 12 parts of glucose are added and reacted at 60°C for 24 h to obtain Reactant A;

[0048] Reactant A is formulated into a 40% suspension using a 0.05 mol / L phosphate buffer (pH 8.0), 7.5 parts of microbial transglutaminase are added, and the mixture is subjected to directional stirring and enzymatic hydrolysis at 37°C and pH 6.0 for 5 h. Subsequently, steam is introduced to raise the temperature to 95°C, and high-speed stirring (2500 rpm - 3000 rpm) is carried out for 5 min to terminate the reaction, obtaining Reactant B;

[0049] Add 0.6 parts of sodium alginate and 8.5 parts of tea polyphenols to reactant B, stir at medium speed (1500 rmp - 2000 rmp) for 10 min until uniform to obtain mixed material C;

[0050] Feed mixed material C into an extruder at a preset constant speed (20 kg / h (dry basis)), add water online in the first zone (at a speed of 21 kg / h) to maintain the final moisture content of the material at 55% (w / w), with a screw speed of 175 rpm, and the barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, 110°C in sequence from the first zone to the sixth zone; the cooling zone at the end always maintains the die temperature at 70°C to obtain wet-extruded protein.

[0051] It should be noted that to fully illustrate the necessity, irreplaceability of the above raw materials and why the weight parts or parameters are adopted, the test results of multiple control examples will be compared below. First, conduct the first-step comparison of Examples 1, 2, 3, and 4, then take the optimal solution in the first-step test and conduct the second-step comparison with Examples 5 and 6, and finally take the optimal solution in the second-step test and conduct the comparison with Examples 7, 8, and 9 to obtain the overall best implementation plan.

[0052] Example 1:

[0053] Formula: 100 parts of pea protein isolate (protein content > 80%);

[0054] Process: Feed pea protein isolate into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, maintain the final feed moisture content at 55% (w / w), with a screw speed of 175 rpm, and the barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, 110°C in sequence from the first zone to the sixth zone; the cooling zone uses tap water for cooling and always maintains the die temperature at 70°C; after the extrusion is stable, collect the samples, subpackage the samples after cooling to room temperature, and store them at -20°C for standby.

[0055] Example 2:

[0056] Formula: 90 parts of pea protein isolate (protein content > 80%) and 10 parts of yeast protein (protein content > 82%);

[0057] Process: Add pea protein isolate and yeast protein into 50 parts of normal-temperature water, and then use a mixer to mix at a stirring speed of 1200 rpm - 2000 rpm for 0.5 h until the moisture is evenly mixed; Feed the mixed material into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, keep the final feed moisture content at 55% (w / w), the screw speed is 175 rpm, and the barrel temperature is maintained at 25 °C, 60 °C, 90 °C, 160 °C, 160 °C, 110 °C respectively from the first zone to the sixth zone; Use tap water to cool in the cooling zone and always keep the die temperature at 70 °C; After the extrusion is stable, collect the samples, sub-pack the samples after cooling to room temperature, and store them at -20 °C for later use.

[0058] Example 3:

[0059] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%);

[0060] Process: Add pea protein isolate and yeast protein into 50 parts of normal-temperature water, and then use a mixer to mix at a stirring speed of 1200 rpm - 2000 rpm for 0.5 h until the moisture is evenly mixed; Feed the mixed material into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, keep the final feed moisture content at 55% (w / w), the screw speed is 175 rpm, and the barrel temperature is maintained at 25 °C, 60 °C, 90 °C, 160 °C, 160 °C, 110 °C respectively from the first zone to the sixth zone; Use tap water to cool in the cooling zone and always keep the die temperature at 70 °C; After the extrusion is stable, collect the samples, sub-pack the samples after cooling to room temperature, and store them at -20 °C for later use.

[0061] Example 4:

[0062] Formulation: 50 parts of pea protein isolate (protein content > 80%), 50 parts of yeast protein (protein content > 82%);

[0063] Process: Add pea protein isolate and yeast protein to 50 parts of normal-temperature water, and then use a mixer to mix at a stirring speed of 1200 rpm - 2000 rpm for 0.5 h until the moisture is evenly mixed; Feed the mixed material into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, keep the final feed moisture content at 55% (w / w), the screw speed at 175 rpm, and the barrel temperature from the first zone to the sixth zone at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C respectively; Use tap water to cool in the cooling zone and always keep the die temperature at 70°C; After the extrusion is stable, collect the samples, divide them into packages after cooling to room temperature, and store them at -20°C for standby.

[0064] (1) Sensory evaluation (appearance and texture):

[0065] After refrigerating and thawing the extruded proteins prepared in Examples 1 - 4 above, divide them into 3 parts; Put two of them into 2 cooking bags respectively, vacuum package them using a vacuum packaging machine, and then place them in a water bath at 80°C for pasteurization for 30 min and sterilize them at 121°C in an autoclave for 20 min respectively; Finally, after thawing (fresh), pasteurizing (80°C, 30 min), and high-temperature sterilizing (121°C, 20 min) and balancing to room temperature (25°C), cut them into long strips and place them on plates, and randomly number them. Select 50 evaluators to form an evaluation group to evaluate the samples, and the sensory detection scoring criteria are shown in Table 1 below.

[0066] Table 1: Sensory detection scoring criteria for extruded protein

[0067]

[0068]

[0069] Before the evaluation, conduct evaluation training for the evaluators to enable them to evaluate objectively without mixing personal emotions; During the evaluation process, avoid discussion; Before the test, avoid contact with strong-smelling items, such as smoking, chewing gum, eating food, etc., and using scented cosmetics and detergents; Also, require the evaluators to wipe off their lipsticks, avoid heavy makeup, and not wash their hands with scented soap. Then provide the extruded protein to the evaluators in an unknown order for objective evaluation and fill in the sensory evaluation. The results are shown in Table 2 below.

[0070] Table 2: Sensory (appearance and texture) evaluation results of extruded protein

[0071]

[0072] (2) Sensory evaluation (flavor) (before high temperature):

[0073] The sensory panel was selected according to the method in GB / T 16291.1—2012 General Guidelines for the Selection, Training and Management of Appraisal Personnel in Sensory Analysis - Part 1: Preferred Assessors. 30 assessors (18 females and 12 males, aged 25 - 40 years old) were recruited and trained using the following definitions of flavor attributes and their reference standards.

[0074] Table 3: Sensory Evaluation Definitions and Reference Standards for the Flavor of Extruded Protein

[0075]

[0076] Table 4: Sensory Evaluation Results of the Flavor of Extruded Protein (Before High Temperature)

[0077]

[0078] Measurement:

[0079] The TA.XT2 texture analyzer (Stable Micro Systems, UK) was used to detect the extruded protein. Before the test, the fresh, pasteurized, and highly pasteurized extruded proteins were equilibrated to room temperature (25 °C). Based on the extrusion flow direction of the extruded protein sample in the extruder, the direction perpendicular to the extrusion flow was defined as the vertical direction, and the direction parallel to the extrusion flow was defined as the parallel direction.

[0080] For each extruded protein sample, while keeping the original thickness unchanged, 10 samples with a length and width of 10x10 mm were taken respectively; the A / CKB craft knife probe was used to cut 5 times along the vertical direction or the parallel direction respectively. Keeping a constant test speed of 1 mm / s, the shear degree of each sample was 95%. The peak shear force in the vertical direction and the peak shear force in the parallel direction were detected. The average value of the 5 peak shear forces in the vertical direction was defined as the vertical hardness; the average value of the 5 peak shear forces in the parallel direction was defined as the parallel hardness. The ratio of the vertical hardness to the parallel hardness was defined as the degree of texturization, which was used to quantitatively characterize the degree of fibrosis of the texturized protein.

[0081] The A / TG probe (probe and fixture) was selected to stretch the sample at a speed of 0.5 mm·s -1 until the protein broke, and the tensile resistance was recorded. Square blocks (2.5×2.5 mm) were cut from the sample, and compressed with the P / 36R probe (cylinder, 036 mm) at a speed of 1 mm·s -1 for 5 s until the compression thickness reached 50% of the original thickness, and the hardness and elasticity were recorded.

[0082] Table 5: Texture Data of Extruded Protein

[0083]

[0084]

[0085] (4) Color measurement:

[0086] Use a CS-600 color difference meter (CHN Spec, China) to measure the color values of the extruded protein. Place the sample on the surface of the white standard plate and measure the lightness (L), redness (a), and yellowness (b), repeating at least 5 times. The standard L*s, a*s, and b*s values of the calibration plate are 97.99, -0.01, and 1.44 respectively. The total color difference (ΔE) of the extruded protein is calculated by the following formula:

[0087]

[0088] The color difference meter test results of each sample are shown in Table 6 below.

[0089] Table 6: Color difference meter test results

[0090] Sample L a b △E Example 1 45.45±0.46 5.27±0.25 16.42±0.81 54.89±0.54 Example 2 45.48±1.00 5.05±0.44 15.98±1.18 54.73±0.91 Example 3 46.91±0.48 5.98±0.28 18.22±0.28 54.10±0.53 Example 4 48.19±0.56 6.56±0.52 18.59±0.72 53.08±0.74

[0091] (5) Water-holding and oil-holding capacity measurement:

[0092] Weigh approximately 1.0 g of the sample and place it in a centrifuge tube. Add 10 ml of deionized water, try to keep the sample shape consistent, and make the solution submerge the sample. Mix well, let it stand at room temperature for 30 min, and then use a centrifuge to centrifuge at 3000 rpm for 15 min. Immediately pour out the supernatant after centrifugation, take out the sample, and weigh its wet weight. Each group of samples is measured 3 times.

[0093] The method for measuring oil-holding capacity is the same as that for measuring water-holding capacity. After adding 10 ml of soybean oil, let it stand for 30 min, centrifuge, pour out the supernatant and weigh it. The calculation formula is the same as the water-holding capacity calculation formula above.

[0094] Table 7: Water-holding and oil-holding capacity measurement results

[0095] Sample Water holding capacity Oil holding capacity Example 1 0.40±0.03 0.31±0.02 Example 2 0.40±0.02 0.30±0.03 Example 3 0.41±0.03 0.31±0.02 Example 4 0.41±0.02 0.31±0.02

[0096] (6) Thermodynamic property measurement:

[0097] Use a differential scanning calorimeter to analyze the thermodynamic properties of the freeze-dried powder of the extruded sample. Accurately weigh 3.0 ± 0.2 mg of the sample powder, use a tablet press to seal it in an aluminum crucible, and use a blank crucible as a reference. The scanning temperature range is 55°C to 160°C, the heating rate is 10°C / min, and the N2 flow rate is 20 ml / min. Conduct a comprehensive analysis of the peaks and record the starting point temperature, ending point temperature, peak temperature of the thermal transition, and peak area (enthalpy value ΔH). The results are shown in Table 8 below.

[0098] Table 8: Thermodynamic property measurement results

[0099]

[0100]

[0101] It can be found from the above experimental results that in terms of texture sensory properties (surface state, color, filamentous structure, hardness), Example 3 is the best; in terms of flavor sensory properties, both Example 3 and Example 4 have better improvement in bean flavor, but Example 3 preserves the bean fragrance better; in terms of color, Example 3 has higher brightness and redness, is closer to real meat but the yellowness increases, and there is little difference among groups in terms of water and oil holding capacity, and the thermodynamic stability of each group shows attenuation (peak temperature decreases). Therefore, through comprehensive evaluation, Example 3 is the best overall.

[0102] Example 5:

[0103] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of vital wheat gluten (protein content > 80%);

[0104] Process: Add pea protein isolate, yeast protein and vital wheat gluten to 50 parts of normal temperature water, and then use a mixer to mix at a stirring speed of 1200 rpm - 2000 rpm for 0.5 h until the moisture is evenly mixed; Feed the mixed material into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, keep the final feed moisture content at 55% (w / w), the screw speed is 175 rpm, and the barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, 110°C from the first zone to the sixth zone respectively; Use tap water to cool in the cooling zone and always keep the die temperature at 70°C; After the extrusion is stable, collect the samples, sub-pack the samples after cooling to room temperature, and store them at -20°C for standby.

[0105] Example 6:

[0106] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 40 parts of vital wheat gluten (protein content > 80%);

[0107] Process: Add pea protein isolate, yeast protein, and wheat gluten into 50 parts of normal-temperature water, and then use a mixer to mix at a stirring speed of 1200 rpm - 2000 rpm for 0.5 h until the moisture is evenly mixed; Feed the mixed material into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), add water online in the first zone at a speed of 21 kg / h, keep the final feed moisture content at 55% (w / w), the screw speed at 175 rpm, and the barrel temperature from the first zone to the sixth zone at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C respectively; Use tap water for cooling in the cooling zone to keep the die temperature at 70°C all the time; After the extrusion is stable, collect the samples, divide them into packages after cooling to room temperature, and store them at -20°C for standby.

[0108] (1) Sensory evaluation (appearance and texture):

[0109] After refrigerating and thawing the extruded proteins prepared in Examples 3, 5, and 6 respectively, divide them into 3 portions; Put two of the portions into 2 cooking bags respectively, vacuum-pack them using a vacuum packaging machine, and then place them in a water bath at 80°C for pasteurization for 30 min & sterilize them in an autoclave at 121°C for 20 min; Finally, after thawing (fresh), pasteurizing (80°C for 30 min), and autoclaving (121°C for 20 min) and equilibrating to room temperature (25°C), cut them into long strips and place them on plates, and randomly number them. Select 50 evaluators to form an evaluation group to evaluate the samples. The sensory detection scoring criteria are shown in Table 1 above.

[0110] Before the evaluation, train the evaluators to make them evaluate objectively without mixing personal emotions; During the evaluation process, avoid discussion; Before the test, avoid contacting strong-smelling items, such as smoking, chewing gum, eating food, etc. and using scented cosmetics and detergents; Also, require the evaluators to wipe off their lipsticks, avoid heavy makeup, and do not wash their hands with scented soap. Then provide the extruded proteins to the evaluators in a random order for objective evaluation and fill in the sensory evaluation. The results are shown in Table 9 below.

[0111] Table 9: Sensory evaluation results

[0112]

[0113]

[0114] (2) Sensory evaluation (flavor):

[0115] The screening of sensory evaluation panelists was carried out according to the method in GB / T 16291.1—2012 General Guidelines for the Selection, Training and Management of Sensory Evaluation Panelists—Part 1: Preferred Assessors. 30 panelists (18 females and 12 males, aged 25 to 40 years old) were screened and recruited, and the panelists were trained using the following definitions of flavor attributes and their reference standards. The sensory evaluation definition and reference standards of extruded protein flavor can be seen in Table 3 above.

[0116] After refrigerating and thawing the extruded proteins prepared in Examples 3, 5, and 6, they were divided into 3 portions; two of the portions were respectively placed into 2 cooking bags and vacuum-packed using a vacuum packaging machine, and then were respectively placed in a water bath at 80 °C for pasteurization for 30 min and sterilized at 121 °C in an autoclave for 20 min; finally, the thawed (fresh), pasteurized (80 °C, 30 min), and highly sterilized (121 °C, 20 min) samples were equilibrated to room temperature (25 °C), cut into long strips, placed on plates, and randomly numbered. Before the evaluation, the panelists were given evaluation training to enable them to evaluate objectively without mixing personal emotions; during the evaluation process, discussions were avoided; before the test, contact with strong-smelling items such as smoking, chewing gum, eating food, etc., and the use of scented cosmetics and detergents should be avoided; the panelists were also required to wipe off their lipsticks, avoid heavy makeup, and not wash their hands with scented soap. Then the extruded proteins were provided to the panelists in a random order for objective evaluation, and the sensory evaluation form was filled out. The results are shown in Table 10 below.

[0117] Table 10: Results of Flavor Sensory Evaluation

[0118]

[0119]

[0120] (3) Texture test:

[0121] The TA.XT2 texture analyzer (Stable Micro Systems, UK) was used to detect the extruded proteins. Before the test, the fresh, pasteurized, and highly sterilized extruded proteins were equilibrated to room temperature (25 °C). Based on the extrusion flow direction of the extruded material of the extruded protein sample, the direction perpendicular to the extrusion flow was defined as the vertical direction, and the direction parallel to the extrusion flow direction was defined as the parallel direction.

[0122] For each extruded protein sample, while keeping the original thickness unchanged, 10 samples with lengths and widths of 10x10 mm were taken respectively; a cutter head of A / CKB art knife was used to perform 5 cuts along the vertical direction and the parallel direction respectively. Keeping a constant test speed of 1 mm / s, the shear degree of each sample was 95%, and the peak shear force in the vertical direction and the peak shear force in the parallel direction were detected. The average value of the 5 peak shear forces in the vertical direction was taken and defined as the vertical hardness; the average value of the 5 peak shear forces in the parallel direction was taken and defined as the parallel hardness. The ratio of the vertical hardness to the parallel hardness was defined as the degree of texturization, which was used to quantitatively characterize the fibrosis degree of the texturized protein.

[0123] Select an A / TG probe (probe and fixture) to stretch the sample at a speed of 0.5 mm·s -1 until the protein breaks, and record the tensile resistance. Cut a square block (2.5×2.5 mm) from the sample, and use a P / 36R probe (cylinder, 0.36 mm) to compress it at a speed of 1 mm·s -1 for 5 s, compress the thickness to 50% of the original thickness, and record the hardness and elasticity. The texture test data are shown in Table 11 below.

[0124] Table 11: Texture test results

[0125]

[0126]

[0127] (4) Color measurement:

[0128] Use a CS-600 color difference meter (CHN Spec, China) to measure the color values of the extruded protein. Place the sample on the surface of a white standard plate, and measure the lightness (L), redness (a), and yellowness (b), with at least 5 repetitions. The standard L*s, a*s, and b*s values of the calibration plate are 97.99, -0.01, and 1.44 respectively. The total color difference (△E) of the extruded protein is calculated by the following formula:

[0129]

[0130] The color difference meter test results of each sample are shown in Table 12 below.

[0131] Table 12: Color measurement results

[0132] Sample L a b △E Example 3 45.45±0.46 5.27±0.25 16.42±0.81 54.89±0.54 Example 5 46.51±0.32 4.23±0.08 15.52±0.14 53.53±0.11 Example 6 47.52±0.43 2.72±0.10 13.94±0.24 52.07±0.29

[0133] (5) Water holding capacity measurement:

[0134] Weigh approximately 1.0 g of the sample and place it in a centrifuge tube. Add 10 ml of deionized water, try to keep the shape of the sample consistent, and submerge the sample in the solution. Mix well, let it stand at room temperature for 30 min, and then centrifuge at 3000 rpm for 15 min using a centrifuge. Immediately pour out the supernatant after centrifugation, take out the sample, and weigh its wet weight. Repeat the measurement 3 times for each group of samples.

[0135] The method for measuring oil-holding capacity is the same as that for water-holding capacity. After adding 10 ml of soybean oil, let it stand for 30 min, centrifuge, pour out the supernatant and weigh it. The calculation formula is the same as the above water-holding capacity calculation formula.

[0136] Table 13: Results of water-holding and oil-holding capacity measurements

[0137] Sample Water holding capacity Oil holding capacity Example 3 0.41±0.03 0.31±0.02 Example 5 0.43±0.03 0.32±0.03 Example 6 0.42±0.04 0.33±0.03

[0138] (6) Determination of the thermodynamic properties of extruded protein:

[0139] Use a differential scanning calorimeter to analyze the thermodynamic properties of the freeze-dried powder of the extruded sample. Accurately weigh 3.0 ± 0.2 mg of the sample powder, seal it in an aluminum crucible using a tablet press, and use a blank crucible as a reference. The scanning temperature range is 55 - 160 °C, the heating rate is 10 °C / min, and the N2 flow rate is 20 ml / min. Conduct a comprehensive analysis of the peaks and record the starting temperature, ending temperature, and peak temperature of the thermal transition. The results are shown in Table 14 below.

[0140] Table 14: Results of thermodynamic property measurements

[0141] Sample Initial temperature / °C Final temperature / °C Peak temperature Tp / °C Example 3 94.25 96.62 95.42 Example 5 95.44 97.65 96.51 Example 6 93.49 95.77 94.58

[0142] It can be found from the experimental results of the further tests in Examples 3, 5, and 6 above that: in terms of texture sensory (surface state, color, filamentous structure, hardness), Example 5 is better; in terms of flavor sensory, the beany smell in both Example 5 and Example 6 has been improved, but the bean fragrance in Example 5 is relatively better preserved; in terms of color, Example 5 is slightly inferior to Example 6, there is no obvious difference in water-holding capacity and oil-holding capacity among each group, and the thermodynamic stability of Example 5 is relatively better. Therefore, comprehensively evaluating Examples 3, 5, and 6, Example 5 is the best overall.

[0143] Example 7 (including Comparative Example 1, Comparative Example 2, Comparative Example 3):

[0144] Comparative Example 1:

[0145] Formula: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g);

[0146] Process: Separate pea protein, yeast protein, and wheat gluten are formulated into a 45% suspension using 0.05 mol / L phosphate buffer (pH 8.0), then glucose is added and the reaction is carried out at 60 °C for 12 h; the reactant from the previous step is formulated into a 40% suspension using 0.05 mol / L phosphate buffer (pH 8.0), microbial transglutaminase is added, and then the reaction mixture is stirred enzymatically in a directional manner at 37 °C and pH 6.0 for 2 h, and then steam is introduced to raise the temperature to 95 °C and high-speed stirring (2500 rpm - 3000 rpm) is carried out for 5 min to terminate the reaction.

[0147] Comparative Example 2:

[0148] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g);

[0149] Process: Separate pea protein, yeast protein, and wheat gluten are formulated into a 45% suspension using 0.05 mol / L phosphate buffer (pH 8.0), then glucose is added and the reaction is carried out at 60 °C for 24 h; the reactant from the previous step is formulated into a 40% suspension using 0.05 mol / L phosphate buffer (pH 8.0), microbial transglutaminase is added, and then the reaction mixture is stirred enzymatically in a directional manner at 37 °C and pH 6.0 for 5 h, and then steam is introduced to raise the temperature to 95 °C and high-speed stirring (2500 rpm - 3000 rpm) is carried out for 5 min to terminate the reaction.

[0150] Comparative Example 3:

[0151] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g);

[0152] Process: Separate pea protein, yeast protein, and wheat gluten are formulated into a 45% suspension using 0.05 mol / L phosphate buffer (pH 8.0), then glucose is added and the reaction is carried out at 60 °C for 30 h; the reactant from the previous step is formulated into a 40% suspension using 0.05 mol / L phosphate buffer (pH 8.0), microbial transglutaminase is added, and then the reaction mixture is stirred enzymatically in a directional manner at 37 °C and pH 6.0 for 8 h, and then steam is introduced to raise the temperature to 95 °C and high-speed stirring (2500 rpm - 3000 rpm) is carried out for 5 min to terminate the reaction.

[0153] The protein samples prepared by the above comparative examples 1-3 through the enzymatic Maillard reaction were successively subjected to grafting degree, solubility, surface hydrophobicity, and water holding capacity measurements.

[0154] (1) Grafting degree measurement:

[0155] After freeze-drying the mixed protein after the reaction, 40 mg of the protein sample was weighed and dissolved in 40 mL of 0.05 mol / L NaCl, pH 9.2, 2.9 g / L SDS (Sodium Dodecyl Sulfate) solution, and stirred for 30 min; 1 mL of the above suspension was taken, and 1 mL of 0.05 mol / L Na 2 HPO 4 and 1 mL of 2.9 g / L TNBS (2,4,6-Trinitrobenzenesulfonic Acid) solution were added, and the reaction was carried out in a water bath at 60 °C for 2 h, left standing at room temperature for 10 min, then 1 mL of 100 g / L SDS solution and 0.5 mL of 1 mol / L HCl were added, and the absorbance was measured at 340 nm, with no sample added to the blank. Using the same method, lysine was used instead of the sample to make a standard curve, and the content C of free amino groups in the sample was calculated according to the curve. Among them, the calculation formula for the grafting degree is:

[0156] Among them, C 0 is the content of free amino groups in the solution before the grafting reaction, with the unit of mol / L; C 1 is the content of free amino groups in the solution after the grafting reaction, with the unit of mol / L.

[0157] (2) Solubility measurement:

[0158] Protein solubility was expressed by the nitrogen solubility index (NSI%): A 1% sample solution was adjusted to pH 8.0, stirred for 1 h to dissolve the sample, then centrifuged for 20 min (4000 r / min), and the protein content in the supernatant was measured by the Folin-Ciocalteu method, using bovine serum albumin as a standard curve. The protein content in the sample was measured by the micro-Kjeldahl method.

[0159] (3) Measurement of surface hydrophobicity;

[0160] Dissolve the protein sample in 0.01 mol / L phosphate buffer (pH 7), and dilute it into different concentration gradients from 0.5 mg / mL to 0.005 mg / mL respectively. Take 5 mL of different sample dilutions, add 50 μL of 8 mmol / L ANS, oscillate, and let it stand for 3 min. Set the excitation wavelength at 338 nm, the emission wavelength at 496 nm, and the slit correction at 5 nm. Make a curve with fluorescence intensity against protein concentration, and the slope of the initial segment is the surface hydrophobicity index of protein molecules.

[0161] (4) Water-holding capacity determination:

[0162] Weigh about 1.0 g of the sample and place it in a centrifuge tube. Add 10 ml of deionized water, try to keep the sample shape consistent, and make the solution submerge the sample. Mix well, let it stand at room temperature for 30 min, and then centrifuge at 3000 rpm for 15 min using a centrifuge. Immediately pour out the supernatant after centrifugation, take out the sample, and weigh its wet weight. Each group of samples is measured 3 times repetitively.

[0163]

[0164] The test results of the proteins prepared by the enzyme-linked Maillard reaction in Comparative Examples 1, 2, and 3 are shown in Table 15 below.

[0165] Table 15: Test results of the proteins prepared by the enzyme-linked Maillard reaction

[0166]

[0167]

[0168] Combined with the above results, it can be seen that the process conditions of Comparative Example 2 have been fully reacted with the mixed protein. Therefore, Comparative Example 2 is preferably combined for Example 7:

[0169] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g);

[0170] Process: Dissolve pea protein isolate, yeast protein, and wheat gluten in 0.05 mol / L phosphate buffer (pH 8.0) to prepare a 45% suspension, then add glucose and react at 60 °C for 24 h; dissolve the reactant from the previous step in 0.05 mol / L phosphate buffer (pH 8.0) to prepare a 40% suspension, add microbial transglutaminase, and perform directional stirring enzymolysis at 37 °C and pH 6.0 for 5 h, then pass steam to raise the temperature to 95 °C and perform high-speed stirring (2500 rpm - 300 rpm) for 5 min to terminate the reaction;

[0171] The mixed materials are fed into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis). Water is added online in the first zone at a speed of 21 kg / h, keeping the final feed moisture content at 55% (w / w). The screw speed is 175 rpm, and the barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C respectively from the first zone to the sixth zone. The cooling zone uses tap water for cooling to keep the die temperature at 70°C all the time. After the extrusion is stable, samples are collected. After the samples are cooled to room temperature, they are sub-packed and stored at -20°C for future use.

[0172] Example 8:

[0173] Formulation: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g), 0.6 parts of sodium alginate;

[0174] Process: Pea protein isolate, yeast protein, and wheat gluten are made into a 45% suspension in 0.05 mol / L phosphate buffer (pH 8.0), and then glucose is added and reacted at 60°C for 24 h. The reactant from the previous step is made into a 40% suspension in 0.05 mol / L phosphate buffer (pH 8.0), and microbial transglutaminase is added and enzymatically hydrolyzed under directional stirring at 37°C and pH 6.0 for 5 h. Then, steam is introduced to raise the temperature to 95°C, and high-speed (2500 - 300 rpm) stirring is carried out for 5 min to terminate the reaction;

[0175] 0.6 parts of sodium alginate are added to the reactant from the second step, and medium-speed (1500 - 2000 rmp) stirring is carried out for 10 min until it is uniform;

[0176] The mixed materials are fed into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis). Water is added online in the first zone at a speed of 21 kg / h, keeping the final feed moisture content at 55% (w / w). The screw speed is 175 rpm, and the barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C respectively from the first zone to the sixth zone. The cooling zone uses tap water for cooling to keep the die temperature at 70°C all the time. After the extrusion is stable, samples are collected.

[0177] Example 9:

[0178] Formula: 70 parts of pea protein isolate (protein content > 80%), 30 parts of yeast protein (protein content > 82%), 20 parts of wheat gluten (protein content > 80%), 12 parts of glucose, 7.5 parts of microbial transglutaminase (MTG, 1600 U / g), 0.6 part of sodium alginate, 8.5 parts of tea polyphenols (purity > 96.5%);

[0179] Process: Pea protein isolate, yeast protein, and wheat gluten are made into a 45% suspension in 0.05 mol / L phosphate buffer (pH 8.0), then glucose is added and the reaction is carried out at 60 °C for 24 h; the reactant from the previous step is made into a 40% suspension in 0.05 mol / L phosphate buffer (pH 8.0), microbial transglutaminase is added, and it is directionally stirred and enzymatically hydrolyzed at 37 °C and pH 6.0 for 5 h, then steam is introduced to raise the temperature to 95 °C and high-speed (2500 rpm - 3000 rpm) stirring is carried out for 5 min to terminate the reaction;

[0180] Sodium alginate and tea polyphenols are added to the reactant from the second step, and medium-speed (1500 rmp - 2000 rmp) stirring is carried out for 10 min until uniform;

[0181] The mixed material is fed into an extruder (co-rotating intermeshing twin-screw extruder) at a constant speed of 20 kg / h (dry basis), water is added online in the first zone at a speed of 21 kg / h, the final feed moisture is maintained at 55% (w / w), the screw speed is 175 rpm, and the barrel temperature is maintained at 25 °C, 60 °C, 90 °C, 160 °C, 160 °C, and 110 °C from the first zone to the sixth zone respectively; the cooling zone is cooled with tap water to always maintain the die temperature at 70 °C. After the extrusion is stable, samples are collected.

[0182] (1) Sensory evaluation (appearance and texture):

[0183] The extruded proteins prepared in Examples 5, 7, 8, and 9 are respectively divided into 3 parts after refrigerated thawing; two of them are respectively put into 2 cooking bags, vacuum-packed using a vacuum packaging machine, and respectively placed in a water bath at 80 °C for 30 min of pasteurization and sterilized at 121 °C for 20 min in an autoclave; finally, the thawed (fresh), pasteurized (80 °C, 30 min), and high-temperature sterilized (121 °C, 20 min) samples are balanced to room temperature (25 °C), cut into long strips and placed on plates, and randomly numbered. 50 evaluators are selected to form an evaluation group to evaluate the samples, and the sensory detection scoring criteria are shown in Table 1 above.

[0184] Before evaluation, the assessors should be given evaluation training to enable them to evaluate objectively without being influenced by personal emotions. During the evaluation process, discussions should be avoided. Before the test, contact with strong-smelling substances such as smoking, chewing gum, eating food, etc., and the use of scented cosmetics and detergents should be avoided. The assessors should also be required to wipe off their lipsticks, avoid heavy makeup, and not wash their hands with scented soap. Then, the extruded proteins should be provided to the assessors in a random order for objective evaluation, and the sensory evaluation should be filled out. The results are shown in Table 16 below.

[0185] Table 16: Sensory Evaluation Results

[0186]

[0187]

[0188] (2) Sensory Evaluation (Flavor):

[0189] For the screening of sensory personnel, refer to the method in GB / T 16291.1—2012 General Guidelines for the Selection, Training and Management of Sensory Evaluation Panels - Part 1: Expert Sensory Assessors. Recruit 30 assessors (18 females and 12 males, aged 25 - 40 years old), and train the assessors using the following definitions of flavor attributes and their reference standards (refer to Table 3 above).

[0190] After refrigerating and thawing the extruded proteins prepared in Examples 5, 7, 8, and 9, divide them into 3 portions respectively. Put two of the portions into 2 cooking bags, vacuum-pack them using a vacuum packaging machine, and then place them in a water bath at 80°C for 30 min of pasteurization and in an autoclave at 121°C for 20 min of sterilization respectively. Finally, after equilibrating the thawed (fresh), pasteurized (80°C, 30 min), and highly sterilized (121°C, 20 min) samples to room temperature (25°C), cut them into long strips and place them on plates, and randomly number them. Before evaluation, the assessors should be given evaluation training to enable them to evaluate objectively without being influenced by personal emotions. During the evaluation process, discussions should be avoided. Before the test, contact with strong-smelling substances such as smoking, chewing gum, eating food, etc., and the use of scented cosmetics and detergents should be avoided. The assessors should also be required to wipe off their lipsticks, avoid heavy makeup, and not wash their hands with scented soap. Then, the extruded proteins should be provided to the assessors in a random order for objective evaluation, and the sensory evaluation should be filled out. The results are shown in Table 17 below.

[0191] Table 17: Flavor Sensory Evaluation Results

[0192] Sample Soybean flavor Soybean fishy smell Sweet flavor Greasy smell Burnt smell Example 5 8.1 3.2 5.5 2.7 2.0 Example 7 8.0 3.0 5.5 2.6 2.0 Example 8 8.0 3.0 5.5 2.6 2.0 Example 9 8.0 2.9 5.5 2.6 2.0

[0193] (3) Texture Test:

[0194] The extrusion protein was detected using a TA.XT2 texture analyzer (Stable Micro Systems, UK). Before testing, the freshly prepared, pasteurized, and highly pasteurized extrusion proteins were equilibrated to room temperature (25 °C). Based on the extrusion flow direction of the material in the extruder, the direction perpendicular to the extrusion flow was defined as the vertical direction, and the direction parallel to the extrusion flow was defined as the parallel direction.

[0195] For each extrusion protein sample, while keeping the original thickness unchanged, 10 samples with dimensions of 10x10 mm in length and width were taken; using an A / CKB craft knife probe, 5 cuts were made along the vertical direction and 5 cuts were made along the parallel direction respectively. Keeping a constant test speed of 1 mm / s, the shear degree of each sample was 95%. The peak shear force in the vertical direction and the peak shear force in the parallel direction were detected. The average value of the 5 peak shear forces in the vertical direction was defined as the vertical hardness; the average value of the 5 peak shear forces in the parallel direction was defined as the parallel hardness. The ratio of the vertical hardness to the parallel hardness was defined as the degree of texturization, which was used to quantitatively characterize the fibrosis degree of the texturized protein.

[0196] Select an A / TG probe (probe and fixture) to stretch the sample at a speed of 0.5 mm·s -1 until the protein breaks, and record the tensile resistance. Cut a square block (2.5×2.5 mm) from the sample, and compress it with a P / 36R probe (cylinder, 0.36 mm) at a speed of 1 mm·s -1 for 5 s, compress the thickness to 50% of the original thickness, and record the hardness and elasticity. The texture test results are shown in Table 18 below.

[0197] Table 18: Texture test results

[0198]

[0199] (4) Color measurement:

[0200] The color values of the extrusion protein were measured using a CS-600 color difference meter (CHN Spec, China). The sample was placed on the surface of a white standard plate, and the brightness (L), redness (a), and yellowness (b) were measured, with at least 5 repetitions. The standard L*s, a*s, and b*s values of the calibration plate were 83.80, 0.3176, and 0.3241 respectively. The total color difference (ΔE) of the extrusion protein was calculated by the following formula:

[0201]

[0202] The color difference meter test results for each sample are shown in Table 19 below.

[0203] Table 19: Color difference meter test results

[0204]

[0205]

[0206] (5) Determination of water-holding capacity and oil-holding capacity:

[0207] Weigh about 1.0 g of the sample and place it in a centrifuge tube. Add 10 ml of deionized water, try to keep the shape of the sample consistent, and make the solution submerge the sample. Mix well, let it stand at room temperature for 30 min, and then use a centrifuge to centrifuge at 3000 rpm for 15 min. Immediately pour out the supernatant after centrifugation, take out the sample, and weigh its wet weight. Repeat the determination 3 times for each group of samples. The test results are shown in Table 20 below.

[0208] The method for determining oil-holding capacity is the same as that for determining water-holding capacity. After adding 10 ml of soybean oil, let it stand for 30 min, pour out the supernatant after centrifugation and weigh it. The calculation formula is the same as the above water-holding capacity calculation formula.

[0209] Table 20: Results of water-holding capacity and oil-holding capacity determination

[0210] Sample Water holding capacity (g / g) Oil holding capacity Example 5 0.43±0.03 0.32±0.03 Example 7 0.59±0.02 0.52±0.03 Example 8 0.61±0.03 0.55±0.04 Example 9 0.65±0.03 0.58±0.02

[0211] (6) Determination of the thermodynamic properties of extruded protein:

[0212] Use a differential scanning calorimeter to analyze the thermodynamic properties of the freeze-dried powder of the extruded sample. Accurately weigh 3.0 ± 0.2 mg of the sample powder, use a tablet press to seal it in an aluminum crucible, and use a blank crucible as a reference. The scanning temperature range is 55 - 160 °C, the heating rate is 10 °C / min, and the N2 flow rate is 20 ml / min. Conduct a comprehensive analysis of the peaks and record the starting point temperature, ending point temperature, and peak temperature of the thermal transition. The results of the thermodynamic property determination are shown in Table 21.

[0213] Table 21: Results of thermodynamic property determination

[0214] Sample Initial temperature / °C Final temperature / °C Peak temperature Tp / °C Example 5 95.44 97.65 96.51 Example 7 108.68 111.45 110.24 Example 8 113.25 116.55 115.36 Example 9 143.35 147.02 145.46

[0215] From the experimental results of Examples 5, 7, 8, and 9 above, in terms of texture and sensory properties (surface state, color, filamentous structure, hardness), Example 9 is the best and has a high similarity to real meat; in terms of odor sensory properties, Example 9 has the weakest soybean smell; in terms of color, Example 9 is generally similar to real meat; in terms of water-holding and oil-holding capacity, Example 9 has a significant improvement; in terms of thermodynamic stability, Example 9 has a good performance. Therefore, comprehensively evaluating, Example 9 is the best overall.

[0216] Therefore, after pasteurization and high-temperature sterilization, the taste of Example 9 did not show obvious decline, which means that the high-moisture extruded protein in Example 9 has good thermal stability. This will provide a solution to the industry problem of the softening and cottoniness of plant proteins after thermal processing in cooking applications and snack applications. At the same time, combined with Figure 2 and Figure 3 as shown, the appearance color of Example 9 has a high similarity to real meat, and the present invention will greatly contribute to the further popularization of plant proteins.

[0217] In summary, the wet-extruded protein with high juice content, low soybean odor and high thermal stability provided by the present invention has the following beneficial effects:

[0218] (1) Using a new source of protein with higher production efficiency and lower carbon, namely a mixture of yeast protein and pea protein isolate, improves the chromaticity and soybean odor problems of extruded protein and enhances the degree of fibrillation;

[0219] (2) By adding microbial transglutaminase, the enzyme-linked Maillard technology is used to increase the hydrophilic groups in the protein to improve the water-holding capacity of the extruded protein and increase the juiciness of the end product;

[0220] (3) The synergistic effect of modifiers (tea polyphenols & sodium alginate) improves the thermal stability of the extruded protein and forms a hierarchical chemical fiber micro-network by enhancing the protein complexation reaction and the hydrophobic interaction and hydrogen bond linkage of amino acid residues.

[0221] The present invention is not limited only to what is described in the specification and embodiments. Therefore, for those skilled in the art, additional advantages and modifications can be easily achieved. Thus, without departing from the spirit and scope of the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details, representative devices, and illustrated examples shown and described herein.

Claims

1. A juicy, low beany flavor, high thermal stability wet extruded protein, characterized in that: Contains the following raw materials in parts by weight: 50-90 parts of pea protein isolate with a protein content greater than 70%, 20-40 parts of yeast protein with a protein content greater than 75%, 15-25 parts of gluten with a protein content greater than 70%, 10-15 parts of glucose, 6-9 parts of microbial glutamine transaminase, 0.3-0.9 parts of sodium alginate, and 7-10 parts of tea polyphenols with a purity greater than 90%.

2. The juicy, low beany flavor, high heat stability wet extruded protein according to claim 1, characterized in that: Contains the following raw materials in parts by weight: 70 parts of pea protein isolate with a protein content greater than 80%, 30 parts of yeast protein with a protein content greater than 82%, 20 parts of gluten with a protein content greater than 80%, 12 parts of glucose, 7.5 parts of microbial glutamine transaminase, 0.6 parts of sodium alginate, and 8.5 parts of tea polyphenols with a purity greater than 96.5%.

3. The juicy, low beany flavor, high heat stability wet extruded protein according to claim 1, characterized in that: The enzyme activity of the microbial glutamine transaminase is 1600 U / g.

4. A method for preparing a juicy, low beany smell, high thermal stability wet extruded protein, characterized in that: include: Step S10: 50-90 parts of pea protein isolate, 20-40 parts of yeast protein, and 15-25 parts of gluten are prepared into a 40%-50% suspension using 0.03 mol / L-0.07 mol / L phosphate buffer, and then 10-15 parts of glucose are added to react at 50° C.-70° C. for 15 h-30 h to obtain reactant A; Step S20: the reactant A is prepared into a 35%-45% suspension using 0.03mol / L-0.07mol / L phosphate buffer, 6-9 parts of microbial glutamine transaminase are added, and enzymolysis is performed under directional stirring at 35°C-39°C and pH 5.5-6.5 for 3h-7h, and then steam is introduced to raise the temperature to 90°C-100°C and high-speed stirring is performed for 3min-7min to terminate the reaction, thereby obtaining a reactant B; Step S30: adding 0.3-0.9 parts of sodium alginate and 7-10 parts of tea polyphenols to the reactant B, stirring at a medium speed for 10 minutes until uniform, to obtain a mixed material C; Step S40, the mixed material C is fed into the extruder at a preset constant speed, water is added online in the first zone to keep the final material moisture content at 50%-60%, and the barrel temperature is maintained at 20℃-30℃, 50℃-70℃, 80℃-100℃, 150℃-170℃, 150℃-170℃, and 105℃-115℃ from the first zone to the sixth zone respectively; the cooling zone at the end always maintains the mold temperature at 65℃-75℃ to obtain wet extruded protein; wherein the extruder comprises six barrel zones and a long cooling mold arranged at the end, the six barrel zones are defined as the first zone, ..., the sixth zone, respectively, and the long cooling mold is defined as the cooling zone.

5. The method for preparing the juicy, low beany smell, high thermal stability wet extruded protein according to claim 4, characterized in that: The following steps are involved: 70 parts of pea protein isolate, 30 parts of yeast protein, and 20 parts of gluten powder were prepared into a 45% suspension using 0.05 mol / L phosphate buffer, and then 12 parts of glucose were added to react at 60° C. for 24 hours to obtain reactant A; The reactant A is prepared into a 40% suspension using 0.05 mol / L phosphate buffer, 7.5 parts of microbial glutamine transaminase are added, and enzymolysis is carried out under directional stirring at 37° C. and pH 6.0 for 5 hours, and then steam is introduced to raise the temperature to 95° C. and high-speed stirring is performed for 5 minutes to terminate the reaction, thereby obtaining a reactant B; 0.6 parts of sodium alginate and 8.5 parts of tea polyphenols were added to the reactant B, and stirred at a medium speed for 10 minutes until uniform, to obtain a mixed material C; The mixed material C is fed into the extruder at a preset constant speed, and water is added online in the first zone to maintain the final material moisture content of 55%. The barrel temperature is maintained at 25°C, 60°C, 90°C, 160°C, 160°C, and 110°C from the first zone to the sixth zone, respectively; the cooling zone at the end always maintains the mold temperature at 70°C to obtain wet extruded protein.

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