Preparation method of minced fillet-soybean meal double-protein extruded product with meat flavor

Abstract

The invention relates to the technical field of food processing, in particular to a method for preparing a minced fillet-soybean meal double-protein product with meat fragrance through a twin-screw extrusion technology. The preparation method comprises the following specific steps: S1, moderately unfreezing frozen surimi, scattering the unfrozen surimi, and uniformly mixing the unfrozen surimi and defatted soybean meal according to a certain proportion; s2, fish fat is obtained by collecting a floating fat layer in surimi rinsing water; s3, adding a certain amount of water and fish fat into the uniformly mixed material, stirring and mixing for a certain time by using a mixer, and standing to fully and uniformly mix; s4, feeding the uniformly mixed materials into a twin-screw extruder, and performing twin-screw extrusion forming to prepare a double-protein extrusion product with fiber texture and obvious meat flavor; and S5, collecting fresh extruded products, cooling to room temperature, sealing, storing at normal temperature, and cooking, rehydrating and heating before eating. The minced fillet, the fish fat and the yeast extract are added into the soybean meal extruded product, so that the problem that a single bean protein extruded product is heavy in beany flavor is solved, and the prepared product is free of fishy smell and peculiar smell, obvious in meat flavor, balanced in nutrition and high in digestibility.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a method for preparing a fish paste-soybean meal powder dual-protein product with meat flavor through a twin-screw extrusion process. Background Art

[0002] Extrusion texturization technology is the primary method for producing and processing "plant protein meat," offering advantages such as scale, industrialization, continuity, and high efficiency and energy conservation. Soy protein or defatted soybean meal is the primary raw material for producing "plant protein meat." Defatted soybean meal is a byproduct of soybean oil extraction, and defatted soybean meal is further processed to produce soy protein. Patent CN 107549444 A discloses a method for preparing textured soy protein. The method uses high-gluten wheat protein and soy protein isolate as raw materials, along with supplementary ingredients such as transglutaminase, nano-grade dietary fiber, and starch. Water is added and heated to a moisture content of 35% to 40%. Extrusion molding is then used to produce a textured soy protein product characterized by high water absorption, high elasticity, and fine fibers.

[0003] Filamentous product characteristics; Patent CN 117296983A discloses a high-moisture plant protein extrudate and its preparation method. Using twin-screw high-moisture extrusion technology, the extrusion parameters, the amount of soy protein added to the material, and the moisture content are adjusted during the high-moisture extrusion process. Based on the material properties of the plant protein and the interactions during the extrusion process, the structural properties of the extrudate are regulated. A variety of plant-based products have been developed using a single soy protein extrudate as the raw material. The production process is simple, and the product simulates meat and egg white, improving the product texture and enriching the product taste. However, extruded products made from a single soy protein generally have problems such as limiting amino acids, unsatisfactory amino acid composition patterns, low protein digestibility, and a strong beany odor.

[0004] Patent CN 119073442 A discloses a flavorful, high-moisture textured plant protein product and its preparation method. This product uses soybean meal as the primary raw material, with soy protein and cereal protein as supplementary ingredients. This product improves the utilization rate of plant-based protein and reduces resource waste. The addition of seaweed powder makes the product structure softer and more elastic, while also giving the textured plant protein product a unique flavor. While this invention improves protein utilization through compounded plant protein and improves product flavor through the addition of seaweed, the problem of an unsatisfactory amino acid composition and a strong beany odor in extruded plant protein products still exists. Summary of the Invention

[0005] In order to solve the problems of unsatisfactory amino acid composition pattern, low protein digestibility and strong beany smell of single bean protein extruded products, the present invention provides a method for preparing a fish paste-soybean meal powder dual protein extruded product with meaty flavor.

[0006] The present invention adopts the following technical solutions: A method for preparing a meaty-flavored fish paste-soybean meal powder dual-protein extrusion product comprises the following steps: S1, thawing the frozen surimi moderately and breaking it up, and then mixing the thawed surimi and defatted soybean meal powder in a certain proportion; S2, obtaining fish fat by collecting the floating fat layer in the surimi rinse water; S3, adding a certain amount of water and fish fat to the mixed material, stirring and mixing with a mixer for a certain period of time and then letting it stand to make it fully uniform; S4, feeding the uniformly mixed materials into a twin-screw extruder, and preparing a dual-protein extruded product with a fibrous texture and a distinct meaty aroma through twin-screw extrusion; S5, collect the fresh extruded product, cool it to room temperature, seal it and store it at room temperature.

[0007] Preferably, the frozen surimi in S1 is commercially available AA grade or above frozen surimi, thawing conditions are 4°C to 10°C and allowed to stand for 1 to 12 hours, and the ratio of frozen surimi to defatted soybean meal powder is 2:8 to 3:7.

[0008] Preferably, the fish fat layer above the surfacing layer in the surfacing water in S2 is collected using the surfacing procedure commonly used by surfacing companies (i.e., the minced fish meat after meat removal is placed in a rinsing tank, 5 times the amount of clean water is added, and the surfacing layer is collected after slow stirring for 10 minutes, and then allowed to stand for 5 minutes to collect the floating layer). The surfacing layer contains 60% to 70% fat, 20% to 30% moisture, and 5% to 10% protein and ash. The fish fat is stored in a vacuum freezer and thawed at 4°C to 10°C before use.

[0009] Preferably, the amount of water added in S3 is 15% to 30% (w / w, based on the total weight of the frozen surimi and soybean meal powder), and the amount of fish fat added is 4% to 8% (w / w, based on the total weight of the frozen surimi and soybean meal powder).

[0010] Preferably, the mixed material in S3 is stirred and mixed by a mixer for 14 to 30 minutes and then allowed to stand for 20 to 50 minutes to make it fully uniform.

[0011] Preferably, in S4, the screw aspect ratio of the twin-screw extruder is 15~36, there are no less than 4 heating zones, the heating temperature increases successively along the extrusion direction, the overall temperature range is 60℃~180℃, the maximum heating temperature is in the range of 130℃~150℃, the screw speed is 100~300 r / min, and the feeding speed is 20~70 r / min.

[0012] Preferably, in S4, there are no less than 4 heating zones, and there are 4 heating zones. The heating temperatures of the first three zones along the extrusion direction are 60-80°C, 80-95°C, and 110-130°C, respectively, and the last heating temperature is 120°C-180°C.

[0013] Preferably, the fresh extruded product collected in S5 should be collected after the instrument working condition is stable. The packaging method is vacuum packaging and the storage method is room temperature. The product state is a double-protein extruded product with fibrous texture and obvious meaty aroma, which can be eaten after steaming and reheating.

[0014] Beneficial effects of the present invention: 1. Adding surimi to traditional "plant meat" products prepared by extrusion and texturization makes up for the shortcomings of single soy protein extrusion products, such as the suboptimal amino acid composition pattern and low protein digestibility. This meets the demand of "focusing on developing new nutritious and healthy dual-protein foods" proposed in the "National Nutrition Plan (2017-2030)"; 2. The present invention unexpectedly discovered that by adding unprocessed fish fat, under appropriate high temperature conditions (130°C to 150°C), the content of 3-methyl-2-butanone, 2-methylvaleraldehyde, isobutyl acetate, 2,3-butanediol, 2-heptanone, 2-pentylfuran, nonanal and γ-nonalactone in the product is increased, giving the product a distinct meaty aroma, and significantly reducing the content of aromatic compounds and nitrogen-containing compounds in the product, thereby reducing its fishy odor; 3. The fish fat used comes from the rinsing water of fish paste, which improves the utilization rate of processing by-products and is more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The apparent morphology of extruded products with different ratios of frozen surimi and defatted soybean meal powder; Figure 2 Maximum tensile force (A) and tensile strength (B) of extruded products with different ratios of frozen surimi and defatted soybean meal powder; Figure 3 Protein digestibility (A) and free amino group concentration (B) of extruded products with different ratios of frozen surimi and defatted soybean meal at different digestion stages. G stands for gastric digestion, and GI stands for gastrointestinal digestion. Figure 4Particle size distribution and average particle size of digestion sediments of extruded products with different ratios of frozen surimi and defatted soybean meal powder: A: undigested sample; B: gastric digestion; C: gastrointestinal digestion; D: average particle size; Figure 5 DFA graph (A) and radar graph (B) of the electronic nose response values of extruded products with different fish fat addition amounts; Figure 6 Odor sensory radar chart of extruded products with different fish fat addition amounts; Figure 7 Principal component analysis biplot (A) and cluster analysis heat map (B) of the odorous substance content in extruded products with different fish fat addition amounts; Figure 8 Odor profiles of extruded products with different final heating temperatures; Figure 9 the odor profile of extruded products with added rinsed recycled fish fat, refined fish fat, and pork fat; Figure 10 Effects of heated rinsing of recovered fish fat on the odor profile of extruded products; Figure 11 Effect of low-voltage electrostatic field treatment on TBARS value of rinsed recovered fat; Figure 12 Effect of low-voltage electrostatic field treatment on the odor profile of extruded products. DETAILED DESCRIPTION

[0016] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] The fish fat used in the embodiment was obtained from a minced fish production enterprise in Honghu, Hubei Province. The floating layer of the rinse water in the minced fish rinsing tank after standing was the fish fat; the fat content in the floating layer was 65%, the water content was 25%, the protein content was 8%, and the ash content was 2%.

[0018] Example 1: Effect of the Mixing Ratio of Frozen Surimi and Defatted Soybean Meal Powder on Product Properties 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Thawed surimi and defatted soybean meal were mixed in different mass ratios (0:10, 1:9, 2:8, 3:7 and 4:6), and appropriate amount of water was added to each to adjust the moisture content of the mixture to 37%; (3) The mixed materials were stirred in a mixer for 20 min and then allowed to stand for 30 min to make them fully uniform; (4) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and four heating zones. The heating temperatures along the extrusion direction were 70°C, 90°C, 120°C, and 140°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (5) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0019] 2. Performance testing: Frozen surimi and defatted soybean meal were mixed in different mass ratios (0:10, 1:9, 2:8, 3:7 and 4:6) to prepare dual-protein extruded products. The apparent viscosity of the mixed raw materials, the structural characteristics of the extruded products, the moisture status, sensory evaluation and flavor characteristics were characterized. The effect of the raw material ratio on the nutritional characteristics of the extruded products was studied from the perspective of basic nutrients, fatty acid and amino acid content and essential amino acid nutritional evaluation. At the same time, a protein in vitro simulated digestion method was used to explore the effect of the raw material ratio on the protein digestibility of the extruded products through changes in protein digestibility, free amino acid concentration, particle size and amino acid content, and molecular weight of the digestion products. The results are shown in Figure 2. Figure 1-4 , Table 1-6.

[0020] Increasing the surimi ratio increased the viscosity of the mixed raw materials, reducing the thickness of the extruded product from a maximum of 0.415 mm to 0.325 mm and improving its color. When the raw material ratio did not exceed 2:8, the macromorphology of the extruded product remained intact, and the microfiber structure became compact, but the tensile properties did not change significantly. When the raw material ratio exceeded 2:8, the macromorphology of the extruded product fractured, the microfiber structure broke into flakes, and the tensile strength decreased by a maximum of 46.15%. Sensory results showed that increasing the surimi ratio effectively masked the beany odor of the extruded product and produced a distinct fishy aroma, umami, and sweetness. However, excessive surimi ratios could introduce a fishy odor. Considering the structural structure and flavor quality of the extruded product, a raw material ratio between 2:8 and 3:7 was found to be optimal.

[0021] In terms of nutritional composition, amino acid score, and protein digestibility, increasing the surimi ratio resulted in a slight increase in crude protein content in the extruded products, while moisture, crude fat, total sugar, and ash contents gradually decreased. Increasing the surimi ratio increased the contents of arachidonic acid, EPA, and DHA in the extruded products, but gradually decreased total fatty acids and total polyunsaturated fatty acids, with linoleic acid content decreasing the most, by 555 mg / 100g. Pure soy flour extruded products had the lowest methionine content, with essential amino acid / total amino acid and essential amino acid / non-essential amino acid values of 36.92 and 58.54, respectively, failing to meet the standard protein profile recommended by the FAO / WHO. Increasing the surimi ratio gradually increased the essential amino acid content of the extruded products. At raw material ratios of 3:7 and 4:6, the amino acid profile met the standard protein profile. The essential amino acid index and biological value of the essential amino acid nutritional score significantly increased, improving the nutritional properties of the extruded products. Increasing the surimi ratio also increased the protein digestibility of the dual-protein extruded products after gastrointestinal digestion, and the sediment particle size gradually decreased. The content of free amino acids in the digestive juice gradually increases, the molecular weight of the protein gradually decreases, more low-molecular-weight and potentially bioactive peptides are produced, and the digestion characteristics of the extruded product are improved.

[0022] Table 1 Flavor sensory evaluation standards

[0023] Table 2 Flavor sensory evaluation scores of extruded products with different ratios of frozen surimi and defatted soybean meal powder

[0024] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0025] Table 3 Basic components of extruded products with different ratios of frozen surimi and defatted soybean meal powder (%)

[0026] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0027] Table 4 Fatty acid composition and content (mg / 100g) of extruded products with different ratios of frozen surimi and defatted soybean meal powder

[0028] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0029] Table 5 Amino acid content of extruded products with different ratios of frozen surimi and defatted soybean meal powder (g / 100g)

[0030] Note: * indicates essential amino acids; different superscript letters indicate significant differences between groups ( P <0.05).

[0031] Table 6 Essential amino acid nutritional evaluation of extruded products with different ratios of frozen surimi and defatted soybean meal powder

[0032] Example 2: Effect of fish fat addition on the meaty flavor of dual-protein extruded products 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Mix the thawed surimi and defatted soybean meal powder in a mass ratio of 3:7; (3) Fish fat was obtained from a minced fish production enterprise in Honghu, Hubei Province. The floating layer of the rinse water collected from the minced fish rinsing tank after standing was fish fat; (4) adding 0%, 2%, 4%, 6% and 8% (w / w, based on the total weight of surimi and defatted soybean meal) of fish fat, respectively; (5) Calculate the amount of water to be added based on the feed moisture of 39%; (6) The mixed material was stirred in a mixer for 20 min and then allowed to stand for 30 min to make it fully uniform; (7) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and had four heating zones. The heating temperatures along the extrusion direction were 70°C, 90°C, 120°C, and 140°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (8) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0033] 2. Performance testing: Dual-protein extrusion products were prepared by mixing frozen surimi and defatted soybean meal in a mass ratio of 3:7 and adding different proportions of fish fat (0%, 2%, 4%, 6%, and 8%). The viscosity of the mixture and the product structure were characterized. Sensory evaluation, odor analyzer, solvent-assisted odor evaporation-gas chromatography-mass spectrometry / olfaction, and solvent-assisted odor evaporation-gas chromatography-mass spectrometry were used to investigate the effect of fish fat addition on the odor characteristics of the extruded products. Figure 5-7Tables 7-8 show that increasing the amount of fish fat added significantly decreases the apparent viscosity of the mixed raw material, resulting in a lower degree of expansion in the extruded product, increased moisture content and degrees of freedom, improved color, a gradually denser microstructure, increased elasticity, and decreased hardness and chewiness. The addition of fish fat alters the odor profile of the extruded product, enhancing the fishy aroma and reducing the beany and roasted notes. Furthermore, the present inventors unexpectedly discovered that the addition of fish fat imparts a "meaty" flavor to the product. Adding 6% fish fat has the greatest effect on enhancing the fishy flavor of the extruded product, with no noticeable fishy odor and a more pronounced meaty flavor.

[0034] Extruded products containing 6% fish fat were selected as typical meaty flavor products, while products without fish fat served as a control group. The specific sources of the meaty flavor after adding 6% fish fat were analyzed. The results showed that compared with the control group, the olfactory intensity of eight odorants, including 3-methyl-2-butanone, 2-methylvaleraldehyde, isobutyl acetate, 2,3-butanediol, 2-heptanone, 2-pentylfuran, nonanal, and γ-nonalactone, was significantly enhanced in the extruded products containing 6% fish fat. These odorants exhibited aroma characteristics such as meaty, nutty, fatty, and buttery roasted. Reconstitution experiments also demonstrated that these eight odorants were the primary source of the extruded products' unique meaty flavor. Furthermore, the present invention unexpectedly found that the odor intensity of aromatic compounds such as benzaldehyde, phenylacetaldehyde, and 4-hydroxybenzaldehyde, as well as nitrogen-containing compounds such as 2,5-dimethylpyrazine and 3-ethyl-2,5-methylpyrazine, was significantly lower in the extruded products containing 6% fish fat than in the control group, weakening the products' roasted, floral, and grassy notes. The combined changes in the above-mentioned odor substances jointly promote the changes in the flavor quality of extruded products.

[0035] Based on the identification of key odorants associated with meaty aroma, quantitative analysis of odorants in samples at various fish fat addition levels revealed that when the fish fat addition level was 8%, the grassy-smelling hexanal content and odor activity significantly increased compared to extruded products without fish fat. This gave the product a more pronounced fishy odor, which in turn weakened the meaty aroma. Therefore, the addition of fish fat should be kept to a minimum, with 6% being the most suitable level. Table 7 Moisture content, color and texture characteristics of extruded products with different fish fat addition amounts

[0036] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0037] Table 8-1 Determination of the intensity and Q value of odor substances in extruded products (added with 0% and 6% fish fat) by AEDA method

[0038] Table 8-2 Determination of the intensity and Q value of odor substances in extruded products (added with 0% and 6% fish fat) by AEDA method

[0039] Table 8-3 Intensity and Q value of odor substances in extruded products (added with 0% and 6% fish fat) determined by AEDA method

[0040] Note: RI means the retention index is consistent with the standard; RIL means the retention index is consistent with the NIST Chemistry WebBook; MS means the mass spectrum of the odorant standard Figure 1 A indicates that the odor attribute is consistent with the reported one; 1, 10, 100, and 1000 are the dilution multiples of the odor substance; Q indicates the Q value; / indicates that the substance could not be smelled.

[0041] Example 3: Enhanced Effect of Maximum Heating Temperature on the Flavor of Dual-Protein Extruded Products 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Mix the thawed surimi and defatted soybean meal powder in a mass ratio of 3:7; (3) Add 6% fish fat obtained from a surimi production company in Honghu, Hubei; (4) Calculate the amount of water to be added based on the feed moisture of 39%; (5) The mixed material was stirred in a mixer for 20 min and then allowed to stand for 30 min to make it fully uniform; (6) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and four heating zones. The first three heating temperatures were 70°C, 90°C, and 120°C along the extrusion direction, and the last heating temperature was set at 120°C, 140°C, and 160°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (7) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0042] 2. Performance testing: Through sensory evaluation and quantitative analysis of odor substances in samples, the results are shown in Figure 8Table 9 shows that the final heating temperature during the extrusion process significantly influences the product's flavor quality. A distinct meaty aroma is only evident in the dual-protein extruded product heated at 140°C. When heated to only 120°C, the product exhibits a distinct overcooked and beany flavor, with a weak aroma. Analysis of odorants also revealed high OAVs for odorants contributing to overcookedness, such as 2,3-pentanedione, 2,6-dimethylpyrazine, 2-propylpyridine, benzothiazole, 2-methoxythiophenol, and 2-furfurylthiol. These compounds have been shown to be produced in fish samples heated at 100°C and 121°C and to contribute significantly to the overcooked flavor. When the heating temperature is increased to 140°C, the overcooked flavor is significantly reduced. This is due to the further decomposition of the overcooked flavoring compounds produced at 120°C or their participation in the formation of other compounds. At this temperature, the product exhibits the strongest meaty aroma and the best flavor quality. However, when the heating temperature is raised to 160°C, roasted, burnt, and charred flavors become the main odors of the product. At this time, the content of furan and furfural compounds formed by the high-temperature Maillard reaction in the product increases significantly. Excessive accumulation of these substances causes the product to have a stronger charred smell, which is detrimental to its overall flavor quality. Table 9-1 Effect of different final heating temperatures on the odor activity values of volatile odor substances in extruded products

[0043] Table 9-2 Effect of different final heating temperatures on the odor activity values of volatile odor substances in extruded products

[0044] Example 4: Effect of adding rinsed and recovered fish fat, refined fish fat, and pork fat on the flavor of dual-protein extruded products.

[0045] 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Mix the thawed surimi and defatted soybean meal powder in a mass ratio of 3:7; (3) 6% fish fat obtained from a surimi production company in Honghu, Hubei, 6% commercial fish oil, and 6% lard were added respectively; (4) Calculate the amount of water to be added based on the feed moisture of 39%; (5) The mixed material was stirred in a mixer for 20 min and then allowed to stand for 30 min to make it fully uniform; (6) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and four heating zones. The heating temperatures along the extrusion direction were 70°C, 90°C, 120°C, and 140°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (7) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0046] 2. Performance testing Sensory evaluations of dual-protein extruded products supplemented with rinsed recycled fish fat, commercially available fish oil, and lard revealed the surprising finding that the sample supplemented with rinsed recycled fish fat exhibited the highest meaty aroma. While some meaty aroma was present in the samples supplemented with commercially available fish oil and lard, the more pronounced fishy odor of the commercially available fish oil sample and the stronger greasy flavor of the lard sample resulted in the overall meaty aroma of these two groups being inferior to that of the sample supplemented with rinsed recycled fish fat. The overall flavor profile of the sample supplemented with rinsed recycled fish fat was still the best. This may be because both commercially available fish oil and lard undergo a high-temperature refining process, and the initial high-temperature heating alters the precursor composition and odoriferous substances in the fat, affecting the odor production during the secondary heating. Alternatively, it may be because rinsed recycled fat contains approximately 10% protein and ash, components that contribute to the product's flavor during high-temperature heating and contribute to the formation of the meaty aroma.

[0047] See the results Figure 9 Table 10. Looking at the relative content of meaty aroma compounds, the data shows that the eight odorants closely associated with meaty aroma—3-methyl-2-butanone, 2-methylvaleraldehyde, isobutyl acetate, 2,3-butanediol, 2-heptanone, 2-pentylfuran, nonanal, and γ-nonalactone—are all found at the highest levels in samples containing recycled fish fat, with the exception of nonanal. This further confirms that samples containing recycled fish fat have a distinct meaty aroma. Nonanal is highest in samples containing commercially available fish oil. This is because nonanal is primarily formed through the oxidative degradation of fat, and commercially available fish oil has a higher fat content, resulting in the highest nonanal content. However, simply increasing the nonanal content alone is not sufficient to impart a distinct meaty aroma to the product. Lard and fish oil differ significantly in their fatty acid composition, resulting in distinct odorants formed after processing. Therefore, the addition of lard to the dual-protein extruded product prepared from surimi and soybean meal is less effective than fish oil in enhancing the meaty aroma of the product. Table 10 Relative contents of meaty aroma compounds in extruded products with rinsed recycled fish fat, refined fish fat, and pork fat (μg / kg)

[0048] Example 5 Effect of Heating, Rinse and Recovered Fish Fat on Product Flavor 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Mix the thawed surimi and defatted soybean meal powder in a mass ratio of 3:7; (3) The rinsed fish fat was obtained from a fish paste production enterprise in Honghu, Hubei Province, and the rinsed fish fat was heated at 100℃ for 15 min, and 6% of heated and unheated rinsed fish fat was added. (4) Calculate the amount of water to be added based on the feed moisture of 39%; (5) The mixed material was stirred in a mixer for 20 min and then allowed to stand for 30 min to make it fully uniform; (6) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and four heating zones. The heating temperatures along the extrusion direction were 70°C, 90°C, 120°C, and 140°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (7) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0049] 2. Performance testing The rinsed and recovered fish fat was heated and then used to prepare the double protein extrusion product. Figure 10 ,Table 11, the results show that the odor profiles of the extruded products with and without heated rinse recovered fat are similar, but the meaty aroma of the extruded products prepared by heating and then adding fat is slightly reduced and the grease flavor is enhanced.

[0050] Compared with the sample in Example 4 in which refined fish fat and lard fat were added, even if the rinsed recovered fat was heated before being added, the effect of enhancing the meat flavor of the product was still better than that of the refined fish fat and lard fat group, proving that the mixture state of the rinsed recovered fat is conducive to the increase of meat flavor. Table 11 Effect of heating on the relative content (μg / kg) of meaty aroma compounds in extruded products after rinsing and recovering fish fat

[0051] Example 6: Enhancement of the Meaty Flavor of Rinsed Fish Fat by Electrostatic Field Treatment 1. The processing steps are as follows: (1) Thaw the frozen surimi at 4°C for 4 h and then break it up; (2) Mix the thawed surimi and defatted soybean meal powder in a mass ratio of 3:7; (3) The method for obtaining rinsed fish fat is as follows: a low-voltage electrostatic field (electric field strength 60 kV / m) is added to the rinsing water of the fish paste and treated for 5 min, 10 min, 15 min and 20 min respectively, and then the upper layer of fish fat in the rinsing liquid is collected. The rinsed fish fat obtained directly without electrostatic field treatment is used as a control. The amount of fish fat added is 6%.

[0052] (4) Calculate the amount of water to be added based on the feed moisture of 39%; (5) The mixed material was stirred in a mixer for 20 min and then allowed to stand for 30 min to make it fully uniform; (6) A twin-screw extruder was used to prepare the dual-protein extrusion product. The extruder screw had a length-to-diameter ratio of 25:1 and four heating zones. The heating temperatures along the extrusion direction were 70°C, 90°C, 120°C, and 140°C, respectively. The screw speed was 240 r / min and the feed speed was 50 r / min. (7) After the extrusion conditions stabilized, the fresh double-protein extruded product was collected, cooled to room temperature, and sealed and stored for analysis.

[0053] 2. Performance testing The results are shown in Tables 12-14. Figure 11-12 After treatment with the low-voltage electrostatic field, some protein flocculated and precipitated in the lower layer of the rinse water. As the low-voltage electrostatic field treatment time increased, the protein content in the upper recovered fat layer gradually decreased, while the fat content increased. However, after the treatment time exceeded 15 minutes, the protein content no longer decreased significantly. In addition, the low-voltage electrostatic field treatment reduced the TBARS value in the rinsed fat, indicating that the antioxidant capacity of the rinsed fat increased after the low-voltage electrostatic field treatment.

[0054] When dual-protein extruded products were prepared using rinsed recycled fat treated with a low-voltage electrostatic field, the product's moisture content, brightness, and whiteness gradually increased with increasing treatment time. Texture characteristics did not change significantly, with slightly decreasing hardness and chewiness, and slightly increasing elasticity. After 15 minutes of treatment, these indicators ceased to change significantly. These indicators indicate that low-voltage electrostatic field treatment of rinsed recycled fat increased the product's whiteness and brightness, improved its color quality, slightly increased its elasticity, and decreased its hardness and chewiness, resulting in enhanced palatability.

[0055] Sensory evaluation results showed that low-voltage electrostatic field treatment of rinse-recovered fat significantly enhanced the meaty aroma of the product, with the meaty aroma being strongest in the group treated for 10 minutes. After 15 minutes of treatment, the greasy flavor of the product increased slightly, somewhat masking the overall meaty aroma, but the meaty aroma of the product was still superior to that of the product not treated with the low-voltage electrostatic field. This indicates that low-voltage electrostatic field treatment of rinse-recovered fat can further enhance the meaty aroma of extruded products. Calculations of the relative content of meaty aroma compounds also confirmed this phenomenon. Furthermore, the present invention unexpectedly discovered that the presence of other substances in the rinse-recovered fat, such as protein and ash, also has a positive effect on the enhancement of the product's meaty aroma. After 15 minutes of electrostatic field treatment, the protein content in the rinse-recovered fat decreased significantly, and the meaty aroma of the extruded product at this time was less pronounced than in the product treated for 10 minutes. This suggests that the meaty aroma of the extruded product is not solely derived from fish fat, but rather from a mixture of compounds in the rinse-recovered fat. Table 12 Effect of low-voltage electrostatic field treatment time on the composition (%) of rinsed recovered fat

[0056] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0057] Table 13 Effect of low-voltage electrostatic field treatment time on moisture content, color and texture of extruded products

[0058] Note: Different superscript letters indicate significant differences between the groups ( P <0.05).

[0059] Table 14 Effect of low-voltage electrostatic field treatment time on the relative content of meat flavor compounds in extruded products (μg / kg)

[0060] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a meaty-flavored fish paste-soybean meal powder dual-protein extrusion product, characterized in that: The method comprises the following steps: S1, thawing the frozen surimi and breaking it up, and mixing the thawed surimi and defatted soybean meal powder to obtain a uniformly mixed material; S2, collecting the floating fat layer in the surimi rinsing water to obtain fish fat; S3, adding water and fish fat to the material mixed in step S1, stirring and mixing with a mixer, and then letting it stand to make it fully uniform; S4, feeding the materials mixed uniformly in step S3 into a twin-screw extruder to prepare a dual-protein extruded product by twin-screw extrusion; S5, collect fresh double-protein extrusion products.

2. The method for preparing the meaty-flavored surimi-soybean meal powder dual-protein extruded product according to claim 1, characterized in that: The thawing conditions of the frozen surimi in step S1 are: standing at 4° C. to 10° C. for 1 to 12 hours, and the ratio of the frozen surimi to the defatted soybean meal powder is (2 to 3): (7 to 8).

3. The method for preparing the meaty-flavored surimi-soybean meal double protein extruded product according to claim 1, characterized in that: The fat content in the upper layer of the fish paste rinsing water in step S2 is 60%-70%, the water content is 20%-30%, and the protein and ash contents are 5%-10%; the fish fat is stored by vacuum freezing and thawed at 4°C-10°C before use.

4. The method for preparing the meaty-flavored surimi-soybean meal powder dual-protein extruded product according to claim 1, characterized in that: The procedure for rinsing the minced fish in step S2 is to put the minced fish into a rinsing tank, add 4-6 times the mass of water, stir and rinse for 8-12 minutes, and then let it stand for 4-6 minutes to collect the floating fat layer.

5. The method for preparing the meaty-flavored surimi-soybean meal powder dual-protein extruded product according to claim 1, characterized in that: The amount of water added in step S3 is 15% to 30%, and the amount of fish fat added is 4% to 8%.

6. The method for preparing the meaty-flavored surimi-soybean meal dual-protein extruded product according to claim 1, characterized in that: In step S3, the mixed material is mixed with a mixer at a stirring speed of 20-100 r / min for 14-30 min and then allowed to stand for 20-50 min to make it fully uniform.

7. The method for preparing the meaty-flavored surimi-soybean meal dual-protein extruded product according to claim 1, characterized in that: In step S4, the twin-screw extruder has a screw aspect ratio of 15 to 36, has no less than 4 heating zones, the heating temperature increases sequentially along the extrusion direction, the overall temperature range is 60°C to 180°C, the screw speed is 100 to 300 r / min, and the feeding speed is 20 to 70 r / min.

8. The method for preparing the meaty-flavored surimi-soybean meal dual-protein extruded product according to claim 7, characterized in that: In step S4, the heating temperature of the last heating zone of the twin-screw extruder is 120° C. to 180° C.

9. The method for preparing the meaty-flavored surimi-soybean meal powder dual-protein extruded product according to claim 7, characterized in that: In the step S4, there are four heating zones, the first three heating temperatures are 60-80°C, 80-95°C, and 110-130°C in the extrusion direction, and the last heating temperature is 120-180°C.

10. The method for preparing the meaty-flavored surimi-soybean meal powder dual-protein extruded product according to claim 1, characterized in that: In step S5, the fresh extruded product should be collected after the instrument working condition is stable. The packaging method is vacuum packaging and the storage method is room temperature. The product state is a double-protein extruded product with fiber texture and obvious meat flavor.

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