Soy sauce added with plant seed meal and preparation method thereof

Abstract

The invention belongs to the technical field of food, and particularly relates to soy sauce added with plant seed meal and a preparation method of the soy sauce. The preparation method of the soy sauce comprises the following steps: (1) soaking the plant seed meal with guar gum salt water, and cooking to obtain cooked plant seed meal; (2) mixing fried wheat with aspergillus oryzae, then adding the plant seed meal clinker, and ventilating to make koji, so as to obtain finished koji; (3) mixing the finished koji with saline water, fermenting, and squeezing to obtain raw soy sauce; and (4) mixing the raw soy sauce with a flavoring agent, sterilizing, and filling to obtain the soy sauce added with the plant seed meal. According to the preparation method, on one hand, the protein hydrolysis efficiency and the raw material utilization rate in the starter propagation stage are remarkably improved, and on the other hand, the flavor balance of the low-salt soy sauce is successfully improved.

Description

Technical Field

[0001] This invention belongs to the field of food technology, and in particular relates to a soy sauce with added plant seed meal and its preparation method. Background Technology

[0002] In traditional soy sauce brewing, the fermentation process is mainly divided into two types based on the fermentation method: low-salt solid-state and high-salt liquid-state. The low-salt solid-state process typically uses soybean meal and wheat bran as raw materials. After steaming and cooking, and preparing koji (fermentation starter) with a single strain of Aspergillus oryzae, it is mixed with an appropriate amount of brine to form a solid mash, which is then fermented at a relatively high temperature of 42-46℃. The high-salt liquid-state process often uses a mixture of soybean meal and roasted wheat. After koji preparation, salt-tolerant lactic acid bacteria and yeast are added for multi-strain synergistic fermentation, resulting in a more flavorful soy sauce mash.

[0003] Under the current dual trends of "green food" and "healthy salt reduction," the soy sauce industry faces an urgent need to transform towards low-sodium, high-protein utilization, and environmentally friendly production. However, existing technologies still have significant limitations: on the one hand, the limited activity of Aspergillus oryzae protease during the koji-making process leads to insufficient degradation of raw material proteins and low nitrogen source utilization, resulting not only in resource waste but also increased carbon emissions and the burden of byproduct treatment; on the other hand, simply reducing salt content can easily result in an abrupt saltiness and insufficient soy sauce aroma in the product, while the discharge of high-salt wastewater also puts pressure on environmental governance. Therefore, how to improve protease activity and flavor stability while achieving low-carbon production and resource recycling in the brewing process has become a key challenge for the green upgrading of the soy sauce industry.

[0004] Against this backdrop, exploring the use of various plant seed meals as supplementary or alternative raw materials not only helps improve the comprehensive utilization rate of protein and reduce dependence on soybean resources alone, but also promotes the high-value utilization of agricultural by-products, reduces the overall carbon footprint of brewing systems, and aligns with the development direction of sustainable food processing. Therefore, this invention provides a method for preparing soy sauce with added plant seed meals. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a simple method for preparing soy sauce with added plant seed meal.

[0006] One of the objectives of this invention is achieved through the following technical solution: A method for preparing soy sauce with added plant seed meal includes the following steps: (1) Soaking plant seed meal in guar gum brine and then steaming it to obtain cooked plant seed meal; (2) Mix roasted wheat with Aspergillus oryzae, then add the cooked plant seed meal, ventilate and ferment to obtain koji; (3) The koji and brine are mixed and fermented, then pressed to obtain raw soy sauce; (4) The raw soy sauce is mixed with seasoning, sterilized, and bottled to obtain the soy sauce with added plant seed meal; The structure of the flavoring agent is as follows: .

[0007] Preferably, the guar gum brine in step (1) comprises the following components by mass percentage: 0.1-0.5% modified guar gum, 4-7% sodium chloride, and the remainder being water.

[0008] Preferably, the preparation process of the modified guar gum is as follows: (a) In an inert gas atmosphere, guar gum was added to ethanol, and then sodium periodate was added to react. After purification, oxidized guar gum was obtained. (b) Under an inert gas atmosphere, the oxidized guar gum and selenocysteine ​​were added to ethanol, and then sodium triacetate borohydride was added to react. After purification, the modified guar gum was obtained.

[0009] Preferably, in step (a), the mass ratio of guar gum to sodium periodate is 5:(0.8-1); the reaction time is 10-16 h; in step (b), the mass ratio of oxidized guar gum, selenocysteine, and sodium borohydride triacetate is 1:(0.8-1.2):(1.2-1.5); the reaction time is 10-16 h.

[0010] Preferably, the preparation method of the flavoring agent in step (4) is as follows: The flavoring agent was prepared by adding vanillin and L-tryptophan to ethanol, then adding glacial acetic acid to react and purify.

[0011] Preferably, the molar ratio of vanillin, L-tryptophan, and glacial acetic acid is 1:(1.2-1.5):(0.1-0.3); and the reaction time is 5-8 hours.

[0012] Preferably, the plant seed meal in step (1) is composed of soybean meal and Eucommia ulmoides seed meal in a mass ratio of 10:1; the soaking time is 5-8 hours; the cooking temperature is 130-140℃ and the cooking time is 30-50 minutes.

[0013] Preferably, in step (2), the mass ratio of the cooked plant seed meal to the roasted wheat is 1:(0.8-1); the amount of Aspergillus oryzae added is 0.5-0.8% of the total mass of the cooked plant seed meal and the roasted wheat; the ventilation koji-making process includes three stages: the koji-making time of the first stage is 0-17h, and the cultivation temperature is 33-36℃; the koji-making time of the second stage is 17-25h, and the cultivation temperature is 29-32℃; the koji-making time of the third stage is 25-48h, and the cultivation temperature is 23-26℃.

[0014] Preferably, in step (3), the ratio of the amount of koji and the amount of brine is 1g:(2-2.5)mL; the concentration of the brine is 15-20wt%; the fermentation temperature is 30-37℃ and the time is 80-100d; and the amount of seasoning added in step (4) is 0.005-0.008wt% of the raw soy sauce.

[0015] The second objective of this invention is to provide a soy sauce with added plant seed meal.

[0016] The second objective of this invention is achieved by the following technical solution: A type of soy sauce with added plant seed meal is prepared using the above-described preparation method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for preparing soy sauce with added plant seed meal, which significantly improves the protein hydrolysis efficiency and raw material utilization rate during the koji-making stage, and successfully improves the flavor balance of low-salt soy sauce. This preparation method is committed to resource conservation, process efficiency improvement, and environmental friendliness in soy sauce manufacturing, providing a feasible technical solution for developing high-quality, low-carbon emission soy sauce products under the dual requirements of "healthy salt reduction" and "green manufacturing".

[0018] 2. The modified guar gum prepared by this invention can improve the protease activity in koji (fermentation starter) and the content of amino acid nitrogen and total nitrogen in soy sauce. Specifically, the modified guar gum of this invention incorporates a slightly negatively charged selenium element in its structure, which can generate electrostatic interactions with the positively charged regions in the raw material protein, thereby effectively adsorbing and enriching the protein even in the presence of salt. After swelling and drying, it forms a unique gradient microporous structure on the surface of soybean meal, simultaneously optimizing hydrophilicity and pore distribution. This microstructure provides an ideal interface for the attachment, anchoring, and proliferation of Aspergillus oryzae spores, significantly enhancing the colonization efficiency of the cells on the raw material surface, and thus deeply inducing the efficient secretion and expression of neutral and alkaline protease systems. Ultimately, it achieves more thorough hydrolysis of plant proteins (including the main raw material soybean meal and the by-product Eucommia ulmoides seed meal), promoting a simultaneous increase in the production rate of total nitrogen and amino acid nitrogen.

[0019] 3. The seasoning agent prepared by this invention can reduce the saltiness of soy sauce. This is because the seasoning agent containing Schiff base is prepared by condensing the amino group of L-lysine with the vanillin aldehyde group. Its special molecular structure can interact with the flavor components in soy sauce, effectively optimizing the taste profile of the fermentation base. It can not only soften the overly sharp saltiness, but also enhance the synergistic expression of umami and mellowness, thereby giving the product a more rounded, full-bodied taste experience and a long-lasting aftertaste while reducing the actual amount of salt used or maintaining the same saltiness. Attached Figure Description

[0020] Figure 1 This is the infrared spectrum of the modified guar gum obtained in Example 1. Detailed Implementation

[0021] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0022] Example 1 This embodiment provides a modified guar gum, the preparation process of which is as follows: (a) Under a nitrogen atmosphere, 5g of guar gum was added to 50mL of ethanol, stirred evenly, and then 0.9g of sodium periodate was added. The reaction was carried out at room temperature for 12h. The reaction was quenched with ethylene glycol and then tert-butanol was added. The mixture was filtered and the filter cake was freeze-dried to obtain oxidized guar gum. (b) Under a nitrogen atmosphere, 1g of oxidized guar gum and 1g of selenocysteine ​​were added to 50mL of ethanol, stirred evenly, and then 1.4g of sodium triacetate borohydride (CAS: 56553-60-7) was added. The mixture was reacted at room temperature for 14h, filtered, and the filter cake was washed with ethanol and freeze-dried to obtain the modified guar gum.

[0023] Example 2 This embodiment provides a modified guar gum, the preparation process of which is as follows: (a) Under a nitrogen atmosphere, 5g of guar gum was added to 50mL of ethanol, stirred evenly, and then 0.8g of sodium periodate was added. The reaction was carried out at room temperature for 10h. The reaction was quenched with ethylene glycol and then tert-butanol was added. The mixture was filtered and the filter cake was freeze-dried to obtain oxidized guar gum. (b) Under a nitrogen atmosphere, 1 g of oxidized guar gum and 0.8 g of selenocysteine ​​were added to 50 mL of ethanol, stirred evenly, and then 1.2 g of sodium triacetate borohydride was added. The mixture was reacted at room temperature for 10 h, filtered, and the filter cake was washed with ethanol and freeze-dried to obtain the modified guar gum.

[0024] Example 3 This embodiment provides a modified guar gum, the preparation process of which is as follows: (a) Under a nitrogen atmosphere, 5g of guar gum was added to 50mL of ethanol, stirred evenly, and then 1g of sodium periodate was added. The reaction was carried out at room temperature for 16h. The reaction was quenched with ethylene glycol and then tert-butanol was added. The mixture was filtered and the filter cake was freeze-dried to obtain oxidized guar gum. (b) Under a nitrogen atmosphere, 1 g of oxidized guar gum and 1.2 g of selenocysteine ​​were added to 50 mL of ethanol, stirred evenly, and then 1.5 g of sodium triacetate borohydride was added. The mixture was reacted at room temperature for 16 h, filtered, and the filter cake was washed with ethanol and freeze-dried to obtain the modified guar gum.

[0025] Example 4 This embodiment provides a flavoring agent, the preparation process of which is as follows: Vanillin (10 mmol) and L-tryptophan (14 mmol) were added to 20 mL of ethanol and stirred until homogeneous. Then, glacial acetic acid (2 mmol) was added and the mixture was reacted at room temperature for 7 h. The pH was adjusted to 9 with saturated sodium carbonate solution, and the reaction solution was filtered. The pH of the filter cake was adjusted to 5 with 1 mol / L hydrochloric acid, and the hydrochloric acid aqueous phase was extracted with ethyl acetate. The ethyl acetate phase was dried and concentrated to obtain the flavoring agent. The NMR and mass spectrometry results of the flavoring agent are shown below: 1 HNMR (C 19 H 18 N2O4, 400MHz, DMSO): δ 12.68 (s, 1H), 10.72 (s, 1H), 9.54 (s, 1H), 8.74 (s, 1H), 7.56 (dd, 1H), 7.37-7.33 (m, 3H), 7.16 (s, 1H), 7.05-6.88 (m, 3H), 4.39 (t, 1H), 3.81 (s, 3H), 3.15-2.91 (m, 2H); HRMS(ESI+): [M+H]+ Calculated to be 339.13, found to be 339.13.

[0026] Example 5 This embodiment provides a flavoring agent, the preparation process of which is as follows: Vanillin (10 mmol) and L-tryptophan (15 mmol) were added to 20 mL of ethanol and stirred until homogeneous. Then, glacial acetic acid (3 mmol) was added and the mixture was reacted at room temperature for 8 h. The pH was adjusted to 9 with saturated sodium carbonate solution, and the reaction solution was filtered. The pH of the filter cake was adjusted to 5 with 1 mol / L hydrochloric acid, and the hydrochloric acid aqueous phase was extracted with ethyl acetate. The ethyl acetate phase was dried and concentrated to obtain the flavoring agent. The NMR and mass spectrometry results of the flavoring agent were the same as in Example 4.

[0027] Example 6 This embodiment provides a flavoring agent, the preparation process of which is as follows: Vanillin (10 mmol) and L-tryptophan (12 mmol) were added to 20 mL of ethanol and stirred until homogeneous. Then, glacial acetic acid (1 mmol) was added and the mixture was reacted at room temperature for 5 h. The pH was adjusted to 9 with saturated sodium carbonate solution. The reaction solution was filtered, and the pH of the filter cake was adjusted to 5 with 1 mol / L hydrochloric acid. The hydrochloric acid aqueous phase was extracted with ethyl acetate, and the ethyl acetate phase was dried and concentrated to obtain the flavoring agent. The NMR and mass spectrometry results of the flavoring agent were the same as in Example 4.

[0028] Example 7 This embodiment provides a method for preparing soy sauce with added plant seed meal, including the following steps: (1) Soak the plant seed meal consisting of soybean meal and Eucommia ulmoides seed meal in guar gum brine for 7 hours, then cook it at 135°C for 40 minutes and cool it to room temperature to obtain the cooked plant seed meal; wherein the guar gum brine includes the following components in the following mass percentages: 0.4% modified guar gum from Example 1, 6% sodium chloride, and the remainder is water; (2) The roasted wheat and Aspergillus oryzae are mixed in a mass ratio of 1:0.9:0.114, and then the roasted wheat and Aspergillus oryzae are added. The mixture is then ventilated and fermented to obtain koji. The koji-making process includes three stages: the first stage has a koji-making time of 0-17h and a cultivation temperature of 33-36℃; the second stage has a koji-making time of 17-25h and a cultivation temperature of 29-32℃; and the third stage has a koji-making time of 25-48h and a cultivation temperature of 23-26℃. (3) With a ratio of 1g to 2.4mL of koji and brine, the koji and brine with a concentration of 18wt% were mixed, fermented at 35℃ for 90 days, and then pressed to obtain raw soy sauce; (4) The amount of seasoning added is 0.007 wt% of the raw soy sauce. The raw soy sauce is mixed with the seasoning of Example 4, sterilized, and bottled to obtain the soy sauce with added plant seed meal.

[0029] This embodiment also provides a soy sauce with added plant seed meal, which is prepared using the above-described preparation method.

[0030] Example 8 This embodiment provides a method for preparing soy sauce with added plant seed meal, including the following steps: (1) Soak the plant seed meal consisting of soybean meal and Eucommia ulmoides seed meal in guar gum brine for 5 hours, then cook it at 130°C for 50 minutes and cool it to room temperature to obtain the cooked plant seed meal; wherein the guar gum brine includes the following components in the following mass percentages: 0.1% modified guar gum from Example 2, 4% sodium chloride, and the remainder is water; (2) The roasted wheat and Aspergillus oryzae are mixed in a mass ratio of 1:0.8:0.09, and then the roasted wheat and Aspergillus oryzae are added. The mixture is then ventilated and fermented to obtain koji. The koji-making process includes three stages: the first stage has a koji-making time of 0-17h and a cultivation temperature of 33-36℃; the second stage has a koji-making time of 17-25h and a cultivation temperature of 29-32℃; and the third stage has a koji-making time of 25-48h and a cultivation temperature of 23-26℃. (3) With a ratio of 1g to 2mL of koji and brine, the koji and brine with a concentration of 15wt% were mixed, fermented at 30℃ for 100 days, and then pressed to obtain raw soy sauce. (4) The amount of seasoning added is 0.005 wt% of the raw soy sauce. The raw soy sauce is mixed with the seasoning of Example 5, sterilized, and bottled to obtain the soy sauce with added plant seed meal.

[0031] This embodiment also provides a soy sauce with added plant seed meal, which is prepared using the above-described preparation method.

[0032] Example 9 This embodiment provides a method for preparing soy sauce with added plant seed meal, including the following steps: (1) Soak the plant seed meal consisting of soybean meal and Eucommia ulmoides seed meal in guar gum brine for 8 hours, then cook it at 140°C for 30 minutes and cool it to room temperature to obtain the cooked plant seed meal; wherein the guar gum brine includes the following components in the following mass percentages: 0.5% modified guar gum of Example 3, 7% sodium chloride, and the remainder is water; (2) The roasted wheat and Aspergillus oryzae are mixed in a mass ratio of 1:1:0.16 with the cooked plant seed meal, roasted wheat and Aspergillus oryzae, and then the cooked plant seed meal is added. The mixture is then ventilated and fermented to obtain koji. The koji-making process includes three stages: the first stage has a koji-making time of 0-17h and a cultivation temperature of 33-36℃; the second stage has a koji-making time of 17-25h and a cultivation temperature of 29-32℃; and the third stage has a koji-making time of 25-48h and a cultivation temperature of 23-26℃. (3) With a ratio of 1g to 2.5mL of koji and brine, the koji and brine with a concentration of 20wt% were mixed, fermented at 37℃ for 80 days, and then pressed to obtain raw soy sauce; (4) The amount of seasoning added is 0.008 wt% of the raw soy sauce. The raw soy sauce is mixed with the seasoning of Example 6, sterilized, and bottled to obtain the soy sauce with added plant seed meal.

[0033] This embodiment also provides a soy sauce with added plant seed meal, which is prepared using the above-described preparation method.

[0034] Comparative Example 1 The difference between Comparative Example 1 and Example 7 is that the modified guar gum in Example 1 was replaced with guar gum.

[0035] Comparative Example 2 The difference between Comparative Example 2 and Example 7 is that the flavoring agent of Example 4 is omitted.

[0036] Experimental Example 1 The modified guar gum obtained in Example 1 was analyzed by Fourier transform infrared spectroscopy (FT-IR), and the results are as follows: Figure 1 As shown.

[0037] Figure 1 The image shows the infrared spectrum of the modified guar gum obtained in Example 1. Curve a is the infrared spectrum of the original guar gum, and curve b is the infrared spectrum of the modified guar gum. (Observation) Figure 1 Knowing that 567 cm is in curve b −1 The characteristic peak is attributed to the diselenylene bond Se-Se; 1080 cm⁻¹ −1 The characteristic peaks are attributed to CN, indicating that selenocysteine ​​has been successfully grafted onto guar gum.

[0038] Experimental Example 2 Sodium chloride solutions with mass concentrations of 0-20% were prepared using distilled water, and salinity scores were set according to the concentration gradient. Sodium chloride solutions of different concentrations were used as standard solutions for salinity evaluation (see Table 1). Ten evaluators were trained on salinity evaluation using the standard solutions until each evaluator achieved a blind evaluation accuracy of over 90% for the salinity of the standard solutions. Then, the salinity of the soy sauces prepared in Examples 7-9 and Comparative Examples 1-2 was evaluated. The final results are the average values, and the results are shown in Table 2. The protease activity in the koji of Examples 7-9 and Comparative Examples 1-2 was detected according to Zhang Yanfang’s “Research on Enzyme System Optimization and Soy Sauce Quality Improvement through Multi-Strain Koji Making”. The results are shown in Table 2. The amino acid nitrogen content in the soy sauces prepared in Examples 7-9 and Comparative Examples 1-2 was tested according to GB5009.235-2016 "National Food Safety Standard for Amino Acid Nitrogen in Food". The results are shown in Table 2. The total nitrogen content in the soy sauces prepared in Examples 7-9 and Comparative Examples 1-2 was tested according to GB5009.5-2016 "National Food Safety Standard for Food Protein". The results are shown in Table 2.

[0039] Table 1 Table 2 Table 2 shows that, compared with Comparative Example 1, the protease activity in the koji obtained in Example 7 was higher, and the content of amino acid nitrogen and total nitrogen in the soy sauce was also higher. These results indicate that the modified guar gum of the present invention can improve the protease activity in the koji and the content of amino acid nitrogen and total nitrogen in the soy sauce. This is because the modified guar gum of the present invention incorporates a slightly negatively charged selenium element, which can generate electrostatic interactions with the positively charged regions in the raw material protein, thus effectively adsorbing and enriching the protein even in the presence of salt. After swelling and drying, it forms a unique gradient microporous structure on the surface of soybean meal, simultaneously optimizing hydrophilicity and pore distribution. This microstructure provides an ideal interface for the attachment, anchoring, and proliferation of Aspergillus oryzae spores, significantly enhancing the colonization efficiency of the cells on the raw material surface, thereby deeply inducing the efficient secretion and expression of neutral and alkaline protease systems. Ultimately, it achieves more thorough hydrolysis of plant proteins (including the main raw material soybean meal and the by-product Eucommia ulmoides seed meal), promoting a simultaneous increase in the production rate of total nitrogen and amino acid nitrogen.

[0040] From a resource efficiency and environmental perspective, the use of modified guar gum improves protein conversion rates. Higher enzyme activity and nitrogen utilization mean that raw material consumption can be reduced when producing the same amount of soy sauce; or a higher quality product (i.e., higher nitrogen content) can be obtained with the same input, thereby reducing the carbon footprint from raw material cultivation to processing. Furthermore, the efficient utilization of agricultural byproducts such as Eucommia ulmoides seed meal aligns with the concept of byproduct resource utilization in a circular economy, helping to reduce environmental impact.

[0041] Table 2 shows that the soy sauce obtained in Example 7 has a lower saltiness compared to Comparative Example 2. These results demonstrate that the seasoning agent of the present invention can reduce the saltiness of soy sauce. This is because the seasoning agent of the present invention, prepared by condensing the amino group of L-lysine with the vanillin aldehyde group, contains a Schiff base. Its unique molecular structure allows it to interact with the flavor components in soy sauce, effectively optimizing the taste profile of the fermented base. It not only softens excessively sharp saltiness but also enhances the synergistic expression of umami and richness, thereby providing a more rounded, full-bodied taste experience and a longer aftertaste while reducing the actual amount of salt used or maintaining the same saltiness.

[0042] From an environmental perspective, this seasoning provides a key technological path for the substantial reduction of salt in soy sauce. Lowering the salt content not only responds to the demand for healthy eating, but also reduces the amount and difficulty of treating high-salt wastewater generated during the brewing process, effectively reducing the environmental pressure of end-of-pipe treatment and promoting the transformation of the soy sauce industry towards a cleaner production model that "reduces salt without reducing flavor and reduces emissions without reducing quality."

[0043] In summary, this invention, through the synergistic use of modified guar gum and flavoring agents, significantly improves protein hydrolysis efficiency and raw material utilization during the koji-making stage, while successfully enhancing the flavor balance of low-sodium soy sauce. Both contribute to resource conservation, process efficiency improvement, and environmental friendliness in soy sauce manufacturing, providing a feasible technical solution for developing high-quality, low-carbon-emission soy sauce products under the dual requirements of "healthy salt reduction" and "green manufacturing."

[0044] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for producing a soy sauce added with plant seed meal, characterized by, The method comprises the following steps: (1) soaking plant seed meal in guar gum brine, cooking to obtain plant seed meal; (2) mixing wheat with Aspergillus oryzae, then adding the plant seed meal, and ventilating to obtain koji; (3) mixing the koji with brine, fermenting, and squeezing to obtain raw soy sauce; (4) mixing the raw soy sauce with a flavoring agent, sterilizing, and filling to obtain the plant seed meal added soy sauce; The structure of the flavoring agent is: 。 2. The method of producing a soy sauce added with plant seed meal according to claim 1, characterized by, The guar gum brine in step (1) comprises the following components with the following mass percentages: 0.1-0.5% modified guar gum, 4-7% sodium chloride, and the rest water.

3. The method of producing a soy sauce added with plant seed meal according to claim 2, characterized by, The preparation process of the modified guar gum is as follows: (a) under an inert gas atmosphere, adding guar gum into ethanol, then adding sodium periodate for reaction, and purifying to obtain oxidized guar gum; (b) under an inert gas atmosphere, adding the oxidized guar gum, selenocystamine into ethanol, then adding sodium borohydride for reaction, and purifying to obtain the modified guar gum.

4. The method of producing a soy sauce added with plant seed meal according to claim 3, characterized by, The mass ratio of the guar gum to sodium periodate in step (a) is 5:(0.8-1); the reaction time is 10-16h; the mass ratio of the oxidized guar gum, selenocystamine, and sodium borohydride in step (b) is 1:(0.8-1.2):(1.2-1.5); the reaction time is 10-16h.

5. The method of claim 1, wherein the soy sauce with added plant meal is prepared by adding the plant meal to the soy sauce after the fermentation of the soy sauce. The preparation method of the flavoring agent in step (4) is as follows: adding vanillin and L-tryptophan into ethanol, then adding glacial acetic acid for reaction, and purifying to obtain the flavoring agent.

6. The method of producing a soy sauce added with plant seed meal according to claim 5, characterized by, The molar ratio of the vanillin, L-tryptophan, and glacial acetic acid is 1:(1.2-1.5):(0.1-0.3); the reaction time is 5-8h.

7. The method of claim 1, wherein the soy sauce is prepared by adding the plant meal to the soy sauce. The plant seed meal in step (1) is composed of soybean meal and eucommia seed meal with a mass ratio of 10:1; the soaking time is 5-8h; the cooking temperature is 130-140℃, and the time is 30-50min.

8. The method of claim 1, wherein the soy sauce with added plant meal is prepared by adding the plant meal to the soy sauce after the fermentation of the soy sauce. The mass ratio of the plant seed meal to wheat in step (2) is 1:(0.8-1); the added amount of the Aspergillus oryzae is 0.5-0.8% of the total mass of the plant seed meal and wheat; the ventilating koji-making process comprises three stages: the koji-making time of the first stage is 0-17h, and the culture temperature is 33-36℃; the koji-making time of the second stage is 17-25h, and the culture temperature is 29-32℃; the koji-making time of the third stage is 25-48h, and the culture temperature is 23-26℃.

9. The method of claim 1, wherein the soy sauce with added plant meal is prepared by adding the plant meal to the soy sauce after the fermentation of the soy sauce. The added amount of the flavoring agent in step (4) is 0.005-0.008wt% of the raw soy sauce.

10. A soy sauce to which plant seed meal is added, characterized by, The plant seed meal added soy sauce is prepared by the preparation method in any one of claims 1-9.

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