A method for targeted color protection of 10-30 kda melanoidins in soy sauce

Abstract

The application discloses a kind of 10-30 kDa melanoidins in soy sauce directional color protection method, belong to food processing technical field.The defects that present soy sauce color protection technology targeting is poor, safety is low, product flavor is easily damaged, and insufficient adaptability, the application is added 0-0.1% mountain warehouse son oil or / and 0-0.5% chitosan in the post-processing stage of soy sauce brewing, chitosan molecular weight is 1-20 kDa, wherein 10-12 kDa color protection effect is optimal;While preferred process sequence is: after adding mountain warehouse son oil stirring evenly, then add chitosan.The application is by specific component raw material synergy and exclusive feeding process timing, and 10-30 kDa melanoidins in soy sauce is protected directionally.The method process is simple, safety is high, and it is suitable for low-salt solid, solid and dilute fermentation, high-salt dilute and other multi-class soy sauce, can effectively stabilize soy sauce color, significantly improve soy sauce finished product sensory quality and shelf stability, with good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for targeted color protection of 10-30 kDa melanin in soy sauce. Background Technology

[0002] Color is a core sensory quality indicator of soy sauce and a key factor determining its market competitiveness. Melanoids are high-molecular-weight polymers generated during the fermentation stage of soy sauce through Maillard reactions and amino acid condensation reactions. They are the core functional substances contributing to the color of the finished soy sauce, with over 90% of the reddish-brown core color of soy sauce attributed to melanoidins. Among the melanoidin components in soy sauce, the chromophores in the 10–30 kDa molecular weight range are enriched and have stable molecular structures, representing the most potent melanoidin fragments in terms of color development.

[0003] During the entire process of sterilization, storage, transportation, and sales of finished soy sauce, residual oxygen within the system and environmental oxidation can easily cause oxidative degradation and molecular chain breakage of melanoidins (10-30 kDa), leading to a continuous decrease in the L* value of the soy sauce. This results in quality deterioration issues such as dull color, loss of redness, decreased brightness, and overall fading, severely impacting the appearance quality of the soy sauce and consumer purchasing desire. Currently, the industry's soy sauce color protection technology has significant shortcomings, and the applicability of mainstream color protection solutions is limited. Firstly, artificial antioxidants for color protection only have broad-spectrum antioxidant effects and cannot specifically protect the 10-30 kDa high-quality melanoidin components, resulting in poor color protection targeting. Furthermore, some synthetic additives pose food safety risks and do not meet the production requirements of high-end clean label foods. Secondly, process optimization for color protection reduces color loss by lowering sterilization temperature and shortening sterilization time, but this method weakens the sterilization effect of soy sauce and easily leads to excessive microbial levels, failing to balance product quality and food safety. Thirdly, exogenous pigments compensate for fading defects by using artificial pigments, which covers the natural fermentation color of soy sauce, destroys the original sensory characteristics of the product, and has low consumer acceptance.

[0004] In addition, existing color-protecting ingredients in soy sauce generally suffer from complex compositions and high dosages, which can alter the original flavor, texture, and appearance of the soy sauce. Currently, there is no targeted color-protecting technology for melanoidins with specific molecular weights of 10–30 kDa in soy sauce, representing a significant technological gap. Therefore, developing a targeted color-protecting method for soy sauce that is highly targeted, safe, widely adaptable, and does not damage the original quality of the product has significant value for production applications and market promotion. Summary of the Invention

[0005] This invention addresses the industry pain points of existing soy sauce color protection technologies, such as poor targeting, insufficient safety, easy damage to product flavor, and weak process adaptability. It provides a targeted color protection method for melanoidins (10-30 kDa) in soy sauce. This invention uses two types of pure natural food ingredients as color-protecting components. By limiting the precise range of ingredient addition, molecular weight classification of excipients, and a specific addition sequence, it achieves targeted protection of melanoidins (10-30 kDa) in soy sauce, effectively inhibiting their oxidative degradation, stabilizing the color of the finished soy sauce, and is suitable for the industrial production of multiple types of soy sauce, balancing product safety and sensory quality.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution: A method for targeted color protection of 10-30 kDa melanoidins in soy sauce, comprising the steps of performing color protection treatment during the post-brewing stage of soy sauce, wherein the color protection raw materials are pure natural food raw material Shancangzi oil (compliant with GB / T 11424-2008) and / or chitosan; wherein the amount of Shancangzi oil added is 0-0.1%, the amount of chitosan added is 0-0.5%, and the molecular weight range of chitosan is 1-20 kDa; wherein the amount of Shancangzi oil and chitosan added cannot be 0 at the same time.

[0007] Preferably, the amount of shancangzi oil added is 0.03 to 0.07% of the soy sauce mass; more preferably, the amount of shancangzi oil added is 0.05% of the soy sauce mass.

[0008] Preferably, the amount of chitosan added is 0.1 to 0.3% of the weight of soy sauce; more preferably, the amount of chitosan added is 0.2% of the weight of soy sauce.

[0009] Preferably, the chitosan molecular weight is in the range of 1–3 kDa, 3–5 kDa, 5–10 kDa, 10–12 kDa, 12–20 kDa, or 10–12 kDa. More preferably, the chitosan molecular weight is in the range of 10–12 kDa.

[0010] Preferably, the methods of adding *Salvia miltiorrhiza* oil and / or chitosan include: adding *Salvia miltiorrhiza* oil and chitosan simultaneously, adding *Salvia miltiorrhiza* oil first and stirring evenly before adding chitosan, or adding chitosan first and stirring evenly before adding *Salvia miltiorrhiza* oil.

[0011] Even better, there is a specific order for adding the sago palm oil and chitosan: first add the sago palm oil, then add the chitosan after stirring continuously until well mixed, with the stirring time being 10-15 minutes.

[0012] The method is used for the targeted color protection of 10-30 kDa melanin in soy sauce.

[0013] This invention establishes standardized testing conditions: Blank control (without added sage oil and chitosan) and sample soy sauce (with added sage oil and / or chitosan) are uniformly placed in a 50 ℃ oven for 72 hours. Following the method of Li Hanhan et al. (Li Hanhan et al. Physicochemical properties of melanoidins in soy sauce and their quantitative contribution to color analysis [J]. Food and Fermentation Industries, 2026, 52(03): 283-290), 10–30 kDa melanoidins are extracted and prepared from the blank control and sample soy sauce, and then formulated into a 1 mg / mL melanoidin solution. The L* value of the 10–30 kDa melanoidin solution in the blank control and sample soy sauce is detected. Compared with the blank control, the increase in the L* value of the 10–30 kDa melanoidin in the sample soy sauce is analyzed to evaluate the color-protecting effect.

[0014] The beneficial effects of this invention are: (1) Targeted and precise color protection: This invention specifically protects the 10-30 kDa melanoidin components with the strongest coloring properties in soy sauce. Unlike traditional broad-spectrum color protection processes, it precisely inhibits the oxidative degradation of melanoidin and effectively improves the problems of L* value decrease and dark color fading in soy sauce during storage.

[0015] (2) Raw materials are safe and do not affect the flavor: The mountain barley oil and chitosan used are pure natural food raw materials with extremely low addition amounts. They will not change the original flavor, taste and texture of the soy sauce. The food safety level is high and it is suitable for the production of high-end soy sauce products.

[0016] (3) Controllable process and wide adaptability: The optimal feeding sequence, stirring time, chitosan molecular weight and addition range are clearly defined, the process parameters are standardized, and there are no strict equipment requirements; at the same time, it is suitable for mainstream soy sauce categories such as high-salt dilute state and low-salt solid state, and has extremely strong versatility.

[0017] (4) Significant synergistic effect: Through the synergistic effect of two-component pure natural raw materials, the optimal molecular weight and the order of addition are limited, the color protection effect is far superior to that of single raw materials, synchronous addition and reverse addition processes, which greatly extends the shelf life of soy sauce and reduces the cost of product quality loss. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0020] While only preferred methods and materials have been described in this invention, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe the methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] Example 1: Effect of different ingredient addition methods on the L* value of melanin in soy sauce The sample group consisted of soy sauce prepared according to the brewing standard GB 18186-2025. Fermentation broth was collected after 180 days, sterilized at 85°C for 30 minutes, and filtered through qualitative filter paper to obtain the soy sauce. First, sorghum oil was added to the soy sauce, stirred for 10 minutes, and then chitosan was added.

[0023] Five control groups were set up: ① Blank control group: Soy sauce without added sorghum oil or chitosan; ②Add Yamakura oil separately to the soy sauce; ③ Soy sauce with chitosan added separately; ④ Reverse addition group: first add chitosan to soy sauce, stir for 10 minutes, and then add sago palm oil; ⑤ Synchronous addition group: Soy sauce with simultaneous addition of sorghum oil and chitosan group.

[0024] The amounts of *Solanum lyratum* oil and chitosan added to the control and sample samples are shown in Table 1.

[0025] All samples and control groups were placed in a 50℃ oven for 72 h. Following the method of Li Hanhan et al. (Li Hanhan et al. Physicochemical properties of melanoidins in soy sauce and their quantitative contribution to color analysis [J]. Food and Fermentation Industries, 2026, 52 (03): 283-290.), 10-30 kDa melanoidins were extracted and prepared from soy sauce, and a melanoidin solution with a concentration of 1 mg / mL was prepared. The L* value of the melanoidin solution was then detected.

[0026] Table 1. Effects of different additive methods on the L* value of black pigment in soy sauce.

[0027] Note: The L* values ​​and improvement rates for the control and sample values ​​above are the average of three replicates.

[0028] As shown in Table 1, there is a synergistic effect between sago palm oil and chitosan on the protective effect of soy sauce melanin L* value. The order of addition of the two substances also has a significant impact on the protective effect of soy sauce melanin L* value, which verifies that the technology of the present invention is one of the core key conditions for achieving efficient directional color protection.

[0029] Example 2: Effect of different molecular weights of chitosan on the L* value of melanin in soy sauce Soy sauce was prepared in accordance with the brewing standard GB 18186-2025. After fermentation for 180 days, the fermentation liquid was collected, sterilized at 85°C for 30 minutes, and filtered through qualitative filter paper to obtain soy sauce.

[0030] Six equal amounts of soy sauce were taken, and a blank control group was set up. The optimal feeding process was uniformly adopted for all samples: first, add sorghum oil, stir for 10 min, and then add chitosan. The amount of sorghum oil added accounted for 0.05% of the mass of soy sauce, and the amount of chitosan added accounted for 0.2% of the mass of soy sauce. Only the molecular weight of chitosan was changed, and five molecular weight groups were set up in sequence: 1-3 kDa, 3-5 kDa, 5-10 kDa, 10-12 kDa, and 12-20 kDa. All controls and samples were placed at a constant temperature of 50 ℃ for 72 h. Following the method of Li Hanhan et al. (Li Hanhan et al. Physicochemical properties of melanoidins in soy sauce and their quantitative contribution to color analysis [J]. Food and Fermentation Industries, 2026, 52 (03): 283-290.), 10-30 kDa melanoidins in soy sauce were extracted and prepared from soy sauce, and a melanoidin solution with a concentration of 1 mg / mL was prepared. The L* value of the melanoidin solution was detected. A single-variable study was conducted to investigate the effect of chitosan molecular weight on the L* value of black pigment in soy sauce.

[0031] Table 2. Effects of different chitosan molecular weights on the L* value of black pigment in soy sauce.

[0032] Note: The L* values ​​and improvement rates for the control and sample values ​​above are the average of three replicates.

[0033] As shown in Table 2, the molecular weight of chitosan has a significant impact on the L* value of black pigment in soy sauce. Chitosan in the 10-12 kDa molecular weight range has the best synergistic color-protecting effect, while the color-protecting effect of chitosan in other molecular weight ranges is significantly reduced.

[0034] Example 3: Effect of different addition ratios of sago palm oil and chitosan on the L* value of black pigment in soy sauce Soy sauce was prepared in accordance with the brewing standard GB 18186-2025. After fermentation for 180 days, the fermentation liquid was collected, sterilized at 85°C for 30 minutes, and filtered through qualitative filter paper to obtain soy sauce.

[0035] Six groups of soy sauce with equal amounts were taken, and a blank control group was set up. The optimal addition process was used for all samples: first add sorghum oil, stir for 10 min, and then add chitosan. The amount of sorghum oil and chitosan added is shown in Table 3.

[0036] All controls and samples were placed at a constant temperature of 50 ℃ for 72 h. Following the method of Li Hanhan et al. (Li Hanhan et al. Physicochemical properties of melanoidins in soy sauce and their quantitative contribution to color analysis [J]. Food and Fermentation Industries, 2026, 52(03): 283-290.), 10–30 kDa melanoidins were extracted from soy sauce and prepared into a melanoidin solution with a concentration of 1 mg / mL. The L* value of the melanoidin solution was then measured. The effect of different addition ratios of sago palm oil and chitosan on the L* value of melanoidins in soy sauce was investigated.

[0037] Table 3. Effects of different addition ratios of sago palm oil and chitosan on the L* value of black pigment in soy sauce.

[0038] Note: The L* values ​​and improvement rates for the control and sample values ​​above are the average of three replicates.

[0039] As shown in Table 3, both sago palm oil and chitosan can effectively protect the color within the specified addition range. The color protection effect is best when 0.05% sago palm oil is combined with 0.2% chitosan. Too high or too low a ratio will affect the synergistic color protection efficiency to varying degrees, which verifies the rationality and reliability of the addition range of the present invention.

[0040] Example 4: Color Protection Test of Low-Salt Solid Soy Sauce This embodiment uses low-salt solid-state fermented soy sauce as the application object. The raw materials for soy sauce production are defatted soybean meal and wheat bran. Low-salt solid-state soy sauce is prepared according to the method of SB / T 10311-1999. Before sterilizing the low-salt solid soy sauce, add 0.01% of the soy sauce mass with sorghum oil. After stirring for 10 minutes, add 0.05% of the soy sauce mass with chitosan. The molecular weight of chitosan is 1-3 kDa.

[0041] A blank control (without the addition of sago palm oil and chitosan) was set up. Three replicates were set up for both the sample and the control. The sample and the control were placed in a 50 ℃ oven for 72 h and the change of L* value was detected.

[0042] The analysis results show that the average L* value of the blank control group was 26.32, while the average L* value of the soy sauce samples after processing in this embodiment was 29.12, representing a 10.64% increase in L* value compared to the blank control. This indicates that the process of this invention has an improving effect on the L* value of low-salt solid soy sauce and can alleviate the problems of fading and darkening of soy sauce during storage.

[0043] Example 5: Color Protection Experiment of Solid-Liquid Fermentation Soy Sauce (Lower and Mid-Range Values ​​of All Process Parameters) This embodiment uses solid-liquid fermented soy sauce as the application object. The raw materials for soy sauce production are defatted soybean meal and wheat bran. Solid-liquid fermented soy sauce is prepared according to the method of SB / T10313-1999. Before sterilization of solid-liquid fermented soy sauce, add 0.03% of the soy sauce mass with sorghum oil. After stirring for 10 minutes, add 0.1% of the soy sauce mass with chitosan. The molecular weight of chitosan is 3-5 kDa.

[0044] A blank control (without the addition of sago palm oil and chitosan) was set up. Three replicates were set up for both the sample and the control. The sample and the control were placed in a 50 ℃ oven for 72 h and the change of L* value was detected.

[0045] The analysis results show that the average L* value of the blank control group was 25.62, while the average L* value of the soy sauce samples treated by the process in this embodiment was 33.16, which is 29.43% higher than that of the blank control group. This indicates that the process of this invention has a significant effect on improving the L* value of solid-liquid fermented soy sauce and can alleviate the problems of fading and darkening of soy sauce during storage.

[0046] Example 6: Color Protection Test of High-Salt Dilute Fermented Soy Sauce This embodiment uses high-salt dilute-state fermented soy sauce as the application object. The raw materials for soy sauce production are soybeans and wheat. High-salt dilute-state fermented soy sauce is prepared according to the method of SB / T10312-1999. Before sterilization, add 0.05% of the mass of high-salt dilute fermented soy sauce to the mountain barley oil. After stirring for 10 minutes, add 0.2% of the mass of soy sauce to the chitosan, which has a molecular weight of 10-12 kDa.

[0047] A blank control (without the addition of sago palm oil and chitosan) was set up. Three replicates were set up for both the sample and the control. The sample and the control were placed in a 50 ℃ oven for 72 h and the change of L* value was detected.

[0048] The analysis results show that the average L* value of the blank control group was 27.11, while the average L* value of the soy sauce samples after processing in this embodiment was 36.30, which is 33.90% higher than that of the blank control group. This indicates that the process of this invention has a significant effect on improving the L* value of high-salt dilute-state fermented soy sauce, and can alleviate the problems of fading and darkening of soy sauce during storage.

[0049] Example 7: Color Protection Test of High-Salt Dilute-State Fermented Soy Sauce This embodiment uses high-salt dilute-state fermented soy sauce as the application object. The raw materials for soy sauce production are soybeans and flour. High-salt dilute-state fermented soy sauce is prepared according to the method of SB / T10312-1999. Chitosan was added to high-salt, dilute-state fermented soy sauce before sterilization. The amount added was 0.4% of the soy sauce mass, and the molecular weight of chitosan was 12–20 kDa.

[0050] A blank control (without the addition of sago palm oil and chitosan) was set up. Three replicates were set up for both the sample and the control. The sample and the control were placed in a 50 ℃ oven for 72 h and the change of L* value was detected.

[0051] The analysis results showed that the average L* value of the blank control group was 27.33, while the average L* value of the soy sauce samples after the process in this embodiment was 32.70, which was 19.65% higher than that of the blank control group. This indicates that the process of the present invention has a significant effect on improving the L* value of high-salt dilute-state fermented soy sauce, and can alleviate the problems of fading and darkening of soy sauce during storage.

[0052] Example 8: Color Protection Test of High-Salt Dilute-State Fermented Soy Sauce This embodiment uses high-salt dilute-state fermented soy sauce as the application object. The raw materials for soy sauce production are soybeans and flour. High-salt dilute-state fermented soy sauce is prepared according to the method of SB / T10312-1999. Before sterilization, add 0.1% of the weight of the high-salt dilute fermented soy sauce to the mountain barley oil. After stirring for 10 minutes, add 0.5% of the weight of the soy sauce to the chitosan, which has a molecular weight of 12-20 kDa.

[0053] A blank control (without the addition of sago palm oil and chitosan) was set up. Three replicates were set up for both the sample and the control. The sample and the control were placed in a 50 ℃ oven for 72 h and the change of L* value was detected.

[0054] The analysis results showed that the average L* value of the blank control group was 25.62, while the average L* value of the soy sauce samples after processing in this embodiment was 35.70, representing a 39.34% increase in L* value compared to the blank control. This indicates that the process of this invention has a significant effect on improving the L* value of high-salt dilute-state fermented soy sauce, and can alleviate the problems of fading and darkening of soy sauce during storage.

[0055] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for targeted color protection of 10-30 kDa melanoidins in soy sauce, characterized in that, In the post-processing of soy sauce brewing, sago palm oil and / or chitosan are added, wherein the amount of sago palm oil added is 0-0.1%, the amount of chitosan added is 0-0.5%, and the molecular weight range of chitosan is 1-20 kDa; wherein the amount of sago palm oil and chitosan added cannot be 0 at the same time.

2. The method according to claim 1, characterized in that, The amount of yam oil added is 0.03-0.07%.

3. The method according to claim 2, characterized in that, The preferred addition amount of mountain barley oil is 0.05%.

4. The method according to claim 1, characterized in that, The amount of chitosan added is 0.1-0.3%.

5. The method according to claim 4, characterized in that, The preferred addition amount of chitosan is 0.2%.

6. The method according to claim 1, characterized in that, Chitosan has molecular weight segments of 1–3 kDa, 3–5 kDa, 5–10 kDa, 10–12 kDa, 12–20 kDa, or 10–12 kDa.

7. The method according to claim 6, characterized in that, Chitosan is preferably selected with a molecular weight range of 10–12 kDa.

8. The method according to claim 1, characterized in that, The methods for adding safflower oil and / or chitosan include: adding safflower oil and chitosan simultaneously, adding safflower oil first and stirring evenly before adding chitosan, or adding chitosan first and stirring evenly before adding safflower oil.

9. The method according to claim 8, characterized in that, There is a specific order for adding the sago palm oil and chitosan. The preferred method is to add the sago palm oil first, stir continuously until well mixed, and then add the chitosan. The stirring time should be 10-15 minutes.

10. The color-protecting method according to any one of claims 1 to 9, characterized in that, The method is applied to the targeted color protection of 10-30 kDa melanoidins in soy sauce.

Images