Shrimp paste based on waxy rice and synergistic fermentation and flavor enhancement method

Abstract

This invention relates to the field of food fermentation technology, specifically to a shrimp paste and flavor enhancement method based on the co-fermentation of glutinous rice. The method involves fermenting fresh shrimp to obtain a shrimp paste base, then mixing the shrimp paste base with fermented glutinous rice and co-fermenting it. The fermented glutinous rice is prepared by alcoholic fermentation of glutinous rice raw materials with yeast containing Rhizopus oryzae and Saccharomyces cerevisiae. This method significantly shortens the fermentation cycle and greatly improves the flavor quality of the shrimp paste, giving the product the potential to improve with age. It also significantly reduces unpleasant odors such as fishy smell, foul smell, soy sauce aroma, and salty aroma, while increasing acidity and richness, resulting in a fuller flavor profile and achieving a fundamental transformation from a single salty and savory flavor to a complex and multi-layered aroma.

Description

Technical Field

[0001] This invention relates to the field of food fermentation technology, and more specifically, to a shrimp paste based on the co-fermentation of glutinous rice and a method for enhancing its flavor. Background Technology

[0002] The current traditional shrimp paste production process has the following technical defects: First, the product has a single flavor profile and lacks complexity. The flavor profile of pure shrimp paste fermentation is relatively narrow, mainly consisting of alcohols, ketones, and sulfur-containing compounds, presenting a salty, savory, and fishy taste, lacking complex aromas. Its flavor mainly comes from the degradation of shrimp protein and fat, resulting in a salty and heavy taste, rarely possessing rich layers such as fruity or ester aromas.

[0003] Secondly, relying on high salt content for preservation is detrimental to health. Traditional processes require maintaining a high salt content (usually above 10%) to inhibit harmful microorganisms. This results in excessively high sodium content in the product, which does not align with modern low-salt healthy eating trends and also limits the expression of the product's mild flavor and umami.

[0004] For example, in the prior art (CN102204666A), although there are attempts to add cooked glutinous rice and other grains to shrimp paste to improve its flavor, this method essentially involves the physical mixing and co-fermentation of static food ingredients. In this mode, the grains only serve as substrates, and their interaction with the shrimp paste flavor system is insufficient. It fails to actively introduce a mature fermentation system rich in precursor substances and specific functional microbial communities, resulting in limited flavor enhancement. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a shrimp paste based on the co-fermentation of glutinous rice and a method for enhancing its flavor.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice. Fresh shrimp raw materials are fermented to obtain shrimp paste base material, and then the shrimp paste base material is mixed with fermented glutinous rice and co-fermented. The fermented glutinous rice is prepared by mixing glutinous rice raw materials with yeast for alcoholic fermentation, and the yeast contains Rhizopus oryzae and brewing yeast.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, the alcoholic fermentation temperature of the fermented glutinous rice is 23℃-27℃, and the fermentation time is 3-5 days.

[0009] Furthermore, the inoculation mass ratio of the yeast in the glutinous rice raw material is 0.15%-0.25%.

[0010] Furthermore, the mass ratio of Rhizopus oryzae to Saccharomyces cerevisiae is 9:1.

[0011] Furthermore, the mass ratio of the shrimp paste base to the fermented glutinous rice is 4:1-6.

[0012] Furthermore, the co-fermentation is a constant-temperature fermentation under anaerobic conditions, with a fermentation temperature of 23℃-27℃ and a fermentation time of 5-7 hours.

[0013] Furthermore, the co-fermentation process includes at least one venting operation.

[0014] Furthermore, the shrimp paste base is obtained by mixing and fermenting the fresh shrimp raw material with sodium chloride, wherein the mass percentage of sodium chloride is 8%-12% of the fresh shrimp raw material, the fermentation temperature is 20℃-26℃, and the fermentation time is 10-14 months.

[0015] The present invention also provides a shrimp paste based on the co-fermentation of glutinous rice, which is prepared by the method described above.

[0016] Furthermore, the pH value of the shrimp paste is 4.7-5.2.

[0017] The beneficial effects of this invention are as follows: (1) The shrimp paste and flavoring method based on glutinous rice co-fermentation of the present invention adopts fermented glutinous rice and shrimp paste base material co-fermentation, which significantly reduces the pH value of the co-fermentation system and effectively inhibits the growth of common spoilage bacteria and pathogenic bacteria such as Pseudomonas, Enterobacteriaceae and Bacillus cereus. Thus, the microbial safety of the fermentation process is guaranteed without relying on traditional high salt preservation, providing key scientific basis and process feasibility for the production of low salt healthy shrimp paste products; (2) The shrimp paste and aroma enhancement method based on glutinous rice co-fermentation of the present invention adopts fermented glutinous rice and shrimp paste base material co-fermentation, which greatly increases the total number of volatile flavor compounds and the concentration of total aroma substances in the final product; (3) The shrimp paste and flavoring method based on glutinous rice co-fermentation of the present invention, by mixing fermented glutinous rice that has completed alcohol fermentation with shrimp paste base material in the fermentation period in proportion for co-fermentation, significantly shortens the total fermentation cycle, greatly improves production efficiency and reduces time cost; (4) The shrimp paste based on glutinous rice co-fermentation of the present invention effectively reduces the prominent fishy, ​​foul, soy sauce and salty odors of traditional shrimp paste, while significantly increasing the sourness of the product and enhancing the richness and mellowness of the flavor. (5) The shrimp paste based on glutinous rice co-fermentation of the present invention effectively increases alcohols, aldehydes, esters and ketones, especially the significant increase in esters, which gives the product a rich and pleasant aroma of fruit, flowers and sweetness. At the same time, alcohols and aldehydes, as important flavor precursors, can be further transformed into compounds with richer flavor through slow esterification, condensation and other reactions during subsequent storage and aging, so that the product has the quality potential to become more fragrant with age. Attached Figure Description

[0018] Figure 1 This is a comparison chart of pH values ​​for each embodiment and comparative example in Example 1 of the present invention; Figure 2 This is a comparison diagram of the flavor composition of each embodiment and comparative example in Example 2 of the present invention. Figure 2 Figure A shows a comparison of the number of flavor compounds. Figure 2 Figure B shows the concentration composition of various flavor compounds; Figure 3 This is a comparison diagram of the aroma sensory characteristics of each embodiment and comparative example in Embodiment 3 of the present invention. Figure 3 A in the diagram represents the aroma sensory profile. Figure 3 B in the diagram represents the flavor profile. Detailed Implementation

[0019] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] The present invention relates to a shrimp paste flavoring method based on glutinous rice co-fermentation, wherein fresh shrimp raw materials are fermented to obtain shrimp paste base material, and then the shrimp paste base material is mixed with fermented glutinous rice and co-fermented; wherein the fermented glutinous rice is prepared by mixing glutinous rice raw materials with yeast for alcoholic fermentation, and the yeast contains Rhizopus oryzae and brewing yeast.

[0021] The present invention relates to a shrimp paste flavor enhancement method based on glutinous rice co-fermentation. This method involves mixing shrimp paste base obtained from the fermentation of fresh shrimp raw materials with fermented glutinous rice prepared by alcoholic fermentation of glutinous rice raw materials and yeast containing Rhizopus oryzae and brewer's yeast, and then co-fermenting the mixture. This significantly shortens the fermentation cycle and greatly improves the flavor and quality of the shrimp paste. Specifically, the pH value of the fermentation system is significantly reduced, effectively inhibiting the growth of common spoilage bacteria such as Pseudomonas, Enterobacteriaceae, and Bacillus cereus. This ensures microbial safety without relying on high-salt preservatives, providing a scientific basis for the production of low-salt, healthy shrimp paste. Simultaneously, this method significantly increases the total number of volatile flavor compounds and the concentration of total aroma substances, with a synergistic increase in alcohols, aldehydes, esters, and ketones. In particular, the significant increase in esters endows the product with a rich fruity, floral, and sweet aroma. Alcohols and aldehydes, as flavor precursors, can be further transformed into more concentrated compounds during subsequent storage, giving the product the potential to become more fragrant with age. In addition, this method also significantly reduces unpleasant odors such as fishy, ​​foul, soy sauce, and salty aromas, while increasing acidity and mellowness, making the flavor structure more complete. Overall, it achieves an essential transformation from a single salty and umami flavor to a complex and multi-layered aroma.

[0022] The method of this invention differs from traditional shrimp paste preparation in that it does not simply add glutinous rice, but introduces pre-fermented glutinous rice at a specific fermentation stage. This pre-fermented rice not only contains abundant ester synthesis precursors (such as ethanol and organic acids), but also carries an adaptively cultured active functional microbial community, including ester-producing yeasts and saccharifying molds. When mixed with shrimp paste, the two fermentation ecosystems merge and interact, thereby producing characteristic aroma substances such as esters and aromatic compounds that cannot be produced in large quantities in pure shrimp paste or pure glutinous rice fermentation.

[0023] Preferably, the alcoholic fermentation temperature of fermented glutinous rice is 23℃-27℃, and the fermentation time is 3-5 days. This fermentation method can ensure that Rhizopus oryzae and Saccharomyces cerevisiae metabolize efficiently within the optimal growth temperature range, so that the glutinous rice starch is fully saccharified and converted into ethanol and ester synthesis precursors such as organic acids, while forming a stable fermentation system rich in active functional microbial communities.

[0024] Preferably, the inoculation mass ratio of the yeast in the glutinous rice raw material is 0.15%-0.25%. This amount can ensure that Rhizopus oryzae and Saccharomyces cerevisiae obtain a sufficient number of cells to quickly start saccharification and alcoholic fermentation, while avoiding excessive consumption of nutrients or abnormal metabolites due to excessive microbial proliferation caused by excessive inoculation amount, and also avoids problems such as slow fermentation start, prolonged fermentation cycle or incomplete fermentation caused by insufficient inoculation amount.

[0025] Preferably, the mass ratio of Rhizopus oryzae to Saccharomyces cerevisiae is 9:1.

[0026] Preferably, the mass ratio of shrimp paste base to fermented glutinous rice is 4:1-6; within this range, the best balance between the flavor of shrimp paste and the aroma-enhancing effect of glutinous rice can be achieved. If the mass ratio of fermented glutinous rice is too low, the flavor enhancement effect will be poor and the cost will increase; while if the mass ratio of glutinous rice is too high, the fishy (fishy) flavor will be too low, and the original fresh and fragrant characteristics of shrimp paste will be lost.

[0027] More preferably, the shrimp paste base has a mass percentage of 40% and the fermented glutinous rice has a mass percentage of 60%, or the shrimp paste base has a mass percentage of 80% and the fermented glutinous rice has a mass percentage of 20%.

[0028] Preferably, the co-fermentation is a constant-temperature fermentation under anaerobic conditions, with a fermentation temperature of 23℃-27℃ and a fermentation time of 5-7 months. This co-fermentation condition can simulate and optimize the microbial metabolic environment of traditional shrimp paste fermentation, allowing the active functional microorganisms such as Rhizopus oryzae and Saccharomyces cerevisiae carried in the fermented glutinous rice to fully integrate and interact with the salt-tolerant microbial community in the shrimp paste base. Under stable temperature conditions, biochemical processes such as alcoholic fermentation, esterification reaction and protein degradation are continuously carried out, thereby efficiently converting precursor substances such as ethanol and organic acids to generate a large number of esters and other pleasant aroma substances.

[0029] The anaerobic environment is conducive to the metabolic activities of acid-producing bacteria such as lactic acid bacteria, keeping the pH value of the system stable in the acidic range of 4.7-5.2. It effectively inhibits the growth and reproduction of putrefactive bacteria such as Pseudomonas and Enterobacteriaceae, ensuring the microbial safety of the product without relying on high-salt preservation. The fermentation cycle is significantly shortened compared to the fermentation time of more than 12 months for traditional shrimp paste.

[0030] Preferably, the co-fermentation process includes at least one venting operation; this ensures the stability of the co-fermentation system.

[0031] The shrimp paste base of the present invention is obtained by mixing fresh shrimp raw materials with sodium chloride and fermenting, wherein the mass percentage of sodium chloride is 8%-12% of the fresh shrimp raw materials, the fermentation temperature is 20℃-26℃, and the fermentation time is 10-14 months.

[0032] The shrimp paste based on glutinous rice co-fermentation of the present invention is prepared by the above-described method.

[0033] The effects of the present invention will be specifically illustrated below through specific embodiments.

[0034] Example 1: pH difference between flavored shrimp paste and regular shrimp paste An acidic environment is a key barrier factor inhibiting the growth of common spoilage and pathogenic bacteria in food. Lower pH can effectively disrupt the membrane structure of microbial cells, inhibit enzyme activity and transmembrane transport, thereby slowing their growth or even causing their death. Many spoilage bacteria commonly found in aquatic products and fermented foods have an optimal growth pH in a neutral or slightly alkaline environment, and their growth is significantly inhibited when the pH drops below 5.5.

[0035] For example, *Pseudomonas*, a typical spoilage bacterium in aquatic products, has an optimal growth pH of approximately 6.0-8.5, and its growth is severely limited below pH 5.5. Enterobacteriaceae, including many bacteria that cause spoilage and safety hazards, have an optimal growth pH of approximately 6.0-7.5, and their growth is difficult in acidic environments (pH < 5.0). Some salt-tolerant strains of *Bacillus cereus* can grow in fermented foods, with an optimal pH of 6.0-7.0; acidic conditions effectively inhibit their vegetative growth.

[0036] Therefore, this embodiment sets up two experimental groups of flavored shrimp paste (S4, S8) and a control group of traditional shrimp paste (S10), and measures the pH value of each group to evaluate the pH difference between flavored shrimp paste and ordinary shrimp paste.

[0037] In each experimental group and control group, the total mass fraction of shrimp paste base and fermented glutinous rice was 100 parts. The specific proportions for each group are as follows: Group S4: 40 parts shrimp paste base and 60 parts fermented glutinous rice.

[0038] Group S8: 80 parts shrimp paste base and 20 parts fermented glutinous rice.

[0039] S10 group: 100 portions of shrimp paste base.

[0040] After thoroughly mixing the raw materials from each group, the mixture was placed into fermentation containers and sealed with fermentation plugs to maintain an anaerobic environment while allowing gas release. Each group underwent uniform fermentation for 6 months at a constant temperature of 25±2℃. Three biological replicates were set up for each group.

[0041] like Figure 1 As shown in the results, the pH values ​​of the flavored shrimp paste in experimental groups S4 and S8 were significantly lower, indicating that acidic fermentation conditions had a certain inhibitory effect on the growth of spoilage bacteria. Specifically, the pH value of the flavored shrimp paste in group S4 was 4.73, and the pH value of the flavored shrimp paste in group S8 was 5.16, both of which were acidic; while the pH value of the traditional shrimp paste (S10) used as the control was 7.80, which was in the neutral range.

[0042] As can be seen, this invention, by introducing pre-fermented glutinous rice, naturally creates a stable acidic environment (pH 4.7-5.2) in the mixed fermentation system. This acidic condition effectively inhibits the growth of common spoilage bacteria such as Pseudomonas and Enterobacteriaceae, thus ensuring the microbial safety of the fermentation process without relying on traditional high salt concentrations. This provides crucial scientific evidence and technological feasibility for producing low-salt, healthy shrimp paste products.

[0043] Example 2: Composition of flavoring substances in flavor-enhanced shrimp paste and ordinary shrimp paste In this embodiment, flavor compounds were detected in experimental groups S4 and S8 and control group S10 in Example 1 to compare their composition.

[0044] like Figure 2 As shown in Figure A, compared with the traditional shrimp paste (82 kinds) in S10, the total number of volatile flavor compounds in the flavor-enhanced shrimp paste S4 and S8 increased significantly, reaching 90 kinds and 87 kinds respectively. This indicates that the flavor compound spectrum of the flavor-enhanced shrimp paste obtained by the fermentation method of the present invention is more complex and richer.

[0045] More importantly, such as Figure 2 As shown in Figure B, the total aroma compound concentration in flavor-enhanced shrimp paste S4 and S8 was significantly increased, rising dramatically from 242.07 mg / kg in traditional shrimp paste S10 to 493.31 mg / kg (S8) and 744.51 mg / kg (S4), representing increases of 104% and 208%, respectively. This significant increase in concentration is mainly due to the synergistic increase in alcohols, aldehydes, esters, and ketones.

[0046] Alcohols (such as phenylethyl alcohol) typically contribute a rich, slightly sweet aroma base; aldehydes (such as hexanal) provide grassy and fatty notes, and at low concentrations, impart a fresh "top note" to the product; esters (such as ethyl acetate and ethyl hexanoate) are the core source of pleasant fruity, floral, and sweet aromas, directly enhancing the elegance and acceptability of the flavor; while ketones (such as 2,3-butanedione) may contribute roasted aromas such as cream and nuts, adding complexity to the flavor profile. Crucially, these significantly increased alcohols and aldehydes are not only end products but also important flavor precursors.

[0047] During the subsequent storage and aging process of the product, these compounds can be further transformed into esters and other compounds with richer flavors through slow esterification, condensation, and other reactions. This characteristic means that the product of this invention not only has a rich initial aroma, but also has the potential to become more fragrant with age, and its flavor quality is expected to be continuously optimized and improved during storage.

[0048] Example 3: Aroma sensory characteristics of flavored shrimp paste and ordinary shrimp paste In this embodiment, the aroma sensory evaluation of experimental groups S4 and S8 and control group S10 in Example 1 was carried out to compare the aroma sensory characteristics.

[0049] like Figure 3 As shown in the test results, flavor-enhanced shrimp pastes S4 and S8 exhibit richer fruity, sweet, and floral aromas, and these three aroma types are enhanced with an increased proportion of fermented glutinous rice. Simultaneously, the fishy (fishy) odor, unpleasant smell, soy sauce aroma, and salty aroma are reduced in the flavor-enhanced shrimp paste, indicating that the flavor-enhancing process can be used as a method for controlling the flavor of shrimp paste. It is evident that, in terms of flavor profile, the shrimp paste flavor-enhancing method of this invention significantly increases the acidity of the product, enhances the richness and fullness of the flavor, and gives the product a more complete flavor structure.

[0050] In addition, there is a method in the existing technology that uses cooked glutinous rice mixed with shrimp paste base. However, this production method does not involve the co-fermentation process of cooked glutinous rice and shrimp paste base. Its pH value, flavor and sensory characteristics are basically not significantly different from traditional shrimp paste, so no specific comparison was made.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice, characterized in that, Fresh shrimp raw materials are fermented to obtain shrimp paste base material, and then the shrimp paste base material is mixed with fermented glutinous rice and fermented together; wherein, the fermented glutinous rice is prepared by mixing glutinous rice raw materials with yeast and fermenting alcohol, and the yeast contains Rhizopus oryzae and brewing yeast.

2. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 1, characterized in that, The alcoholic fermentation temperature of the fermented glutinous rice is 23℃-27℃, and the fermentation time is 3-5 days.

3. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 2, characterized in that, The inoculation ratio of the yeast in the glutinous rice raw material is 0.15%-0.25%.

4. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 3, characterized in that, The mass ratio of Rhizopus oryzae to Saccharomyces cerevisiae is 9:

1.

5. A method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to any one of claims 1-4, characterized in that, The mass ratio of the shrimp paste base to the fermented glutinous rice is 4:1-6.

6. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 5, characterized in that, The co-fermentation is a constant-temperature fermentation under anaerobic conditions, with a fermentation temperature of 23℃-27℃ and a fermentation time of 5-7 months.

7. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 6, characterized in that, The co-fermentation process includes at least one venting operation.

8. The method for enhancing the flavor of shrimp paste based on the co-fermentation of glutinous rice according to claim 5, characterized in that, The shrimp paste base is obtained by mixing fresh shrimp raw materials with sodium chloride and fermenting, wherein the mass percentage of sodium chloride is 8%-12% of the fresh shrimp raw materials, the fermentation temperature is 20℃-26℃, and the fermentation time is 10-14 months.

9. A shrimp paste based on the co-fermentation of glutinous rice, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. A shrimp paste based on the co-fermentation of glutinous rice according to claim 9, characterized in that, The shrimp paste has a pH value of 4.7-5.2.

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