Pickled zizania latifolia and fermentation preparation method thereof

Abstract

The invention discloses pickled zizania aquatica and a fermentation preparation method thereof. According to the method, traditional pickle fermentation liquor is domesticated and improved, it is determined that strains playing a key positive influence role on the quality of the fermented zizania aquatica product are lactococcus lactis, lactobacillus plantarum and leuconostoc mesenteroides, and a fermentation inoculum suitable for production of the fermented zizania aquatica product is obtained. Furthermore, the appropriate inoculation stage and inoculation amount of the key fermentation strain return inoculation process are determined, compared with a process mode of direct zizania aquatica fermentation, the return inoculation process can shorten the fermentation period from 30 days to 18 days, the content of a key volatile component (ethyl isobutyrate) in the fermented zizania aquatica is increased by about 21% compared with a common process in the same stage, and the yield of the key volatile component (ethyl isobutyrate) in the fermented zizania aquatica is increased by about 20%. The fermented product is sour and refreshing in taste and good in sensory evaluation result.

Description

Technical Field

[0001] The invention relates to wild rice stem pickles and a fermentation preparation method thereof, belonging to the technical field of food processing. Background Art

[0002] Zizania latifolia, also known as "sou shou," "zizania shoots," and "zizania melon," is a key aquatic vegetable in my country. It belongs to the genus Zizania in the Poaceae family and is a perennial aquatic herb. It prefers swampy, wet environments and overwinters as a perennial root. Zizania latifolia is a spindle-shaped fungus formed from the flower stems of Zizania latifolia by the smut fungus Zizania latifolia. Originally a cereal, its seeds are called wild rice. Zizania latifolia is native to China and Southeast Asia. In my country, it is primarily distributed south of the Huaihe River basin, where it is abundant. It is the second most popular aquatic vegetable in my country, after lotus root. Its delicate, white stems are delicious and nutritious, making it one of the "three famous dishes of Jiangnan," along with sea bass and water shield. The peak period for water bamboo harvesting is from mid-to-late May to mid-June, with the average daily output in some areas reaching tens of thousands of tons. However, the quality of water bamboo deteriorates rapidly after harvesting, and its storage time at room temperature does not exceed 3 days. Therefore, during the period when water bamboo is concentrated on the market, it is very easy to have a temporary surplus and poor sales of fresh water bamboo. In addition, the existing water bamboo processed products are single and cannot meet market demand, which seriously affects the development of the water bamboo industry.

[0003] Wild rice stems can be cooked in a variety of ways, including roasting, stir-frying, steaming, stewing, and braising. Furthermore, fresh wild rice stems can be processed into fermented wild rice stems, which not only creates a unique flavor and texture but also prolongs its shelf life. Fermented wild rice stems are fermented under controlled conditions using beneficial microorganisms. Processing fermented wild rice stems into fermented wild rice stems not only expands the product range and enriches consumer choice, but also helps alleviate the difficulty of fresh sales during peak seasons.

[0004] Kimchi is a uniquely flavored lactic acid fermented vegetable product. It utilizes diverse raw materials, is easy to prepare, is low-cost, and is convenient to consume. It boasts excellent sensory qualities and a pleasant taste. Generally speaking, any fiber-rich vegetable or fruit can be fermented using the kimchi process. The vegetable fermentation system is a microecological environment containing a variety of microorganisms, including lactic acid bacteria, yeasts, and acetic acid bacteria. Different vegetable processing methods, such as pickling, pickling, and sauce-making, all involve varying degrees of microbial fermentation. As a cold processing method, vegetable fermentation is highly beneficial for preserving the nutritional value, color, and flavor of vegetables. The products offer excellent sensory qualities while conserving energy. It also offers advantages such as simple equipment, easy operation, low cost, abundant raw materials, and convenient consumption. Lactic acid fermentation technology employed in fermented vegetable processing has significantly impacted the nutritional value, edible quality, and environmental and economic benefits of the products. Furthermore, with the advancement of modern microbiology, research on the beneficial effects of lactic acid bacteria on human health is increasingly recognized. Research and product development using artificially inoculated lactic acid bacteria to ferment vegetables is also becoming increasingly extensive and in-depth, transforming traditional fermented foods into emerging, modern nutritional and health foods.

[0005] Vegetable fermentation processes are generally categorized into two modes: natural fermentation and inoculated fermentation. Natural fermentation utilizes microorganisms native to the surface of vegetables, inducing lactic acid bacteria to become the dominant bacterial population through strict control of the fermentation environment. However, due to the poor controllability and relatively low abundance of natural microorganisms, natural fermentation suffers from limitations in fermentation speed, product stability, and food safety, making it unsuitable for large-scale production. Inoculated fermentation involves artificially adding fermentation microorganisms to the raw materials. Compared to natural fermentation, inoculated fermentation offers advantages such as controllable fermentation quality and faster fermentation speed. Currently, the most commonly used inoculated fermentation method is mother liquor inoculation, where fermentation broth from finished kimchi is added as an inoculum to the raw materials to be fermented. Due to the varying nutritional and structural characteristics of different vegetables, the microbial populations in the fermentation broth can undergo adaptive shifts depending on the type of raw material, primarily manifested in variations in the abundance of the dominant bacterial species. However, these microbial variations can also impact other aspects such as product quality and fermentation cycle. Therefore, selecting the appropriate inoculum (microbial flora) is a critical process for vegetable fermentation production.

[0006] However, the current fermentation and processing technology for wild rice stem is still immature. When using traditional kimchi fermentation liquid (cabbage fermentation liquid) to ferment wild rice stem, it is found that the fermentation cycle is long and the product flavor cannot reach commercial level. The main reason is that the inoculum is derived from fermented cabbage. The microorganisms in the fermentation liquid are mainly adapted to the fermentation of cabbage, and wild rice stem has significant differences in nutrition and structure from cabbage, resulting in poor fermentation efficiency and product quality. In addition, during the fermentation process of wild rice stem, microorganisms undergo dynamic succession. Therefore, when directly adding improved strains to the traditional kimchi fermentation liquid, the improvement effect will be masked by the dominant strains in the traditional kimchi fermentation liquid, resulting in limited effect. Summary of the Invention

[0007] In order to address the deficiencies of the prior art, the present invention domesticates and improves traditional kimchi fermentation liquid, identifies the bacterial species that have a key positive impact on the quality of fermented wild rice stem products, and provides a method for fermenting wild rice stem kimchi based on the key bacterial species.

[0008] The present invention is achieved through the following technical solutions:

[0009] The first object of the present invention is to provide a fermentation preparation method of wild rice stem kimchi, comprising the following steps:

[0010] S1, adding the mixed wild rice stem and kimchi mother liquor into an anaerobic fermentation device for anaerobic fermentation culture;

[0011] S2. After 5 to 7 days of fermentation, inoculate 0.5% to 2% of lactic acid bacteria seed liquid by mass to volume ratio and continue fermentation until completion.

[0012] In one embodiment of the present invention, the kimchi mother liquor is traditional kimchi fermentation liquor.

[0013] In one embodiment of the present invention, the lactic acid bacteria are one or more of Lactobacillus plantarum CICC 22696, Leuconostoc mesenteroides CICC 22184 or Lactococcus lactis CICC 23609.

[0014] In one embodiment of the present invention, the anaerobic fermentation culture conditions are a temperature of 24° C. to 26° C. and a humidity of 70% RH to 75% RH.

[0015] In one embodiment of the present invention, the wild rice stem and kimchi mother liquor are mixed in a mass ratio of 1:8 to 12.

[0016] In one embodiment of the present invention, 10 6 CFU / mL~10 8 CFU / mL.

[0017] In one embodiment of the present invention, the lactic acid bacteria seed liquid is prepared by the following method: activating lactic acid bacteria in MRS culture medium at 35°C to 38°C for 20h to 30h, centrifuging and suspending the bacteria in 0.8% to 0.9% sterile saline to obtain the lactic acid bacteria seed liquid.

[0018] The second object of the present invention is to provide wild rice stem pickles prepared by the method.

[0019] Beneficial effects of the present invention:

[0020] (1) By domesticating and improving the traditional kimchi fermentation liquid, it was determined that the bacteria that have a key positive impact on the quality of fermented wild rice stem products are Lactococcus lactis, Lactobacillus plantarum and Leuconostoc mesenteroides, and a fermentation inoculum suitable for the production of fermented wild rice stem products was obtained.

[0021] (2) The appropriate inoculation stage and inoculation amount of the key fermentation strain re-inoculation process were determined. Compared with the process mode of direct fermentation of water bamboo, the re-inoculation process can shorten the fermentation cycle from 30 days to 18 days. The content of the key volatile component (ethyl isobutyrate) in the fermented water bamboo is increased by about 21% compared with the ordinary process at the same stage. The fermented product has a sour and refreshing taste, and the sensory evaluation results are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The pH value and total acid content of the fermentation liquid for different fermentation strains;

[0024] Figure 2 Soluble sugar content and nitrite content for different fermentation strains;

[0025] Figure 3 The degree of color change of the sample after fermentation compared to the initial state for different fermentation strains;

[0026] Figure 4 The hardness and chewiness of fermented wild rice stem with different fermentation strains;

[0027] Figure 5 Sensory evaluation of samples after 18 days of fermentation for different fermentation strains;

[0028] Figure 6 are the pH value and total acid content of the fermentation liquid at different inoculation times;

[0029] Figure 7 The soluble sugar content and nitrite content at different inoculation times;

[0030] Figure 8 The color change degree of the fermented sample compared with the initial state at different inoculation times;

[0031] Figure 9 The hardness and chewiness of fermented wild rice stem at different inoculation times;

[0032] Figure 10 Sensory evaluation of samples after 18 days of fermentation at different inoculation times;

[0033] Figure 11 are the pH value and total acid content of the fermentation liquid at different inoculation amounts;

[0034] Figure 12 The hardness and chewiness of fermented wild rice stem at different inoculum amounts;

[0035] Figure 13 This is the sensory evaluation of samples fermented for 18 days at different inoculation amounts. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific examples. These implementation cases are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims appended hereto.

[0037] Source of raw materials:

[0038] The traditional kimchi fermentation liquid is the cabbage kimchi fermentation liquid obtained from Shanghai Jinshan Pickle and Condiment Factory Co., Ltd.

[0039] Detection methods involved:

[0040] (1) Texture testing of wild rice stem

[0041] The hardness and chewiness of fermented wild rice stem were measured using a TA.XT plus texture analyzer. The analysis probe was P2 / E, the probe pressure was 10g, the test depth was 5mm, and each group of samples was sampled 10 times for testing.

[0042] (2) Physical and chemical testing of samples

[0043] Soluble sugar content: Determine using the anthrone colorimetric method. Homogenize 1 g of sample and add 10 mL of distilled water. Boil in a boiling water bath for 30 minutes. Cool to room temperature, filter through a 50 mL volumetric flask with filter paper, and adjust to volume. Add 1 mL of solution to 1 mL of water, 0.5 mL of a 2% anthrone solution in ethyl acetate, and 5 mL of concentrated sulfuric acid. Mix thoroughly, then boil in a boiling water bath for 1 minute. Measure the absorbance at 630 nm. Determine the content by comparing to a glucose standard curve.

[0044] Nitrite content: Determined by Griess reagent method. Take 1g of sample slurry and add 20ml of distilled water, 1.2mL of 2.6% (w / v) Na2B4O7 solution and 0.5g of activated carbon, then heat to 70℃ and keep warm for 15min. Add 0.5mL of 30% (w / v) ZnSO4 solution, shake for 15s, then add 0.5mL of 15% (w / v) K4Fe(CN)6 solution and continue shaking for 15s. Let stand in a cold water bath for 30min, filter and dilute to a 50mL volumetric flask. Take 6mL of the solution to be tested, add 0.76mL of glacial acetic acid and 0.76mL of Griess reagent, mix well and let stand at room temperature for 30min, measure the absorbance at 538nm, and determine the content by comparing with the nitrite standard curve.

[0045] Fermentation broth pH value: The pH of the fermentation broth was directly measured using a Shanghai Leiji pH meter.

[0046] Total acid in fermentation broth: determined in accordance with GB 12456-2021.

[0047] Sample color difference: Use a colorimeter to test, and the color difference is expressed as ΔE. The calculation formula is as follows:

[0048]

[0049] Note: The subscript "0" is the color of the fresh sample of WBS.

[0050] (3) Analysis of the succession of fermentation broth microbial communities

[0051] The composition map of the fermentation broth microbial community was obtained by 16S rDNA sequencing analysis.

[0052] (4) Analysis of volatile flavor components in fermented wild rice stem

[0053] By using HS-GC-IMS (FlavorSpec (GAS, Dortmund, Germany) analyzed the changes in volatile flavor components of the samples. All GC-IMS chromatograms were viewed and analyzed using a laboratory analyzer, dynamic principal component analysis, and gallery plot analysis. VOCs were identified by comparing their drift times with standards in a GAS-supported GC-IMS library search.

[0054] (5) Sensory evaluation

[0055] The samples were taken out and the clarity of the fermentation liquid, the surface color of the wild rice stem and the fermentation odor were observed. Five assessors with certain experience and who had received sensory training were invited to conduct sensory evaluation.

[0056] The technical solutions of the present invention are described in detail below with reference to specific embodiments. In the following embodiments, unless otherwise specified, the reagents, materials and equipment used can be purchased from commercial sources, or prepared by conventional methods, or are commonly used in the industry.

[0057] Example 1: Effect of re-inoculation strains on the quality and fermentation cycle of fermented wild rice stem

[0058] (1) Fermentation preparation and sample pretreatment

[0059] Traditional kimchi fermentation liquid was obtained from the Jinshan Pickle Factory and stored at 4°C. The initial microbial composition of the kimchi fermentation liquid was determined by analyzing the 16S rDNA microbial community diversity. Fresh wild rice stems were cleaned, the husks and stale parts removed, and then cut into strips (3 × 1 cm). Blanched in boiling water for 1 minute, the strips were then soaked in clean water and set aside.

[0060] (2) Mother liquid inoculation and domestication

[0061] Wild rice stem and kimchi mother liquor were mixed at a mass-to-volume ratio of 1 g:10 mL and added to anaerobic fermentation bags. The bags were sealed with a heat sealer to expel any remaining air. Seven samples were prepared simultaneously under the same conditions and cultured in a constant temperature and humidity incubator at 25°C and 72% relative humidity. Samples were collected on days 1, 3, 6, 12, 18, 24, and 30. The wild rice stem and fermentation liquor were mixed and ground at a ratio of 1:10, then quickly frozen in liquid nitrogen and stored at -80°C. 16sDNA sequencing was used to analyze the microbial community succession in the kimchi fermentation liquor during the wild rice stem fermentation process.

[0062] (3) Quality analysis of wild rice stem fermented with traditional kimchi fermentation liquid

[0063] The firmness and chewiness of fermented wild rice stems were measured using a full texture analyzer. The samples were analyzed for soluble sugar, nitrate, and nitrite content. The pH and titratable acidity of the fermentation broth were measured, and changes in volatile flavor components were analyzed using GC-IMS. Based on Spearman correlation analysis, key fermentation strains with a significant positive impact on the quality of fermented wild rice stems were identified.

[0064] (4) Research on the re-inoculation process of key fermentation strains

[0065] Based on the results of the mother liquor inoculation acclimation experiment analysis, the key fermentation strains that were significantly correlated with the flavor quality of wild rice stem were back-inoculated into the initial fermentation liquid. The key fermentation strains were determined by the correlation analysis results and purchased from CICC. The strains were cultured and activated according to the strain instructions. The key fermentation strains were Lactobacillus plantarum (CICC 22696), Leuconostoc mesenteroides (CICC 22184), and Lactococcus lactis (CICC 23609). They were activated in MRS medium at 37°C for 24 hours, and the second-generation bacterial solution was centrifuged at 3000xg and suspended in 0.85% sterile saline. All strain suspensions were stored in a refrigerator at 4°C. The strain suspension was diluted to 10 before inoculation. 7 CFU / mL.

[0066] Wild rice stem and kimchi mother liquor were mixed in an anaerobic fermentation bag at a mass-to-volume ratio of 1g:10mL. The bags were sealed with a heat sealer to remove any remaining air, and the samples were placed in a constant temperature and humidity incubator at 25°C and 72% RH for fermentation. On the sixth day of incubation, a 1% (1g / 100mL) suspension of the corresponding strain was inoculated through the inoculation port with a sterile syringe, and fermentation continued. A control group was treated with normal saline. Samples were collected on days 1, 3, 6, 12, 18, 24, and 30 of fermentation. The wild rice stem and fermentation liquor samples were mixed and ground in a ratio of 1:10, then quickly frozen in liquid nitrogen and stored at -80°C.

[0067] (1) Physical and chemical indicators

[0068] like Figure 1 As shown in the figure, different fermentation bacteria species significantly change the pH value and total acid content of the fermentation broth. Among them, Lactobacillus plantarum (LB) has a strong acid production ability, resulting in a lower pH value and higher total acid content in the fermentation broth. In contrast, Lactococcus lactis and Leuconostoc mesenteroides produce relatively less acid, resulting in a higher pH value and lower total acid content in the fermentation broth than the control group.

[0069] like Figure 2 As shown, the soluble sugar content of the samples was rapidly consumed during the first three days of fermentation and then stabilized. The soluble sugar content of the Lactobacillus plantarum sample was low, with no significant differences between the other groups. Nitrite content peaked on the sixth day of fermentation and then rapidly decreased. Nitrite content in the sample with the re-inoculated strain was lower than that in the control group on the 12th day, but there was no significant difference during subsequent fermentation.

[0070] The color difference value reflects the degree of color change of the sample compared to its initial state. Figure 3 As shown in the figure, all samples changed color after fermentation, among which the color changes of samples inoculated with Lactobacillus plantarum and Lactococcus lactis were relatively small, but the differences were not significant.

[0071] (2) Texture quality

[0072] The hardness and chewiness of fermented wild rice stem were measured using a texture analyzer. Figure 4 As shown, the firmness of wild rice stem gradually decreased during fermentation, but no significant differences were found between the groups. The chewiness of samples inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides was significantly higher than that of the control group after 12 days of fermentation, with the Lactobacillus plantarum group showing a slightly higher chewiness than the Leuconostoc mesenteroides group. This comprehensive analysis suggests that Lactobacillus plantarum can effectively maintain the taste of fermented wild rice stem.

[0073] (3) Volatile flavor quality

[0074] Table 1

[0075]

[0076]

[0077] GC-IMS identified 111 volatile flavor components from the samples, and 25 key volatile components were screened using the ROAV method. Ethyl isobutyrate played a major role in the aroma of samples throughout the entire fermentation cycle, imparting a fruity aroma to the fermented wild rice stem. Throughout the fermentation process, the total amount of volatile compounds increased continuously, but the proportion of compounds with earthy, green, and fresh fruity flavors gradually decreased, while the proportion of compounds with malt and mushroom flavors increased, shifting the wild rice stem's flavor from a raw to a cooked vegetable flavor. The key volatile compound, ethyl isobutyrate, gradually increased in content during fermentation. Samples inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides had higher levels of ethyl isobutyrate than the control group, and the level in the Lactobacillus plantarum group on day 18 of fermentation was comparable to that in the control group after 30 days of fermentation.

[0078] (4) Sensory evaluation

[0079] Based on food safety considerations, samples fermented 18 days later were selected for sensory evaluation. Figure 5 As shown in the figure, the Lactobacillus plantarum group achieved a relatively high comprehensive score on the 18th day, while the Lactococcus lactis group and the control group obtained higher scores on the 30th day of fermentation, which shows that re-inoculation of Lactobacillus plantarum can shorten the fermentation cycle to a certain extent and enhance the sensory experience.

[0080] Example 2: Effect of re-inoculation time on the quality and fermentation cycle of fermented wild rice stem

[0081] The key fermentation strain Lactobacillus plantarum (CICC 22696) was activated in MRS medium at 37°C for 24 h. The second generation bacterial suspension was centrifuged at 3000xg and suspended in 0.85% sterile saline. All strain suspensions were stored in a refrigerator at 4°C. Before inoculation, the strain suspension was diluted to 10 7 CFU / mL.

[0082] Wild rice stem and pickle mother liquor are mixed and added in the anaerobic fermentation bag according to the mass volume ratio of 1g:10mL, and residual air is exhausted after the heat sealer seals, and is positioned over 25 ℃, 72%RH constant temperature and humidity incubator to carry out fermentation culture.On the 0th, 3rd, and 6th day of fermentation, the bacterial strain suspension of plant lactobacillus is inoculated according to the ratio of 1% (1g / 100mL) by aseptic syringe through the inoculation port, and continues fermentation, and the control group is normal saline.Respectively at the 1st, 3rd, 6th, 12th, 18th, 24th and 30th day of fermentation sampling, sample wild rice stem and fermented liquid are ground by the ratio mixing of 1:10, and then liquid nitrogen quick-freeze,-80 ℃ of preservations.

[0083] (1) Physical and chemical indicators

[0084] like Figure 6 As shown in the figure, after inoculation with Lactobacillus plantarum, the pH of the fermentation broth decreased rapidly and the total acid content increased. The earlier the inoculation time, the higher the total acid content, which may affect the sour taste of the final product.

[0085] The changes in soluble sugar content and nitrite content of the samples are as follows Figure 7 As shown, inoculation time had no significant effect on the soluble sugar content of the samples. Inoculation on day 0 resulted in an earlier nitrite peak, but among the samples inoculated on day 6, the lowest nitrite content was observed on day 18 of fermentation. Premature inoculation may affect the microbial community succession in the fermentation broth and potentially negatively impact fermentation.

[0086] The change of sample color difference value is as follows Figure 8 As shown, the color difference values ​​of the samples inoculated on day 0 were relatively low, but there was no significant difference.

[0087] (2) Texture quality

[0088] like Figure 9 As shown in the figure, the inoculation time had no significant effect on the hardness of the samples, but slightly affected the chewiness. The chewiness of the samples inoculated on the 6th day was slightly higher than that of the other treatment groups.

[0089] (3) Volatile flavor quality

[0090] Table 2

[0091]

[0092] The effects of inoculation time on volatile components are shown in Table 2. The formation of fermented product flavor is related to the complex metabolic processes of multiple microorganisms. Premature inoculation may result in insufficient accumulation of flavor precursors or ineffective expansion of the relevant microbial flora. Overall evaluation suggests that inoculation on the sixth day is more conducive to the synthesis of key volatile flavor components in fermented wild rice stem.

[0093] (4) Sensory evaluation

[0094] like Figure 10 As shown, samples inoculated on day 6 achieved higher sensory scores during fermentation. Premature inoculation enhances the activity of Lactobacillus plantarum within the fermentation system, impairing flavor development and producing excessive organic acids, resulting in an overly sour product and reduced sensory quality. Comprehensive evaluation suggests that inoculation on day 6 is more suitable for wild rice fermentation.

[0095] Example 3: Effect of re-inoculation amount on the quality and fermentation cycle of fermented wild rice stem

[0096] The key fermentation strain Lactobacillus plantarum (CICC 22696) was activated in MRS medium at 37°C for 24 h. The second generation bacterial suspension was centrifuged at 3000xg and suspended in 0.85% sterile saline. All strain suspensions were stored in a refrigerator at 4°C. Before inoculation, the strain suspension was diluted to 10 7 CFU / mL.

[0097] Wild rice stem and pickle mother liquor are mixed and added in the anaerobic fermentation bag according to the mass volume ratio of 1g:10mL, and residual air is exhausted after the heat sealer seals, and is positioned over 25 ℃, 72%RH constant temperature and humidity incubator and carries out fermentation culture.On the 6th day of fermentation, the bacterial strain suspension of plant lactobacillus is inoculated according to 1%, 2%, 5% (1g / 100mL) ratio by aseptic syringe through inoculation port, and continues fermentation, and the control group is normal saline.Respectively at fermentation the 1st, 3rd, 6th, 12th, 18th, 24th and 30th day sampling, sample wild rice stem and fermented liquid are ground by the ratio mixing of 1:10, and then liquid nitrogen quick-freeze,-80 ℃ of preservations.

[0098] (1) Physical and chemical indicators

[0099] like Figure 11 As shown in the figure, the pH values ​​of the samples in the 2% and 5% inoculum groups were significantly lower than those in the 1% inoculum group, while the total acid content was significantly higher than that in the 1% inoculum group. Increasing the inoculum size will enhance the quantitative advantage of the inoculum, thereby increasing the relative abundance of Lactobacillus plantarum in the fermentation broth, ultimately affecting the product pH and total acid content.

[0100] (2) Texture quality

[0101] like Figure 12 As shown in the results, the inoculum size did not significantly affect the hardness of the product, but did affect the chewiness. The chewiness of the sample in the 5% inoculum group was significantly lower than that of the 1% and 2% inoculum groups after fermentation on day 18. This may be due to the excessive decomposition of plant tissue by Lactobacillus plantarum, which affected the texture quality of the product.

[0102] (3) Volatile flavor quality

[0103] Table 3

[0104]

[0105]

[0106] The effects of inoculum size on volatile components are shown in Table 3. It can be seen that the 1% and 2% inoculum sizes had similar effects on the volatile flavor components of the samples, with the 1% inoculum size exhibiting a slight advantage on fermentation day 18, while the 2% inoculum size exhibited a slight advantage on fermentation day 30. The relative contents of key volatile components in the 5% inoculum sample were lower, likely due to the restricted growth of flavor-related microorganisms other than Lactobacillus plantarum, which hindered the metabolic pathways of related flavor precursors and affected the synthesis of key volatile components.

[0107] (4) Sensory evaluation

[0108] like Figure 13 As shown, the 1% inoculum group achieved higher sensory scores. The flavor and sensory quality of fermented wild rice stem stems from the combined effects of multiple microorganisms. While increasing the inoculum level can enhance the relative abundance of the key bacterial species (Lactobacillus plantarum), it can also affect other species that assist or pre-metabolize, ultimately negatively impacting the product's sensory quality. Comprehensive evaluation suggests that 1% is the optimal inoculum level for Lactobacillus plantarum.

[0109] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A fermentation method for preparing wild rice stem kimchi, characterized in that: The steps include: S1, adding the mixed wild rice stem and kimchi mother liquor into an anaerobic fermentation device for anaerobic fermentation culture; S2. After 5 to 7 days of fermentation, inoculate 0.5% to 2% of lactic acid bacteria seed liquid by mass to volume ratio and continue fermentation until completion.

2. The fermentation preparation method according to claim 1, characterized in that The kimchi mother liquor is traditional kimchi fermentation liquor.

3. The fermentation preparation method according to claim 1, characterized in that The lactic acid bacteria are one or more of Lactobacillus plantarum CICC22696, Leuconostoc mesenteroides CICC 22184 or Lactococcus lactis CICC 23609.

4. The fermentation preparation method according to claim 1, characterized in that The conditions for the anaerobic fermentation culture are a temperature of 24° C. to 26° C. and a humidity of 70% RH to 75% RH.

5. The fermentation preparation method according to claim 1, characterized in that: The wild rice stem and the pickle mother liquor are mixed in a mass ratio of 1:8-12.

6. The fermentation preparation method according to claim 1, characterized in that The lactic acid bacteria seed liquid 10 6 CFU / mL~10 8 CFU / mL.

7. The fermentation preparation method according to claim 6, characterized in that: The lactic acid bacteria seed liquid is prepared by the following method: activating lactic acid bacteria in MRS culture medium at 35-38° C. for 20-30 hours, centrifuging and suspending the bacteria in 0.8%-0.9% sterile physiological saline to obtain the lactic acid bacteria seed liquid.

8. Wild rice stem kimchi prepared by the fermentation preparation method according to any one of claims 1 to 7.

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