Cured beef and preparation method thereof

Abstract

The invention discloses cured beef and a preparation method thereof, and belongs to the technical field of fermented food. Comprising the following steps: trimming and dicing beef, adding seasoning spices, and adding a microbial agent for fermentation, the microbial agent is prepared from lactobacillus plantarum NR1-7 and aroma-producing yeast. According to the invention, the cured beef fermented by adding the Chinese prickly ash extracting solution, the lactobacillus plantarum NR1-7 and the aroma-producing yeast is relatively high in viable count, good in color and luster, rich in free amino acid quantity, moderate in protease activity and appropriate in organic acid content, and the pH value is stabilized to be about 5.5. Compared with natural fermentation, the growth and reproduction of inoculated dominant bacteria can accelerate the degradation of beef components and generate rich flavor, the pepper extract can ensure the complete beef structure by weakening the activity of endogenous enzyme, and in addition, the sour taste can be alleviated, the excessive degradation of fat can be relieved, and the fermentation quality of the cured beef can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fermented foods, in particular to dried beef and a preparation method thereof. Background Art

[0002] Beef jerky, a dried, fermented meat product with a unique flavor and easy preservation, is beloved by people in Yunnan, Guizhou, and Sichuan. It's primarily produced in Tongren and Xingyi, Guizhou. Traditionally, beef jerky is mostly produced in family workshops, resulting in poor quality and a lack of rich flavor.

[0003] To improve the shortcomings of these meat products, researchers have conducted extensive research, but most of it has focused on ham, sausage, and bacon, with very little research on dried beef. While research on dry-cured and fermented beef in Yunnan and Xinjiang has yielded significant results, research on dried beef in Guizhou is just beginning. Previous laboratory research has shown that adding exogenous fermentation agents such as Staphylococcus xylosus, Lactobacillus pentosus MT-4, and aroma-producing yeast can shorten fermentation time and improve quality and flavor (Liu Hanyu et al., 2019). However, this research focused solely on the quality of the finished product and did not examine the quality of dried beef during fermentation or the mechanisms of flavor formation. Furthermore, Lactobacillus pentosus MT-4 is not on the list of foods directly permitted for consumption by the government. Furthermore, Liu Fangrui (2023) found that Sichuan pepper extract improved the texture of dried beef when fermented with Staphylococcus xylosus alone, but did not investigate mixed-bacteria fermentation or its mechanisms. Summary of the Invention

[0004] The purpose of the present invention is to provide a dried beef and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for preparing dried beef, comprising the following steps: trimming and cutting the beef into pieces, adding seasoning spices, and adding microbial agents for fermentation;

[0007] The microbial agent consists of plant lactobacillus NR1-7 and aroma-producing yeast.

[0008] The second technical solution of the present invention is the dried beef prepared by the preparation method.

[0009] Based on the above technical solution, the present invention has the following technical effects:

[0010] The present invention found that the dried beef bacon fermented with Zanthoxylum bungeanum extract, Lactobacillus plantarum NR1-7 and aroma yeast has a high number of viable bacteria, good color, rich free amino acid quantity, moderate protease activity and suitable organic acid content, and the pH value is stable at about 5.5. Compared with natural fermentation, the growth and reproduction of the inoculated dominant bacteria can accelerate the degradation of beef components and produce rich flavor, while the Zanthoxylum bungeanum extract (ZBE) can ensure the integrity of the beef structure by weakening the endogenous enzyme activity. In addition, it can also alleviate the sour taste, relieve excessive fat degradation, and improve the fermentation quality of the dried beef bacon. The water activity, pH, color, texture and other indicators of the finished product quality of the dried beef bacon fermented with ZBE and Lactobacillus plantarum NR1-7 mixed with aroma yeast are improved compared with the naturally fermented dried beef bacon, with high sensory evaluation scores, a decrease of about 29.4% in nitrite content, a weakened degree of myofibril breakage, a more regular secondary structure, and a tight and complete microstructure. The content of flavor compounds in dried beef is 816.63ug / g, among which alcohols, ketones, esters, hydrocarbons, terpenes, pyrazines, furans and heterocyclic compounds have positive contributions to the flavor. Pyrazine and pyrrole compounds contribute to the barbecue aroma, aldehydes and ketones provide oil aroma, guaiacol and other phenols provide smoky aroma, pinene provides spice aroma, furans provide caramelization aroma, aroma yeast provides suitable alcohol aroma, and ZBE adds a unique herbal aroma, which together constitute the unique aroma of dried beef. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 pH and a during the fermentation of dried beef w Among them, (A) pH value changes of dried beef in the fermentation process without ZBE addition; (B) pH value changes of dried beef in the fermentation process with ZBE addition; (C) pH value changes of dried beef in the fermentation process without ZBE addition w (D) ZBE-added beef jerky fermentation process w Value changes.

[0012] Figure 2 Figure 3. Changes in color during the fermentation of dried beef. (A) L* change in the group without ZBE; (B) L* change in the group with ZBE; (C) a* change in the group without ZBE; (D) a* change in the group with ZBE; (E) b* change in the group without ZBE; (F) b* change in the group with ZBE.

[0013] Figure 3Figure 3. Titratable acid, malondialdehyde, and TCA-soluble peptide contents during fermentation of dried beef. (A) Changes in titratable acid content during fermentation of dried beef without ZBE; (B) Changes in titratable acid content during fermentation of dried beef with ZBE; (C) Changes in TBARS content during fermentation of dried beef without ZBE; (D) Changes in TBARS content during fermentation of dried beef with ZBE; (E) Changes in TCA-soluble peptide content during fermentation of dried beef without ZBE; (F) Changes in TCA-soluble peptide content during fermentation of dried beef without ZBE.

[0014] Figure 4 The free amino acid and myofibrillar protein contents during the fermentation of dried beef. (A) Changes in free amino acid content during fermentation of dried beef without ZBE; (B) Changes in free amino acid content during fermentation of dried beef with ZBE; (C) Changes in myofibrillar protein content during fermentation of dried beef without ZBE; (D) Changes in myofibrillar protein content during fermentation of dried beef with ZBE.

[0015] Figure 5 The following table shows the protease and SOD activities in dried beef. (A) Changes in protease activity during fermentation of dried beef without ZBE; (B) Changes in protease activity during fermentation of dried beef with ZBE; (C) Changes in SOD activity during fermentation of dried beef without ZBE; (D) Changes in SOD activity during fermentation of dried beef with ZBE.

[0016] Figure 6 A for dried beef w and pH value.

[0017] Figure 7 It represents the nitrite content and myofibril fragmentation index (MFI) of the finished dried beef.

[0018] Figure 8 This is the Fourier infrared spectrum of dried beef.

[0019] Figure 9 This is a scanning electron microscope image of dried beef, with a magnification of 600 times.

[0020] Figure 10 This is a classification chart of flavor compounds. DETAILED DESCRIPTION

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] Unless otherwise specified, the technical solutions described in the present invention are all conventional solutions in the field, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0023] The embodiment of the present invention provides a method for preparing dried beef, comprising the following steps: trimming and cutting the beef into pieces, adding seasoning spices, and adding microbial agents for fermentation;

[0024] The microbial agent consists of plant lactobacillus NR1-7 and aroma-producing yeast.

[0025] In some specific embodiments, the seasoning spices include: fresh ginger, red pepper, fresh garlic, star anise, bay leaves, chili powder, glucose, salt, orange peel, tea polyphenols and pepper extract.

[0026] In some specific embodiments, based on the weight fraction of beef, the added amount of the seasoning spices is: 6% fresh ginger, 0.6% red pepper, 6% fresh garlic, 1% star anise, 1% bay leaf, 6% chili powder, 1.5% glucose, 2% salt, 1% orange peel, 0.1 g / kg tea polyphenols and 16% Sichuan pepper extract.

[0027] In some specific embodiments, the preparation method of the Zanthoxylum bungeanum extract is: soaking Zanthoxylum bungeanum powder in water, ultrasonically extracting for 30 minutes at 60°C and 240W; cooling and filtering to obtain the Zanthoxylum bungeanum extract; the mass ratio of the Zanthoxylum bungeanum powder to water is 1:20.

[0028] In some specific embodiments, the viable bacterial count of the microbial agent is 1×10 8 CFU / g; based on the weight fraction of beef, the added amount of the microbial agent is 3%.

[0029] In some specific embodiments, the ratio of the number of live bacteria of Lactobacillus plantarum NR1-7 and aroma-producing yeast is 1:1.

[0030] In some specific embodiments, the fermentation time is 60 hours; and a drying step is further included after the fermentation is completed.

[0031] The embodiment of the present invention also provides dried beef prepared by the preparation method.

[0032] The present invention uses Lactobacillus plantarum NR1-7, aroma-producing yeast, and Staphylococcus xylosus as fermentation strains. The changes in indicators during the fermentation process of dried beef shanks were compared between natural fermentation and fermentation with single, double, or triple bacteria, as well as with or without the addition of Sichuan pepper extract, to analyze the effects of microorganisms and Sichuan pepper extract on its quality. The results of the fermentation process showed that the dried beef shanks fermented with Sichuan pepper extract, Lactobacillus plantarum NR1-7, and aroma-producing yeast had a higher viable cell count (5.5×10 13), good color (L*: 34.53, a*: 7.93, b*: 13.53), abundant free amino acids (35.69 mg / 100 g), moderate protease activity (311.41 U / g), and appropriate organic acid content (10.15 mg / mL), with a stable pH value around 5.5. Compared with natural fermentation, the growth and reproduction of inoculated dominant bacteria can accelerate the degradation of beef components and produce a richer flavor. ZBE can ensure the integrity of the beef structure by weakening endogenous enzyme activity. In addition, it can also alleviate sourness and alleviate excessive fat degradation, thereby improving the fermentation quality of dried beef. The quality of the finished product of the dried beef with ZBE and Lactobacillus plantarum NR1-7 fermented with aroma yeast was improved compared with that of the naturally fermented dried beef, including water activity (0.90), pH (4.96), color (L*: 23.07, a*: 13.92, b*: 14.23, ΔE: 70.63), texture (hardness: 32.15N, elasticity: 3.26mm, chewiness: 66.53mJ, cohesion: 0.66, adhesiveness: 2331g, shear force: 98.8N), etc. The sensory evaluation score was high (overall acceptability: 8.36 / 9), the nitrite content decreased by about 29.4%, the degree of myofibril breakage was weakened, the secondary structure was more regular (the irregular coil content decreased by about 22.2%, and the β-turn content increased by about 9.1%), and the microstructure was tight and complete. The content of flavor compounds in dried beef is 816.63ug / g, among which alcohols, ketones, esters, hydrocarbons, terpenes, pyrazines, furans and heterocyclic compounds have positive contributions to the flavor. Pyrazine and pyrrole compounds contribute to the barbecue aroma, aldehydes and ketones provide oil aroma, guaiacol and other phenols provide smoky aroma, pinene provides spice aroma, furans provide caramelization aroma, aroma yeast provides suitable alcohol aroma, and ZBE adds a unique herbal aroma, which together constitute the unique aroma of dried beef.

[0033] The Lactobacillus plantarum NR1-7 used in the embodiments of the present invention was deposited in the China Center for Type Culture Collection on December 6, 2021, with the deposit address being Wuhan University, Wuhan, China, and the deposit number being CCTCC NO: M 20211541.

[0034] The aroma-producing yeast used in the examples of the present invention was purchased from Angel Yeast Co., Ltd.; Staphylococcus xylosus was purchased from Guangdong Provincial Microbiological Culture Collection Center (ATCC29971).

[0035] Example 1

[0036] 1. Preparation of fermented beef

[0037] Preparation of Zanthoxylum bungeanum extract: Weigh 25.0 g of Zanthoxylum bungeanum powder and soak in 500 mL of distilled water for 30 minutes. Then, extract in an ultrasonic bath at 60°C and 240W for 30 minutes. Cool and filter to obtain the Zanthoxylum bungeanum aqueous extract.

[0038] Preparation of dried beef during the fermentation process: Based on the weight fraction of yellow cattle hind leg meat, add 6% fresh ginger, 0.6% red pepper, 6% fresh garlic, 1% star anise, 1% bay leaf, 6% chili powder, 1.5% glucose, 2% salt, 1% orange peel, 0.1g / kg tea polyphenols, 3% bacterial strain (live bacteria amount 1×10 8 CFU / g) and Zanthoxylum bungeanum extract 16%.

[0039] Among them, the bacterial species are single bacteria: (Lactobacillus plantarum NR1-7 or aroma-producing yeast);

[0040] Double bacteria: (Lactobacillus plantarum NR1-7, aroma-producing yeast and Staphylococcus xylosus are combined in pairs, and mixed in a 1:1 ratio of live bacteria);

[0041] Three bacteria: (Lactobacillus plantarum NR1-7, Staphylococcus xylosus and aroma-producing yeast, mixed in a ratio of 1:1:1 according to the number of live bacteria).

[0042] Process: Trim and cut the beef into pieces → Add seasonings (fresh ginger, red chili pepper, fresh garlic, star anise, bay leaves, chili powder, glucose, salt, orange peel, tea polyphenols, and Sichuan pepper extract) → Mix evenly at room temperature → Add the culture medium → Place in separate jars and seal → Ferment at 20°C for 60 hours. Sampling: Samples are collected at three key stages: before fermentation (0 hours), during fermentation (30 hours), and after fermentation (60 hours).

[0043] 2. Biochemical index detection

[0044] The total colony counts of Lactobacillus plantarum, Staphylococcus xylosus, and aroma-producing yeast were measured during fermentation. A portable pH meter (Testo 205, Testo Instruments Co., Ltd., Shenzhen) was used to measure pH. Water activity was determined according to the national standard GB 5009.238-2016. The L* (lightness), a* (redness), and b* (yellowness) values of the beef jerky surface were measured using an HP-2132 colorimeter. The instrument was calibrated with a standard white plate before measurement. Titratable acid content during beef jerky fermentation was determined according to GB / T 12456-2008. The determinations were made according to Peiretti et al. (2011) and the national standard GB 5009.181-2016. TCA-soluble peptides in beef during fermentation were determined according to the method of Fang et al. (2022). The free amino acid content of beef during fermentation was determined using conventional methods. Myofibrillar protein was extracted according to the method of Wang et al. (2022b), and the concentration of myofibrillar protein was determined using the BCA method. Protease activity was determined spectrophotometrically according to the industry standard SB / T 10317-1999. Superoxide dismutase (SOD) was determined using a detection kit (WST-1 method). The organic acid content of dried beef during fermentation was determined according to the method of Zheng Shasha (2023).

[0045] 3. Data Statistics and Analysis

[0046] Data were analyzed using univariate analysis of variance (ANOVA) and Tukey's test for significance. Differences in means were considered significant when P < 0.05. SPASS 26.0 and Excel 2019 were used for data processing. Origin 2021 was used for plotting. PeakFit (v4) was used for protein secondary structure data processing, and OMNIC was used to calculate the relative content of protein secondary structures.

[0047] 4 Experimental results

[0048] 4.1 Microbial changes during fermentation

[0049] The results showed that regardless of whether Sichuan pepper extract was added, the number of microorganisms in dried beef increased significantly with the increase in fermentation time. During the 0-30 hour fermentation stage, Sichuan pepper extract did not significantly affect the growth trend of microorganisms. However, during the 30-60 hour fermentation stage, the number of microorganisms in dried beef with Sichuan pepper extract added was significantly lower than that in dried beef without Sichuan pepper extract added, indicating that Sichuan pepper extract has a certain inhibitory effect on the growth of microorganisms. Plant Lactobacillus NR1-7 had the best growth, reaching 13 times in each group when fermentation was completed, followed by aroma yeast, and the growth of Staphylococcus xylosus was the worst, but it could also reach 12 times.

[0050] 4.2 pH changes

[0051] The pH value changes of dried beef inoculated with different starter cultures before, during and after fermentation are as follows: Figure 1 As shown in (A) and (B). Compared with the control group, the pH value of the dried beef inoculated with the starter culture decreased significantly with the extension of fermentation time. Before 30 hours, the pH value change trend of the aroma yeast group and the aroma yeast + Staphylococcus xylosus group was relatively gentle compared with the other groups. The pH value of the dried beef inoculated with Lactobacillus plantarum NR1-7 changed most significantly throughout the fermentation process, decreasing from 5.6 to 4.23. After the fermentation of the dried beef inoculated with single / double / triple bacterial starter culture, its pH value was between 4.2-4.7, which is in a slightly acidic range. This slightly acidic environment creates favorable conditions for inhibiting the growth rate of undesirable microorganisms. After adding Sichuan pepper extract (ZBE), the pH value of the dried beef stabilized at around 5.5, which is higher than the group without ZBE. After adding ZBE, the pH is stabilized at around 5.5, which helps prevent the decomposition and loss of nutrients caused by bacterial metabolism, and can better preserve nutrients such as protein, vitamins and minerals in the beef. In addition, after adding ZBE, the acidity of beef jerky is closer to people's tolerance for acid, which can provide a better taste and eating experience and is easier to chew and digest.

[0052] 4.3 Water activitya w

[0053] During the fermentation process of dried beef inoculated with single / double / triple bacteria w The changing trend of Figure 1 As shown in (C) and (D). w The change trend of the control group was similar. From before fermentation (0h) to fermentation (30h), its a w As time went on, there was a slight increase. The water activity of dried beef with ZBE and bacteria added was stable at an average of 0.94, slightly higher than that of the group without ZBE. This shows that the pepper extract has a certain positive effect on stabilizing the water activity of dried beef during fermentation. w It showed a slight decrease, which may be due to the slowdown of microbial metabolism as the fermentation time prolonged. However, during the entire fermentation process, the water activity of dried beef remained between 0.92 and 0.95, which is in a relatively high water activity range. w The lower limit is about 0.91, 0.80 for fungi, 0.61 for most yeasts, and most enzymes function above 0.80. This high water activity range is conducive to the growth and reproduction of bacteria, especially the acidification reaction of yeast, which can improve the tenderness of meat.

[0054] 4.4 Color Difference

[0055] The L* value changes during the fermentation process of dried beef Figure 2 As shown in (A) and (B), the L* value of the beef increased after 60 hours of fermentation. However, unlike the control group, the L* value of the dried beef fermented after inoculation with the bacteria showed an upward trend during the 0-30 hours fermentation period, while the control group showed a slight decrease. After fermentation was completed, the L* values of the dried beef inoculated with two bacteria (Lactobacillus plantarum NR1-7 + aroma yeast) and three bacteria (Lactobacillus plantarum NR1-7 + aroma yeast + Staphylococcus xylosus) were higher than the control group, while the L* values of the other groups were equal to or lower than the control group. This shows that the combined fermentation of Lactobacillus plantarum NR1-7 and aroma yeast can improve the brightness of the beef after fermentation, while the addition of Staphylococcus xylosus weakens the combined effect of the two bacteria. After ZBE treatment, the L* value of the dried beef decreased after fermentation was completed, but the upward trend during fermentation was similar. The L* value of the aroma yeast and Staphylococcus xylosus groups changed significantly, reaching the highest brightness value after fermentation was completed, but was still lower than the group without ZBE. This indicates that the pepper extract can reduce the L* value of beef jerky.

[0056] The changes of a* value during the fermentation of dried beef Figure 2 As shown in (C) and (D). Regardless of whether ZBE was added or not, the a* value of beef jerky during the fermentation process gradually increased with the extension of fermentation time. Among them, the a* value change trend of beef jerky containing Lactobacillus plantarum NR1-7 was the most obvious. The a* value of beef jerky in the ZBE group during the fermentation process was higher than that in the group without ZBE, which indicates that the Sichuan pepper extract has a promoting effect on the change of the a* value of beef jerky. In addition, the polyphenols in the Sichuan pepper extract have good antioxidant properties, which can effectively inhibit fat oxidation of meat during processing and storage, avoid discoloration, and thus maintain the bright color of beef jerky.

[0057] The changes of b* value during the fermentation process of dried beef Figure 2As shown in (E) and (F), similar to the changing trend of L* and a* values during the fermentation process, the b* value of dried beef increased with the extension of fermentation time after inoculation with bacterial strains. After the fermentation was completed, the b* value of dried beef inoculated with microbial strains was much higher than that of the control group. After adding ZBE treatment, the change in the b* value of dried beef mainly occurred during the fermentation process of 0-30h, while the change trend in the later period was relatively gentle. During the fermentation process, its b* value showed an upward trend like the group without ZBE addition, but the overall b* value was lower than that of the group without addition. Among several inoculation fermentation treatments, the dried beef fermented with three bacteria (Lactobacillus plantarum NR1-7, aroma yeast and Staphylococcus xylosus) had the largest b* value of 16.74, which was about 1.3 times that before fermentation and 1.8 times that of the control group before fermentation. It can be seen that whether the fermentation is carried out with a single bacteria (Lactobacillus plantarum NR1-7 and aroma-producing yeast), a double bacteria (a combination of Lactobacillus plantarum NR1-7, aroma-producing yeast, and Staphylococcus xylosus), or a three-bacteria mixed fermentation, the effect is better than that of the control group, among which the b* value change of the three-bacteria mixed fermentation is the most ideal.

[0058] 4.5 Titratable acid content

[0059] The changes in titratable acid content of dried beef with added bacterial culture during 60h fermentation are as follows: Figure 3 As shown in (A) and (B). The titratable acid content of dried beef shank fermented without ZBE added changed more than that of the group with ZBE added, especially in the early stage of fermentation (0-30h). After adding ZBE for co-fermentation, the titratable acid of dried beef shank decreased by about 20mg / kg, which shows that the pepper extract can weaken the acid production ability of the bacteria during the fermentation process. In the group without ZBE added, the titratable acid content of dried beef shank fermented with added bacteria increased significantly compared with the control group. Among them, the Lactobacillus plantarum NR1-7 group and the Lactobacillus plantarum NR1-7 and Staphylococcus xylosus group had the highest titratable acid content at 30h and 60h, respectively. In the group with ZBE added, Lactobacillus plantarum NR1-7 had the highest titratable acid content at both 30h and 60h. This shows that the contribution of Lactobacillus plantarum NR1-7 in acid production is more prominent than that of other bacteria. Too high a titratable acid content may adversely affect the color of the sample, so the titratable acid content needs to be controlled within an appropriate range (30-70 g / kg) to maintain the good color of the beef jerky.

[0060] 4.6TBARS content

[0061] The trend of lipid oxidation degree in dried beef after inoculation of starter culture during the fermentation process is as follows: Figure 3As shown in (C) and (D). The degree of lipid oxidation during the fermentation of beef deepens with the extension of fermentation time. At the end of fermentation, the MDA value of the control group was 0.15 mg / kg, which was about twice that before fermentation. The MDA values of the NR1-7+ xylosococcus group, NR1-7+ aroma yeast group, aroma yeast group and three-bacteria fermentation group after fermentation were higher than those of the natural fermentation group. The MDA content of the fermented dried beef after adding ZBE increased significantly compared with that without adding ZBE. In this embodiment, the decrease in the MDA value after fermentation may be because TBARS may be reduced in the product, which may be due to the covalent bond formed by Schiff base or nitrite residues (MDA may undergo nitrosation reaction) and covalent binding with amino acids in the protein hydrolysis reaction. The maximum value of MDA of the dried beef fermented by the three bacteria after fermentation was about 0.45 mg / kg, which was still far below 0.5g / 100g (the minimum peroxide value of bacon specified in the national standard), indicating that it did not produce rancidity.

[0062] 4.7TCA-soluble peptide content

[0063] like Figure 3 As shown in (E) and (F), the TCA-soluble peptide content of dried beef increases with the increase of fermentation time. Among them, the dried beef without ZBE added had the highest TCA-soluble peptide content, which could reach 80.91 (μg BSA) / g. The dried beef with only Lactobacillus plantarum NR1-7 added to the ZBE group had the highest soluble peptide content, which could reach about 40.01 (μg BSA) / g. Treatment with Sichuan pepper extract reduced the maximum value of TCA-soluble peptide by about 50%. This shows that Lactobacillus plantarum plays an important role in promoting protein degradation in beef, and the addition of Sichuan pepper extract can reduce the degradation of protein in dried beef.

[0064] 4.8 Free amino acid content

[0065] like Figure 4As shown in (A) and (B), the free amino acid content in dried beef increased significantly after the use of these fermentation agents. Among them, the dried beef fermented with both Lactobacillus plantarum NR1-7 and aroma yeast had the highest free amino acid content, reaching approximately 60.81 mg / 100 g. Furthermore, the free amino acid content of the dried beef containing aroma yeast increased linearly throughout the fermentation process, while the free amino acid content of the other groups increased rapidly during the 0-30 h fermentation phase and decreased slightly during the 30-60 h fermentation phase. The free amino acid content of dried beef increased after fermentation. After adding ZBE, the free amino acid content of dried beef increased with fermentation time, but was lower than that of the group without ZBE. Among the groups with ZBE, the group with aroma yeast had the highest free amino acid content, at 40.03 mg / 100 g. Compared with the group without ZBE, the maximum value decreased by approximately 20 mg / 100 g. This suggests that ZBE can reduce protein degradation, a result that is consistent with the results of TCA-soluble peptides.

[0066] 4.9 Myofibrillar protein content

[0067] Figure 4 Middle (C) shows the changes in myofibrillar protein content during the fermentation of dried beef without the addition of ZBE. Compared with the changes in myofibrillar protein content in the natural fermentation group, the myofibrillar protein content in the inoculated fermentation group was lower than that in the control group. Among them, the dried beef co-fermented with Lactobacillus plantarum NR1-7 and aroma yeast maintained the highest myofibrillar protein content after fermentation, indicating that the combination of Lactobacillus plantarum NR1-7 and aroma yeast has the weakest effect on the degradation of myofibrillar protein. The changes in myofibrillar protein content in dried beef co-fermented with ZBE and single / double / triple bacteria fermentation are shown in Figure 2. Figure 4 As shown in (D). ZBE mainly affects the myofibrillar protein content in the later stage of beef jerky fermentation and weakens the degree of myofibrillar protein degradation. In single-bacteria fermentation, the protein content changes more significantly, while the protein content changes more slowly in multi-bacteria mixed fermentation. In the natural fermentation group, beef jerky with ZBE added had a higher myofibrillar protein content (0.55 mg / mL), while the protein content of beef jerky without ZBE was 0.37 mg / mL. This shows that ZBE has a certain inhibitory effect on the degradation of myofibrillar protein.

[0068] 4.10 Protease activity

[0069] The changes of protease activity during the fermentation of dried beef Figure 5As shown in (A) and (B). During the fermentation of dried beef without the addition of ZBE, the protease activity of the natural fermentation, NR1-7, and NR1-7 + aroma yeast groups first increased and then decreased. In the early stage of fermentation, the bacterial species grew and reproduced rapidly, had strong metabolic capacity, and could produce a large number of metabolites with protease activity. As fermentation continued, the growth and metabolic rate of the bacterial species slowed down, and the protein substrate was decomposed in large quantities, resulting in a decrease in protease activity. The protease activity of the aroma yeast + xylosus Staphylococcus group continued to increase, and the increased enzyme activity in the early stage of fermentation was higher than that in the later stage of fermentation. The protease activity of the aroma yeast, NR1-7 + xylosus Staphylococcus, and three-bacteria groups first decreased and then increased. After fermentation was completed, the protease activity of the inoculated fermentation groups was higher than that of the natural fermentation group. This is because the bacterial species metabolism can produce proteases, thereby significantly increasing the activity. After adding ZBE treatment, the protease activity of each group showed a trend of first increasing and then decreasing during the fermentation process. During the mid-fermentation period, the three-bacteria group exhibited the highest protease activity, reaching 241.9 U / g, while the aroma-producing yeast + xylosus Staphylococcus group exhibited the lowest protease activity, at 93.9 U / g. After fermentation, all inoculated groups exhibited higher protease activity than the naturally fermented group, consistent with the results of the treatment without ZBE. Protease activity in all fermentation groups after ZBE treatment was lower than that in the non-ZBE treatment group, indicating that ZBE treatment inhibits protease activity. The reduced protease activity after ZBE treatment facilitates the preservation of dried beef jerky.

[0070] 4.11SOD enzyme activity

[0071] Changes in SOD enzyme activity during the fermentation of dried beef Figure 5 As shown in (C) and (D). The enzyme activity did not change much during the natural fermentation process. Compared with the natural fermentation group, the activity of the SOD enzyme decreased with the increase of fermentation time after the addition of the strain. When the fermentation was completed, the SOD enzyme activity of each group was significantly lower than that of the natural fermentation group. After adding ZBE treatment, the SOD enzyme activity of dried beef was significantly reduced, by about 45%. This shows that ZBE can inhibit the activity of SOD enzyme. After the fermentation was completed, the SOD enzyme activity of the aroma yeast group and the aroma yeast + Staphylococcus xylosus group increased significantly. In addition, the change trend of the SOD enzyme in dried beef was consistent with the trend of fat oxidation. After adding ZBE, the SOD enzyme activity decreased and the degree of fat oxidation increased.

[0072] 4.12 Organic acid content

[0073] In the group without ZBE, oxalic, formic, and acetic acid levels decreased with fermentation time, while tartaric and malic acids increased. Lactic and citric acids initially increased and then decreased during fermentation (except in the control group). At time 0 of fermentation, the acetic acid content was highest in the beef jerky containing aroma yeast. After adding ZBE, formic and acetic acid levels were undetectable from 0 to 30 hours of fermentation, but at 60 hours, formic acid reached approximately 1.0 mg / mL and acetic acid reached approximately 0.3 mg / mL. Lactic acid levels rose slightly from 0 to 30 hours of fermentation but were undetectable after fermentation was complete. This indicates that lactic acid is consumed in the second half of fermentation, producing formic and acetic acid. Oxalic, malic, and citric acid levels accumulated significantly after fermentation was complete, while tartaric acid levels continued to decline. Tartaric and lactic acids were the primary organic acids in the first half of fermentation, while oxalic, malic, and citric acids dominated in the second half. Compared with the ones without ZBE, the contents of organic acids in the dried beef shanks treated with ZBE increased significantly after fermentation, especially the organic acid content in the group co-fermented by Lactobacillus plantarum NR1-7 and aroma yeast increased by about 30%.

[0074] In this example, the changes in the fermentation process of dried beef inoculated with single / double / triple bacteria and Sichuan pepper extract were studied. It was found that compared with natural fermentation, the pH, myofibrillar protein content, and SOD enzyme activity of dried beef inoculated with single / double / triple bacteria decreased during the fermentation process due to the rapid growth of plant lactobacillus NR1-7, aroma yeast, and xylosus Staphylococcus; the water activity increased slightly; the L*, a*, b* values, titratable acid content, TBARS content, TCA-soluble peptide content, free amino acid content, and organic acid content increased. After adding Sichuan pepper extract (ZBE), the viable count, L*, b* value, titratable acid content, TCA-soluble peptide content, free amino acid content, myofibrillar protein content, protease activity, and SOD enzyme activity of the fermentation strain decreased; the pH value, water activity, a* value, and organic acid content increased. This shows that compared with natural fermentation, the large-scale growth, reproduction, and metabolites produced by the fermenting microorganisms accelerate the degradation of components such as protein and fat in beef, producing a richer flavor. Sichuan pepper extract can reduce the excessive degradation of myofibrillar protein by slowing down the growth and reproduction of microorganisms and inhibiting the activity of endogenous enzymes (such as proteases) in beef to ensure the integrity of the beef structure. It can also moderately increase the pH value of beef jerky and alleviate the overly sour taste produced during the fermentation process of Lactobacillus plantarum NR1-7, aroma yeast and xylose Staphylococcus. In addition, Sichuan pepper extract can also alleviate the excessive degradation of fat in beef by inhibiting the activity of SOD enzyme, prevent the generation of rancid smell, and give beef jerky a more harmonious flavor. In the study of the fermentation process, based on whether Sichuan pepper extract was added and the differences in various indicators of beef jerky fermented with single / double / triple bacteria, it was found that beef jerky fermented with Sichuan pepper extract, Lactobacillus plantarum NR1-7 and aroma yeast had the best effect after fermentation. The average total colony count of this sample can reach 5.5×10 13 , pH is stable at around 5.5, water activity can reach 0.93, L*(34.53), a*(7.93), b*(13.53), titratable acid content (22.61g / kg), malondialdehyde content (0.31mg / kg), TCA soluble peptide (33.5 (μg BSA) / g), free amino acid content (35.69mg / 100g), myofibrillar protein content (0.60mg / mL), protease activity (133.33U / g), SOD enzyme activity (311.41U / g), total organic acid content (10.15mg / mL). Therefore, in subsequent experiments, dried beef with added pepper extract and mixed fermentation of Lactobacillus plantarum NR1-7 and aroma yeast was selected for finished product quality research.

[0075] Example 2

[0076] 1. Sample preparation

[0077] The beef prepared in Example 1 and fermented for 60 hours with the addition of Zanthoxylum bungeanum extract, Lactobacillus plantarum NR1-7 and aroma yeast was placed in an electric blast drying oven and dried at 90° C. until the moisture content was about 30%. After cooling to room temperature, the beef was sealed in a vacuum bag and stored for later use.

[0078] 2 Sensory evaluation

[0079] Sensory evaluation of dried beef samples was conducted. The samples were randomly divided into groups, and 10 food science students (5 males and 5 females, aged 20-30 years old) who had received sensory evaluation training were selected. In a sensory scoring room with the same environmental conditions, the dried beef samples were subjected to sensory evaluation based on five indicators: appearance, structure, flavor, taste, and overall acceptability. Each evaluation indicator was scored 9 points, with a total score of 45 points. Ensure that everyone evaluates each group of samples. After each sensory evaluation, the evaluator needs to rinse his mouth with water before proceeding to the next sensory evaluation. Specific evaluation criteria are shown in Table 1.

[0080] Table 1 Sensory scoring standards

[0081]

[0082]

[0083] 3 indicator detection

[0084] Nitrite content in dried beef was determined using the UV spectrophotometric method described by Chen Cuixia et al. (2019). The types and contents of free amino acids in dried beef were determined using an S-433D fully automatic amino acid analyzer. The free sulfhydryl and disulfide bond contents in dried beef were determined using the method described by Xu Ru (2021). Fourier transform infrared spectroscopy was performed using the method described by Diao Jingjing et al. (2023). The myofibril fragmentation index (MFI) was determined using the method described by Hao Wanming et al. (2019). Texture was determined using the method described by Yang Mingyang (2019). Scanning electron microscopy was performed using the method described by Wang Ning (2022). Data statistical analysis was performed using the same method as in Example 1.

[0085] 4 Experimental results

[0086] 4.1 Water activity a w and pH

[0087] The water activity and pH value of dried beef Figure 6As shown. The water activity of dried beef remains at around 0.90. Compared with the control group (natural fermentation), the water activity of dried beef fermented with Lactobacillus plantarum and aroma yeast did not change significantly, while the water activity of dried beef fermented with ZBE, Lactobacillus plantarum NR1-7 and aroma yeast increased significantly to 0.916. During the fermentation process, the beef was soaked in ZBE for a long time, and ZBE filled into the fiber network of the beef to undergo a hydration reaction, which increased the bound water content in the beef. The pH value of dried beef decreased significantly after the inoculation of the bacteria, from 5.89 in natural fermentation to 4.79. After adding ZBE treatment, its pH increased slightly (4.96), but there was no significant difference.

[0088] 4.2 Chromatic Aberration

[0089] The color difference changes of the finished dried beef are shown in Table 2. After adding ZBE, Lactobacillus plantarum NR1-7 and aroma yeast, the color difference index ΔE value increased. This indicates that the color changes positively during the fermentation process. The L* value indicates the brightness of the sample, the a* value indicates the hue from red (+a*) to green (-a*), and the b* value indicates the hue from yellow (+b*) to blue (-b*). After adding ZBE, Lactobacillus plantarum NR1-7 and aroma yeast, the L* value decreased, indicating that the color darkened; the a* value increased, indicating that the red color increased; the b* value increased slightly, indicating that the yellow color increased slightly, and the dried beef tended to be dark red and slightly yellowish. Compared with the group with only the addition of bacteria, ZBE treatment can significantly increase the ΔE value, which shows that the pepper extract can improve the color of the dried beef.

[0090] Table 2 Color difference of finished beef jerky

[0091]

[0092] 4.3 Sensory evaluation

[0093] In this example, a sensory evaluation of dried beef was conducted based on appearance, structure, flavor, mouthfeel, and overall acceptability. The scores are shown in Table 3. Compared to the naturally fermented group, the groups treated with ZBE and a bacterial strain, as well as the group treated with a single bacterial strain, had higher sensory scores. The appearance was more rosy and lustrous. Lactobacillus plantarum lowered the pH of the sausage, accelerating the acidification and gelatinization processes, and enhancing the meat product's color. The structure was more compact, with an attractive gloss and an appropriate elasticity. The beef jerky had a rich, beef jerky aroma. The ZBE-treated beef jerky, in particular, had a subtle Sichuan peppercorn fragrance. The meat was flavorful and neither mushy nor dry when chewed. The overall acceptability of the beef jerky after addition of bacterial strains and ZBE treatment was high. Compared to naturally fermented beef, Lactobacillus has a beneficial effect on the sensory properties of fermented meat products. Selecting the appropriate bacterial strain can influence the development of the unique flavor and aroma of fermented meat products. The inoculated beef jerky had a stronger sour taste. However, after ZBE treatment, the Sichuan peppercorn aroma masked the stronger sour taste, making the beef jerky more acceptable to consumers.

[0094] Table 3 Sensory score table of finished dried beef

[0095]

[0096] 4.4 Nitrite Residual

[0097] Nitrite residue in beef jerky Figure 7 The nitrite content of the naturally fermented beef jerky was 34.52 mg / kg, while the nitrite content of the beef jerky fermented with Lactobacillus plantarum NR1-7 and aroma yeast was 11.56 mg / kg. The nitrite content of the beef jerky fermented with Lactobacillus plantarum NR1-7 and aroma yeast was far below the national safety standard. However, the nitrite content of the beef jerky fermented with ZBE reached 24.37 mg / kg, which is still below the minimum limit of nitrite residue in cured meat (30 mg / kg) stipulated in my country's food safety regulations.

[0098] 4.5 Free amino acids

[0099] The results showed that compared with the control group, cysteine, tyrosine, and lysine were not detected in the Lactobacillus plantarum NR1-7 and aroma yeast groups, and the essential amino acid content was also much lower than that of the control group. The ZBE group had one less essential amino acid, threonine, compared to the control group. However, the total essential amino acid content of the sample group was higher than that of the control group. Leucine was the highest essential amino acid in both the ZBE and control groups. After adding Zanthoxylum bungeanum extract, Lactobacillus plantarum NR1-7, and aroma yeast, the contents of proline, aspartic acid, threonine, glutamic acid, alanine, cysteine, histidine, and lysine decreased, while the contents of serine, glycine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, and arginine increased. Compared with the experimental group without ZBE, the ZBE group had higher essential amino acid content and total amino acid content, and a wider variety of amino acids.

[0100] 4.6 Free sulfhydryl groups and disulfide bonds

[0101] Table 4 shows changes in the thiol and disulfide bond contents of dried beef bacon. Compared to the naturally fermented group, the free thiol, total thiol, and disulfide bond contents of dried beef bacon fermented with mixed cultures of Lactobacillus plantarum NR1-7 and aroma-producing yeast all decreased significantly. Adding ZBE significantly increased the free thiol, total thiol, and disulfide bond contents of dried beef bacon compared to the group without ZBE. This suggests that ZBE has a positive effect on reducing protein degradation.

[0102] Table 4 Content of sulfhydryl and disulfide bonds in dried beef

[0103]

[0104] 4.7 Secondary structure content

[0105] At 400-4000cm -1 The Fourier infrared spectrum of the dried beef was scanned within the range, and the results were as follows Figure 8 Among them, for 1600-1700cm -1 PeakFit (version 8.2.0, Beijing Uone Info&Tech Co., Ltd.) was used to fit the data within the wavelength range and obtain the corresponding secondary structure content, as shown in Table 5. Compared with the natural fermentation group, the group supplemented with Lactobacillus plantarum NR1-7 and aroma yeast showed an increase in the content of β-sheets and random coils. The change in β-sheet content was not significant, while the change in random coil content was significant. The group supplemented with ZBE showed no change in the content of β-sheets and random coils. The content of β-turns increased from 33% to 34% and 36%, respectively. The content of α-helices decreased from 17% to 16% and then increased to 18%. This indicates that the addition of ZBE and bacterial strains primarily affects the α-helical and β-turn structures.

[0106] Table 5 Secondary structure content of dried beef

[0107]

[0108]

[0109] 4.8 Myofibril fragmentation index (MFI)

[0110] The changes in myofibril rupture index of the finished product of dried beef are as follows Figure 7 As shown. The MFI value of dried beef inoculated with the bacterial starter was significantly higher (27.0) compared to the naturally fermented group (9.47), indicating that Lactobacillus plantarum and aroma-producing yeast can promote myofibril fragmentation. The MFI value of the group treated with both ZBE and inoculation was significantly lower (24.2) than that of the inoculation group alone, indicating that ZBE can weaken myofibril fragmentation caused by the bacterial strain. Lactobacillus plantarum and aroma-producing yeast can promote the softening and decomposition of myofibrils, reducing the dry, rough, and hard texture of dried beef.

[0111] 4.9 Texture characteristics

[0112] As shown in Table 6, the firmness of the meat in the inoculated fermentation group was significantly lower than that of the naturally fermented group. However, after the addition of ZBE and Lactobacillus plantarum NR1-7 + aroma-producing yeast, the firmness significantly increased to 32.15 N. This decrease in firmness is attributed to the degradation of myofibrils by proteases produced by the bacteria, or to a softening phenomenon caused by a decrease in pH. The elasticity of the meat in the inoculated group decreased compared to the naturally fermented group, while the elasticity increased after the addition of ZBE. Compared to the naturally fermented group, the chewiness of the inoculated group decreased, while the elasticity of the ZBE-treated group increased. Cohesion decreased in the inoculated group compared to the naturally fermented group, while it increased in the ZBE-treated group. Adhesion showed a different trend from other indicators, with increases in both the inoculated and ZBE / strain co-treatment groups. Changes in shear force were consistent with those in hardness. Lactobacillus plantarum produces lactic acid to lower pH, potentially making the meat softer. Metabolites produced by aroma-producing yeast may affect collagen conversion in the meat, thereby reducing shear force and firmness. After adding pepper extract, the increase in shear force indicates that pepper extract may have affected the conversion of protein during the fermentation process and enhanced the hardness of the meat.

[0113] Table 6 Texture characteristics of dried beef

[0114]

[0115] 4.10 Scanning electron microscopy

[0116] Scanning electron microscopy (SEM) was used to study the microstructural changes of dried beef samples under the action of ZBE, Lactobacillus plantarum NR1-7, and aroma yeast. Figure 9 As shown, the gaps between myofibrils in the control group were significantly larger, the myofibrils were more broken, and the myofibrils were arranged in a disorderly manner. The muscle fibers in the mixed fermentation group with Lactobacillus plantarum NR1-7 and aroma yeast were more broken and loose than those in the control group. In particular, very obvious pore collapse was observed in the electron micrograph of the cross section. This indicates that the bacteria promoted the degradation of myofibrils, resulting in a significant increase in their breakage and a significant decrease in their firmness. In the beef jerky group with ZBE, the tissue fibers were more tightly bound, the gaps between myofibrils were very small, and they formed a regular aggregated structure. In addition, the fiber structure was relatively complete, and there were few breaks. This shows that the added substances have a good protective effect on the muscle fibers of beef jerky.

[0117] A quality study of dried beef brisket fermented with Zanthoxylum bungeanum extract, Lactobacillus plantarum NR1-7, and aroma-producing yeast found that the water activity of the dried beef brisket remained at around 0.90 and the pH was 4.96. Its L* decreased, its a* and b* values increased, and the dried beef brisket appeared dark red. Based on the sensory evaluation scores, the dried beef brisket fermented with ZBE, Lactobacillus plantarum NR1-7, and aroma-producing yeast had a higher overall score. Lactobacillus plantarum NR1-7 has a strong nitrite-reducing effect. Although the addition of Zanthoxylum bungeanum increased its nitrite content by about half compared to fermentation without ZBE inoculation, it was still much lower than the naturally fermented group. Compared with natural fermentation and inoculation fermentation, the free amino acid content (92.89 mg / 100 g) and types (16 species) of the dried beef brisket with ZBE decreased slightly, indicating that ZBE can inhibit protein degradation to a certain extent. The free thiol and disulfide bond contents of dried beef shank were 493.89 μmol / g and 8221.98 μmol / g, respectively, indicating increases compared to the other two groups. The increase in free thiol groups can be attributed to the addition of Sichuan pepper extract, while the increase in disulfide bond content can be attributed to the active ingredients in the Sichuan pepper extract promoting the production of flavor compounds. These compounds may react with proteins during fermentation, increasing disulfide bond content. Changes in secondary structure content revealed that Lactobacillus plantarum NR1-7 and aroma-producing yeast influenced the content of four structural structures, while Sichuan pepper extract primarily affected the content of random coils, α-helices, and β-turns. The random coil and β-turn contents were most significantly affected by the additives, with dried beef shank fermented with Sichuan pepper extract and the culture exhibiting more regular secondary structures. The trend in the myofibril fragmentation index between the ZBE-treated and inoculated fermentation groups suggests that Sichuan pepper extract mitigates myofibril degradation in dried beef shank. The results of the texture properties show the positive effects of Sichuan pepper extract on the hardness, elasticity, chewiness, cohesion, adhesion and shear force of dried beef. The increase in the six texture index parameters shows that the dried beef treated with ZBE and bacteria has a better taste. The microstructure displayed by scanning electron microscopy shows that among the three types of treated dried beef, bacterial fermentation accelerates the degradation of myofibrils. The cross-sectional structure shows coarse pores and increased depressions, and the longitudinal section shows fiber breakage. The dried beef co-fermented with ZBE and bacteria has the most compact, complete and smooth microstructure, which is consistent with the results of secondary structure, MFI and texture properties. In summary, the dried beef co-fermented with ZBE and inoculated with Lactobacillus plantarum NR1-7 and aroma yeast has better quality characteristics.

[0118] Example 3

[0119] 1. Sample preparation

[0120] The beef prepared in Example 1 and fermented for 60 hours with the addition of Zanthoxylum bungeanum extract, Lactobacillus plantarum NR1-7 and aroma yeast was placed in an electric blast drying oven and dried at 90° C. until the moisture content was about 30%. After cooling to room temperature, the beef was sealed in a vacuum bag and stored for later use.

[0121] 2. Index determination

[0122] Volatile flavor compounds, metabolomics, and proteomics were detected with reference to the methods provided by Wuhan Maiwei Metabolic Biotechnology Co., Ltd.

[0123] 3 Experimental results

[0124] 3.1 Volatile flavor compound content

[0125] Results of testing for volatile flavor compounds in dried beef brisket fermented with natural fermentation, Lactobacillus plantarum NR1-7 + aroma yeast, and ZBE + Lactobacillus plantarum NR1-7 + aroma yeast revealed that, compared with the natural fermentation group, the inoculated fermentation group showed a decrease in the total content of aldehydes, ketones, esters, hydrocarbons, heterocyclic compounds, alcohols, amines, benzene and its derivatives, terpenes, organic acids and their derivatives, nitrogen-containing compounds, halogenated hydrocarbons, and other flavor compounds. The ZBE-treated group showed an increase in the total content of aldehydes, ketones, esters, hydrocarbons, and halogenated hydrocarbons, while the total content of other compounds decreased. The addition of ZBE increased the total content of all 11 compounds in the inoculated group compared with the ZBE-added and co-inoculated groups. The total content of volatile flavor compounds in dried beef brisket decreased after co-fermentation with Lactobacillus plantarum and aroma yeast (632.97 μg / g), compared with the natural fermentation group (908.97 μg / g). Compared to natural fermentation, the total volatile flavor compound content of dried beef bacon also decreased after adding Sichuan pepper extract to co-fermentation with Lactobacillus plantarum and aroma-producing yeast (816.63ug / g). Compared to fermentation with only the added bacteria, the total volatile flavor compound content of dried beef bacon increased after adding Sichuan pepper extract.

[0126] 3.2 Classification of flavor compounds

[0127] like Figure 10As shown, compared with the natural fermentation group, the group with the addition of the bacterial strain alone showed an increase in only alcohol content; the levels of other substances were the lowest among the three groups. The group with the addition of ZBE and the bacterial strain co-fermentation showed the highest levels of aldehydes, esters, heterocyclic compounds, and other substances. Ketones, amines, terpenes, hydrocarbons, halogenated hydrocarbons, organic acids and their derivatives, nitrogen-containing compounds, and benzene and its derivatives showed the highest levels among the three groups. Among the 14 substance categories, terpenes, heterocyclic compounds, and hydrocarbon compounds ranked in the top three, respectively, while ether compounds showed very little difference among the three groups. Compared with the natural fermentation group, the advantages of inoculation and ZBE addition were reflected in a significant decrease in amine content and a significant increase in alcohol, aldehyde, and ester content, respectively. This indicates that inoculation and ZBE addition can significantly improve the flavor and aroma of dried beef jerky. In particular, the decrease in amine content indicates a significant improvement in the odor of the dried beef jerky.

[0128] 3.3 Analysis of main flavor compounds

[0129] Compared to naturally fermented beef jerky, fermented with added strains of bacteria exhibited significantly reduced woody and licorice notes. Adding Sichuan pepper extract significantly enhanced camphor, pepper, terpenes, and caramel notes. In addition to the typical beef jerky aroma, beef jerky fermented with added strains and ZBE also exhibited floral, fruity, and nutty notes, resulting in a pleasant overall aroma profile.

[0130] 3.4 Analysis of aroma components in dried beef (OAV>1)

[0131] Analysis of the aroma components of dried beef with an OAV greater than 1 identified barbecue aroma (pyrazine, furan, pyrrole, etc.), oil aroma (aldehydes, ketones, etc.), smoky aroma (guaiacol, methylguaiacol, etc.), pungent spice aroma (linalool, β-pinene, etc.), sweet and caramelized aroma (furans, pyrans, etc.), and sour and fermented aroma (lactic acid, alcohol, etc.) as the characteristic aroma components of dried beef. Adding Sichuan pepper extract to dried beef imparted an additional herbal aroma. Although the content of some aroma-active compounds in dried beef was relatively low, their FC factors were large, indicating that they may still contribute significantly to the overall aroma. A total of 171 aroma compounds with an OAV greater than 1 were found in dried beef. The naturally fermented dried beef contained 18 aroma compounds with an OAV greater than 1000, the Lactobacillus plantarum NR1-7 + aroma yeast group contained 17, and the ZBE + Lactobacillus plantarum NR1-7 + aroma yeast group contained 15. Screening of substances with an OAV greater than 1000 revealed β-ionone, octenone, 2-methylpropyl-butyric acid, dihydro-2-methyl-3(2H)-furanone, (E)-2-nonenal, 4-methoxybenzaldehyde, 2-ethyl-3,5-dimethylpyrazine, and 2,4-undecenal as key aroma compounds shared by the three dried beef groups. p-Isopropylbenzene, o-cymene, 1,8-cineole, (+)-δ-carbutene, methyl α-ionone, (E)-2-hexanal, γ-undecalactone, 3-octen-2-one, and 4-(2,6,6-trimethylcyclohexa-1,3-dienyl)but-3-en-2-one contributed significantly more to the naturally fermented beef than to the other two groups. Anethole, with its sweet, floral, and stewy aroma, was a key aroma compound in the Lactobacillus plantarum NR1-7 + aroma yeast group. p-Cresol, with its smoky and herbal notes, was a key aroma compound in the ZBE + Lactobacillus plantarum NR1-7 + aroma yeast group. The beef jerky treated with either fermentation or Sichuan pepper extract exhibited a richer aroma composition, resulting in a more pleasant aroma and flavor.

[0132] Analysis of flavor compounds revealed that alcohols, ketones, esters, hydrocarbons, heterocyclic compounds, terpenes, and alcohol and amine compounds all accounted for over 10%, contributing significantly to the flavor of dried beef. During fermentation, Lactobacillus plantarum and aroma-producing yeast break down macromolecules such as protein and fat in beef into amino acids and fatty acids. These smaller molecules undergo further reactions such as the Maillard reaction and Strecker degradation, generating a variety of flavor compounds such as pyrazines, aldehydes, and ketones. Pyrazine compounds such as 5-isopropyl-2-methylpyrazine, generated during the Maillard reaction, impart a rich, meaty, and roasted aroma to dried beef. Organic acids produced during fermentation can regulate the pH of dried beef, influencing the formation and stability of flavor compounds and contributing to a richer and more balanced flavor profile. Terpenes in Sichuan pepper extract add a fresh, aromatic aroma to dried beef, enriching its overall flavor. Ortho-cymene, with its minty and citrus-like aromas, imparts a cool, refreshing feeling to dried beef, complementing other flavor components to enhance its taste and flavor. Analysis of the aroma components of dried beef has revealed its characteristic aroma components. The barbecue aroma is primarily derived from pyrazines, furans, and pyrroles; the oily aroma is contributed by aldehydes and ketones; the smoky aroma is closely associated with guaiacol and methylguaiacol; linalool and β-pinene contribute to the spicy aroma; the sweet and caramelized aroma can be traced back to compounds such as furans and pyrans; and the sour and fermented aroma is the result of the action of components such as lactic acid and alcohol. The addition of Sichuan pepper extract adds a unique herbal aroma to the already rich aroma of dried beef, further enriching its aroma.

[0133] Proteomics studies have shown that fermentation and ZBE primarily control protein transport, synthesis, and degradation during dried beef fermentation by regulating the lysosomal pathway and the ubiquitin-proteasome system. Zanthoxylum bungeanum extract was found to upregulate GAA expression in the lysosomal pathway, enabling lysosomes to more efficiently degrade glycogen to produce glucose, providing a carbon source for the fermenting microorganisms, promoting their growth and metabolism, and producing more flavorful substances such as organic acids and esters. Simultaneously, it downregulates the expression of cathepsins, LGMN, LAMP, and AP-3 proteins, moderately controlling protein degradation to avoid excessive degradation that produces unpleasant flavors and affects meat quality. It also maintains a stable intracellular environment, preserves muscle fiber integrity, improves texture, inhibits adverse metabolism, stabilizes the microbial community, and enhances overall quality.

[0134] Metabolomics analysis found that microbial fermentation and Sichuan pepper extract mainly involved amino acid metabolic pathways, especially through the upregulation of glutamate dehydrogenase (GDH) in the alanine, aspartate and glutamate metabolic pathways, the downregulation of aspartate aminotransferase (AST) and the bidirectional regulation of alanine aminotransferase (ALT) to adjust the metabolism and synthesis of amino acids, giving beef jerky a richer flavor system.

[0135] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing dried beef, characterized in that: The following steps are involved: The beef is trimmed and cut into pieces, seasoned with spices, and fermented with microbial agents; The microbial agent consists of plant lactobacillus NR1-7 and aroma-producing yeast.

2. The preparation method according to claim 1, characterized in that The seasoning spices include: fresh ginger, red pepper, fresh garlic, star anise, bay leaf, chili powder, glucose, salt, orange peel, tea polyphenols and pepper extract.

3. The preparation method according to claim 2, characterized in that Calculated by weight of the beef, the added amounts of the seasoning spices are: 6% of fresh ginger, 0.6% of red pepper, 6% of fresh garlic, 1% of star anise, 1% of bay leaf, 6% of chili powder, 1.5% of glucose, 2% of salt, 1% of orange peel, 0.1 g / kg of tea polyphenols and 16% of Sichuan pepper extract.

4. The preparation method according to claim 2, characterized in that The preparation method of the Zanthoxylum bungeanum extract comprises the following steps: soaking Zanthoxylum bungeanum powder in water, performing ultrasonic extraction for 30 minutes at 60° C. and 240W; cooling and filtering to obtain the Zanthoxylum bungeanum extract; and the mass ratio of the Zanthoxylum bungeanum powder to water is 1:

20.

5. The preparation method according to claim 1, characterized in that The amount of viable bacteria of the microbial agent is 1×10 8 CFU / g; based on the weight fraction of beef, the added amount of the microbial agent is 3%.

6. The preparation method according to claim 1, characterized in that The ratio of the number of live bacteria of the plant lactobacillus NR1-7 and the aroma-producing yeast is 1:

1.

7. The preparation method according to claim 1, characterized in that The fermentation time is 60 hours; after the fermentation is completed, a drying step is also included.

8. Dried beef prepared by the method according to any one of claims 1 to 7.

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