Low-temperature fermented beef sausage and preparation method thereof

Abstract

The invention discloses a preparation method of a low-temperature fermented beef sausage, which comprises the following steps: mixing lean beef and diced fat according to a ratio of 4: 1, compounding a leavening agent by using lactobacillus sake and staphylococcus xylosus according to a ratio of 1: 2, pickling at 4 DEG C, filling into a collagen casing, fermenting at 28 DEG C for 24 hours, carrying out gradient cooling maturation in two stages, and dynamically regulating and controlling the humidity and the pH value. According to the method, the air permeability is optimized through sodium lactate soaking of casings, hole pricking and exhausting and ultrasonic treatment, and CO2 closed-loop control and cold air circulation are combined, so that the content of flavor substances is increased, linoleic acid oxidation is reduced, the texture compactness is enhanced, and the shelf life is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of food. More specifically, the present invention relates to a low-temperature fermented beef sausage and a preparation method thereof. Background Art

[0002] In the preparation process of traditional fermented meat products, there are several technical bottlenecks in the fermentation and ripening control of beef sausage. Especially in the low-temperature fermentation system, the synergistic effect between the regulation of microbial activity and physical and chemical changes has not been fully optimized. In the prior art, the selection and compounding ratio of starter cultures lack pertinence. For example, single-strain or fixed-ratio compound bacterial agents are difficult to balance the acid production rate and the synthesis of flavor substances, resulting in too high acidity of the product or insufficient content of characteristic flavor substances. If the ratio of Lactobacillus sakei to Staphylococcus xylosus is not dynamically adapted, it is likely to cause too slow acid production in the early stage of fermentation, prolonging the production cycle, or too fast acid accumulation in the later stage, inhibiting the growth of beneficial bacteria and affecting the texture and flavor stability of the product.

[0003] In terms of humidity control, the traditional process mostly adopts a linear humidity decline mode, without considering the dynamic relationship between the moisture migration of the sausage body and the metabolic rate of the flora at different ripening stages. For example, too fast a decline in humidity in the initial stage of ripening is likely to cause premature hardening of the sausage surface, hindering the uniform diffusion of internal moisture, while too high humidity in the later stage may lead to the growth of miscellaneous bacteria. In the prior art, the humidity regulation parameters (such as a 5% daily decline) do not form a feedback mechanism with the casing air permeability index, resulting in local water activity imbalance often occurring in actual production, manifested as too wet in the sausage core or cracked on the surface, directly affecting the product shelf life and sensory quality.

[0004] There are also limitations in the treatment process of fat components. The traditional method of directly blanching pig fat after cutting is difficult to effectively control the fat oxidation process. Especially when the blanching temperature fluctuates beyond the critical range (such as below 45°C or above 60°C), insufficient denaturation of the surface protein of the fat cubes will lead to the exudation of free fat during the subsequent mixing process, exacerbating lipid oxidation and producing off-flavors. In addition, the uniformity of fat particle distribution depends on the mechanical mixing intensity, but too high a rotation speed is likely to damage the muscle fiber structure, resulting in loose meat quality, while insufficient mixing leads to fat aggregation, affecting the texture uniformity of the product.

[0005] The deficiency of casing treatment technology further restricts the fermentation efficiency. The conventional collagen casing soaking process lacks refined regulation of osmotic pressure and ionic strength. For example, soaking only with physiological saline is difficult to improve the anti-tensile performance of the casing, and microcracks are likely to occur due to mechanical stress concentration during the variable-temperature ripening process. In addition, there is no quantitative relationship between the hole punching and exhaust parameters (such as hole diameter and spacing) and the casing thickness and air permeability, resulting in a mismatch between the gas exchange rate and the metabolic requirements of the flora, which may cause the formation of anaerobic areas or excessive water loss, affecting the fermentation uniformity.

[0006] The root cause of the above problems is that traditional process parameters are mostly set empirically, lacking a systematic analysis of the coupling of multiple factors among microorganisms, matrix and environment. For example, key links such as the dynamic response mechanism of starter activity and temperature / humidity, the correlation between the degree of thermal denaturation of fat and the penetration efficiency of antioxidants, and the quantitative relationship between the microstructure of casings and macroscopic mechanical properties have not yet established a controllable process model, resulting in difficulty in ensuring process stability and product consistency. These technical bottlenecks make the industrial production of low-temperature fermented beef sausage face realistic challenges such as difficult quality control, high energy consumption, and short product shelf life. Summary of the invention

[0007] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0008] In order to achieve these purposes and other advantages according to the present invention, a method for preparing low-temperature fermented beef sausage is provided, comprising the following steps: Lean beef and diced fat are mixed in a mass ratio of 4:1 to obtain a mixed meat material, wherein the lean beef is beef hind leg meat with fascia removed, and the diced fat is prepared by cutting the fat fat of the pig into 0.4×0.4×0.4 cm diced fat and blanching in 45-60° C. water for 10 min±3 min; Mix the mixed meat, edible salt, sugar, rice wine, chili powder, thirteen spice powder, tomato powder and fermentation agent, and marinate at 4°C for 12-15 hours. The amount of each component is 2.0% edible salt, 4.0% sugar, 1.5% rice wine, 0.1% chili powder, 0.15% thirteen spice powder, 0.5% tomato powder, 0.5-3% fermentation agent, and the balance is the mixed meat. The fermentation agent is prepared by compounding sake lactobacillus and xylose staphylococcus in a ratio of 1:2. Stuff the marinated meat into a collagen casing with a diameter of 22-25 mm to form a sausage body; Place the intestines in an environment of 28°C and 90% humidity for 24 hours to ferment until the acidity of the intestines reaches 4.6-5.0; The fermented intestines were placed in an environment of 15°C for the first stage of maturation, with the humidity controlled to decrease by 5%±1% per day from 85% to 70% for 3 days; The intestines were transferred to a 13°C environment for the second stage of maturation, and the humidity was controlled to decrease by 5%±1% per day from 70% to 50% for 4 days; During the maturation process, the pH value on the surface of the intestine is monitored every day. When the pH value fluctuates by more than 0.3, the ambient humidity decrease rate is adjusted to 3% per day. The pH value monitoring uses multi-point contact electrodes with an electrode spacing of 1 / 4 of the circumference of the intestine. When the pH value fluctuates by more than 0.3, the ambient temperature is simultaneously reduced by 0.5°C / h until the pH fluctuation amplitude is ≤0.2.

[0009] Preferably, in the step of filling the collagen casing with a diameter of 22-25 mm, the casing is soaked in 4°C normal saline containing 0.5% sodium lactate for 30 min before filling. After filling, holes are punched in the surface of the sausage body at intervals of 5 cm for air exhaust, and the depth of the punched holes is 1 / 2 of the casing thickness; the casing thickness is 0.8-1.2 mm, the water content of the soaked casing is controlled at 35-38%, and the diameter of the punched holes is 0.3-0.5 mm.

[0010] Preferably, during the soaking treatment with normal saline, ultrasonic oscillation at 15-20 kHz is applied synchronously, the temperature of the sodium lactate solution is maintained at 4±0.5°C, and the soaked casing is stored in a refrigerator at 2-4°C for 6-8 hours; in the step of punching holes for air exhaust, after the punching is completed, the sausage body is placed in a roller rotating at 30-50 r / min and rolled for 10-15 min. Hemispherical protrusions with a spacing of 2 mm are provided on the inner wall of the roller, and the height of the protrusions is 0.5 mm; the punching direction forms a 45° angle with the axial direction of the sausage body.

[0011] Preferably, in the fermentation stage, when the acidity of the sausage body reaches 4.8, the ambient temperature fluctuation range is controlled within ±0.5°C, and the oxygen content is maintained at 3-5% by adjusting the CO2 concentration. The CO2 concentration is adjusted in real time by an infrared sensor, and the adjustment response time ≤ 30 seconds; During the second-stage ripening period, when the humidity drops to 60%, an intermittent cold air circulation is started. The cold air circulation is set at a temperature 2°C lower than the ambient temperature, and it is blown at a wind speed of 0.8 m / s for 10 min every 2 hours. The oxygen concentration during blowing does not increase by more than 1%.

[0012] Preferably, in the mixing step, first, table salt and a starter are premixed in 4°C normal saline to form a bacterial salt suspension. The amount of normal saline used is 3-5% of the total mass of the meat material. After the pH value of the bacterial salt suspension is adjusted to 6.2-6.5, it is added to the meat material in three portions at intervals of 15 min. After each addition, it is stirred at a speed of 8-10 r / min for 5 min; The remaining auxiliary materials are added in two portions. When adding white sugar and yellow rice wine for the first time, a vacuum tumbler is started synchronously, the vacuum degree is maintained at -85 kPa, the tumbling speed is 6 r / min, and after tumbling for 15 min, it is left standing for 10 min; When adding chili powder, thirteen-spice powder and tomato powder for the second time, the tumbler is switched to the normal pressure mode, the speed is increased to 12 r / min, and the tumbling time is 8-10 min. During this period, the temperature of the meat material is controlled below 4°C; The pickling stage adopts a stepped cooling method. The temperature is maintained at 4°C for the first 3 hours, and then decreased by 0.5°C per hour until the final temperature of 2°C. When the pickling is completed, the water activity aw value of the meat material ≤ 0.92; Among them, 0.02% sodium pyrophosphate is added as an ionic strength regulator during the premixing of the bacterial salt suspension.

[0013] Preferably, when the sodium pyrophosphate is mixed with the bacterial salt suspension, it is first dissolved in 0.1 mol / L phosphate buffer solution at 4 °C to form a complex ion solution, the conductivity of the solution is controlled at 12 - 15 mS / cm, and the bacterial salt suspension and the complex ion solution are mixed at a volume ratio of 1:3 and then left to stand and activate for 20 min; Among them, the molar ratio of sodium pyrophosphate to sodium dihydrogen phosphate in the complex ion solution is 1:1.2.

[0014] Preferably, the lean beef is pre-cooled in an environment of -4 °C to -2 °C for 40 - 50 min before being minced, the meat temperature is controlled at 0 - 2 °C during mincing, and the aperture of the sieve plate of the meat grinder is 4 mm; Before cutting the fat cubes, the pork fat is placed in an environment of 8 - 10 °C to balance for 2 hours, the temperature of the cutting tool is maintained at -5 °C to 0 °C, and immediately after cutting, it is put into water at 45 - 60 °C containing 0.1% sodium ascorbate for blanching. After blanching, the fat cubes are quickly cooled in an ice-water bath at 0 - 4 °C for 5 - 8 min; When mixing the meat materials, the step-by-step feeding method is adopted. First, 1 / 2 of the fat cubes and the lean beef are mixed at a speed of 12 r / min for 3 min, and then the remaining fat cubes and 0.02% monoglyceride emulsifier are added, and the speed is switched to 8 r / min and mixed for 5 min.

[0015] Preferably, the low-temperature fermented beef sausage has a bright red color, contains essential amino acids and fatty acids, and contains characteristic flavor substances such as 3-methylbutanal, 3-methylbutanol and hexanal.

[0016] The present invention also provides a low-temperature fermented beef sausage obtained by the above preparation method.

[0017] The present invention has at least the following beneficial effects: The preparation method of the low-temperature fermented beef sausage in this application uses a multi-point contact electrode to monitor the pH value on the surface of the sausage body, combined with the dynamic adjustment of humidity and temperature, reducing the pH fluctuation from 0.42 to 0.18. This improvement effectively inhibits the imbalance of bacterial metabolism, reduces the risk of the growth of miscellaneous bacteria caused by excessive local acidity, and at the same time avoids the texture loosening caused by excessive protein decomposition; Through the compounding of the starter and the control of humidity in stages, the content of the characteristic flavor substance 3-methylbutanal increases from 8.73×10 7 / g to 12.45×10 7 / g, with an increase of 42%. Through step-by-step feeding and antioxidant treatment, the content of 3-methylbutanal is further increased to 18.50×10 7 / g, and the content of hexanal increases from 37.51×10 7 / g to 60.10×10 7 / g, making the flavor level more abundant; The casing pre-treatment combined with the tumbling process increases the shear force from 32.8 N to 53.2 N, making the texture of the sausage body firmer. The stepwise cooling curing and vacuum tumbling reduce the water activity from 0.88 to 0.68, extending the shelf life by more than 30% while inhibiting microbial growth; The optimization of starter culture activity promotes protein decomposition, increasing the glutamic acid content from 34.38 mg / 100 g to 190.80 mg / 100 g, significantly enhancing the umami flavor. The oxidative loss of linoleic acid is reduced by 34.5%, and the retention rate of oleic acid is increased to 805.70 mg / 100 g, making the fatty acid composition more stable; The CO2 closed-loop control and real-time feedback of infrared sensors form a dynamic regulation system. The humidity reduction rate is adjusted according to the gas permeability of the casing, improving production stability. The cold air circulation and ultrasonic treatment further optimize the gas permeability of the casing, avoiding cracking or local over-wetting.

[0018] In summary, through strain adaptation, parameter linkage, and process closed-loop control, this method solves the technical bottlenecks such as pH out-of-control, insufficient flavor, uneven texture, and oxidative loss in traditional processes, providing a reliable solution for the industrial production of low-temperature fermented meat products.

[0019] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed Description of the Invention

[0020] The following is a further detailed description of the present invention in conjunction with embodiments, enabling those skilled in the art to implement it according to the description in the specification.

[0021] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0022] <Example 1> A method for preparing low-temperature fermented beef sausage, comprising the following steps: Mix lean beef and diced fat in a mass ratio of 4:1 to obtain a mixed meat material. The lean beef is the beef hind leg meat without fascia. The method for making the diced fat is to cut the pork fat into fat cubes of 0.4×0.4×0.4 cm and then blanch them in water at 45 - 60 °C for 10 min ± 3 min; Mix the mixed meat, edible salt, sugar, rice wine, chili powder, thirteen spice powder, tomato powder and fermentation agent, and marinate at 4°C for 12-15 hours. The amount of each component is 2.0% edible salt, 4.0% sugar, 1.5% rice wine, 0.1% chili powder, 0.15% thirteen spice powder, 0.5% tomato powder, 0.5-3% fermentation agent, and the balance is the mixed meat. The fermentation agent is prepared by compounding sake lactobacillus and xylose staphylococcus in a ratio of 1:2. Stuff the marinated meat into a collagen casing with a diameter of 22-25 mm to form a sausage body; Place the intestines in an environment of 28°C and 90% humidity for 24 hours to ferment until the acidity of the intestines reaches 4.6-5.0; The fermented intestines were placed in an environment of 15°C for the first stage of maturation, with the humidity controlled to decrease by 5%±1% per day from 85% to 70% for 3 days; The intestines were transferred to a 13°C environment for the second stage of maturation, and the humidity was controlled to decrease by 5%±1% per day from 70% to 50% for 4 days; During the maturation process, the pH value on the surface of the intestine is monitored every day. When the pH value fluctuates by more than 0.3, the ambient humidity decrease rate is adjusted to 3% per day. The pH value monitoring uses multi-point contact electrodes with an electrode spacing of 1 / 4 of the circumference of the intestine. When the pH value fluctuates by more than 0.3, the ambient temperature is simultaneously reduced by 0.5°C / h until the pH fluctuation amplitude is ≤0.2.

[0023] <Example 2> On the basis of Example 1, the following process is added: In the step of filling the collagen casing with a diameter of 22-25 mm, the casing is soaked in 4°C saline containing 0.5% sodium lactate for 30 minutes before filling, and after filling, holes are punctured on the surface of the intestine at intervals of 5 cm to exhaust air, and the puncture depth is 1 / 2 of the casing thickness; the casing thickness is 0.8-1.2 mm, the casing water content after soaking is controlled at 35-38%, and the puncture diameter is 0.3-0.5 mm.

[0024] <Example 3> On the basis of Example 2, the following process is added: During the physiological saline immersion treatment, 18kHz ultrasonic oscillation is applied synchronously, the temperature of the sodium lactate solution is maintained at 4±0.5°C, and the casing is refrigerated at 2-4°C for 7 hours after immersion; in the puncturing and exhaust step, after the puncturing is completed, the intestine is placed in a drum with a rotation speed of 40r / min and rolled for 12min, and the inner wall of the drum is provided with hemispherical protrusions with a spacing of 2mm and a protrusion height of 0.5mm; wherein the puncturing direction is at an angle of 45° with the axial direction of the intestine.

[0025] <Example 4> Based on Example 3, the following process is added: During the fermentation stage, when the acidity of the intestinal body reaches 4.8, control the ambient temperature fluctuation range within ±0.5 °C, and maintain the oxygen content at 3-5% by adjusting the CO2 concentration. The CO2 concentration is adjusted in real-time feedback by an infrared sensor, and the adjustment response time ≤ 30 seconds; During the second-stage ripening period, start intermittent cold air circulation when the humidity drops to 60%. The set temperature of the cold air circulation is 2 °C lower than the ambient temperature. Blow for 10 minutes at a wind speed of 0.8 m / s every 2 hours. When blowing, the oxygen concentration increase does not exceed 1%.

[0026] <Example 5> Based on Example 4, the following process is added: In the mixing step, first premix edible salt and starter in 4 °C physiological saline to form a bacterial salt suspension. The dosage of the physiological saline is 4% of the total mass of the meat material. After adjusting the pH value of the bacterial salt suspension to 6.2-6.5, add it to the meat material in three portions at intervals of 15 minutes. After each addition, stir at a speed of 9 r / min for 5 minutes; The remaining auxiliary materials are added in two times. When adding white sugar and yellow rice wine for the first time, start the vacuum tumbling machine simultaneously. The vacuum degree is maintained at -85 kPa, the tumbling speed is 6 r / min, and after tumbling for 15 minutes, let it stand for 10 minutes; When adding chili powder, thirteen-spice powder and tomato powder for the second time, switch the tumbling machine to the atmospheric pressure mode, increase the speed to 12 r / min, and the tumbling time is 9 minutes. During this period, control the temperature of the meat material below 4 °C; In the marinating stage, the step-down cooling method is adopted. Maintain at 4 °C for the first 3 hours, and then reduce by 0.5 °C per hour until the final temperature of 2 °C. When the marinating ends, the water activity aw value of the meat material ≤ 0.92; Among them, 0.02% sodium pyrophosphate is added as an ionic strength regulator during the premixing of the bacterial salt suspension.

[0027] <Example 6> Based on Example 5, the following process is added: When sodium pyrophosphate is mixed with the bacterial salt suspension, first dissolve it in 0.1 mol / L phosphate buffer solution at 4 °C to form a composite ion solution. Control the conductivity of the solution at 12-15 mS / cm. Mix the bacterial salt suspension and the composite ion solution in a volume ratio of 1:3 and let it stand for activation for 20 minutes; Among them, the molar ratio of sodium pyrophosphate to sodium dihydrogen phosphate in the composite ion solution is 1:1.2.

[0028] <Example 7> Based on Example 6, the following process is added: The lean beef is pre-cooled in an environment of -4°C to -2°C for 40-50 minutes before being minced, the meat temperature is controlled at 0-2°C during mincing, and the mesh plate aperture of the meat grinder is 4mm; Before cutting the fat cubes, the pig fat is placed in an environment of 8-10°C for 2 hours, and the cutting tool temperature is maintained at -5°C to 0°C. After cutting, the fat cubes are immediately put into 45-60°C water containing 0.1% sodium ascorbate for blanching. After blanching, the fat cubes are rapidly cooled in an ice water bath at 0-4°C for 5-8 minutes. When mixing the meat, a step-by-step feeding method was adopted. First, 1 / 2 of the diced fat and lean beef were added and mixed at a speed of 12 r / min for 3 minutes. Then, the remaining diced fat and 0.02% monoglyceride emulsifier were added and the speed was switched to 8 r / min and mixed for 5 minutes.

[0029] <Comparative Example 1> A method for preparing low-temperature fermented beef sausage comprises the following steps: Lean beef and diced fat are mixed in a mass ratio of 4:1 to obtain a mixed meat material, wherein the lean beef is beef hind leg meat with fascia removed, and the diced fat is prepared by cutting the fat fat of the pig into 0.4×0.4×0.4 cm diced fat and blanching in 45-60° C. water for 10 min±3 min; Mix the mixed meat, edible salt, sugar, rice wine, chili powder, thirteen spice powder, tomato powder and fermentation agent, and marinate at 4°C for 12-15 hours. The amount of each component is 2.0% edible salt, 4.0% sugar, 1.5% rice wine, 0.1% chili powder, 0.15% thirteen spice powder, 0.5% tomato powder, 0.5-3% fermentation agent, and the balance is the mixed meat. The fermentation agent is prepared by compounding sake lactobacillus and xylose staphylococcus in a ratio of 1:2. Stuff the marinated meat into a collagen casing with a diameter of 22-25 mm to form a sausage body; Place the intestines in an environment of 28°C and 90% humidity for 24 hours to ferment until the acidity of the intestines reaches 4.6-5.0; The fermented intestines were placed in an environment of 15°C for the first stage of maturation, with the humidity controlled to decrease by 5%±1% per day from 85% to 70% for 3 days; The intestines were transferred to a 13°C environment for the second stage of maturation, and the humidity was controlled to decrease by 5%±1% every day from 70% to 50% for 4 days.

[0030] <Detection test> Thirty beef sausages were prepared by the preparation methods of Example 1 and Comparative Example 1, and ten sausages were taken from each of the groups of Examples 1 to 7 and Comparative Example 1. The following indicators were tested on the 7th day of maturity and the average values ​​were taken: Color: Take the middle section of the finished beef sausage, cut off the irregular parts at both ends, and cut it into uniform slices with a thickness of 10 ± 0.5 mm; Trim the surface with a sharp blade to ensure no pores, cracks or fat exudation; Place the sample in a constant temperature and humidity chamber at 25 °C and 50% humidity for 1 hour to eliminate the interference of condensed water; Use a spectrophotometric colorimeter (such as Konica Minolta CM-5), equipped with a D65 standard light source and a 10° viewing angle; Turn on the machine and preheat for 30 minutes, and use a standard white board (L* = 97.5, a* = 0.2, b* = 1.8) for zero calibration; Use a standard black board (L* = 0.0) to verify the dark field data to ensure that the instrument error ≤ ±0.2 units; Keep the instrument measurement aperture (8 mm) close to the sample surface to avoid environmental light interference; Continuously read the data 3 times at each measurement point, and take the average value as the L*, a*, b* value of this point; If the deviation of the L* value at the same measurement point > 0.5, the sample needs to be prepared again and detected; pH stability: Record the daily pH fluctuation range (highest value - lowest value) during ripening; Flavor substance content: Use gas chromatography - mass spectrometry (GC-MS) to detect the contents of 3-methylbutanal, 3-methylbutanol and hexanal, expressed in unit mass: expressed as AU×10 7 / g; Amino acid and fatty acid composition: Analyze the contents of glutamic acid, leucine, oleic acid and linoleic acid by high performance liquid chromatography (HPLC), unit mg / 100g; Texture properties: 1) Measuring the shear force of the intestine body (N). The measurement method includes: taking the intestine body at the end of ripening, cutting off the irregular parts at both ends, and retaining the middle section (length 50 mm); cutting with a cylindrical mold with a diameter of 22 - 25 mm to ensure that the height-to-diameter ratio of the sample is 1:1 (error ≤ 0.5 mm); balancing in a constant temperature oven at 15°C for 2 hours before testing to avoid the influence of temperature fluctuations on texture; using a texture analyzer (such as TA.XT Plus) equipped with a Warner-Bratzler shear blade probe; setting the probe downward speed at 2 mm / s, trigger force 5 g, and shear stroke distance as 80% of the sample height; test temperature: 15 ± 0.5°C (the same as the temperature in the ripening stage); data sampling frequency: 200 Hz, recording the maximum peak force (N) in the shear force-time curve; placing the intestine body sample horizontally on the test platform with the center aligned with the blade; starting the equipment, and the probe pressing vertically downward until the sample is completely sheared; repeating the test 10 times for each group of samples, and eliminating the outliers (deviating more than ±15% from the mean); calculating the mean and standard deviation of the shear force, with the unit of Newton. 2) Measuring the water activity of the intestine body. The measurement method: taking the middle section of the beef sausage at the end of ripening, cutting off the irregular parts at both ends, and cutting 10 ± 0.5 g of uniform minced meat; placing the sample in a sterile mortar and quickly grinding it to a particle size ≤ 2 mm to avoid water evaporation caused by temperature rise during the grinding process; loading the sample into a special test cup (diameter 25 mm, height 10 mm), sealing it, and balancing it in a constant temperature oven at 25 ± 0.5°C for 2 hours to eliminate the influence of temperature gradient; using a cold mirror dew point method water activity meter (such as Aqualab4TE), with a measurement range of 0.00 - 1.00 aw and a resolution of ±0.001; quickly placing the balanced test cup into the sample chamber of the instrument to avoid environmental humidity interference (operating environment humidity 50 ± 5%RH); the sample filling volume accounts for 80% - 90% of the test cup volume to ensure full contact with the sensor; the instrument automatically detects the dew point temperature and calculates the aw value, with a single measurement time ≤ 5 minutes; repeating the measurement 3 times for each sample, and eliminating the abnormal data deviating more than ±0.005 aw from the mean.

[0031] Permeability of sausage casing (this index is tested before stuffing): Selecting a complete and undamaged sausage casing segment and cutting it into a circular specimen with a diameter of 50 mm; placing the specimen in a constant temperature and humidity chamber at 25°C and 60%RH to balance for 24 hours to remove the surface free moisture; using a differential pressure method gas permeation instrument (such as VAC-V2 type), the test cavity is divided into a high-pressure cavity and a low-pressure cavity, and the specimen is clamped between the two cavities, and the sealing performance needs to be verified by a helium mass spectrometer leak detector (leak rate ≤ 1×10 -5Pa·m³ / s); The high-pressure chamber is filled with dry nitrogen (purity ≥ 99.999%); the low-pressure chamber is initially in a vacuum state; the set pressure difference is 1 kPa (error ≤ ±0.01 kPa), the test temperature is kept constant at 25 ± 0.5 °C, and the humidity is 60 ± 2%RH; record the change in the gas volume in the low-pressure chamber over time, and the test time lasts at least 1 hour; calculate the gas permeability Q (unit: mL / (m²·h·kPa)): Q = V / (Δt•A•Δp) Where, V is the volume of the permeated gas (mL), Δt is the test time (h), A is the effective area of the specimen (m², calculated as 0.00196 m² according to a diameter of 50 mm), and Δp is the pressure difference (kPa).

[0032] Tensile strength of sausage casing (this index is tested before enema): Take a complete sausage casing segment and cut it axially into dumbbell-shaped specimens (total length 50 mm, gauge section width 6 mm, parallel section length 20 mm), and measure the thickness accurately to 0.01 mm (range 0.8 - 1.2 mm); the specimens are equilibrated in an environment of 25 ± 0.5 °C and humidity 60 ± 2%RH for 24 hours to eliminate environmental interference; use a universal material testing machine (such as Instron 5965), equipped with pneumatic clamps, with a range ≥ 500 N and an accuracy of ±0.5%; the initial grip distance is set to 20 mm, and the tensile speed is 10 mm / min; clamp both ends of the specimen into the clamps to ensure that the force application axis coincides with the long axis of the specimen; record the load-displacement curve during the tensile process until the specimen breaks; exclude the data where the fracture position deviates from the gauge section by ±2 mm; calculate the tensile strength σ: σ = F max / A Where, F max is the maximum load (N), and A is the cross-sectional area of the specimen (mm², thickness × gauge section width).

[0033] Use an independent samples t-test to compare the differences in each group of data (α = 0.05), and use SPSS software for one-way analysis of variance (ANOVA) to verify the correlation between pH fluctuations and the content of flavor substances. The experimental results are shown in Tables 1 - 6 below: Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 In Table 1, for Examples 1 to 7, by optimizing the casing treatment and fermentation process, the color index of the finished product was gradually improved. The brightness (L* value) of Example 1 was 46.12, higher than 44.83 of Comparative Example 1, mainly because the dynamic humidity control reduced the uneven evaporation of surface moisture. After the casing was soaked in sodium lactate in Example 2, the redness (a* value) increased from 24.78 to 25.16, and the reduction of fat oxidation made the color more translucent. Through stepwise feeding and antioxidant treatment in Example 7, the yellowness (b* value) decreased to 10.15, and the fat stability was significantly improved. The data show that the synergistic effect of casing water content control and blanching temperature is the key to color optimization.

[0034] In Table 2, the pH fluctuation of Comparative Example 1 was 0.42. In Example 1, through multi-point electrode monitoring and humidity-linked regulation, the fluctuation was reduced to 0.18. In Example 4, CO2 closed-loop control was introduced, and the response time was shortened to 0.3 hours, and the pH fluctuation was further reduced to 0.10. In Example 7, combined with temperature fine-tuning, the fluctuation amplitude was only 0.05. The technical correlation shows that the matching of the humidity decrease rate and the casing air permeability is the core mechanism for suppressing pH mutation.

[0035] In Table 3, the content of 3-methylbutyraldehyde in Comparative Example 1 was 8.73×10 7 / g, and it was increased to 12.45×10 7 / g in Example 1, due to the enhanced synergistic metabolism of Lactobacillus sakei and Staphylococcus xylosus. In Example 3, ultrasonic treatment and drum rolling were used, and the hexanal content increased from 37.51×10 7 / g to 48.60×10 7 / g, and the by-products of fat oxidation decreased. Through stepwise feeding and addition of monoglyceride in Example 7, the 3-methylbutyraldehyde reached 18.50×10 7 / g, indicating that the antioxidant process effectively protected the flavor precursor substances.

[0036] In Table 4, the glutamic acid content of Comparative Example 1 was 95.23 mg / 100 g. In Example 5, through stepwise cooling curing and vacuum tumbling, the glutamic acid was increased to 175.30 mg / 100 g, and the decomposition efficiency of myofibrillar protein was improved. The linoleic acid content in Example 7 decreased from 313.70 mg / 100 g to 205.40 mg / 100 g, and the fat oxidation loss decreased by 34.5%, which was directly related to the rapid cooling treatment after blanching. The data confirm that the synergistic effect of emulsifiers and antioxidants is the main reason for fatty acid stability.

[0037] In Table 5, the shear force of Comparative Example 1 was 32.8 N. In Example 2, by venting through perforations, the shear force was increased to 53.2 N, and the moisture distribution became more uniform. In Example 6, a sodium pyrophosphate complex ion solution was used, and the aw value decreased from 0.88 to 0.70, extending the shelf life by 30%. Technical correlation shows that the tensile strength of the casing and the tumbling parameters jointly affect the texture compactness.

[0038] In Table 6, the air permeability of Comparative Example 1 was 105 mL / (m²·h·kPa). In Example 2, through soaking in sodium lactate and perforation treatment, the air permeability was increased to 135. In Example 3, ultrasonic oscillation was added, and the air permeability reached 148 because the fiber structure of the casing was more porous. The data prove that the dynamic matching of air permeability and humidity gradient (decreasing by 5%±1% per day) is the core control point to avoid intestinal body cracking.

[0039] The preparation method of the low-temperature fermented beef sausage in this application uses a multi-point contact electrode to monitor the pH value on the surface of the intestinal body, combined with the dynamic adjustment of humidity and temperature, reducing the pH fluctuation from 0.42 to 0.18. This improvement effectively inhibits the imbalance of microbial metabolism, reduces the risk of the growth of miscellaneous bacteria caused by excessive local acidity, and at the same time avoids the texture loosening caused by excessive protein decomposition; Through the compounding of fermenting agents and staged humidity control, the content of the characteristic flavor substance 3-methylbutyraldehyde increased from 8.73×10 7 / g to 12.45×10 7 / g, with an increase of 42%. In Example 7, through stepwise feeding and antioxidant treatment, the content of 3-methylbutyraldehyde was further increased to 18.50×10 7 / g, and the content of hexanal increased from 37.51×10 7 / g to 60.10×10 7 / g, making the flavor more rich; The combination of casing pretreatment and tumbling process increased the shear force from 32.8 N to 53.2 N, making the texture of the intestinal body more compact. Stepwise cooling salting and vacuum tumbling reduced the water activity from 0.88 to 0.68, extending the shelf life by more than 30% and at the same time inhibiting the growth of microorganisms; The optimization of the activity of the fermenting agent promoted protein decomposition, and the content of glutamic acid increased from 34.38 mg / 100 g to 190.80 mg / 100 g, significantly enhancing the umami taste. The oxidation loss of linoleic acid decreased by 34.5%, and the retention rate of oleic acid increased to 805.70 mg / 100 g, making the fatty acid composition more stable; The CO2 closed-loop control and the real-time feedback of the infrared sensor form a dynamic adjustment system. The humidity decrease rate is adjusted according to the air permeability of the casing, improving the production stability. The cold air circulation and ultrasonic treatment further optimize the air permeability of the casing, avoiding cracking or local over-wetting.

[0040] In summary, through strain adaptation, parameter linkage, and process closed-loop control, the present method solves the technical bottlenecks such as out-of-control pH, insufficient flavor, uneven texture, and oxidative loss in the traditional process, providing a reliable solution for the industrial production of low-temperature fermented meat products.

[0041] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing low-temperature fermented beef sausage, characterized in that, The following steps are involved: Lean beef and diced fat are mixed in a mass ratio of 4:1 to obtain a mixed meat material, wherein the lean beef is beef hind leg meat with fascia removed, and the diced fat is prepared by cutting the fat fat of the pig into 0.4×0.4×0.4 cm diced fat and blanching in 45-60° C. water for 10 min±3 min; Mix the mixed meat, edible salt, sugar, rice wine, chili powder, thirteen spice powder, tomato powder and fermentation agent, and marinate at 4°C for 12-15 hours. The amount of each component is 2.0% edible salt, 4.0% sugar, 1.5% rice wine, 0.1% chili powder, 0.15% thirteen spice powder, 0.5% tomato powder, 0.5-3% fermentation agent, and the balance is the mixed meat. The fermentation agent is prepared by compounding sake lactobacillus and xylose staphylococcus in a ratio of 1:

2. Stuff the marinated meat into a collagen casing with a diameter of 22-25 mm to form a sausage body; Place the intestines in an environment of 28°C and 90% humidity for 24 hours to ferment until the acidity of the intestines reaches 4.6-5.0; The fermented intestines were placed in an environment of 15°C for the first stage of maturation, with the humidity controlled to decrease by 5%±1% per day from 85% to 70% for 3 days; The intestines were transferred to a 13°C environment for the second stage of maturation, and the humidity was controlled to decrease by 5%±1% per day from 70% to 50% for 4 days; During the maturation process, the pH value on the surface of the intestine is monitored every day. When the pH value fluctuates by more than 0.3, the ambient humidity decrease rate is adjusted to 3% per day. The pH value monitoring uses multi-point contact electrodes with an electrode spacing of 1 / 4 of the circumference of the intestine. When the pH value fluctuates by more than 0.3, the ambient temperature is simultaneously reduced by 0.5°C / h until the pH fluctuation amplitude is ≤0.

2.

2. The preparation method of the low-temperature fermented beef sausage according to claim 1, characterized in that, In the step of filling the collagen casing with a diameter of 22-25 mm, the casing is soaked in 4°C saline containing 0.5% sodium lactate for 30 minutes before filling, and after filling, holes are punctured on the surface of the intestine at intervals of 5 cm to exhaust air, and the puncture depth is 1 / 2 of the casing thickness; the casing thickness is 0.8-1.2 mm, the casing water content after soaking is controlled at 35-38%, and the puncture diameter is 0.3-0.5 mm.

3. The preparation method of the low-temperature fermented beef sausage according to claim 2, characterized in that During the physiological saline immersion treatment, 15-20kHz ultrasonic oscillation is applied synchronously, the temperature of the sodium lactate solution is maintained at 4±0.5°C, and the casing is refrigerated at 2-4°C for 6-8 hours after immersion; in the puncturing and exhaust step, after the puncturing is completed, the intestine is placed in a drum with a rotation speed of 30-50r / min and rolled for 10-15min, and the inner wall of the drum is provided with hemispherical protrusions with a spacing of 2mm and a protrusion height of 0.5mm; wherein the puncturing direction is at an angle of 45° with the axial direction of the intestine.

4. The preparation method of the low-temperature fermented beef sausage according to claim 3, characterized in that, During the fermentation stage, when the acidity of the intestine reaches 4.8, the ambient temperature fluctuation range is controlled within ±0.5°C, and the oxygen content is maintained at 3-5% by adjusting the CO2 concentration. The CO2 concentration is adjusted in real time through feedback from an infrared sensor, and the adjustment response time is ≤30 seconds; During the second-stage ripening, when the humidity drops to 60%, an intermittent cold air circulation is started. The set temperature of the cold air circulation is 2°C lower than the ambient temperature. It is purged at a wind speed of 0.8 m / s for 10 minutes every 2 hours, and the oxygen concentration increase during purging does not exceed 1%.

5. The preparation method of the low-temperature fermented beef sausage according to claim 3, characterized in that, In the mixing step, first premix edible salt and starter culture in 4°C physiological saline to form a bacterial salt suspension. The dosage of the physiological saline is 3-5% of the total mass of the meat material. After adjusting the pH value of the bacterial salt suspension to 6.2-6.5, it is added to the meat material in three portions at intervals of 15 minutes. After each addition, it is stirred at a speed of 8-10 r / min for 5 minutes; The remaining auxiliary materials are added in two times. When adding white sugar and yellow rice wine for the first time, the vacuum tumbler is started simultaneously. The vacuum degree is maintained at -85 kPa, the tumbling speed is 6 r / min, and after tumbling for 15 minutes, it is left standing for 10 minutes; When adding chili powder, thirteen-spice powder and tomato powder for the second time, the tumbler is switched to the normal pressure mode, the speed is increased to 12 r / min, and the tumbling time is 8-10 minutes. During this period, the temperature of the meat material is controlled below 4°C; In the marinating stage, the step-down cooling method is adopted. It is maintained at 4°C for the first 3 hours, and then decreased by 0.5°C per hour until the final temperature of 2°C. When the marinating ends, the water activity aw value of the meat material is ≤ 0.92; Among them, 0.02% sodium pyrophosphate is added as an ionic strength regulator during the premixing of the bacterial salt suspension.

6. The preparation method of the low-temperature fermented beef sausage according to claim 5, wherein, When the sodium pyrophosphate is mixed with the bacterial salt suspension, it is first dissolved in 0.1 mol / L phosphate buffer solution at 4°C to form a composite ion solution. The conductivity of the solution is controlled at 12-15 mS / cm. The bacterial salt suspension and the composite ion solution are mixed at a volume ratio of 1:3 and then left standing for activation for 20 minutes; Among them, the molar ratio of sodium pyrophosphate to sodium dihydrogen phosphate in the composite ion solution is 1:1.

2.

7. The preparation method of the low-temperature fermented beef sausage according to claim 1, characterized in that The lean beef is pre-cooled in an environment of -4°C to -2°C for 40-50 minutes before being minced. The meat temperature is controlled at 0-2°C during mincing, and the aperture of the screen plate of the meat grinder is 4 mm; Before cutting the fat cubes, the pork fatback is placed in an environment of 8-10°C for 2 hours. The temperature of the cutting tool is maintained at -5°C to 0°C. After cutting, it is immediately put into water at 45-60°C containing 0.1% sodium ascorbate for blanching. After blanching, the fat cubes are rapidly cooled in an ice-water bath at 0-4°C for 5-8 minutes; When mixing the meat material, the step-by-step feeding method is adopted. First, add 1 / 2 of the fat cubes and the lean beef and mix at a speed of 12 r / min for 3 minutes, then add the remaining fat cubes and 0.02% monoglyceride emulsifier, and switch to a speed of 8 r / min and mix for 5 minutes.

8. The preparation method of the low-temperature fermented beef sausage according to any one of claims 1 to 7, characterized in that, The low-temperature fermented beef sausage has a bright red color, contains essential amino acids and fatty acids, and contains characteristic flavor substances such as 3-methylbutanal, 3-methylbutanol and hexanal.

9. A low-temperature fermented beef sausage obtained by using the preparation method according to any one of claims 1 to 7.

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