A method of identifying grass-fed beef

Abstract

The application discloses a method for identifying grazing beef, and relates to the technical field of livestock product quality identification, and comprises the following steps: detecting three core indexes of a beef sample, i.e., a yellowness value, an n-6 / n-3 polyunsaturated fatty acid ratio and a shear force, and quickly and accurately determining whether the beef is raised by grazing or feeding in a shed. The application is based on the key quality differences between grazing beef and feeding beef, and establishes a scientific identification method and threshold standard. The method is simple to operate and has high accuracy, can be used for grassland beef quality certification and brand protection, and has important economic value and market application prospect.

Description

Technical Field

[0001] This invention relates to the field of livestock product quality identification technology, and in particular to a method for identifying free-range beef. Background Technology

[0002] As consumers increasingly focus on the quality and health benefits of beef, free-range beef is gaining popularity due to its unique flavor and superior fatty acid composition. Free-range beef has a lower n-6 / n-3 polyunsaturated fatty acid ratio, which better aligns with healthy dietary standards; simultaneously, the fat exhibits a higher yellowness value due to the deposition of β-carotene from pasture grasses. The muscles have higher shear force due to sufficient exercise. Currently, there is a phenomenon in the market where stall-fed beef is being passed off as free-range beef, which harms consumer rights and the value of premium brands.

[0003] Existing identification methods mostly rely on production record tracing or simple sensory evaluation, lacking scientific, objective, and quantifiable technical means. This study found that pasture-fed and stall-fed beef differed in yellowness value ( Based on the significant differences in the n-6 / n-3 ratio and shear force, an accurate and efficient method for identifying pasture-raised beef is proposed.

[0004] To solve these problems, a method for identifying free-range beef is urgently needed. Summary of the Invention

[0005] To address the aforementioned issues, this application proposes a method for identifying free-range beef, aiming to accurately distinguish between free-range and stall-fed beef based on core physicochemical indicators and key fatty acid ratios. The specific details are as follows: A method for identifying free-range beef includes the following steps: S1. Collect beef samples and pre-process the beef samples; S2. The characteristic indicators of the pretreated beef samples were detected to obtain the test results. The characteristic index detection includes key fatty acid ratio detection and physicochemical quality detection; S3. Determine whether the sample beef is free-range beef based on the test results.

[0006] Preferably, the beef sample in S1 is longissimus dorsi muscle beef.

[0007] Preferably, the preprocessing step in S1 includes: Remove the fascia and peripheral fat from the beef sample to obtain a fresh sample; Divide the fresh sample into two equal parts; A portion of the fresh sample was cut into uniform small pieces, vacuum freeze-dried, and then pulverized through a 1mm sieve to obtain beef jerky powder samples; Another portion of the fresh samples were used directly for physicochemical index testing; The vacuum freeze-drying process was carried out at a temperature of -50℃ for 48 hours.

[0008] Preferably, the specific content of the detection of key fatty acid ratios in S2 includes: The fatty acid composition of beef jerky powder samples was determined by gas chromatography, and the n-6 / n-3 polyunsaturated fatty acid ratio was calculated.

[0009] Preferably, the gas chromatograph uses an HP-88 capillary column; The dimensions of the HP-88 capillary column are: 100m × 0.25mm × 0.20μm.

[0010] Preferred column temperature program for gas chromatograph: initial temperature 60℃, hold for 1 min, increase to 180℃ at 10℃ / min, hold for 10 min, then increase to 220℃ at 2℃ / min, hold for 20 min; Inlet temperature 250℃, detector temperature 280℃; The carrier gas was nitrogen, and the flow rate was 1.0 mL / min; The split ratio is 10:1; Injection volume: 1 μL.

[0011] Preferably, the physicochemical quality testing in S2 includes: The yellowness value of fresh beef samples was determined using a colorimeter. ); The colorimeter testing conditions were: D65 light source, observation angle 10°, samples were placed at 4℃ for 30 minutes before measurement, three different sites were selected for each sample, and the average value was taken, defined as the yellowness value. ).

[0012] Preferably, the shear force is determined using a texture analyzer (equipped with a Warner-Bratzler shear blade); The shear force was measured under the following conditions: the beef sample was heated to a core temperature of 70°C in an 80°C constant temperature water bath, cooled to room temperature, and a cylindrical sample with a diameter of 1.27 cm was drilled along the direction parallel to the muscle fibers. The measurement speed was 2 mm / s, and each sample was measured 3 times. The average value of the result was defined as the shear force.

[0013] Preferably, when the sample to be identified meets both the key fatty acid ratio standard and the physicochemical quality standard, it is determined to be free-range beef; otherwise, it is determined to be non-free-range beef.

[0014] Preferably, the key fatty acid ratio standard is: n-6 / n-3 polyunsaturated fatty acid ratio ≤ 10; The physicochemical quality standard is: yellowness value ( ≥8.0; Shear force ≥ 8.5 kg.

[0015] In summary, the method for identifying free-range beef of the present invention has the following advantages compared with traditional techniques: 1. Concise and efficient identification indicators: Select yellowness value ( The core indicators of the three items (n-6 / n-3 ratio, shear force, etc.) with extremely significant differences between groups are eliminated, redundant indicators are discarded, and the risk of misjudgment by a single indicator is avoided. The identification accuracy rate can reach over 98%. 2. Simple and quick operation: It adopts conventional gas chromatograph, colorimeter, texture analyzer and other equipment. The sample pretreatment is simple and the detection cycle is short. It does not require complicated pretreatment and large precision instruments, which makes it easy for laboratories and enterprises to promote and apply. 3. High specificity and stability: The three core indicators directly reflect the differences in feeding methods and are less affected by factors such as breed and age. The thresholds have been verified by a large number of comparative experiments, and the differentiation effect is stable and reliable. 4. Wide range of applications: It can be used in scenarios such as quality certification of free-range beef, brand building, and market supervision, providing consumers with reliable judgment criteria, helping high-quality free-range beef achieve premium prices, and promoting the high-quality development of the beef cattle industry.

[0016] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the steps of a method for identifying free-range beef according to the present invention. Detailed Implementation

[0018] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0019] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application or its use.

[0020] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0021] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] This invention provides a method for identifying free-range beef by detecting the yellowness value (Y ... Based on three core indicators—n-6 / n-3 polyunsaturated fatty acid ratio, shear force—a discrimination method was established to accurately distinguish between pasture-fed and stall-fed beef.

[0024] Example 1 One method for identifying free-range beef, such as Figure 1 As shown, it includes the following steps: S1. Collect beef from the longissimus dorsi muscle and pre-process the beef from the longissimus dorsi muscle. The pretreatment steps include: removing the fascia and peripheral fat of the beef sample to obtain a fresh sample; dividing the fresh sample into two parts; cutting one part of the fresh sample into uniform small pieces; vacuum freeze-drying (-50℃, 48h); pulverizing the fresh sample through a 1mm sieve to obtain beef jerky powder; and using the other part of the fresh sample directly for physicochemical index testing.

[0025] S2. The characteristic indicators of the pretreated beef samples were detected to obtain the test results. The characteristic index detection includes key fatty acid ratio detection and physicochemical quality detection; The physicochemical quality indicators of beef from the grazing group and the stall-fed group were compared, as shown in Table 1. The yellowness value of fresh beef was determined. (and the shear strength of fresh beef are key physicochemical qualities.)

[0026] Table 1. Comparison of Physicochemical Quality Indicators of Beef from Grazing Group and Confinement Group

[0027] The indicators for detecting characteristic indicators of the beef samples included saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and characteristic fatty acids, including myristic acid (C14:0), palmitic acid (C16:0), oleic acid (C18:1n9c), linoleic acid (C18:2n6t), DHA (C22:6n3), and trans oleic acid (C18:1n9t). The detection results are shown in Table 2.

[0028] Table 2 Comparison of Fatty Acid Composition of Beef from Grazing Group and Confinement Group

[0029] Based on Table 2, the effects of stall feeding and grazing on the fatty acid profile of beef were determined, and the n-6 / n-3 polyunsaturated fatty acid ratio was screened and determined as the key fatty acid ratio. The fatty acid composition of beef jerky powder samples was determined by gas chromatography, and the n-6 / n-3 polyunsaturated fatty acid ratio was calculated.

[0030] The gas chromatograph detection conditions were as follows: the column was an HP-88 capillary column (100m × 0.25mm × 0.20μm); the column temperature program was: initial temperature 60℃, hold for 1 min, increase to 180℃ at 10℃ / min, hold for 10 min, then increase to 220℃ at 2℃ / min, hold for 20 min; the injection port temperature was 250℃, the detector temperature was 280℃; the carrier gas was nitrogen, with a flow rate of 1.0 mL / min; the split ratio was 10:1; and the injection volume was 1 μL.

[0031] Physicochemical quality testing: The yellowness value of fresh beef samples was determined using a colorimeter. Shear force was measured using a texture analyzer (equipped with a Warner-Bratzler shear blade). The colorimeter testing conditions were: D65 light source, observation angle 10°, samples were allowed to stand at 4℃ for 30 minutes before measurement, and three different sites were selected for each sample; the average value was taken. The shear force measurement conditions were: beef samples were heated to a core temperature of 70℃ in an 80℃ constant temperature water bath, cooled to room temperature, and then a 1.27cm diameter cylindrical sample was drilled along the direction parallel to the muscle fibers. The measurement speed was 2mm / s, and each sample was measured three times; the average value was taken.

[0032] S3. Determine whether the sample beef is free-range beef based on the test results.

[0033] When a sample to be identified meets both the key fatty acid ratio standard and the physicochemical quality standard, it is determined to be free-range beef; otherwise, it is determined to be non-free-range beef.

[0034] The key ratio standard for fatty acids is: n-6 / n-3 polyunsaturated fatty acid ratio ≤ 10; The physicochemical quality standard is: yellowness value ( ≥8.0; Shear force ≥ 8.5 kg.

[0035] Example 2 In this embodiment, Simmental cattle (grazing group, 16 heads) were selected from the pastoral area of ​​Siziwang Banner, Ulanqab City, Inner Mongolia. The longissimus dorsi muscle was collected after slaughter.

[0036] The grazing cattle graze freely on natural grasslands, with an average daily exercise time of ≥4 hours and a fattening cycle of 36 months.

[0037] Sample pretreatment: The longissimus dorsi muscle sample was divided into two parts. One part had its fascia and peripheral fat removed and was cut into 1cm pieces. 3 Small pieces were vacuum freeze-dried (-50℃, 48h), pulverized, passed through a 1mm sieve, sealed, and stored for later use; another portion of fresh samples were refrigerated at 4℃ and their physicochemical properties were tested within 24h.

[0038] Feature index detection: (1) Detection of key fatty acid ratios: The Agilent 6890N gas chromatograph was used to determine the ratios according to the detection conditions described in the technical solution. The chromatographic column was an HP-88 capillary column. The fatty acids were methyl esterified before injection analysis, and the external standard method was used for quantification.

[0039] (2) Physicochemical quality testing: The yellowness value was measured using a CR-400 colorimeter. For each sample, three sites were measured and the average value was taken. The shear force was measured using a TA-XT2i texture analyzer at a rate of 2 mm / s, and each sample was measured three times and the average value was taken.

[0040] Example 3 In this embodiment, Simmental cattle raised in stalls in Kailu County, Tongliao City (stallized group, 17 heads) were selected, and samples of the longissimus dorsi muscle were collected after slaughter.

[0041] The stall-fed beef cattle were fed a total mixed ration (TMR), with an average daily exercise time of ≤1 hour and a fattening period of 18 months.

[0042] Sample pretreatment: The longissimus dorsi muscle sample was divided into two parts. One part had its fascia and peripheral fat removed and was cut into 1cm pieces. 3 Small pieces were vacuum freeze-dried (-50℃, 48h), pulverized, passed through a 1mm sieve, sealed, and stored for later use; another portion of fresh samples were refrigerated at 4℃ and their physicochemical properties were tested within 24h.

[0043] Feature index detection: (1) Detection of key fatty acid ratios: The Agilent 6890N gas chromatograph was used to determine the ratios according to the detection conditions described in the technical solution. The chromatographic column was an HP-88 capillary column. The fatty acids were methyl esterified before injection analysis, and the external standard method was used for quantification.

[0044] (2) Physicochemical quality testing: The yellowness value was measured using a CR-400 colorimeter. For each sample, three sites were measured and the average value was taken. The shear force was measured using a TA-XT2i texture analyzer at a rate of 2 mm / s, and each sample was measured three times and the average value was taken.

[0045] Results analysis for Examples 2 and 3: (1) Grazing group: Yellowness value ( The beef measured 8.89 kg, n-6 / n-3 ratio 9.31 kg, and shear force 9.65 kg. All three indicators met the standards, and the beef was judged to be free-range beef.

[0046] (2) Indoor feeding group: Yellowness value ( The beef was found to be non-grazing beef, with an n-6 / n-3 ratio of 30.15 and a shear force of 4.16 kg. All three indicators failed to meet the standards.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for identifying free-range beef, characterized in that, Includes the following steps: S1. Collect beef samples and pre-process the beef samples; S2. The characteristic indicators of the pretreated beef samples were detected to obtain the test results. The characteristic index detection includes key fatty acid ratio detection and physicochemical quality detection; S3. Determine whether the sample beef is free-range beef based on the test results.

2. The method for identifying free-range beef according to claim 1, characterized in that, The beef sample in S1 is longissimus dorsi muscle beef.

3. The method for identifying free-range beef according to claim 1, characterized in that, The preprocessing steps in S1 include: The fascia and peripheral fat of the sample beef were removed to obtain a fresh sample; Divide the fresh sample into two equal parts; A portion of the fresh sample was cut into uniform small pieces, vacuum freeze-dried, and then pulverized through a 1mm sieve to obtain beef jerky powder samples; Another portion of the fresh samples were used directly for physicochemical index testing; The vacuum freeze-drying process was carried out at a temperature of -50℃ for 48 hours.

4. The method for identifying free-range beef according to claim 1, characterized in that, The specific content of the key fatty acid ratio detection in S2 includes: The fatty acid composition of beef jerky powder samples was determined by gas chromatography, and the n-6 / n-3 polyunsaturated fatty acid ratio was calculated.

5. The method for identifying free-range beef according to claim 4, characterized in that, The gas chromatograph uses an HP-88 capillary column; The dimensions of the HP-88 capillary column are: 100m × 0.25mm × 0.20μm.

6. The method for identifying free-range beef according to claim 5, characterized in that, The column temperature program for the gas chromatograph is as follows: initial temperature 60℃, hold for 1 min, increase the temperature to 180℃ at 10℃ / min, hold for 10 min, then increase the temperature to 220℃ at 2℃ / min, hold for 20 min. Inlet temperature 250℃, detector temperature 280℃; The carrier gas was nitrogen, and the flow rate was 1.0 mL / min; The split ratio is 10:1; Injection volume: 1 μL.

7. The method for identifying free-range beef according to claim 1, characterized in that, The physicochemical quality testing in S2 includes: The yellowness value of fresh beef samples was determined using a colorimeter. ; The colorimeter was tested under the following conditions: D65 light source, 10° observation angle, and the sample was placed at 4°C for 30 minutes before measurement. Three different sites were selected for each sample, and the average value was taken and defined as the yellowness value.

8. The method for identifying free-range beef according to claim 1, characterized in that, Shear force was determined using a texture analyzer; The shear force was measured under the following conditions: the beef sample was heated to a core temperature of 70°C in an 80°C constant temperature water bath, cooled to room temperature, and a cylindrical sample with a diameter of 1.27 cm was drilled along the direction parallel to the muscle fibers. The measurement speed was 2 mm / s, and each sample was measured 3 times. The average value of the result was defined as the shear force.

9. The method for identifying free-range beef according to claim 1, characterized in that, When a sample to be identified meets both the key fatty acid ratio standard and the physicochemical quality standard, it is determined to be free-range beef; otherwise, it is determined to be non-free-range beef.

10. A method for identifying free-range beef according to claim 9, characterized in that, The key ratio standard for fatty acids is: n-6 / n-3 polyunsaturated fatty acid ratio ≤ 10; The physicochemical quality standard is: yellowness value ≥ 8.0; Shear force ≥ 8.5 kg.

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