牛肉肌纤维直径和结缔组织含量与嫩度相关性研究

分别选取来自安徽大明牧业牛场的18、36、54、72月龄西门塔尔杂交公牛各6头,在同一商业屠宰场进行屠宰。测定其背最长肌肌纤维直径、羟脯氨酸含量和剪切力。结果表明：背最长肌剪切力随着肌纤维直径的增大而增大,随着羟脯氨酸含量的增加而增大;背最长肌剪切力与肌纤维直径、羟脯氨酸含量有较高的相关性;剪切力与肌纤维直径和羟脯氨酸含量的相关系数r分别为0.833和0.835,为强正相关;建立的剪切力与肌纤维直径的指数回归方程为y＝1.162e0.034x,R2＝0.932,说明回归方程拟合较好;建立的剪切力与羟脯氨酸含量的指数回归方程为y＝1.793e27.430x,R2＝0.947,说明回归方程拟合较好。     

Phosphate and Modified Beef Connective Tissue Effects on Reduced Fat, High Water-added Frankfurters

The effects of acidic, neutral and alkaline phosphates and amounts of modified beef connective tissue (0, 10 or 20%) were determined on the characteristics of 20% fat/20% water-added frankfurters or 10% fat/30% water-added frankfurters. Processing yields were lowest in both formulations with acidic phosphate. Cured meat color intensity was higher with the acidic phosphate than with alkaline or neutral phosphates. Alkaline or neutral phosphate samples partially recovered losses in emulsion stability that had occurred due to connective tissue level. The addition of 20% connective tissue improved processing yields and decreased cohe-siveness of 10% fat/30% water added frankfurters. Connective tissue addition had no effect on microbial stability. Acidic phosphates might be more effective in direct treatment of high collagen materials in a preblend rather than in direct addition into a frankfurter formulation.     

Rapid Determination of Spinal Cord Content in Ground Beef by Near-Infrared Spectroscopy

The potential of near‐infrared spectroscopy to measure spinal cord content in ground beef was investigated. Near‐infrared spectra were obtained for ground beef adulterated with 0 to 100 ppm spinal cord. A partial least square model was developed with 2nd derivative near‐infrared spectral data (5400/cm to 10000/cm). The model showed a calibration of R_val= 0.94 and a validation of R_val= 0.90. The detection limit of the model was 21 ppm, and sensitivity to detect true positive spinal cord–adulterated samples was 87%. Near‐infrared spectroscopy has the potential to identify spinal cord–adulterated ground beef.     

Nondestructive Assessment of Lipid Oxidation in Minced Poultry Meat by Autofluorescence Spectroscopy

To develop a rapid method to assess lipid oxidation, autofluorescence spectra (excitation wavelengths 365, 380, and 400 nm) from large samples (17 cm2) of minced poultry meat were collected by an optical system to determine directly lipid oxidation level. The same samples were also measured by 2-thiobarbituric acid method (TBARS). High correlations could be made between the TBARS method and autofluorescence spectra, especially those from 380 nm excitation. Partial least squares regression resulted in a root mean square error of 0.15 (R = 0.87) for chicken meat and 0.24 (R = 0.80) for mechanically recovered turkey meat. Classification analysis between fresh (TBARS < 0.25) and rancid (TBARS > 0.25) samples was done with high success rates. Autofluorescence spectroscopy might be well suited for rapid on-line determination of lipid oxidation level in minced poultry meat.     

Rapid Determination of Spinal Cord Content in Ground Beef by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

ABSTRACT: The potential of attenuated total reflectance Fourier transform infrared spectroscopy to measure spinal cord in ground beef was investigated. Mid‐infrared spectra were obtained for ground beef adulterated with 0 to 100 ppm spinal cord. Partial least squares models were developed using 400 to 4000 cm^‐1. The model in the 400 to 4000 cm‐1 range showed a calibration of R_call= 0.94 (RMSE = 11.24) and validation of R_val= 0.87 (RMSE = 17.22). The P‐O‐C and N‐H stretches were found to correlate positively with spinal cord content. Fourier transform infrared spectroscopy has the potential to rapidly determine spinal cord adulteration in ground beef.     

Natural Antioxidant Extract from Fenugreek (Trigonella foenumgraecum) for Ground Beef Patties

Ground beef patties (75% lean) containing synthetic antioxidants, or Fenugreek (Trigonella foenumgraecum) extracts were cooked to internal temperature 70°C, and evaluated for storage stability at 4°C. Thiobarbituric acid values of raw or cooked samples containing fenugreek extracts were lower than controls (P<0.05). Fenugreek extracts delayed the induction period of oxidative rancidity. No differences were observed in psychrotrophic bacterial counts, and samples containing fenugreek extracts had lower Hunterlab “a” and higher “b” values. Samples with Fenugreek extracts had better oxidative stability and Fenugreek may be a promising natural antioxidant source.     

Detection of E. coli O157:H7 from Ground Beef Using Fourier Transform Infrared (FT-IR) Spectroscopy and Chemometrics

Abstract: FT-IR spectroscopy methods for detection, differentiation, and quantification of E. coli O157:H7 strains separated from ground beef were developed. Filtration and immunomagnetic separation (IMS) were used to extract live and dead E. coli O157:H7 cells from contaminated ground beef prior to spectral acquisition. Spectra were analyzed using chemometric techniques in OPUS, TQ Analyst, and WinDAS software programs. Standard plate counts were used for development and validation of spectral analyses. The detection limit based on a selectivity value using the OPUS ident test was 10⁵ CFU/g for both Filtration-FT-IR and IMS-FT-IR methods. Experiments using ground beef inoculated with fewer cells (10¹ to 10² CFU/g) reached the detection limit at 6 h incubation. Partial least squares (PLS) models with cross validation were used to establish relationships between plate counts and FT-IR spectra. Better PLS predictions were obtained for quantifying live E. coli O157:H7 strains (R²≥ 0.9955, RMSEE ≤ 0.17, RPD ≥ 14) and different ratios of live and dead E. coli O157:H7 cells (R²= 0.9945, RMSEE = 2.75, RPD = 13.43) from ground beef using Filtration-FT-IR than IMS-FT-IR methods. Discriminant analysis and canonical variate analysis (CVA) of the spectra differentiated various strains of E. coli O157:H7 from an apathogenic control strain. CVA also separated spectra of 100% dead cells separated from ground beef from spectra of 0.5% live cells in the presence of 99.5% dead cells of E. coli O157:H7. These combined separation and FT-IR methods could be useful for rapid detection and differentiation of pathogens in complex foods.     

Liking of Ground Beef Patties is Not Affected by Irradiation

ABSTRACT: Our objectives were to determine the acceptability of irradiated fresh ground beef and to determine whether the acceptability was affected by information about benefits or by identifying the samples. The 218 subjects were separated into 4 groups comprising a 2 × 2 design of benefits and information. All subjects tasted 4 patties: 2 irradiated and 2 control. Ratings of overall liking, toughness, and flavor and texture liking were equal for both. Subjects rated the irradiated beef patties juicier than the nonirradiated. Benefit information and sample identification increased the liking ratings of the patties-because the group with no benefit information and no sample identification generally rated all samples lower.     

Qualitative and Quantitative Textural Assessment of Cooked Ground Beef Patties

Cohesiveness of extruded, sliced hamburger patties from two manufacturers was studied in relation to cooking performance. Tensile determinations of ultimate strength and toughness were related to cohesiveness as measured with an Instron Universal Testing Machine. Light and environmental scanning electron microscopy was used to relate physical and macroscopic observations. Very cohesive samples had values of ultimate strength 7>1.45N and toughness >3.70 × 10^?4J, and noncohesive samples had values of ultimate strength <0.90N and toughness <1.50 × 10^?4J. Tensile results allowed discrimination between levels of cohesiveness among ground beef patties and could serve as a monitoring device to ensure consistency and indicate failure of the product at the serving outlet.     

Differentiation of Beef and Kangaroo Meat by Visible/Near-Infrared Reflectance Spectroscopy

A visible/near-infrared (NIR) spectroscopic method was developed with canonical discriminant analysis and stepwise multiple linear regression to differentiate beef from kangaroo meat. Results showed that beef and kangaroo meat could be separated when samples were analyzed by spectrophotometry as minced meat or cut meat. For minced meat, scatter correction and derivative treatment of reflectance spectra improved classification. For cut meat, original reflectance spectra produced better classification. Overall classification accuracy was 83% to 100%, and no kangaroo meat was misclassified. NIR spectroscopy might be an efficient test method for species identification.     

Storage Stability of Low-fat Ground Beef Made with Lower Value Cuts of Beef

Five combinations of low-fat ground beef treatments were prepared with lower value raw-materials: 90% lean cow trimmings, 50/50 Choice trimmings, 95% lean Choice trimmings, defatted clods and rounds, cow knuckles, and cow chucks. They were compared to a 20% fat control for quality attributes during 24 wk frozen (?20°C) storage. Control patties had greater (P<0.05) cooking loss, shear force, and connective tissue, and lower (P<0.05) juiciness scores than low-fat treatments. All low-fat pattie treatments were rated higher (P<0.05) in flavor intensity than control patties. Low-fat patties manufactured with a majority of lean cow trimmings had a greater color (pigment) and oxidative (lipid) stability.     

基于拉曼光谱法测定冷鲜牛肉中肌红蛋白相对含量

为研究4 ℃贮藏期间冷鲜牛肉3?种化学形式肌红蛋白相对含量变化,对采集的一维拉曼光谱,用2D-shige二维相关分析软件对其光谱数据进行二维相关分析,得出3?种化学形式肌红蛋白的相对含量最佳推导公式。结果表明：肌红蛋白、氧合肌红蛋白与高铁肌红蛋白相对含量的最佳推导公式分别为：脱氧肌红蛋白相对含量/%=（－0.305?5x＋19.570）×100;氧合肌红蛋白相对含量/%=（－2.933?9x＋154.17）×100;高铁肌红蛋白相对含量/%=（1.574?3x－14.369）×100。3?种化学形式的肌红蛋白相对含量的预测效果为高铁肌红蛋白＞脱氧肌红蛋白＞氧合肌红蛋白,其中波数为1?033～1?248?cm－1时,高铁肌红蛋白相对含量的误差值最小为4.76%。研究表明,基于拉曼光谱法无损检测冷鲜牛肉中肌红蛋白相对含量是可行的。?     

Evaluation of Garam Masala Spices and Phosphates as Antioxidants in Cooked Ground Beef

ABSTRACT:  This study determined antioxidant effects and sensory attributes of individual ingredients (black pepper, caraway, cardamom, chili powder, cinnamon, cloves, coriander, cumin, fennel, ginger, nutmeg, salt, star anise) of an Indian spice blend (garam masala) in cooked ground beef. Thiobarbituric acid (TBA) values were measured as an indicator of rancidity for cooked samples on 1-, 8-, or 15-d refrigerated storage. Cooked samples were evaluated by a trained panel ( n = 13) for the intensity of rancid odor/flavor, beef flavor, and spice flavor and correlated with TBA values of same day samples. We also investigated possible additive effects between spice antioxidants and iron binding (type II) antioxidants on lipid oxidation by measuring TBA values. All spices had antioxidant effects on cooked ground beef, compared to controls. Among spices, cloves were the most effective in controlling lipid oxidation, with TBA values of 0.75, after 15-d refrigerated storage. All spices at their recommended levels lowered rancid odor and flavor in cooked ground beef, compared to controls. As expected, most spices also imparted distinctive flavors to cooked ground beef. There was a positive correlation (0.77) between TBA values on 15-d refrigerated storage and rancid odor/flavor. Type II antioxidants (iron-binding phosphate compounds) were more effective than individual type I antioxidants (spices and butylated hydroxytoluene; BHT) for maintenance of low TBA values in cooked ground beef during storage. Additive effects were observed with rosemary + milk mineral or sodium tripolyphosphate (STP) compared to rosemary alone.     

Color and Heat Denaturation of Myoglobin Forms in Ground Beef

To determine the effects of myoglobin forms on internal cooked color in ground beef, patties containing predominantly deoxy-(DMb), oxy-(OMb), or metmyoglobin (MMb) were cooked to 55, 65, or 75 °C. Only patties with DMb appeared red and undercooked at 55 °C, and their color became progressively more brown at 65 and 75 °C. Patties with OMb and MMb were brown at 55 °C and could be mistakenly perceived as being cooked enough to consume. Judging the doneness of ground beef using internal cooked color alone would be valid only if the pigment at time of cooking was predominantly DMb. In model studies, DMb had greater thermal stability than MMb especially at higher pH.     

Pork Skin Connective Tissue Gel Utilization in Reduced-Fat Bologna

This study determined temperature (50°, 60°, 70° and 80°C) and time (0.5, 1.0, 1.5 and 2.0h) factors that enhanced the water binding of pork skin connective tissue (PCT); the functionality of added water (AW, 100–600%, w/w) PCT gels; and attributes of bologna containing 10-30% addition of 100–600% AW PCT gels. Heating (70°C) PCT increased water binding. Gels (100–600% AW) were formed by heating PCT (70°C) for 30 min. Higher AW levels increased (p < 0.05) gel moisture content, while decreasing fat, melting points, collagen content, and hardness. Addition of PCT gels in bologna decreased (p < 0.05) hardness and increased juiciness, indicating the potential of PCT gels as water binders and texture-modifying agents.     

Sensory Evaluation of Ground Beef Stored in High-oxygen Modified Atmosphere Packaging

ABSTRACT: The quality of ground beef stored in high-oxygen modified atmosphere packaging (MAP) (80% O₂ and 20% CO₂) was evaluated and compared to controls stored in oxygen-impermeable chubs. Patties were formed from the stored ground meat at d 1, 6, and 10. Color, microbial load, thiobarbituric acid (TBA) number, and sensory acceptability were measured. Patties from both treatments bloomed to red with a* values > 16. Aerobic plate counts increased to 9 × 10⁵CFU/gby 10 d storage, but were not different (p < 0.05) between treatments. TBA number of high-oxygen samples increased to 2.1 after 10 d, compared to 0.8 for controls. The flavor of samples in high-oxygen were rated less desirable after 6 or 10 d.     

Tenderizing Effect of High Hydrostatic Pressure on Bovine Intramuscular Connective Tissue

ABSTRACT:  The effect of high-pressure treatment on bovine intramuscular connective tissue was investigated under various pressures (0.1 to 500 MPa) at 8 °C for 5 min. Shear force value, heat solubility of collagen, and structural changes of pressurized intramuscular connective tissues were evaluated. High hydrostatic pressure tenderized bovine intramuscular connective tissue as well as meat. The heat solubility of collagen increased ( P < 0.05) with high pressure, which indicates a reduction of collagen thermal stability. However, high pressure could not degrade collagen molecules by sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis. Collagen-derived peptide analysis also suggested that high pressure could not degrade the molecular structure of collagen, but could dissociate the collagen fibers or fibrils into fibrils or molecules. Histological study showed that high pressure induced structural weakening of intramuscular connective tissue, especially perimysium.     

不同肌纤维走向下牛肉剪切力的差异

肌纤维走向(平行或垂直于肌纤维)影响牛肉的各项嫩度指标,该研究从肌纤维和结缔组织两方面出发探究肌纤维走向引起嫩度差异的原因。以牛半腱肌为原料肉,分别在60、70、80、90、100 ℃的水浴温度下加热30、60、90、120、150 min,测定不同肌纤维走向下的剪切力、结缔组织机械强度、质构特性、胶原蛋白共价交联的变化以及扫描电镜观察,最后通过相关性分析得出肌纤维走向影响嫩度的关键因素。结果显示,相同温度和加热时间下,垂直于肌纤维方向的剪切力、硬度、凝聚性显著高于平行方向(p<0.05)。垂直肌纤维方向的剪切力与结缔组织机械强度和咀嚼性呈极显著正相关(p<0.01),与硬度、胶黏性、羟赖氨酸吡啶含量呈显著正相关(p<0.05);平行于肌纤维方向的剪切力与硬度、凝聚性、胶黏性、咀嚼性、回弹性呈极显著正相关(p<0.01),与结缔组织机械强度呈显著负相关(p<0.05)。由此得出垂直方向的嫩度特性由肌纤维和结缔组织共同决定,平行方向的嫩度特性由少数结缔组织和肌纤维变形挤压力决定。