清酱牛肉改良工艺研究

为了加大对传统清酱牛肉的开发利用度,进行清酱牛肉的改良工艺研究,试验结果表明:以普通牛肉为原料,在添加发色剂用量为0.01%的条件下搅拌15min,在20℃温度下腌制24h,在各种香辛料调制的酱汤中加入干黄酱和蚝油比例为2∶1。在温度为80℃条件煮制40min,再在酱汁中浸泡30min,装袋、抽气、杀菌、包装成色香味俱佳的清酱牛肉。     

新疆褐牛高档牛肉感官评定比较

利用评分检验法对新疆褐牛育肥牛与未育肥牛、公牛与母牛高档部位的里脊、外脊从颜色、光泽、细致度、坚挺度等进行感官评定比较与感官指标相关性分析,结果表明:除汁液浸出、残留度无显著差异外,其他各项指标育肥牛均显著高于未育肥牛。通过对感官指标相关性分析作感官指标简化,鲜肉简化后指标主要有颜色、光泽、细致度、坚挺度、形态、鲜度、香气、整体可受性8项。熟制牛肉感官指标主要有色泽、美食欲、咬入度、嚼透度、初始多汁性、持续多汁性、细腻程度7项。     

Effect of α-tocopherol on lactone formation in marbled beef and changes in lactone volatility during storage

Dynamic-headspace sampling with a standard-addition method was employed to quantitatively analyze aliphatic lactones in rendered fat from marbled beef and to evaluate the effect of the matrix on volatility. Further, the effects of different levels of the antioxidant α-tocopherol on lactone formation were examined. The slopes of the linear regression curves from the standard-addition method were significantly changed (P < 0.05 or 0.01) for all lactones after storage, with the exception of γ-octalactone, indicating the volatility of the longer-chain lactones were increased after storage. The concentrations of γ-lactones were increased after 7 d of storage at 2 °C (P < 0.01), and the α-tocopherol content in the meat affected the formation of γ-octalactone (P < 0.05) and γ-nonalactone (P < 0.01). The greatest increase was observed for γ-nonalactone in the lowest α-tocopherol (2.9 ppm) group: the concentration of 51.4 ppb was 11.7-fold higher than that before storage. Meanwhile, δ-tetradecalactone in the highest α-tocopherol (28.8 ppm) group showed the highest concentration for the lactones at 415.8 ppb, which was 2.6-fold higher than the concentration before storage. The effect of α-tocopherol was unclear for the δ-lactones. The results indicate that most of the γ-lactones are produced by oxidation during storage but that the other lactones are also generated by other processes as well.     

低温酱牛肉贮藏期的品质变化规律

以美好酱牛肉为原料,采用0～4℃、7～11℃二个温度贮藏样品,每10d对酱牛肉pH、肉色、保水性、水分含量、弹性和菌落总数、大肠菌群等指标进行测定。结果表明:感官品质处于下降趋势,且高温贮藏变化较大;pH变化不大,一直处于缓慢下降;水分含量上升,保水性下降;菌落总数处于上升趋势,但都未超过卫生标准。     

基于图像的牛肉大理石纹理自动评级方法研究

研究一种基于图像处理技术的牛肉大理石花纹自动等级评定方法。通过图像重采样、单阈值分割、形态学腐蚀及膨胀等方法分割出大理石花纹,再提取图像的特征参数组,并用多元回归分析的方法构造牛肉大理石花纹评级模型,并用VC++实现了自动评级软件。通过对多个牛肉图像的检测,表明此评级计算模型具有良好的准确性和鲁棒性。     

气调包装中气体浓度对牛肉保鲜的影响

研究了气调包装中不同气体浓度对牛肉保鲜效果的影响。运用均匀设计法,对新鲜牛肉分别进行不同水平的气调保鲜包装(O2与CO2浓度在0%～100%均匀分布),在(4±1)℃贮藏过程中,隔天对包装内的气体浓度、牛肉的菌落总数、pH值、TVB-N值、液汁流失率、红度值等指标进行测定分析,并采用重回归分析法找出气调包装中O2浓度、CO2浓度、贮藏时间与菌落总数之间的关系式。结果表明:高氧或高CO2浓度的气调包装对牛肉保鲜效果都不理想,而适当的气体组合45%O2/30%CO2/25%N2的气调包装牛肉货架期最长。     

基于线粒体编码基因差异对食品中牛肉与猪肉成分的鉴别

市场上有不法厂商使用深加工后的猪肉冒充或添加于牛肉进行销售,但针对熟制食品中猪肉和牛肉成分的辨别方法仍不够成熟。为建立灵敏、可靠的食品中猪肉和牛肉成分的鉴定方法,分别根据线粒体基因组和细胞基因组编码基因的差异设计多组物种特异性引物,应用PCR技术对加工食品中的猪肉和牛肉成分进行鉴别。结果表明,两组基于线粒体编码基因差异所设计的引物各具优势,均可有效地进行食品中猪肉和牛肉成分的鉴定,检测灵敏度达纳克级DNA,且鉴定效果显著优于使用基于细胞基因组编码基因差异的引物。对市售食品样本的鉴别验证了方法的实用价值。总之,建立并优化了可用于深加工熟制食品中猪肉和牛肉成分鉴别的PCR方法,为肉制品质量控制提供了新的途径。     

结冷胶和谷氨酰胺转氨酶对牛肉凝胶持水性与硬度的影响

利用响应面法研究结冷胶(0.2％～1.0％)、谷氨酰胺转氨酶(0.2％～0.6％)、处理温度(40～60℃)和反应时间(120～160min)对牛肉凝胶持水性和硬度的影响及其相互作用.结果表明:谷氨酰胺转氨酶、处理温度和反应时间对牛肉糜凝胶蒸煮损失率和保水性的影响显著,谷氨酰胺转氨酶、处理温度和结冷胶对牛肉糜凝胶硬度的...     

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.     

Thermal Gelation of Stretched and Cold-Shortened Bovine Sternomandibularis Muscle and Myofibrils

Muscle gels (10% protein) and myofibril gels (8% protein) were prepared at pH 6.0 with 2% NaCl and a heating rate of 0.7°C/min. No difference in gel strength occurred between stretched and cold-shortened muscles, but cooking loss was lower for stretched muscle. Stretched muscle sarcomeres were longer than those of cold-shortened muscle. The myofibril fraction from stretched muscle had higher gel strength, viscosity index, elasticity, and lower cooking loss than that from cold-shortened muscle. These results suggest that the contractile state of the muscle affects protein binding and water binding of the myofibrillar fraction.