肉制品的食用品质及其评价

肉类及其制品是膳食中不可缺少的优质蛋白质来源,肉类食用品质尤其是感官品质是消费者选择肉和肉制品的重要衡量指标.目前,肉制品的品质评定缺乏客观的评价方法.本文针对肉制品的系水力、多汁性、质地等食用品质及其评价方法的研究进展进行综述,为促进肉制品品质评定方法的客观化、建立肉制品的食用品质评定标准和体系提供参考.     

应用便携式近红外仪检测生鲜羊通脊肉的嫩度

在北京市内收集生鲜羊通脊肉样品98个,研究应用便携式近红外仪快速无损检测生鲜羊通脊肉嫩度,结合化学计量学的方法建立可以快速无损检测生鲜羊通脊肉嫩度的近红外光谱检测模型。在建模过程中,研究了平滑、求导和信号校正等不同光谱预处理方法对模型的影响。结果表明:最佳的光谱预处理方法为均值中心化、Savitzky-Golay(SG)一阶导数、SG平滑和正交信号校正。应用偏最小二乘法建模所得模型的校正集标准偏差0.90、验证集标准偏差2.39、校正集相关系数(R c)=0.94、验证集相关系数(R p)=0.64、主因子数为4,说明模型具备较好的预测准确性,可应用于生鲜羊通脊肉嫩度的快速无损检测中。     

胶原蛋白与肉品品质

胶原蛋白是肌内结缔组织的主要成分,本文简要介绍了胶原蛋白在肌肉中的分布、架桥结构的形成及其稳定性,并阐述了胶原蛋白随动物年龄变化的规律及其与肌肉嫩度之间的关系。     

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.     

超声波在羊肉嫩化中的应用研究

本试验以山羊肉为材料进行超声波处理,分别处理0、1、3、5、7、10、15min,结束后在0～4℃成熟1、2、3、4、5、7d(每个成熟期设两个重复),检测肉块的MFI、可溶性蛋白浓度和剪切力,实验结果表明频率40kHz,电功率1000W,强度为1.33W/cm2的超声波水浴处理,明显提高了宰后15h的山羊肉块(70±1)g的嫩化速率,可使山羊肉提前3d成熟。     

基于高光谱图谱融合技术的宁夏滩羊肉嫩度检测方法研究

利用可见/近红外高光谱图谱融合技术对宁夏滩 羊肉嫩度检测进行研究。通过高光谱系统(400～1000nm)采集了128个滩羊肉图像,对原始光谱结合偏 最小二乘回归(PLSR)模型进行多种光谱预处理研究,优选出S-G卷积平滑预 处理方法,采用PLSR的加权β系数提取9个特征波长,对比分析 全波段与特征 波长下的PLSR模型;同时提取出与羊肉嫩度相关的4个图像特征参数,建立基 于图像特征的多元线性回归(MLR)模型;在此基础上,融合特征波长与表面脂肪分布图像特 征 参数建立了羊肉嫩度的PLSR模型。结果表明,采用单一光谱数据下S-G卷积平 滑预处理结合特征波长建立的PLSR模型取得了较好预测效果,基于图谱特征 变量融合的PLSR模型相比于单一光谱模型效果更佳,预测集的相关系数和预测 均方根误差(RMSEP)分别为0.89和0.73,表明本文提出的方法 进行羊肉嫩度定量检测是可行的。     

Profile of fatty acids, muscle structure and shear force of musculus longissimus dorsi (MLD) in growing pigs as affected by energy and protein or protein restriction followed by realimentation

Forty-eight gilts were submitted to a 30% restriction of feed (groups F and F1) or protein intake (group P) from 90 to 118 days of age, followed by realimentation from 119 to 168 days of age. Control pigs (C) were fed during the whole experiment according to a semi ad libitum scale. During realimentation all animals were fed according to semi ad libitum scale except pigs F1 which were fed ad libitum. Six pigs from each group were slaughtered at the end of restriction and realimentation. Restriction decreased the weight of musculus longissimus dorsi (MLD) and increased shear force. Restriction of feed intake depressed MUFA concentration and increased n-6/n-3 ratio while protein restriction decreased n-6/n-3 and PUFA:SFA ratios. Structure of fibers was not affected. After realimentation MLD mass was still lower in all previously restricted pigs, shear force was the lowest in F1 pigs. Only percentage of fast twich oxidative fibers was significantly greater in F1 pigs than in others. Significant correlations between parameters investigated during the study were found.     

基于支持向量机的牛肉嫩度等级评价模型研究

目的 利用VIS/NIR反射光谱建立基于支持向量机的生鲜牛肉嫩度等级的评价模型。方法 以牛肉背最长肌为研究对象, 选取样本58个, 在牛肉新鲜切口处采集波长范围400~1700 nm的反射光谱信息, 使用肉类嫩度测量仪测量牛肉剪切力值, 应用支持向量机(SVM)模型评价牛肉嫩度等级。结果 应用SVM模型可以较好地实现对牛肉嫩度等级的评价。尤其是经主成分分析降维预处理, 结合径向基核函数SVM, 对牛肉训练集嫩度等级的回判率达到95%, 对样品校正集判别的准确率进一步提高至83.3%。结论 SVM模型对牛肉嫩度等级评价结果较好, 进行主成分分析后, 判别结果有所提高。     

碳酸氢钠对水煮牛肉片加工和冷藏性能的影响

研究碳酸氢钠对水煮牛肉片加工和冷藏性能的影响。添加碳酸氢钠(0.2%～0.8%)对牛肉片进行腌制,熟制后在4℃条件下分别冷藏0、2、4、6、8 d,测定水煮牛肉片在加工和冷藏期间蒸煮得率、色泽、pH值、剪切力、水分含量和硫代巴比妥酸反应物值的变化。结果表明：碳酸氢钠显著提高水煮牛肉片的蒸煮得率、pH值和水分含量(P<0.05),显著降低剪切力和红度值(a^*)(P<0.05);在冷藏期间,所有样品的水分含量均降低,亮度值和a^*减小,黄度值升高;但碳酸氢钠能抑制脂肪氧化,且随着添加量的增加,抑制效果显著提升,同时,碳酸氢钠对抑制水煮牛肉片a^*的下降有显著作用,添加碳酸氢钠水煮牛肉片的a*均大于对照组。因此,碳酸氢钠能提高水煮牛肉片的保水性、嫩度和抗氧化性。