基于低场NMR研究油炸温度对牛肉干水分分布与品质的影响

Effect of Deep-frying Temperature on Moisture Distribution and Quality of Beef Jerky Based on Low Field NMR

为探讨不同油炸温度(150,160,170,180℃)对牛肉干水分分布与品质的影响,分别测定牛肉干的出品率、剪切力、水分含量、水分活度、颜色、T2弛豫时间和感官评价,并分析它们之间的相关性。结果表明,随着油炸温度的升高,牛肉干的出品率、水分含量、水分活度、a*值、b*值显著降低(P<0.05);剪切力显著增加(P<0.05);在油炸温度为170℃条件下获得最佳的感官评价值(P<0.05)。低场NMR研究发现,拟合后的T2弛豫时间分布为2个主要的峰,然而随着油炸温度的升高使主要峰T21和T22向慢的驰豫方向移动,同时对应的峰面积A21和A22显著降低(P<0.05)。结合相关性分析得出T21的变化与牛肉干水分含量、水分活度和出品率之间存在正相关的线性关系。油炸时间对牛肉干品质的影响主要是因肉中水分的迁移所致。

This study has mainly investigated the relationship between moisture distribution and the quality of beef jerky as affected by different deep-frying temperature（150,160,170,180 ℃）. In my experiment, the cooking yield,shearing force, water content, water activity, color, T2 relaxation time and sensory properties were measured, and the relativity among them was analyzed and discussed. The result indicated the yield, water content, water activity, a＊and b＊values were notably decreased with the temperature increasing（P〈0.05）, while hardness were significantly increased（P〈0.05）; the best sensory valuation was acquired at 170 ℃（P〈0.05）. Furthermore, the analysis of LF-NMR indicates that the distributed of the T2 relaxation time were two major peaks, and the major T21 and T22peak shifted towards to slower relaxation times with the temperature increasing. Simultaneously, the corresponding peak proportion of A21 and A22decreased significantly. Positive linear correlations were obtained with the analysis of the relativity among the variation of T21, water content, water activity and cooking yield of beef jerky. The results indicated that water migrate in meat was the main reason of the influence of different frying temperature on beef jerky＇s quality.