大豆油煎炸过程理化指标与LF-NMR弛豫特性的相关性研究

摘要

在对大豆油无料/薯条煎炸过程[温度:(180±5)℃,持续36 h]中的酸价(AV)、粘度(V)、吸光值(A)及总极性化合物(TPC)含量等及低场核磁共振(LF-NMR)弛豫特性(峰起始时间T21、T22、T23、相应的峰面积比例S21、S22、S23、单组份弛豫时间T2w)变化规律研究的基础上,利用多元回归分析建立了理化指标与其LF-NMR检测结果的相关性模型,并进行验证.结果表明:大豆油的酸价、TPC含量及S21峰面积均随煎炸时间的延长而线性增大,T21、T22峰起始时间及T2w则随煎炸时间的延长而线性减小(r2 ＞0.90),粘度、吸光值随煎炸时间的延长逐渐增加并符合二项式关系(r2 ＞0.90),而T23峰起始时间及S22、S23与煎炸时间之间无明显规律性变化.煎炸薯条后,油样的酸价、粘度、TPC含量、吸光值及S21均较无料煎炸显著增大(P＜0.05),而T21、T22峰起始时间及T2w显著缩短.多元回归分析表明,酸价及TPC含量与T2w、T21,粘度与T2w,吸光值与S21间均可建立良好的相关性模型(R2＞0.93).模型验证合理可靠,可通过油样的LF-NMR检测结果有效预测其理化指标的变化.%The development of rapid and simple test is needed in order to capably monitor the frying oil quality and ensure the fried food safety.In this paper,the evolution of several analytical indicators(e.g.acid value,viscosity,absorbance values and TPC content) and the low field Nuclear Magnetic Resonance(LF-NMR) T2 relaxation characteristics (the relaxation time:T21,T22,T23,the corresponding peak area:S21,S22,S23 and the single component relaxation time:T2w) of soybean oil were studied during the frying process of no foodstuff or potato chips(180 ±5 ℃ for 36 h).The multiple regression analysis method was used to establish the correlation model between LF-NMR results and the analytical indicators.At last,the developed models were experimentally verified.The results indicated that the acid value,TPC content and S21 increased linearly,while T21,T22 and T2w decreased linearly,as the frying process prolonged.And a good binomial relationship was obtained between the viscosity or absorbance values and the frying time (r2 ＞ 0.90).No obvious relationship was found between frying time and T23,S22 or S23.Compared with no foodstuff frying,the acid value,viscosity,TPC content,absorbance values and S21 during potato chip frying process increased significantly,while T21,T22 and T2w obviously shortened (P ＜ 0.05).Multiple regression analysis showed that both acid value and TPC content had a good relationship with T2w and T21,and viscosity had a good linear relationship with T2w,while absorbance had a good logarithmic relationship with S21 (r2 ＞ O.93).These models were successfully verified and could be used to predict the variations of physical and chemical indicators by the LF-NMR characteristics of the frying oil.