猪油煎炸过程中理化性质与低场核磁共振弛豫特性的相关性分析

以猪油为研究对象，以薯条为煎炸原料，研究不同物料比条件下，猪油理化性质与低场核磁共振（lowfield nuclear magnetic resonance，LF-NMR）弛豫特性的变化规律，并分析各理化指标与LF-NMR弛豫特性之间的相关性。结果表明：随着煎炸时间的延长，猪油的总极性化合物（total polar compounds，TPC）含量呈指数增长（R2＞0.992），共轭二烯（K232）和共轭三烯（K270）呈线性增长（R2＞0.952），过氧化值（peroxide value，PV）呈先增后减趋势，峰面积比例S21的升高规律符合二项式关系（R2＞0.974），单组分弛豫时间T2W的降低规律符合二项式关系（R2＞0.901），而峰面积比例S22、S23、峰起始时间T21、T22和T23则规律性不明显。随着物料比的增加，油样的TPC含量和K270显著增大，T2W显著减小。回归分析表明，TPC、K232、K270、PV与S21、T2W能够建立良好的相关模型（R2＞0.948），模型验证合理可靠，说明可以通过猪油的LF-NMR弛豫特性快速、有效预测相关理化指标的变化。

Relationship between Physico-chemical Indexes of Lard and LF-NMR Characteristics during Frying Process

In this study, the evolution of several physico-chemical indexes (TPC content, conjugated diene, conjugated triene, and
peroxide value) 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 lard were studied during the frying
process of potato chips at different loads. In each frying series, two frying loads were applied, namely 0.036 (high) and 0.015 kg of
potato/kg of lard (low) compared with blank control group without foodstuff. The correlation model between LF-NMR results and
physico-chemical indexes was established and experimentally verified. The results indicated that as the frying process prolonged,
the TPC content increased exponentially, conjugated diene and conjugated trienes increased linearly, and peroxide value increased
firstly and decreased later. A good binomial relationship was obtained between S21 or T2W and frying time. No obvious relationship
was found between frying time and S22, S23, T21, T22 or T23. With an increase in frying load, TPC content and K270 increased
significantly, and T2W decreased markedly. Regression analysis showed that TPC content, conjugated diene, conjugated triene
and peroxide value had excellent correlations with S21 and T2W. The models could be used to predict the changes in physicochemical
indexes by the LF-NMR characteristics of frying oil.