冷冻处理对大豆油体微观结构及理化特性的影响

Effect of Freeze-processing on the Microstructure and Physicochemical Properties of Soybean Oil

摘要:

本文研究冷冻处理对大豆油体微观结构及基本物理化学性质的影响，为大豆油体作为功能性食品原料在食品工业中的应用提供一定的参考。通过透射电镜观察冷冻前后大豆子叶细胞中油体形态的变化，发现冷冻处理导致了较大粒径的油体聚集体出现。采用超高速离心的方法提取豆浆中的油体，将油体的分散液进行光学显微镜观察、粒径分布试验和电泳分析。结果显示，未处理组油体的粒径最小（0.54 μm），而冷冻后大多数油体的粒径范围为2~4 μm，且超过4 μm的油体数量随冷冻时间的延长而增加。电泳图像显示冷冻后分子量为24 kDa的oleosin含量减少。油体在不同pH值（pH值2~8）、NaCl 浓度（0~250 mM）条件下的Zeta电位和疏水性进行测定。结果表明，冷冻处理能够轻微地降低油体的等电点，增加油体表面的疏水性。

Abstract:

In this study, the effect of freeze-processing on the microscopic structure and physicochemical properties of soybean oil was evaluated. This study provided a reference for the application of soybean oil as raw material for functional food. Morphological changes in soybean oil particles within cotyledons of soybeans before and after freeze-processing were examined using a transmission electron microscope. Large-diameter oil body was found to be aggregated during freezing. Oil was extracted from soymilk by performing ultra-high-speed centrifugation. Oil body dispersion was visualized by light microscopy and measured by particle size distribution and SDS-PAGE. The results suggested that the smallest diameter of oil body was that of unprocessed oil (0.54 μm), most diameters of freeze-processed oil ranged from 2 to 4 μm, while the number of oil body with a diameter >4 μm increased with increasing freeze duration. Electrophoretic results showed that the amount of oleosin, with a molecular weight of 24 kDa, decreased after freeze-processing. The Zeta-potential and hydrophobicity of oil body at different pH values (pH 2~8) and NaCl concentrations (0~250 mM) were measured. The results indicated that freeze-processing could slightly decrease the isoelectric point (pI) and increase the hydrophobicity at the surface of the oil body.