硬脂烷醇与米糠蜡配比对葵花籽油凝胶微观结构 及结晶行为的影响Effects of ratio of stearyl alcohol to rice bran wax on the microstructure and crystallization behavior of sunflower seed oil oleogels

为探究硬脂烷醇（SA）和米糠蜡（RW）在油凝胶中的相互作用机制，以不同配比的SA和RW为凝胶剂制备了葵花籽油凝胶，采用差示扫描量热仪（DSC）、低场核磁共振仪和偏光显微镜（PLM）探究不同SA与RW配比对油凝胶热性质、微观结构形态和结晶行为的影响。结果发现：不同油凝胶的固体脂肪含量（SFC）随温度的升高出现二次降低现象；随着SA和RW配比的变化，SA和RW在体系中按熔点高低顺序结晶，在结晶过程中出现共晶现象；RW油凝胶的晶体为棒状或针状结构，SA油凝胶的晶体为片状结构，当SA在凝胶剂中占比增加时，晶体聚集体形态由针状或棒状晶体聚集物转变为针状晶体夹杂小片状晶体的聚集物，再转变为片状晶体夹杂细小针状晶体的聚集物；在20 ℃下，当SA与RW质量比为1∶ 9、3∶ 7、5∶ 5和7∶ 3时，油凝胶呈现两步结晶现象，SA与RW质量比为0∶ 10、9∶ 1和10∶ 0时油凝胶呈现一步结晶现象；30 ℃下，SA与RW质量比为7∶ 3时油凝胶呈现两步结晶现象，其余油凝胶呈现一步结晶现象。综上，不同配比的SA和RW对油凝胶的影响主要体现在SFC的熔化趋势变化、热性质差异、晶体形态变化和结晶行为的差异上，这些变化是由于在微观结构上两种凝胶剂晶体粒子之间相互作用导致的。 In order to investigate the interaction mechanism of stearyl alcohol (SA) and rice bran wax (RW) in oleogels, sunflower seed oil oleogels were prepared by the mixture of SA and RW with various ratios as gelators. The effects of the ratio of RW to SA on the thermal properties, microstructure and morphology, and crystallization behavior of these oleogels were investigated by differential scanning calorimeter (DSC), low field nuclear magnetic resonance and polarizing microscope (PLM). The results showed that the solid fat contents(SFC) of different oleogels showed two-step decrease with temperature increasing. As the content of SA increased, RW and SA melted and crystalized sequentially. The cocrystal behavior appeared in the crystallization of the binary oleogels. The crystal morphology of RW oleogel was needle-like or rod-like structure, that of SA oleogel was plate-like. With decrease of the ratio of RW to SA, the morphology of the oleogels changed from the aggregates of needle-like or rod-like crystal to aggregates of needle-like crystals entrapped with small plate crystals, to aggregates of large plate crystals entrapped with small needle-like crystals. The oleogels formed by the gelators with the mass ratio of SA to RW 1∶ 9, 3∶ 7, 5∶ 5 and 7∶ 3 presented two-step crystallization, others showed one-step crystallization at 20 ℃. The oleogels formed by the gelators with the mass ratio of SA to RW 7∶ 3 showed two-step crystallization, and the others indicated one-step crystallization at 30 ℃. In conclusion, the influence of different ratios of SA to RW in oleogels showes variety of SFC melting process, thermal properties differences, variety of crystal morphology and different crystallization behavior, which are caused by the interaction of SA and RW crystals particles in the microstructure.