International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal.
Department of Food Engineering, Faculty of Food Engineering, University of Campinas - UNICAMP, CEP: 13083-862 Campinas, SP, Brazil.
Food Res Int. 2017 Jun;96:161-170. doi: 10.1016/j.foodres.2017.03.021. Epub 2017 Mar 12.
This work aims at evaluating the influence of oil and gelator structure on organogels' properties through rheological measurements, polarized microscopy and small-angle X-ray scattering (SAXS). Four different food-grade gelators (glyceryl tristearate - GT; sorbitan tristearate - ST; sorbitan monostearate - SM and glyceryl monostearate - GM) were tested in medium-chain triglyceride and high oleic sunflower (MCT and LCT, respectively) oil phases. Organogels were prepared by mixing the oil phase and gelator at different concentrations (5, 10, 15, 20 and 25%) at 80°C during 30min. All organogels presented birefringence confirming the formation of a crystalline structure that changed with the increase of the gelator concentration. Through the evaluation of SAXS peaks it has been confirmed that all structures were organized as lamellas but with different d-spacing values. These particularities at micro- and nanoscale level lead to differences in rheological properties of organogels. Results showed that the oil type (i.e. medium- and long-chain triglyceride) and hydrophilic head of gelators (i.e. sorbitan versus glyceryl) exert influence on the organogels physical properties, but the presence of monostearate leads to the formation of stronger organogels. Moreover, gels produced with LCT were stronger and gelled at lower organogelator concentration than MCT.
这项工作旨在通过流变学测量、偏光显微镜和小角 X 射线散射（SAXS）评估油和凝胶剂结构对有机凝胶性质的影响。测试了四种不同的食品级凝胶剂（三硬脂精甘油酯-GT；山梨醇三硬脂酸酯-ST；山梨醇单硬脂酸酯-SM 和单硬脂酸甘油酯-GM）在中链甘油三酯和高油酸葵花籽油（MCT 和 LCT）油相中。有机凝胶通过在 80°C 下将油相和凝胶剂以不同浓度（5、10、15、20 和 25%）混合 30 分钟来制备。所有有机凝胶均表现出双折射，证实形成了一种结晶结构，该结构随凝胶剂浓度的增加而变化。通过评估 SAXS 峰，已确认所有结构均组织为层状，但具有不同的 d 间距值。这些微观和纳米尺度的特殊性导致了有机凝胶流变性质的差异。结果表明，油的类型（即中链和长链甘油三酯）和凝胶剂的亲水头部（即山梨醇与甘油）对有机凝胶的物理性质有影响，但单硬脂酸酯的存在导致形成更强的有机凝胶。此外，与 MCT 相比，用 LCT 生产的凝胶更强，且在较低的有机凝胶浓度下凝胶化。
