Endo Midori, Shibata Masashi
School of Bioscience and Biotechnology, Tokyo University of Technology.
J Oleo Sci. 2019;68(8):739-745. doi: 10.5650/jos.ess19058.
Due to its availability and relatively high melting point, rice bran wax can be used in foods and cosmetics as an oil solidifying agent. The addition of high-melting-point alcohols to the wax to optimize its performance was investigated. Such alcohols were prepared by the hydrolyzation of rice bran wax or carnauba wax. These alcohols had melting points of ～80°C, higher than that of rice bran wax, and consisted of hydrocarbons with alkyl chain lengths ranging from C24 to C34, much longer than the alkyl chains found in commercially available higher alcohols. Oil gel made with only rice bran wax as a solidifying agent has lower hardness than the conventional hydrocarbon wax gel, too low for practical usage in stick cosmetics such as lipsticks and lip creams. Blending high-melting-point alcohols with rice bran wax at 10-20% led to marked increase in gel hardness, equivalent to the gel hardness of the hydrocarbon wax. This effect on rice bran wax was not observed in commercially available higher alcohols and esters with lower melting points. Based upon the change in microstructure observed with SEM, the improved gel hardness of the rice bran wax upon addition of high-melting-point alcohols was probably induced by the disappearance of spherical clusters, originally presented in the gel, resulting in close to uniform morphology.
由于米糠蜡易于获取且熔点相对较高，它可在食品和化妆品中用作油固化剂。研究了向该蜡中添加高熔点醇以优化其性能的情况。此类醇是通过米糠蜡或巴西棕榈蜡的水解制备的。这些醇的熔点约为80°C，高于米糠蜡，由烷基链长度在C24至C34范围内的烃组成，比市售高级醇中的烷基链长得多。仅以米糠蜡作为固化剂制成的油凝胶硬度低于传统烃蜡凝胶，对于口红和唇膏等棒状化妆品的实际使用来说太低。将高熔点醇与米糠蜡按10 - 20%的比例混合会使凝胶硬度显著增加，与烃蜡的凝胶硬度相当。在市售熔点较低的高级醇和酯中未观察到对米糠蜡的这种效果。基于扫描电子显微镜观察到的微观结构变化，添加高熔点醇后米糠蜡凝胶硬度的提高可能是由于凝胶中原本存在的球形聚集体消失，从而形成了接近均匀的形态。
