Crystallization, Physicochemical Properties, and Oxidative Stability of the Interesterified Hard Fat from Rice Bran Oil, Fully Hydrogenated Soybean Oil, and Coconut Oil through Lipase-Catalyzed Reaction

Interesterified hard fat (IEHF) was produced from fully hydrogenated soybean oil (FHSBO) and rice bran oil (RBO) with different molar ratio (RBO/FHSBO = 1:1, 1:2, and 1:3). For interesterification, Lipozyme TL IM (10% of total substrates) was used as a biocatalyst. Further, coconut oil (CO; 40 wt.% on total weight of RBO and FHSBO) was also added in all reactants for providing medium chain fatty acid. After interesterification, the obtained IEHF and physical blend (before interesterification) with same molar ratio were carried out for comparing the physical properties, (i.e., solid fat content, melting and crystallization behavior, and polymorphic forms). From DSC results at 25 °C, solid fat content of the IEHF with different molar ratio (RBO/FHSBO = 1:1, 1:2, and 1:3) were 33.9%, 58.8%, and 72.1%, respectively, whereas physical blends at same molar ratio showed 66.2%, 71.6%, and 74.8%. Besides, short spacing β crystal polymorphic form was observed in the physical blend while only β′ crystal form was observed in IEHF, in which β′ polymorphic form is a desirable for the production of shortenings and margarines. In Rancimat test for oxidative stability, IEHF showed significantly lower induction time than the physical blend. When the catechin (200, 400, and 800 ppm) was added to the IEHF, induction time was significantly increased to 21.4, 34.1, and 44.3 h, respectively. In this study, IEHF from this study may have a potential functionality for the shortenings and margarines.