Lipase catalyzed interesterification of rice bran oil (RBO) with hydrogenated cottonseed oil (HCSO) was carried out for producing a low trans free fat. The interesterification reaction was performed by varying parameters such as weight proportions of RBO and HCSO, reaction temperatures, time period and lipase concentration. Both non specific and specific lipases namely Novozym 435 and Lipozyme TL IM were employed for this study. Based on the data generated, the optimum reaction conditions were found to be: weight proportion of RBO and HCSO, 80:20; lipase concentration, 5 % (w/w) of substrates; reaction temperature, 60 °C; reaction time, 4 h for Lipozyme TL IM and 5 h for Novozym 435. The degree of interesterification, calculated based on the results of solid fat characteristics was used for comparing the catalytic activity of Novozym 435 and Lipozyme TL IM. It was observed that the degree of interesterification (DI) reached a near 100 % at the 4th hour for reaction employing Lipozyme TL IM with a rate constant of 0.191 h(-1) while Novozym 435 catalyzed reaction reached a near 100 % degree of interesterification at the 5th hour with a rate constant of 0.187 h(-1), suggesting that Lipozyme TL IM has a faster catalytic activity.
Keywords: Degree of interesterification; Hydrogenated cottonseed oil; Lipase catalyzed interesterification; Rice bran oil; Trans-free fat.