Research On Lipase-catalyzed Preparation Of Rice Bran Oil Rich In Dag With High Acid Rice Bran Oil

Rice bran oil is a nutrition-rich vegetable oils which contained 15%-20% saturated fatty acids,80%-85% unsaturated fatty acid and the absorption rate of consumption more than 90%. It's also contains a variety of biological active agents and has a variety of nutrition and health functions. So it had caused a widespread attention. Diacylglycerol (DAG) was reported to have diverse physiological functions like reduce visceral fats, lower blood lipids and suppress the increase of body weight. This paper was aimed to conduct the preparation, purification, and oxidation stability of RBO rich with DAG and its application in frying.DAG was prepared by enzymatic catalyzed of high acids RBO and Monoglyceride (MG) in the solvent-free system. Factorial test results indicated that synthesis of DAG catalyzed by Lipozyme RM IM in rotary evaporation reactor was the best model. The major factors were ratio of MG to FFA, dosage of enzyme, reaction temperature and reaction time. And the optimum conditions for the corresponding enzymatic synthetic reaction were:MG to RBO 0.25(g/g), reaction temperature 56℃, reaction time 5.75h, Lipozyme RM IM dosage 4.77%. Under these conditions, DAG content maximum of 27.61% and FFA surplus minimum of 0.25%.Though miscella refining, decoloration and deodorization, we obtained RBO rich with DAG which conformed to the National Standard. Moreover, the physiochemical properties of RBO rich with DAG were determined:color Y35R5.0, acid value 0.27mgKOH/g, DAG content 26.61%, peroxide value 1.15 mmol/kg, iodine value 106.38g/100g, saponification value 183.55mgKOH/g, unsaponification 29.60g/kg.We compared the oxidative stability between DAG RBO and conventional RBO. And after 15 days, the results showed that the PVO, IV, p-AV and oxidation induction time of DAG RBO were more stability than conventional RBO which under (63±1)℃. Moreover, the content of VE was higher in DAG RBO.The changes of frying oil from DAG RBO and Rapeseed oil during the process of frying were investigated.20 hours frying of potato chips was made with DAG RBO and Rapeseed oil. No significant difference was found in AV, the POV, p-AV, OX-IND value and trans fatty acids content between DAG RBO and Rapeseed oil. The results suggested that DAG RBO is worth promoting and its functions and application in food are comparable to or even better than the traditional edible oils.