Optimization of L- ascorbate oleate production using response surface methodology and its properties

L-ascorbate fatty acid esters is hydrophobic antioxidant,which is used widely in the food,cosmetic and phamaceutical fields.In order to solve the present problems that the types of L-ascorbate fatty acid esters in the market are single,L-ascorbate saturated fatty acid esters are not completely soluble in fats and oils and L-ascorbate unsaturated fatty acid esters are expensive,the synthesis method of highly fat-soluble L-ascorbate unsaturated fatty acid esters is particularly imperative. The objective of this study was to synthesize L-ascorbate oleate( L-AO). Oleate acid was used as acyl donors in presence of immobilized lipases and t-amyl alcohol as organic solvent to obationed L-AO,the preparation process of L-AO was optimized via single factors test and response surface test,and the prepared L-AO was characterized by infrared spectroscopy( IR) and nuclear magnetic resonance( NMR),and then its fat solubility and anti-oxygenation were analyzed and compared with L-ascorbyl palmitate( L-AP),tertiary butylhydroquinone( TBHQ) and butylated Hydroxytoluene( BHT). The results showed that under the optimal conditions,namely substrates molar ratio( oleic acid to L-ascorbic) of 3.67 ∶ 1,a reaction temperature of 50.98 ℃,a lipase amount of 5.13%,a reaction time of 24 h,and a molecular sieve amount of60 mg/m L,the yield of L-AO was 53.29%,which was close to the predicted value( 52.60%),indicating that the model was suitable for the preparation of L-AO.In addition,NMR confirmed the form of 6-O-L-ascorbyl oleate.the fat solubility of L-AO was higher than that of L-AP,and the antioxidant effect in oil and fat was that L-AO > TBHQ> L-AP > BHT.