Esterification Activity Of Immobilized Lipase By Different Methods On Pretreatment Soybean Oil Deodorizer Distillate For Concentration Of Natural Tocopherols

Lipase can catalytic fatty acids esterification of soybean oil deodoriser distillate (SODD) for reduce their boiling points is benefit for purifying of VE with mild reaction conditions and tocopherol keeping high activity. But immobilized lipase, which can be continuous used with stability and have better esterification activity than hydrolysis activity, is the basis of its industrial production.First, we studied four Immobilization for immobilized Candida rugosa lipase, as physical adsorption, Covalent/Cross-linked bonding, embedding and ion exchange adsorption. After Experimental study, type 214 of ion exchange adsorption was elected to immobilized carrier. Several factors affecting catalytic activity of immobilized lipase were investigated in details and optimized by Plackett-Burman and central composite design. The optimal immobilized conditions achieved were as follows:lipase concentration 6.09 mg/ml, Tris-HCl Buffer (pH 8.40), rotate speed 134.26 rpm/min, temperature 30.0 ?, time 4.0 h, resin amounts 0.75g, lipase binding amount of immobilized lipase 11.03mg/g resin, esterification ratio of catalysising methanol relative to free lipase 28.94%, which was a much efficient process. Immobilized lipase can catalysis sterols esterification with free fatty acids of SODD, and free lipase cannot but shows hydrolysis activity. It indicates that this immobilization has some use value.Apparent activity of type 214 Ion exchange resins immobilized lipase is 1147.22±5.20 U/g resin, little disparity with Novozym 435. Relative to free lipase after centrifugation, activity of Per gram lipase increased 26.31 times. Immobilized lipase cannot catalysis Palm oil hydrolysis, but can catalysis different hydroxy donor esterification. The results showed the optimal pH of immobilized lipase was 8.4, which was increased 0.2 and extended units relative to free lipase. The optimal temperature of immobilized lipase was 30??55?. The thermal stability and storage stability of immobilized lipase were also improved. The apparent Km of immobilized lipase for stearic acid was 0.480 g/1 while Km of free lipase was 0.456 g/1 (The apparent Km of immobilized lipase for palmitic acid was 0.461 g/1 while Km of free lipase was 0.175 g/1). The lipase activity could be kept about 55.4% after 4 times'esterification.Finally, used polyacrylic acid to simulate type 214 ion exchange resins immobilized lipase. Mechanism of adsorption for immobilized lipase was presumed by analyzing the IR. The hydrogen bond might be ion exchange reaction, and coincide to mechanism of type 214 ion exchange resins immobilized lipase. pH determines the capacity of the resin exchange groups, and it is greater impact on esterification activity of immobilized lipase.