Effects Of Non-ionic Surfactant On The Selectivity Of Fatty Acids During Lipase-catalyzed Interesterfilcation Of Oils And Fats

The effect of modification of Porcine Pancreas Lipase (PPLipase) by Spans and Tweenson the fatty acid selectivity is investigated by comparison of the fatty acid selecitivity duringthe interesterification catalyzed by PPLipase, Span-PPLipase and Tween-PPLipase. Theeffects of the Spans and Tweens modification on the selectivity of the saturated fatty acid andunsaturated fatty acid, and the effects of temperature, water activity and enzyme load on theselectivity of Span-and Tween-PPLipase are studied mainly.During enzymatic interesterification, the selectivity of saturated fatty acids for PPLipaseis D>La＞M＞P, however the difference between them is not obvious. The selectivity ofsaturated fatty acid for Span-PPLipase and Tween-PPLipase is higher than that for PPLiase.The selectivity sequence is P>M＞La＞D, and the selectivity is increased with the acylincorporation increasing, moreover the selectivity is increased dramatically with thedifference of the fatty acid carbon chain increasing.Lipase dosage has a significant impact for the ester interchange reaction rate catalyzedby PPLipase, but has little effect on the fatty acid selectivity. The reaction rate and the acylincorporation of the reaction catalyzed by S20-PPlipase and S60-PPlipase are significantlyhigher than those of the reactions catalyzed by PPLipase, but the effect of lipase dosage onacyl incorporation on reaction catalyzed by modified lipase are not abvious than that of thereaction catalyzed by lipase, and the influence of lipase dosage on the fatty acid selectivity isnot heavy. The ratio of the fatty acid selectivity is increasing but show staggered status withthe increase of acyl incorporation, and the fatty acid selectivity prefer stearate acid with theincreasing of the gap of carbon chain length of the two fatty acids. Based on an overallanalysis of the reaction and the cost, we choose10%of lipase dosage as the optimal enzymedosage concentration.Effect of water activity on the reaction catalyzed by PPLipase is more obvious thanthose of the reaction catalyzed by Span-PPLipase and Tween-PPLipase. The different wateractivity has different influence on the reactions. In addition to a very few reactions, theinfluence of the different water activity are wearing off with the gap of carbon chain length ofthe two fatty acids minish. The influence of the water activity in the reactions glyceryltrioleate as the Stearic acid and Palmitiac acid is approximately same. Comparing with Span-PPLipase and Tween-PPLipase, the influence of temperature onthe reaction catalyzed by PPLipase is obvious. The thermal stability of the modified enzymeis higher than the original enzyme, but the extent of increase are different. The effections oftemperature on the modified enzymes are different. Some reactions have greater impact,while some reactions are almost unaffected.The selectivity of original enzyme for oleic acid and linoleic acid is not obvious, whilethe modified lipases are more inclined to choose linoleic acid and higher degree ofunsaturated fatty acids.As the difference between oleic acid and linoleic acid is only onedouble bond, so the difference of the selective between oleic and linoleic acid is not obvious.