Lipase-catalyzed synthesis of oleic acid sugar ester and surface performance measurement

Four kinds of oleic acid sugar esters were respectively synthesized with sugar (maltose, glucose, sorbitol and xylitol) and acid as raw materials, and with lipase (Novzyme 435) as catalyst. The structures of product were represented by IR and MS. Surface performances (CMC, surface tension, HLB value, emulsification and emulsion stability) of the synthesized oleic acid sugar esters were determined. The test results show that: when the ratio of oleic acid and sugar is 1~1.5:1 (mol:mol), the dosage of lipase (Novzyme 435) is 0.30~0.36 g/mol oleic acid, the dosage of solvent (acetone) for 10-20 mL/mol oleic acid, and the reflux reaction is for 42~72 h, the conversion rate of oleic acid reaches 89%-95%. IR showed that the product was ester; while MS showed that the products were oleic acid maltose ester, oleic acid glucose ester, oleic acid sorbitol ester and oleic acid xylitol ester respectively. all of the four kinds of oleic acid sugar esters have good surface activity. The critical micelle concentrations (CMC) were 7.9410-4-3.9810-5molL-1. Due to the HLB value of 6.8~13.0, they all have good emulsifying properties and can be used as W/O and O/W types of emulsifiers.