Investigation On Synthesis Of Trehalose Unsaturated Fatty Acid Ersters And Their Properties

Carbohydrate fatty acid ester is one kind of non-ionic, biodegradable, and non-toxic amphiphilic which have been broadly used as in food, cosmetic, and pharmaceutical industries. It is safe to the environment as for its degradable by Microorganisms. In recent years, the yield of candy esters were improved, which have presented a further industry value. Most carbohydrate fatty acid esters saled on market are from saturated fatty acid and sugar. However, unsaturated fattty acid have many biological activities and physiological functions and other merits, so the research on carbohydrate unsaturated fatty acid esters attract the interest of many researchers. In this article, we studied on the synthesis and properties of trehalose unsaturated fatty acid esters.First, on the base of the catalyst parameters of the five different of lipase, the optimal lipase which was suit for the unsaturated fatty acid esters was chose. Comparing the catalyst ability of the lipase in different kinds of organic solvents, the efficiency of Novozyme435 was higher than lipozyme RM IM, lipozyme TL IM, Porcine pancreatic, Carcia papaya. So the Novozyme435 was used as the lipase for the experiment.Subsequently, esterification rate and regioselective of products were tested in five different solvents (DMSO, tert-pentanol, acetone, tert-butanol and n-hexane). Along with the five solvents, tert-butanol was the most optimal solvent for the production of monoester, acetone was the most suitable medium for the production of dister. It was fonnd that the highest esterifaction ratio of 6,6'-di-O-erucoyltrehalose (51%) was achieved in the optimized reaction conditions: trehalose of 25 mmol/L initial concentration, 4:1 molar ratio of erucic acid to trehalose, 60 g/L molecular sieve and 20 g/L lipase, condensation for 42 h at 55℃. Also, the structures of the target products were characterized by FT-IR, MS and NMR.The effect of five unsaturated fatty acids with different carbon chain length (oleic acid, linoleic acid, conjugated linoleic acid, eicosenoic acid and erucic acid) on esterification of corresponding trehalose diesters was studied. It could be observed that esterifaction rate decreases with the increasing of carbon chain length of unsaturated fatty acid.Surfactant properties, the melting point, solubility, HLB, foamabilities and emulsifying activities were tested. The melting point increase with the increasing of carbon chain length of unsaturated fatty acid, but solubility presents a contrary tendency. Furthermore, the foamabilities of diesters were poor no matter whether monoester was added, but their emulsifying activities were good. Especially, the emulsion stablities of 6,6'-di-O-linoleoyltrehalose was very good.