Synthesis Of Three Kinds Of Sugar Fatty Acid Esters And Properties

Sugar fatty acid esters are non-ionic surfactants formed by combining a Sugar with one or more fatty acids,and they usually possess excellent emulsification properties,as well as antibacterial and antitumor functional properties.And related products have been applied in the food,pharmaceutical,and cosmetic industries.Therefore,this research synthesized the disaccharide esters of trehalose/lactose with fatty acids,and explores the influence of disaccharide type,acyl side chain length,degree of unsaturation,and degree of esterification on the synthesis and properties.First,the chemical synthesis and properties of trehalose fatty acid monoesters were studied.The synthesis was carried out in pyridine,applying a molar ratio of 1:1.1trehalose and a series of fatty acids with the acyl chain length of 6–18 chemical,catalyzed by 1.1 equivalents of TBTU,and the reaction was carried out at room temperature for 72 h.The reaction was selective on the 6-O position,and the synthesis yield is 31%–41%.The formations of 6-O-acyltrehalose monoesters were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry.By calculating and measuring the HLB value as well as the thermal stability of the series of trehalose monoesters,it was found that these esters have excellent thermal stabilities,and this stability increases with the growth of the acyl chain length.Among them,trehalose monostearate has the best thermal stability.By studying the biological activity of trehalose monoesters,it can be seen that the series of trehalose esters are generally safety.When the acyl chain length varies,different properties of trehalose monoesters are obtained,and the rules can be applied to fit various applications of these esters.Then,the enzymatic synthesis and properties of trehalose fatty acid diesters were studied.Immobilized lipase Novozym 435 was chosen to catalyze the selective synthesis of 6,6'-O-acyltrehalose diesters through the transesterification of trehalose and fatty acid vinyl esters with different carbon chain length(C6–18).The molar ratio of trehalose and the corresponding vinyl ester was 1:4,and a mixed solvent of tert-butanol/pyridine(11:9,v/v)was used.The chemical structures of the products were identified by NMR and MS analyses.It was determined that a series of trehalose diesters were formed,with yields between 43%–75%.The results of HLB values,foaming properties,and thermal stability of the trehalose diester show that trehalose didecanoate and trehalose dilaurate have good foaming properties.Trehalose dioleate has the best thermal stability,indicating that it could be used as an oil-in-water emulsifier in food applications that undergo thermal processing.Also,it was found that these esters were safe and low-toxic by studying the biological activity of these trehalose diesters.So,this research provides a new direction for developing new types of value-added,non-ionic surfactants that can be applied in the food industry.Finally,the enzymatic synthesis and properties of lactose fatty acid monoesters were investigated.First,vinyl acetate and the corresponding fatty acids were used to synthesize a series of fatty acid vinyl esters,with yields between 60%–94%under the chemical catalysis by palladium acetate.And then,the immobilized lipase Lipozyme TL IM was used to catalyze the selective transesterification of anhydrous lactose and the corresponding fatty acid vinyl ester(1:4 in mols)in a mixture solvent of THF/pyridine(1:1,v/v),and molecular sieves were added to remove the moisture generated by the reaction.The yields of the series of lactose monoesters obtained were45%–81%,and the products were confirmed to be 6'-O-acyllactose monoesters according to nuclear magnetic resonance and mass spectrometry analyses.Further study found that their HLB values were between 10–12,and the longer the acyl chain length,the lower the HLB value;the number of double bonds had little effect on the HLB value.By calculating CMC,?_cmc,?and,A,it was found that the CMC decreased with the increase of the acyl chain length and slightly increased due to a higher degree of unsaturation.Overall,lactose monoesters can form micelles easily and can be used as an oil-in-water emulsifier in food.In summary,in the synthesis of sugar fatty acid esters,the yields of the enzymatically synthesized unsaturated fatty acid monoesters are the highest;the longer the carbon chain,the lower the HLB value of the disaccharide fatty acid esters.Disaccharide fatty acid esters have excellent thermal stability,foaming properties,and interface properties while being low toxic,so they are potentially good emulsifiers for food applications,especially those require heat processing.