Date Published: December 22, 2014
Publisher: Public Library of Science
Author(s): Xi Zhang, Fei Song, Maierhaba Taxipalati, Wei Wei, Fengqin Feng, Chien-Sheng Chen.
The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect.
Fatty acid sugar esters are receiving increasing attention as odorless, nontoxic and biodegradable nonionic surfactants, which are mild to the skin. Sucrose fatty acid esters have certification of GRAS FDA 21CFR 172.859, and could be used as food additives. They are interested by the food industry because they possess many attractive properties, such as emulsification, emulsion stabilization, foaming. For example, sugar esters include a wide range of hydrophilic–lipophilic balance (HLB) values from 1 to 16 achieved with different degrees of esterification, and these esters are commonly employed in the food industry as emulsifying agents –. Other fields of application include pharmaceuticals, detergents, cosmetics and pesticides as a result of their excellent surface and antimicrobial properties , –. Previous research has revealed that disaccharide medium–chain fatty acid monoesters display significant activity against several food and clinical isolates. Habulin et al have reported that sucrose monolaurate could inhibit Bacillus cereus at concentration of 9.375 mg/mL.  Ferrer et al measured the effects of lauroylsucrose and lauroylmaltose against Bacillus sp. and Escherichia coli.  Surfactants may influence cell membranes at low concentration, which could lead to change the permeability of cell membrane,  with subsequent metabolic inhibition, growth arrest or cell lysis .
9 different sugar monoesters of three disaccharides with different carbon chain lengths (C8–C12), which synthesized by immobilized lipase (Lipozyme TLIM), have been studied with respect to their CMC and efficiency in reducing the surface tension of water. The CMC increased with decreasing carbon chain length, while caprate monoesters exhibited lower surface tension.