Abstract

The effect of donor substrate and products partitioning on the performance of butyl-beta-galactoside synthesis with Aspergillus oryzae beta-galactosidase was studied. Firstly, the partition coefficient of the donor substrate (lactose) and the reaction products (glucose, galactose and butyl-beta-galactoside) were determined in the aqueous and organic phases of the reaction medium. In the temperature range studied (30 to 50 degrees C), butyl beta-galactoside was roughly 130 and 30-fold more soluble in the organic phase than lactose and the monosaccharides, respectively. Afterward, the effect of the 1-butanol/aqueous phase ratio (alpha) on the reaction was evaluated in the range from 0.25 to 4. Results show that higher values of alpha reduce the incidence of secondary hydrolysis by favoring the extraction of butyl-beta-galactoside into the organic phase where it is not hydrolyzed, leading to higher yields. Also, major interfacial properties for butyl-beta-galactoside were determined at 25 degrees C.