Comparison between discontinuous and continuous lactose conversion processes for the production of prebiotic galacto-oligosaccharides using β-galactosidase from Lactobacilius reuteri

Abstract

Galacto-oligosaccharide (GOS) formation from lactose in discontinuous and continuous modes of conversion was investigated using β-galactosidase (β-gal) from Lactobacillus reuteri. A continuous stirred tank reactor (CSTR) with an external crossflow membrane was set up, and continuous GOS production was analyzed and compared to the batchwise formed GOS product. Marked differences were detected for the two reactor setups. Above 65% lactose conversion, the GOS yield was lower for the CSTR due to a lower content of tri- and tetrasaccharides in the reaction mixture. In the CSTR, β-gal from L. reuteri showed up to 2-fold higher specificity toward the formation of β-(1→6)-linked GOS, with β-D-Galp-(1→6)-D-Glc and β-D-Galp-(1→6)-D-Gal being the main GOS components formed under these conditions. This could be used to synthesize more defined GOS products. © 2007 American Chemical Society.