Development of new strategies for the production of high-purity fructooligosaccharides using β-fructofuranosidase and a novel isolated Wickerhamomycesanomalus

Fructooligosaccharides (FOS), as an internationally recognized prebiotics, are in widespread used in the food industry. However, the purity of FOS syrup produced by enzyme conversion or microbial fermentation is usually only 55% (w/w, called G-type FOS syrup), which limits its application to health food. Thus, the means of improving the purity of G-type FOS syrup to prepare high-purity (greater than 95%, w/w) FOS syrup (i.e., P-type FOS) has long been a topic of concern. In this study, GXL-22, a novel yeast, was isolated and identified as Wickerhamomyces anomalus for use in purifying G-type FOS syrup by removing fructose, glucose, and sucrose. The purity of the G-type FOS syrup was increased to 87.2 ± 1.3% (w/w) after optimization of the process parameters. Three new strategies for the production of P-type FOS syrup from G-type FOS syrup or sucrose were developed from the transglycosidation and hydrolysis activity of β-fructofuranosidase and the fermentation characteristic of the yeast. A maximum FOS purity of 95.6 ± 1.5% (w/w) with yield of 0.63 ± 0.02 gFOS/gsucrose and productivity of 3.44 ± 0.08 gFOS/L·h was obtained through the successive action of β-fructofuranosidase transglycosidation and yeast fermentation in a 10 L fermenter using 300 g/L sucrose as a substrate, which provided a feasible strategy for the industrial production of P-type FOS syrup.