Production of high-purity neofructooligosaccharides by culture of Xanthophyllomyces dendrorhous

Neofructooligosaccharides (neo-FOS) were produced in submerged cultures of Xanthophyllomyces dendrorhous. Among the various strains of X. dendrorhous that have intracellular 6G-fructofuranosidase (6G-FFase), BCRC 21346 with high enzyme activity (3.60 U/mL) and BCRC 22367 with low enzyme activity (0.59 U/mL) were investigated in this work. Neo-FOS were generated in a 5-L jar fermenter at 20 °C, 100 rpm and 2 vvm with the pH controlled at 6.9 ± 0.1, using 250 g/L of sucrose as the substrate. Through the catalytic action of X. dendrorhous 6G-FFase on sucrose, monosaccharides as well as neo-FOS were produced. A portion of these monosaccharides was consumed by the yeast cells. However, the production of monosaccharides was low in concentration in culture with low 6G-FFase activity, indicating they might be used up concurrently during the fermentation. Consequently, neo-FOS at a purity of up to 87.4% could be obtained.