An improved process of isomaltooligosaccharide production in kimchi involving the addition of a Leuconostoc starter and sugars

•An improve method for IMO synthesis during lactate fermentation was proposed.•Highly active dextransucrase of Leuconostoc citreum was used.•Glucose-transferring reaction occurred from sucrose to maltose to make IMO.•This result suggests possible synthesis of prebiotics in fermented foods.

Isomaltooligosaccharides (IMOs) are α-(1 → 6)-linked oligodextrans that show a prebiotic effect on Bifidobacterium spp. This study sought to improve IMO synthesis during lactate fermentation in kimchi by inoculating the kimchi fermentation mix with a starter and sugars; the psychrotrophic Leuconostoc citreum KACC 91035 strain with high dextransucrase activity was used as a starter and sucrose (58 mM) and maltose (56 mM) were added as the donor and acceptor for the glucose-transferring reaction of the dextransucrase, respectively. With the addition of both the starter and the sugars and incubation at 10 °C, IMOs were produced in kimchi after 3 d. Without the starter, the IMO production rate and maximal concentration in kimchi were 15.05 mM/d and 75.27 mM, respectively, whereas with the starter, the rate and concentration increased to 22.04 mM/d and 110.19 mM, respectively. In addition, the sucrose–maltose mix gave an appropriate level of sweetness by releasing fructose and prevented unfavorable polymer synthesis by IMO production. This result suggests that lactic acid bacteria expressing a highly active glycosyltransferase can be used for the synthesis of beneficial oligosaccharides in various fermented foods.