Branched oligosaccharides concentrated by yeast fermentation and effectiveness as a low sweetness humectant

A branched oligosaccharides (BOS) mixture was prepared from liquefied corn starch using Bacillus licheniformis maltogenic amylase (BLMA). A highly concentrated BOS was prepared by removing glucose and maltose through yeast fermentation, which increased the BOS content. Water activity (aw) of bread went from 0.87 to 0.82 when 10% (w/w) or to 0.78 when 20% (w/w) BOS was added. BOS lowered aw, more effectively as concentration of BOS increased. The water sorption isotherm of BOS was much higher than that of sucrose at aw 0.1-0.8. BOS also prevented starch retrogradation in bread, probably due to steric hinderance and to the state of water retained by BOS. Relative sweetness of BOS was approximately 17.5% of sucrose. The BOS mixture produced by BLMA might provide a new type humectant for foods that is low in sweetness and retards retrogradation