Gentiooligosaccharide-containing syrup and powder (Gentose^®) were industrially produced by the condensation and transglucosylation reactions of a fungal β-glucosidase from a high concentration of glucose. Gentose^® is strongly characterized by its bitter taste derived from gentiooligosaccharide; consequently Gentose^® #45 had both a bitter taste and the sweet taste of glucose. The other physicochemical properties of Gentose^® solution such as viscosity, osmotic pressure, water activity, etc . were closely related to those of sucrose solution. Incidentally, the hydrolysis rate of β-glucobioses by rat small intestinal enzymes was much lower than that of lactose. In particular, the hydrolysis rate of gentiobiose was only 4% compared to that of lactose. These results suggested that β-glucooligosaccharides would be low-digestible sugars. Low-digestible sugars in general show the effect of the mineral absorption, and it has also been revealed that these β-glucooligosaccharides developed have a physiologically important function. Furthermore, β-glucooligosaccharides were selectively utilized in vitro , by Bifidobacterium and Lactobacillus , and the administration of β-glucooligosaccharides promoted the growth of Bifidobacteria and lowered fecal pH, in vivo . The applications of Gentose^® to food processing were intensively tested. The unique bitter taste of Gentose^® matched exceedingly well the bitter taste of various foods such as chocolate, coffee, beer, cocoa, tea, etc . The slight addition of Gentose^® to food processing exhibited an unexpected improvement in food tastes. In the case of fruit juices, the addition of a small amount of Gentose^® enhanced the original flavor. Moreover, the addition of Gentose^® to vegetable drinks improved exceedingly the acridity and salient tastes of vegetables. This amazing improvement effects for food tastes pushed up the sales volume of Gentose^®. The surprising usefulness of gentiooligosaccharides will expand the advanced uses of Gentose^® in food processing and additives.