Gentiobiose is a disaccharide composed of two units of D-glucose joined with a β(1->6) linkage. It is a white crystalline solid that is soluble in water or hot methanol. Gentiobiose is incorporated into the chemical structure of crocin, the chemical compound that gives saffron its color. It is a product of the caramelization of glucose.[2] During a starch hydrolysis process for glucose syrup, gentiobiose, which has bitterness, is formed as an undesirable product through the acid-catalyzed condensation reaction of two D-glucose molecules.[3] One β-D-glucose unit elongation of the bitter disaccharide reduces its bitterness by a fifth, as determined by human volunteers using the trimer, gentiotriose.[4] Gentiobiose is also produced via enzymatic hydrolysis of glucans, including pustulan[5] and β-1,3-1,6-glucan.[6]
^Sugisawa, Hirqshi; Edo, Hiroshi (1966). "The Thermal Degradation of Sugars I. Thermal Polymerization of Glucose". Journal of Food Science. 31 (4): 561. doi:10.1111/j.1365-2621.1966.tb01905.x.