Energy Value of a Mixed Glycosidic Linked Dextrin Determined in Rats

A series of in vivo and in vitro experiments was conducted to determine the available energy of a bulking agent, Fibersol 2 (FS-2). Fibersol 2 is obtained by a combination of heat and enzyme treatments of cornstarch to produce a low-viscosity, low-digestible dextrin with an average molecular massweight of 2000 Da. Although the substance is of the type known in Japan as an indigestible dextrin, it also comes within the U.S. Food and Drug Administration's (FDA) definition of "maltodextrin" as found in the FDA Generally Recognized as Safe (GRAS) affirmation regulations. Chemical analysis shows FS-2 to contain glucopyranosyl units with 1,6-anhydro-beta-D-glucose (levoglucosan) at some of the reducing terminals. Linkages in the molecule are randomly distributed among units consisting of alpha- and beta-(1-->4), (1-->6), (1-->2), and (1-->3) glycosidic bonds. In vitro digestion of FS-2 with successive treatments of salivary a-amylase, a gastric juice preparation, pancreatic cl-amylase, and intestinal mucosal enzymes gave 89.8% recovery of the starting material. Rats gavaged with FS-2 were found to have only a 5% increase in plasma glucose concentrations over 120 min compared to rats administered an equal amount of glucose. Approximately 38% of FS-2 administered to rats by gavage is recovered in the feces. Growth rates of rats fed FS-2 indicate less than <10% of the dextrin is contributing net metabolizable energy. FS-2 has an energy value of 2.2 kJ/g.