Glucose polymer taste is not unitary for rats

The present studies examined rats' responses to two maltodextrin preparations. One maltodextrin, a maltooligosaccharide, had an average chain length of 4.4 glucose units. The other maltodextrin was a maltopolysaccharide, having an average chain length of 22. In 24-h preference tests, rats strongly preferred 1% and 5% maltodextrin over water, regardless of the type of maltodextrin offered. When given a choice of two maltodextrins, rats preferred the maltooligosaccharide, but the degree of preference was influenced by the rats' previous experience with maltodextrins. Conditioned flavor aversion experiments were conducted to determine whether rats detect qualitative flavor differences between the these two maltodextrins. Rats trained to avoid one maltodextrin also avoided the other maltodextrin. Nevertheless, rats could be trained to drink maltooligosaccharide but avoid maltopolysaccharide; these rats showed no reliable tendency to respond to the intensity of maltooligosaccharide flavor. Therefore, maltodextrins of varying chain length differ more in flavor quality than in flavor intensity. This difference in flavor quality is not attributable to known sweet and starch flavors because neither maltodextrin contained much glucose and because rats trained to avoid the polysaccharide did not avoid starch. Because rats can discriminate between solutions containing only 0.5-1% maltodextrin, their ability to discriminate among carbohydrates must be far more acute than that of humans.