Abstract:

Potato resistant starches before and after in vitro digestion were made and purified. Their probiotic functions
and structural changes were intensively studied. The results demonstrated that the undigested and digested resistant
starches had good proliferative effects on bifidobacterium and lactobacillus, but inhibitory effects on Escherichia coli
and Clostridium perfringens, and no influence on Enterococcus faecalis, Corynebacterium fusifome or facultative bacteria.
The increase in total acidity after fermentation demonstrated that both these resistant starches could be utilized by intestinal
probiotics. After digestion, the resistant starch had increased specific surface area, which was further increased after in vitro
anaerobic fermentation. In comparison with the native starch, average degree of polymerization of the resistant starch was
decreased significantly and along with the digested resistant starch, was further reduced after fermentation. Both the resistant
starch and its digestion product in vitro were type-B crystals. After fermentation, the crystal type became type A, and
the degrees of microcrystallization and submicrocrystallization as well as total crystallinity were obviously decreased
compared with those measured before fermentation.

Key words: potato, resistant starch, probotic function, structural change