This study investigated interactions of sorghu
m proanthocyanidins (PAs) with starch
molecules and the effect on in vitro starch digestibility. High tannin (predo
minant in PA), black (
mono
meric polyphenols), and white (low in polyphenols) sorghu
m phenolic extracts were
mixed and cooked with starches varying in a
mylose content. Starch pasting properties, polyphenol profile, and resistant starch (RS) were deter
mined. PAs decreased setback of nor
mal starch and were least extractable after cooking with all starches. Pure a
mylose interacted
more strongly with oligo
meric and poly
meric PA co
mpared to a
mylopectin. The PA extract increased the net RS in nor
mal starch by about 2 ti
mes
more than the
mono
meric polyphenol extract; debranching a
mylopectin increased the difference by 4.3 ti
mes. Only treat
ments with PA increased RS in high a
mylose starch (52% higher than the control). Sorghu
m PAs interact strongly with starch, decreasing starch digestibility. The interactions appear to be specific to a
mylose and linear frag
ments of a
mylopectin, suggesting hydrophobic interactions are involved.
Keywords:
m&qsSearchArea=searchText">sorghum; condensed tannins; resistant starch