Rice is a staple diet as well as a major ingredient in many processed foods. The physicochemical and
supra-molecular structure of eight rice varieties with amylose content from 9% to 19% were studied to
elucidate the factors responsible for variation in enzymatic digestibility of raw and cooked rice. Parboiled
rice had a digestion rate coefficient almost 4.5 times higher than the least digestible Low GI rice. The rate
coefficient was found to be independent of helical structure and long range molecular order, possibly
attributed to the effect of rice flour architecture. Strong swelling and pasting behaviour and lower gelatinisation
temperature were linked with apparently higher in vitro digestibility but the relationship was
statistically insignificant. It is concluded that the enzymatic susceptibility of rice flours are independent
of supra-molecular structure and are most likely controlled by external factors not limited to particle size,
presence of intact cell wall and other non-starch polymers