Studies on the in vitro starch digestibility and the glycemic index of six different indigenous rice cultivars from the Philippines

Publication Type

Journal contribution

Authors

Frei, M., Siddhuraju, P. and Becker, K.

Year of publication

2003

Published in

Food Chemistry

Band/Volume

83/

Page (from - to)

395-402

Starch degradability was studied in six indigenous Philippine rice cultivars differing in amylose content. An in vitro enzymatic starch digestion method was applied in order to estimate the expected glycemic index in vivo based on the kinetics of starch hydrolysis in vitro. Two different treatments were investigated: in the first, samples were cooked and analyzed immediately; second samples were cooked and stored in a refrigerator for 24 hours at a temperature of 4 C in order to induce a retrogradation effect. The results indicate substantial differences in the estimated glycemic index between rice cultivars. Values ranged between 68 and 109 for cooked rice and between 64 and 87 for stored rice containing retrograded starch. Starch hydrolysis tended to be more rapid and more complete for waxy cultivars as compared with high amylose cultivars. Storing rice in the refrigerator led to a reduction of the estimated glycemic index for all cultivars. The highest decrease in starch hydrolysis after cool storing was seen for the waxy cultivars.