Investigation on resistant starch content and glucose response in mice of noodles supplemented with native and modified sweet potato starches

Abstract

Resistant starches (RS) which can be classified as dietary fibers due to its resistance to digestive mammalian enzyme have been reported to have many health benefits. Foods supplemented with RS have attracted more attention nowadays. This thesis investigated the resistant starch content of dried noodles supplemented with native and modified sweet potato starches and the blood glucose response, glycemic index (GI) of mice after consuming the noodles. Starch isolated from sweet potato was treated by acid-heat moisture treatment (0.2M citric acid, 30% moisture heat at 1100C for 24h). Three samples of noodles were made with different portions of flours, 100% wheat flour, 20% native sweet potato starch plus 80% wheat flour and 20% modified sweet potato starch plus 80% wheat flour. The RS level of modified sweet potato starch increased to 41.35% and RS level of noodle supplemented with native and modified sweet potato starches increased to 27.3 % and 32.94 %, respectively compared to 10.7% of the control noodle sample. Moreover, blood glucose response and glycemic index of mice after taking 2 starch samples and 3 noodle samples were also determined. Glucose released after taking modified starch was lower than native one and glucose released after taking noodle supplemented with modified sweet potato starch was also lower than control one. The GI values of native sweet potato starch, modified sweet potato starch, noodle 100% wheat flour, noodle supplemented with 20% native starch and noodle supplemented with 20% modified starch were 60.74, 58.06, 100, 60.6 and 59.31, respectively. As a result, the noodle supplemented with sweet potato starch that modified by acid – heat moisture treatment can be considered as a functional food which provides low carbohydrate (low-card food). Key words: sweet potato starch, resistant starch, acid-heat moisture treatment, noodle, glycemic index