In Vitro Glycemic Response of Indigenous Pigmented Rice Cultivars from South India and Influence of Different Carbohydrate Components

Staple diet patterns such as white rice consumption play an important part in the occurrence of chronic lifestyle-related disease like diabetes. This study intended to identify pigmented rice cultivars from India as an alternative to white rice. Nine carbohydrate components were quantified in six red and two black pigmented rice varieties. In vitro starch digestibility was also analyzed and the predicted glycemic index (pGI) was estimated. The relationship between the carbohydrate components and the pGI of the rice varieties was analyzed. The rice varieties, Kattuyanam and Chennangi exhibited high levels of insoluble dietary fibre, total dietary fibre and amylose. High soluble dietary fibre contents were observed in Poonghar and Aruvadam kuruvai. The levels of resistant starch and slowly digestible starch were found to be the highest in Karupakavuni. The results indicated Kattuyanam, Chennangi, Karungkuruvai, and Poonghar to be low pGI rice varieties (< 55). The three varieties, Kesari, Karupakavuni, and Aruvadam kuruvai were categorized under the medium pGI category (56-69). Mapillai samba had a high pGI of 70 which could be due to processing (partially milled and parboiled), but had significantly lower pGI than the white rice, Sona masuri (GI - 76). The dietary fibre components, resistant starch, slowly digestible starch, and the amylose content were negatively correlated with the pGI. Among these components, the insoluble dietary fibre, total dietary fibre, and resistant starch with significantly high (p = 0.01) correlation were found to be the major determining factors of pGI in the studied pigmented rice cultivars. The inclusion of the identified pigmented rice varieties with low to medium glycemic response in the diet could become a key role in the dietary management of diabetes, especially among the rice-eating population.