Rice variety and processing: contribution to glycaemic response

Introduction Glycaemic index (GI) of different varieties of rice (Oryza sativa L.) commonly consumed in Sri Lanka are not widely studied even though it is the staple food. Objectives To determine the proximate compositions and the GI of three different rice meals, namely Bg 360 Samba (raw), Basmati At 405 (raw) and parboiled Nadu Bg 352. Methods The study was a randomised cross over study using healthy volunteers (n=11). GI was determined as the ratio between the incremental areas under curve obtained for the test food and the standard glucose (WHO/FAO method). Proximate compositions were determined by standard methods. Results The GI value so obtained were, 66 +/- 8 (medium GI) for Bg 360 Samba, 73 +/- 7 (high GI) for Basmati At 405 and 40 +/- 4 (low GI) for Nadu Bg 352. Parboiled variety had a significantly low GI and the lowest peak glucose concentration. Significant differences were observed in insoluble dietary fibre (IDF), total dietary fibre (TDF) and moisture contents of the rice varieties. Non significant negative correlations between IDF (r = -0.94, p = >0.05, n = 3) and TDF (r = -0.90, p = > 0.05, n = 3) and GI of the rice varieties were observed. Conclusions Parboiled Nadu Bg 352 and Bg 360 Samba (raw) are of nutritional significance to individuals seeking to control the energy intake and glycaemic response.