Effect of different cooking methods on glycaemic index of Indian and Pakistani basmati rice varieties

Abstract

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Introducton G lycaem jc index (Gl) reflects the blood glucose response after ingestion of a 50g digestible carbohydrate portion. Many factors affect the Gl, including degree of starch gelatinization. I Methods The objective was to determine'the Gl and the effect of different cooking methods on Gl of a Pakistani basmati rice (PBR) and an Indian basmati rice (IBR) frequently purchased by Sri Lankans. This was a crossover study. Participants were ten healthy individuals aged 20-30 years whose BMI range was 18.5-23.5 kgnv2. Proximate composition, (carbohydrate, protein, fat, soluble dietary fibre (SDF), insoluble dietary fibre (IDF) and ash], amylose content and Gl of the two rice varieties were determined by using standard rnethods. Rice was cooked separately in a rice cooker and a microwave by adding 1 cup of rice (110 g) and 1 cup of water (150 ml)). Glucose was used as the standard. G l values were expressed as the average value of 10 participants. Results Fat, total dietary fibre (TD F), S D F and IDF contents were significantly (p<0.05) higher in IBR when compared to P B R . The G l values of IB R and P B R cooked in a rice cooker (Gl=54 SD=8; Gl=64 SD=12) or microwave (Gl=43 SD=28; Gl=56 SD=12) belonged to low and medium Gl categories respectively. A percentage reduction in Gl values was seen in PB R (12.5%) and IBR (20.4%) when cooked in a microwave oven compared to a rice cooker. Conclusions Irrespective of the method, of cooking: PBR had medium Gl and IBR had low Gl.