Background: The prevalence of diabetes has increased dramatically in recent decades in the regions where people excessively consume white rice. In spite of the higher nutritional values and bioactive components, only the low to medium glycaemic index (GI) brown rice could be of interests as an alternative to white rice in these regions.  Methods: Five varieties, Chiang (CH), Sungyod (SY), Lepnok (LP) from Thailand and Long grain specialty 1 (LS1) and Long grain specialty 2 (LS2)  from Malaysia were tested for GI. Ten test foods were prepared from 5 varieties by 2 cooking techniques (pressure cooker, PC and rice cooker, RC). Overnight fasted healthy subjects were fed with 25 g glucose as a reference food (RF) on 3 occasions and amount equivalent to 25 g available carbohydrate portion of test food (TF) on 1 occasion in separate days. Fasting and post-prandial capillary blood glucose was measured via finger-prick methods at 0, 15, 30, 45, 60, 90 and 120 min, and the incremental area under curve (iAUC) was determined. The GI of each TF was calculated as percentage of incremental area under curve (iAUC) of TF over RF.Results: The mean GI values of SY (72 – 81, high), CH and LP (59 – 65, medium) and LS1 and LS2 (64 – 73, medium to high) were found due to cooking by PC and RC methods. The GI did not vary significantly (p>0.05) among varieties as well as between cooking methods. GI showed a significant negative correlation with the amylose content (r = –0.70, p<0.05) and significant positive correlation with cold peak viscosity (r = 0.80, p<0.01).Conclusions: All five varieties by either cooking methods are classified as medium to high GI. Medium GI varieties could have potential of being used in diabetic diet. Cooking methods did not significantly alter the glycaemic characteristics of the studied varieties. Amylose content and pasting properties can be used for predicting GI of brown rice. It is urgent to explore low GI brown rice varieties in these regions.

No abstract

Rice is a major staple food in Thailand and Malaysia. Although brown rice is a highly healthy substitute, preference is very low due to its texture and cooking quality. However, there are some brown rice varieties such as Sungyod (SY), Chiang (CH), Lepnok (LP) from Thailand and long grain specialty 1(LS 1 ) and long grain specialty 2 (LS 2 ) from Malaysian peninsula are commonly consumed in such areas. This study aimed to investigate the physicochemical and the cooking properties of these brown rice to understand the properties for better utilization. Therefore, Rapid visvo analyser (RVA), soaking characteristics, general cooking properties, textural properties and calorific values were measured and compared in 5 varieties of brown rice. Hydration kinetics indicated that LS 1 and LS 2 were faster in water absorption to reach plateau compared to the SY, LP, and CH. The cooking time of these brown rice was in the range from 29 to 35 min. The cooked brown rice had length/breadth (L/B) ratio (2.4 -3.0), water uptake ratio (2.5 -3.0), elongation ratio (1.1 -1.4) and gruel solid loss (3.2 -5.2%). The hardness and the cohesiveness measured from texture analyzer were in the range of 6.75 -15.5 N and 0.13 -0.16. There was a significant variation in RVA pasting property of whole rice flour (p < 0.05). The variations of different properties of brown rice could be considered for the processing of brown rice and its application.

No abstract