Studying Amylose Content in Rice

It has been reported in Ball et al., (1998) study that the amylose content in rice varies from 15-35%. Based on amylose content (%), Juliano (1992) categorized rice lines into different categories such as waxy (0-2% amylose), very low (2-12% amylose), low (12-20% amylose), intermediate (20-25% amylose), and high (25-33% amylose). Low amylose rice cultivars are usually tender, cohesive and glossy, while higher amylose cultivars are dry, fluffy and separated when cooked. It has also been studied that these percentages are mediated by the proportion of amylose to amylopectin in starch granules. According to Unnevehr et al. (1992), Malaysian rice belongs to intermediate to high amylose categories. However, local consumers prefer to consume rice with intermediate amylose content. Hence, in order to satisfy consumer’s taste, the high amylose content (not more than 30%) of the locally produced rice should be improved.

Another previous study (Widowati et al. 2007a) has reported that milled rice of low amylose varieties tends to have high GI (≥70) values, whereas high amylose rice varieties has low GI (≤55) values. However, people in many countries like in Indonesia, like to eat sticky rice with high GI although it is not recommended for diabetic patient. Therefore, a rice processing technology is needed that produces low GI sticky rice to overcome these problems. Based on eating trials, it has been observed that parboiled rice has a lower GI compared with milled rice (Foster-Powell et al. 2002). A previous In vitro study led to the conclusion that an increase in amylose and dietary fiber contents and also decrease in starch digestibility causes declining in GI values (Sri Widowati et al. 2010). However, rice lines with low amylose and l...

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The normal blood glucose levels for most of the healthy subjects ranges from about 72mg/dL (4 mmol/L) to 140 mg/dL (7.8 mmol/L) (Diabetes.co.uk). The blood glucose levels that fall below 40 mg/dL (2.2 mmol/L) may cause coma, seizure, or death. In contrast, blood glucose levels exceeding about 180 mg/dL (10.0 mmol/L) are associated with some other consequences such as immediate glycosuria and calorie loss and long-term renal failure, retinopathy, atherosclerosis (Wilson JD, 1998). Therefore, the blood glucose concentration needs to be tightly regulated by homeostatic regulatory systems. Hyperglycemia stimulates insulin secretion, thus causes glucose uptake by muscle and adipose tissue. Hypoglycemia promotes secretion of glucagon, epinephrine, and other counterregulatory hormones that antagonize insulin action and thus restore normoglycemia (Wilson JD, 1998).