Investigating the diversity of resistant starch in Vietnamese rice collection

The rapid increase of obesity and type 2 diabetes has recently posed an enormous burden on the healthcare system worldwide. Resistant starch (RS) in rice can escape digestion by enzymes in the small intestine, making its calories unavailable for cells to use. As a result, RS can be used by diabetes patients to prevent diabetes and for obese individuals who do not want extra energy. In our study, 75 Vietnamese rice accessions originating from diverse ecosystems were chosen as plant materials to investigate the diversity of RS content in this collection. The Megazyme kit was used to measure the amount of RS. The release of quinonimine was measured using a spectrophotometer at 510 nm. The results showed that approximately 70% of Vietnamese rice accessions had RS content ranging from 0.015 to 0.2% while only 4% of samples had RS content ranging from 0.6 to 0.8%. The Indica subgroups had significantly higher RS content than the Japonica subgroup. Higher RS content was found in medium- and short- grain rice rather than in long grain. Finally, rice plants grown in rainfed lowlands (RL) and irrigated ecosystems had higher RS content than those grown under mangrove and upland ecosystems. Our results firstly give information about the diversity of RS in Vietnamese rice and secondly may contribute to the field of nutrition by developing a suitable rice-based diet for patients with diabetes or obesity.