Resistant Starch Content of Thirty Eight Selected Rice (Oryza sativa L.) Varieties of Sri Lanka

Background: Rice is the staple food of half the world's population including Sri Lanka. Resistant starch (RS) is the starch and starch degradation products that escape digestion in the small intestine by human digestive enzymes and reported to have wide range of health benefits. Rice consists of varying amounts of RS depending on the rice variety. However, RS content of Sri Lankan rice varieties has very limited studied. Objective: To evaluate the RS content of thirty eight selected rice varieties of Sri Lanka. Methods: Twenty seven new improved (NI) [Bg: Bathalagoda and At: Ambalanthota], two old improved (OI) and nine traditional rice varieties of Sri Lanka were used in this study. RS content of whole grain rice varieties were determined according to the Megazyme assay protocol with some modifications. Results: RS content varied significantly (P < 0.05) among the tested rice varieties and it ranged from 0.30 ± 0.02 to 4.65 ± 0.19%. RS content of NI, OI and traditional rice varieties ranged from 0.30 ± 0.02 to 3.11 ± 0.06, 0.55 ± 0.05 to 1.92 ± 0.40 and 0.44 ± 0.14 to 4.65 ± 0.19% respectively. Interestingly, mean RS content was significantly (P < 0.05) high in traditional rice varieties compared to NI and OI rice varieties. Further, rice varieties which showed > 3% RS contents were all traditional rices (except Bg 3-5, a new improved white rice variety). Among the rice varieties studied, a traditional white pericarp rice variety Suduru Samba (4.65 ± 0.19%) had the highest RS content, while NI white pericarp rice variety Bg 305 (0.30 ± 0.02%) had the lowest RS content. Conclusion: It is concluded that RS content varied among the tested rice varieties and especially Sri Lankan traditional rice varieties had the highest RS content. Thus, such rices may have the potential to utilize in developing value added novel functional foods and neutraceuticals for prevention and dietary management chronic diseases.