Physical and nutritional characteristics of less common traditional rice (Oryza sativa L.) varieties of Sri Lanka

Abstract

Consumption and cultivation of traditional rice varieties have increased considerably in recent years due to the increased prevalence of non-communicable diseases in our country. However, the physical properties and nutritional composition of most traditional rice have not been scientifically studied to a satisfactory level. Therefore, this study determined the physical and nutritional properties of some less common rice varieties namely Pokkali, Murugakayan, Rathdel, Madathawalu, Kuruluthuda, Pachchaperumal, Suduheenati, Suwadel and Kaluheenati without subjecting to processing treatments such as polishing and parboiling. Length, width, thickness, diameter, volume and length/ width (shape) ratios as physical properties and moisture content, ash, crude fat and protein, total and digestible carbohydrate contents, resistant starch and insoluble soluble and total dietary fiber contents were determined according to standard methods. Length, width, and thickness of grains varied between 4.0- 6.4 mm, 2.2-2.9 mm and 1.5-2.2 mm respectively. Diameter, volume and length-width ratio were between 2.4-3.3 mm, 3.8-10.5 mm3 and 1.7-2.6 respectively. Accordingly, the varieties were categorized as bold or medium. Moisture contents of varieties were between 5.4-8.3% and ash contents less than 2% (DM). Low crude fat (4.2-4.9% DM) and high protein (5.5-9.2% DM) contents were observed. Digestible carbohydrate and total carbohydrate contents ranged between 77.5-84.6% (DM) and 79.1-85.2% (DM) respectively. Resistant starch content varied between 0.4- 3.2%. Corresponding insoluble, soluble and total dietary fiber contents ranged between 2.8-4.9%, 1.5-2.7% and 4.3-6.5% (DM). According to the data obtained the studied traditional rice varietiesare good sources of digestible carbohydrate, protein with low fat and moisture.