Identification of Important Physical Properties and Amylose Content in Commercially Available Improved and Traditional Rice Varieties in Sri Lanka

Abstract

Commercially available, fourteen different rice varieties (improved and traditional) in Sri Lanka were subjected to determine amylose content and important physical properties. Under physical properties, milling parameters (such as brown rice content, husk content and total milling recovery), hardness and dimensions (length, width & thickness) including water absorption capacity (by dipping at 70°C for four hours) were measured. Amylose content of each rice variety was determined by measuring the optical density of amylose-iodine complex using spectrophotometer, while amylopectin content was obtained using the relationship equation. Results revealed, brown rice content, husk content, total milling recovery, hardness and water absorption capacities of these rice varieties were within the range of 76-78%, 20-23%, 69-72% & 28-30% respectively. Statistical analysis also indicated, those physical properties of fourteen rice varieties were significantly different to each other (p<0.05). Amylose & amylopectin contents of rice varieties were found in the range of 20 to 28% and 71 to 79% respectively, were significantly different (p<0.05) to each other. According to the correlation analysis, weak positive and weak negative correlation ships (p<0.05) were observed for amylose content vs. hardness and amylopectin content vs. hardness respectively. Further, moderate positive correlation ship (p>0.05) was reported in between amylose content and water absorption capacity. While showing negative correlation (p>0.05) between amylopectin and water absorption capacity. Between hardness and water absorption capacity, also had a weak positive correlation ship (p>0.05).