Dietary fibre content of some rice varieties under raw and parboiled conditions

Abstract

There is a growing demand on foods rich in dietary fibre due to their beneficial health effects. Rice is the staple food for over 50% of the world population including Sri Lanka. This study reports the content of total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) in two varieties of raw rice (RW)(BG 300 and BG 352), and two varieties of parboiled rice (PB)(BG 300 and BG 352) under two levels of bran removal (10% and 7%) obtained from the Institute of Post Harvest Technology, Anuradhapura. IDF was calculated by subtracting the protein and ash content from the weight of the residue obtained after hydrolyzing the sample of rice with Tetramyl enzyme, pepsin enzyme solution and pancreatin solution. The SDF was determined by subtracting the protein and ash content from the residue obtained by incubating the filterate from enzyme hydrolysis with ethanol. Protein content was determined by the Kjeldhal method and the ash content by heating in a muffle furnace at 550 0 C. It was observed that percentage of TDF, SDF and IDF ranged from 56.7% - 44.7%, 16.6 - 12.5% and 40.1 - 30.1% respectively in RW while in PB the values ranged from 63.6 -45.4%, 17.3 -10.8%, 46.2 - 34.61% respectively. For raw rice the highest TDF, SDF and IDF were obtained for BG 300 (10%) while in parboiled rice the highest value was obtained for BG 352 (10%). In all samples except for BG 352 (RW) TDF, SDF and IDF increased with increase in percentage of bran . Parboiled rice had a higher TDF and IDF than raw rice. Except in BG 352 (7%) in other varieties the percentage of SDF was higher in par boiled rice than raw rice. Percentages in parenthesis refer to the percentages of bran removed from rice. Financial assistance from ADB is acknowledged.