Comparative Studies on the Nutrient Content of Five Varieties of Rice Brans and Purification, Characterization and Structure Function Analysis of Proteins from the Best Quality Rice Bran

Abstract

Five varieties of rice bran were analyzed to obtain comparative data on their chemical compositions and nutritive values. Rice bran oils were also characterized with respect to their physical and chemical properties. The results indicated that moisture, ash, total soluble solid and crude fiber contents of the different varieties of rice bran were in the ranges of 9.98-10.90%, 9.45-11.12%, 10.06-11.25% and 9.18-10.35% respectively. The ranges in the values of total protein, water soluble protein, dry matter, polysaccharide, total sugar, reducing and non-reducing sugar compositions of rice brans were betweenl2.45- 14.06%, 3.20-4.71 %, 89.10-90.02%, 10.95-12.86%, 4.35-5.04%, 1.08-1.45%, and 3.10-3.96% respectively. Some minerals such as potassium, calcium, magnesium, sodium, phosphorus, Sulphur, iron, zinc and manganese are available in all the varieties of experimental rice brans. Vitamin B1 and vitamin B2 contents of rice brans were found to be ranged from 2.98-3.81 and 0.61-0.95 mg/100 g respectively. Twelve amino acids were detected in all the five varieties of rice bran in the total form by paper chromatography. Among the variety IRRI-28 contained relatively higher amount of amino acids. Rice bran contained about 14.95-16.16% oil. The bran oils were also characterized with respect to their physico-chemical properties such as specific gravity, refractive index, smoke point, flash point, fire point, saponification value, iodine value, peroxide value, acid value, %FFA and unsaponifiable matter. Triglyceride diglyceride monoglyceride, and non-glyceride are the constituents of bran oils were found to be varied from 91.76-93.08%. l.51-2.30%, 1.45-1.96% and 3.63-5.24% respectively. Rice bran oils contained mostly unsaturated fatty acids which was varied from 7 l.06-74.95%. The total lipids were fractionated into lipid classes by silicic acid column chromatography and the bran oil contained triglyceride, hydrocarbon, free sterols, glycolipid, phospholipid arid partial glyceride. GLC analysis of the oil indicated palmitic, stearic, oleic and linoleic acid, as a major fatty acid in all the varieties of rice bran oil. On the other hand, linolenic, myristic and arachidic acid were also detected in small amount.