Improving the value of rice by-products by SFE

Rice is an excellent source of complex carbohydrates, fibre (brown rice), protein and vitamins. The bran layers of brown rice contain protein rich in eight of the essential amino acids, in addition to calcium, phosphorus, potassium, niacin, fibre, B vitamins, vitamin E and a natural oil, which in recent studies appears to have a cholesterol lowering effect. Rice oil contains three different kinds of natural antioxidants tocopherols and tocotrienols (tocochromanols) and oryzanols (feruloylsteroltype), and industry recognizes oxidative stability of rice oil. The aim of this research was to evaluate the use of SFE technology for recovery of by-products and developmental research in novel conversion processes to manufacture value-added food products. Conditions were studied to extract oil from products and by-products of rice processing chain, and to increase the concentration of antioxidants (tocochromanols and oryzanols) in oil. High pressure and temperature, compatible with natural products, enable high yield and efficacious CO2 usage. The extraction conducted at 10 000 psi and 80 degreesC gave the highest extraction yield, and the initial analyses indicated that the oil quality is as suitable for human consumption as the traditionally extracted one. By-products may be valuable sources of antioxidants, and preliminary results indicate that it is possible to improve extraction conditions for their enrichment. (C) 2002 Published by Elsevier Science B.V.