EFFECT OF EXTRUSION ON HYPOCHOLESTEROLEMIC PROPERTIES OF RICE, OAT, CORN, AND WHEAT BRAN DIETS IN HAMSTERS

Brans from rice, oats, corn, and wheat were cooked in a twin-screw ext ruder at either high or low energy input, and their cholesterol-loweri ng effects were compared with those of unprocessed brans when fed to f our-week-old male golden Syrian hamsters (n = 10 per treatment) for th ree weeks. Peanut oil was added to oat, corn, and wheat bran during th e extrusion process to match the oil content of rice bran. Diets conta ined 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.3% cholest erol. Plasma and liver cholesterol and total liver lipids were signifi cantly lower with low-energy extruded wheat bran compared with unproce ssed wheat bran. Extrusion did not alter the hypocholesterolemic effec ts of rice, oat, or corn brans. Plasma and liver cholesterol levels wi th corn bran were similar to those with oat bran. Relative cholesterol -lowering effects of the brans, determined with pooled (extruded and u nextruded) bran data, were rice bran > oat bran > corn bran > wheat br an. Rice bran diets resulted in significantly lower levels of total pl asma cholesterol and very low density lipoprotein cholesterol compared with all other brans. Total liver cholesterol and liver cholesterol c oncentrations (mg/g) were significantly lower with high-energy extrude d rice bran compared with the cellulose control group. Plasma choleste rol and total liver cholesterol values with low-energy extruded wheat bran were similar to those with rice bran (unextruded or extruded) die ts. Lowered cholesterol with rice bran diets may result in part from g reater lipid and sterol excretion with these diets. Results with low-e nergy extruded wheat bran suggest that this type of processing may imp rove the potential for lowering cholesterol with wheat bran products.