Abstract
The effects of processing of oats (whole grains, cut type) and defatted oats with a twin-screw extruder were examined with regard to both compositional changes in the dietary fiber fraction and hypocholesterolemic activity in cholesterol-fed rats. The insoluble and soluble dietary fiber contents of raw materials and extruded products were separately measured using an enzymatic-gravimetric method. All of the extruded products contained more soluble fiber than the corresponding raw material, suggesting that some of the water-insoluble fibers were transformed to soluble ones during extrusion cooking. Male Sprague-Dawley rats, aged 5 weeks, were fed diets containing extruded or steamed oats respectively, at a 55% level for 9-11 days. The oats extruded at a maximum temperature of 177°C tended to reduce the serum cholesterol level in comparison with the steamed material, although there was no significant difference between defatted oats extruded at 139°C and the steamed material. Both extruded products, however, showed a tendency to decrease the apparent accumulation ratio of ingested cholesterol in the liver.
