Effects of moisture and extrusion temperatures on the oxidative stability of milling oat products with granularity below 532 μm

摘要

The present research had as objective to study the effects of moisture and extrusion temperatures on the oxidative stability of oat fine (< 532 μm) milling products. The oat caryopsis were ground in a Brabender mill and separated in two fractions, coarse over 532 μm and fine less than 532 μm. The fine fraction, with higher amount of starch and low amount of crude protein, lipids and dietary fiber content when compared to oat coarse milling products was conditioned to moisture levels (15.5-25.5 %) and extruded in a simple one-screw Brabender laboratory extruder (C/D= 20:1). The conditions of extrusion were compression ratio 3:1, screw speed of 100 rpm, a die of 6 mm in diameter and temperatures between 77.6 and 162.4 oC in the 2nd and 3rd zones while the 1st zone was maintained at 80 oC. The extruded material was dried, ground, conditioned in plastic bag and periodically determined the peroxide value and n-hexanal. The unsaturated fatty acids content of the oil fraction was higher (79.20 %). Independent of moisture level, all extruded products in temperatures less than 120 oC showed low oxidative rancidity.