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

The present research had as objective to study the effects of moisture and extrusion temperatures on the oxidative stability of oat fine (< 532 mu m) milling products. The oat caryopsis were ground in a Brabender mill and separated in two fractions, coarse over 532 mu m and fine less than 532 mu m. 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 mu m, a die of 6 mm in diameter and temperatures between 77.6 and 162.4 degrees C in the 2nd and 3rd zones while the Ist 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 degrees C showed low oxidative rancidity.41440140

Development of extruded snacks using jatoba (Hymenaea stigonocarpa Mart) flour and cassava starch blends

The use of the jatoba trees (Hymenaea stigonocarpa Mart) by the timber industry poses an ecological problem in Brazil. The objective of this research was to investigate the use of jatoba flour for the production of snacks by the thermoplastic extrusion of a composite flour consisting of jatoba and cassava starch. Chemical analysis showed that the jatoba fruit provides high-fibre flour (486 g kg(-1)) with 66 g kg(-1) protein, and 398 and 88 g kg(-1) of insoluble and soluble fibre, respectively. Such flour is of potential use for the production of high-fibre snacks, allowing for the economical exploitation of the jatoba while preserving the tree. Composite flours with jatoba flour and cassava starch mixtures (150:850, 300:700, 450:550), conditioned to moisture levels of 170, 200 and 230 g kg(-1) were processed in a Brabender single-screw extruder. The extrusion conditions were 150 rpm screw speed, 4 mm die diameter and 125, 150 and 175 degrees C of barrel temperatures. The snacks produced were evaluated as to their sensory characteristics and response surface methodology was used to optimise the extrusion process. Response surface and contour diagrams revealed that all mixtures conditioned to 170 g kg(-1) moisture and extruded at 150 degrees C produced snacks of acceptable quality, higher levels of jatoba flour leading to significant quality losses with respect to sensory characteristics. (C) 1998 Society of Chemical Industry.781596