2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

For puffed-wheat products, severe extrusion conditions may decrease vitamin retention. Vitamins in extruded products are typically added post-extrusion. The objectives of this study were to optimize the extrusion conditions for puffed-wheat products using lower temperatures with carbon dioxide gas [CO(2)] as a puffing agent, and determine thiamin retention in the extrudates. Soft white wheat flour blended with 0.3% (w/w) thiamin hydrochloride was the raw material. An APV MP19TC-25 co-rotating twin-screw extruder was used. Pressurized CO(2) was injected 80 mm prior to the exit die. The CO(2)-expanded samples were extruded using 100 psi of CO(2) and a barrel temperature profile of 40/40/50/70/88°C. Steam-expanded control samples were extruded at 30/50/80/110/130°C. Moisture content for raw materials of both samples was 25%. Wall shear rate in the die was estimated, and thiamin retention was determined according to the AOAC thiochrome method. Water solubility and water absorption indices for CO(2) samples were lower than the control samples, though both samples had similar expansion ratios. The CO(2) samples had more uniform air cell distribution and greater thiamin retention. Results indicate a potential for incorporating vitamins into raw flour prior to extrusion coupled with CO(2) gas injection to produce good quality puffed-wheat products.