No abstract

Two half-products were prepared from tapioca starch/catfish fillet-belly flap mince (60:40) and tapioca starch/partially defatted peanut flour (PDPF) (60:40) by twinscrew extrusion. The process variables were temperature in the last two zones of the extruder (90, 95, 100ЊC) and screw speeds (100, 250, 400 rpm). Moisture content (40%, wet basis) and feed rate (27 g/min) were held constant. Simultaneously increasing temperature and screw speed resulted in increased expansion, and decreased bulk density and shear strength. Degree of starch gelatinization in half-products ranged from 87 to 95%. Optimum conditions predicted by response surface methodology were: for fish half-products 94-100°C and 220-400 rpm and for peanut half-products, 95-100ЊC and 230-400 rpm.

Fish-and peanut-containing half-products were obtained by extruding and drying tocopherol-and retinyl palmitate-fortified mixtures of tapioca starch and minced fish or partially defatted peanut flour (PDPF 60:40, wet basis). Half-products were puffed by deep-fat frying. Vitamins were determined simultaneously at each step of snack production using a direct solvent extraction method. Extrusion significantly reduced the content of tocopherols and retinyl palmitate in both products. Reduction of retinyl palmitate in fish and peanut extrudates during snack production was 48% and 27%, respectively. Final products contained more tocopherol than intermediates because of the high tocopherol content in the frying oil and its uptake.

Fish snack half-products were produced using extrusion temperatures and screw speeds of 97ЊC and 285 rpm, 95ЊC and 350 rpm, and 95ЊC and 220 rpm. Peanut snack half-products were produced at 100ЊC and 250 rpm, 95ЊC and 325 rpm, and 95ЊC and 250 rpm. The half-products were fried at 200ЊC for 1.5 min and evaluated for acceptability using a 9-point hedonic scale. Temperature and screw speed influenced consumer acceptance. Aroma, flavor, and overall acceptance of fish snack products were rated significantly higher by Asian consumers (n ϭ 30) than by American consumers (n ϭ 30). There was no significant difference in ratings for all sensory attributes and overall acceptance of peanut snack products by Asian or American consumers.

Extruded weaning foods were produced using cowpea + corn + soybean + soybean oil (35:50:10:5, w/w) and cowpea + corn + peanut (42:43:15, w/w) by twin screw extrusion and fortified with vitamin premix. A direct solvent extraction method was used to assay fortified a-tocopheryl acetate as the ester to differentiate it from the naturally occurring alcohol for accurate assessment of total vitamin E activity. The fortified retinyl palmitate was assayed from the same extraction and assayed as the more stable ester with the same LC conditions after changing the detection wavelengths. Using direct solvent extraction, analytical values of vitamin E homologs in extruded products were higher than those values from saponification.