Texturization of Sunflower/Soy Flour Mixtures: Chemical and Nutritive Evaluation

Abstract

The thermoplastic extrusion technique using a Wenger, X-25 extrusion cooker was applied to mixtures of sunflower flour and soy flour in the ratios 1: 1 (TSP, ) and 3 : 1 (TSP, ). The processing conditions were as follows: extrusion moisture 18%, feed rate 2750 g/min and extrusion temperature 145°C. Proximate analyses were performed on TSP, and TSP,. The amino acid content of sunflower flour and of TSP, were determined in a Perkin-Elmer amino acid analyzer after acid hydrolysis of the proteins. The protein content of TSP, and TSP, was 46 and 48%, respectively, and both samples were tested for their PER in rats. The values obtained were 1.96 for TSP, and 1.63 for TSP,. The casein control diets gave PERs of 2.54 and 2.48, respectively. Supplementation of TSP, with 0.15% DL-methionine improved its PER to 2.32 (P < 0.05), but 0.30% of the same amino acid failed to produce a further increase in protein efficiency ratio. Supplementation of TSP, with 0.1% L-lysine improved the PER to 2.09 but this value was not as good as methionine-supplemented TSP. Apparent digestibilities shown by these texturized, high protein flour mixtures may be considered satisfactory.