Pasta products made from sweetpotato fortified with soy protein

Sweetpotato flour (Beauregard cultivar) was treated with sodium hydroxide solution and then fortified with defatted soy flour (DSF) or soy protein concentrate (SPC) at levels of 0, 15, 30, and 45 g/100 g. Pasta made from 100 g/100 g alkaline-treated sweetpotato flour (ASPF) had the lowest cooking loss (9.9 g/100 g) with the highest firmness (1.8 N). Cooking loss increased as levels of DSF and SPC increased (from 9.9 to 16.6 g/100 g). Addition of DSF and SPC increased the lightness (“L*” value) from 40.6 to 48.7, and decreased the redness (“a*” value) from 21.6 to 15.2. Substitution of DSF and SPC decreased firmness from 1.8 to 0.4 N, cohesiveness from 0.6 to 0.5 and springiness from 1.2 to 1.1 mm. Pasta made from 100% ASPF had highest β-carotene content (9.0 mg/100 g). The β-carotene contents decreased from 7.9 to 2.7 mg/100 g as the levels of DSF and SPC increased.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.