Pea starch noodles: Effect of processing variables on characteristics and optimisation of twin-screw extrusion process

The effects of processing variables (moisture content, barrel temperature and screw speed) on the physicochemical, cooking and textural properties of pea starch noodles prepared by twin-screw extrusion were investigated using response surface methodology. Results indicated that increasing dough moisture content increased the b∗ value (yellowness), expansion ratio, percentage of gelatinised starch, resistant starch content, cooking time, firmness and surface stickiness, but reduced cooking loss. Raising barrel temperature reduced cooking loss and cooked weight, but increased the expansion ratio, percentage of gelatinised starch, resistant starch, firmness and surface stickiness of cooked pea starch noodles. The b∗ value, expansion ratio, percentage of gelatinised starch, resistant starch, cooking time, firmness and surface stickiness were increased as screw speed was increased, whereas the a∗ value and cooked weight were reduced. The optimum processing conditions for pea starch noodle-making by twin-screw extrusion was established. Good agreement was noted between experimental values obtained at optimum process conditions and predicted values. Pea starch noodles prepared by twin-screw extrusion exhibited similar brightness in colour and cooking time to, but firmer texture than, commercial mung bean starch noodles.