Gluten-Free Rice Instant Pasta: Effect of Extrusion-Cooking Parameters on Selected Quality Attributes and Microstructure

Abstract

In the present study, we applied extrusion-cooking to polished rice flour so as to prepare gluten-free pasta. The aim of the work was to investigate the effect of feed moisture (28, 30 and 32%) and screw speed (60, 80 and 100 rpm) on selected rice pasta quality attributes (water absorption, cooking loss, firmness, stickiness and microstructure) and extrusion response (specific mechanical energy). Our results showed that feed moisture significantly affected all tested quality attributes of the rice pasta, while screw speed exhibited a significant effect on all quality attributes except cooking time and stickiness. Moreover, raising the feed moisture increased the cooking time, water absorption, cooking loss, hardness and stickiness, but decreased the firmness at high screw speed. In addition, increasing the screw speed enhanced the cooking loss and hardness, but diminished the water absorption and firmness of pasta with low feed moisture. Rice pasta prepared with 30% moisture content and at 80 rpm showed adequate quality, as confirmed by a firm texture and low cooking loss and stickiness. Microstructure analysis showed a compact and dense internal structure of the dry pasta, and the surface was smooth and even when at least 30% moisture was applied at 80 rpm screw speed during processing.