Characterization of a rice-based pasta : comparison with conventional semolina pasta

Good quality gluten-free products continue to be in demand among the celiac community. In this study we characterized the quality characteristics of gluten-free pasta made using milled and brown rice flour. Two processes were applied to produce pasta from these flours, with similar moisture contents of 40% in dough. In one case, the rice flour was processed in a conventional plant (pilot-scale) for semolina pasta where the dough temperature inside the continuous extruder was maintained at 55°C. In the second process, two extrusion steps were used: rice dough was first heated and extruded at 115° C for about 2 minutes; then the pre-treated dough was extruded again in the continuous extruder at 55°C. All samples were then dried using a low-temperature drying cycle (50 °C for 14 hours). The characteristics of rice pasta were compared with those of semolina pasta obtained by using the conventional continuous extrusion and dried using the same cycle. The weight-increase of cooked pasta, the solids loss into the cooking water and the color of the pasta were evaluated. Starch modifications induced by the pasta-making process were analyzed by using a micro-viscoamylograph test. As expected, the brown rice flour and pasta were darker compared to either white rice flour or semolina, as evidenced by a higher L, a, b values. The pasta making process did not affect the color of the samples. Following cooking, semolina pasta had the highest weight gain. White rice flour pasta made using non-conventional process had a higher weight gain than pasta from either of the brown rice pasta samples. As expected, semolina pasta had the lowest solids loss following cooking; but white rice pasta made using the non-conventional process also had similar low weight loss. Flours from rice were characterized by a lower peak viscosity compared to semolina. Starch gelatinization temperature decreased in the pasta compared to the respective flours. Furthermore, the pasting profiles were significantly influenced by the pasta making procedure. These results suggest that while good quality pasta can be made using rice flour, the structure of the pasta, as influenced by starch gelatinization, is different likely resulting in differences in weight gain and cooking losses. Further studies are underway to better understand the structure that governs a good quality rice-based pasta.