Résumé:
The first objective of the thesis was to study the effect of whey (sweet and acid) on cooking and sensory quality of gluten-free spaghetti based on a rice-corn formula (2/1). Incorporation levels were 25, 50, 75 and 100%. Gluten-free pasta without added whey and commercial wheat-based pasta were considered as controls. The results showed that gluten-free spaghetti with whey had a significantly higher optimal cooking time than those of control gluten-free spaghetti, but significantly lower than those of wheat-based spaghetti. Water absorption capacity decreased with increasing levels of acid or sweet whey incorporation and gluten-free spaghetti absorbed less water than wheat-based spaghettis. Cooking loss was reduced by the incorporation of 25 and 50% acid whey. Regarding sensory quality, firmness, stickiness, taste and overall acceptability of glutenfree spaghetti were improved by the addition of 50% acid whey. The second objective of the thesis was to study the effect of alkaline salts (sodium and potassium carbonates) and/or whey protein isolate (WPI) on the quality of gluten-free macaroni. Incorporation levels were 0.5 and 1% alkaline salts, 5% WPI and 1% alkaline salts with 5% WPI. The quality of gluten-free macaroni was evaluated in terms of viscosity properties, color, geometric characteristics, cooking quality, texture and sensory analysis. The results showed that the viscosity of macaroni increased significantly with the addition of alkaline salts, while it decreased significantly with the addition of 5% WPI. The addition of alkaline salts decreased significantly water absorption capacity while cooking loss increased significantly. The addition of 5% WPI increased significantly cooking loss. The incorporation of alkaline salts decreased significantly the luminance and increased the redness and the yellowness of dry and cooked macaroni. The incorporation of WPI increased significantly the luminance and yellowness of dry macaroni, while in the case of cooked macaroni these parameters were lower. The addition of alkaline salts and/or WPI resulted in a significant decrease in firmness and total compression-extrusion energy of gluten-free macaroni. All gluten-free macaroni obtained acceptable scores for overall sensory acceptability (≥ 5) except macaroni with 0.5% alkaline salts and macaroni with 1% salts and 5% WPI.
