Pastification sans gluten par cuisson-extrusion
Zidoune, Mohammed Nasreddine
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The first objective of the thesis was to study the effect of the moisture content of the formula (28%, 30% and 32%) and the screw speed (60, 80 and 100 rpm) on some quality parameters of gluten-free pasta made from a rice-yellow pea formula (mass ratio 2/1). The phenolic acid composition, anti-radical activity and some properties of pasta were evaluated, such as pasting properties, water absorption capacity, cooking losses, texture characteristics, microstructure and overall sensory acceptability. The results showed that the moisture content significantly influenced all quality parameters tested except firmness. Screw speed showed a significant effect on only some quality parameters. The extrusion cooking process with a moisture content of 30% and a screw speed of 80 rpm was suitable for obtaining gluten-free pasta with adequate quality. These pasta had low cooking losses (< 6%), firm texture, low stickiness and a regular and compact internal structure with high scores for overall sensory acceptability (7.6). After selecting the best processing conditions (moisture content of 30% at 80 rpm), the effect of addition level (10%, 20% and 30%) of legumes flours (yellow pea, chickpea and red lentil) on pasta quality has been approached by chemical composition, physical properties (expansion ratio, minimal preparation time, water absorption capacity, cooking losses, water absorption index, water solubility index and color), texture characteristics (hardness, firmness and adhesiveness), sensory quality and microstructure of pasta. The results revealed that the addition of legumes decreased expansion ratio, hardness and brightness, and increased the yellowness, firmness and stickiness, without affecting the minimum preparation time (8-9 min). The results also showed that gluten-free pasta had low cooking losses (< 6%) and acceptable scores for all sensory attributes and overall sensory acceptability. Concerning the microstructure, all gluten-free pasta had a compact internal structure. Formulas containing up to 30% of legumes flours can be used successfully for the processing of good quality gluten-free pasta. The final objective of the thesis was to determine the effect of processing conditions variation (water content and VRV) and formulation variation on the efficiency of the extrusion cooking process and the energy consumption during the processing of gluten-free pasta based on rice-legumes formulas. The process efficiency varied between 10.56 and 16.80 kg/h, and the specific mechanical energy (SME) varied between 0.14 and 0.35 kWh/kg. The results obtained showed that screw speed had a significant effect on process efficiency and SME values, which increased as the screw speed increased. The moisture content of the formulas also had a significant effect on process efficiency and on SME mainly at low screw speed. The process efficiency increased with the increase of the moisture content while inverse observations were noted for the SME. On the contrary, the variation in the type of legumes and its addition level did not affect the measured parameters.