Farinhas de trigo e soja pré-cozidas por extrusão para uso em molho branco e sopa cremosa semiprontos

Abstract

Mixture of wheat and soybean in appropriate proportions, has not only a mutual complementary effect of aminoacids, but also contributes to the improvement of functional properties. Extrusion-cooking can modify starch and protein structures, improving their functional properties. With the objective of obtaining two pre-cooked wheat-soybean flours (90:10 and 80:20) with good pasting properties (PP) and emulsifying properties (EP), and that its can be formulated one in white sauce and the other in creamy soup, both semiready ones with good sensory characteristics, the present work was carried out, using a Brabender single screw extruder with a constant feeding rates of 2.4kg/h, screw Nº3 and circular shape die with diameter of 1 mm for extruding raw mixed wheat-soybean flours (90:10 and 80:20) in two moistures (26 and 29%), five barrel temperatures (BT, 110 to 150°C) and four screw speeds (SS, 120 to 210rpm). The extruded products were dried, ground and their flours were analyzed. These demonstrated that, mixed flours (10 and 20% of soybean) with 26 and 29% of moisture and extruded in 150 and 180rpm at 120 and 130°C, presented the best PP (cold viscosity at 25°C, pick viscosity at 95°C, holding viscosity at 95°C, final viscosity at 25°C, breakdown viscosity and setback), when compared to raw wheat flour (control) and mixed raw flours (controls). The EP of extruded mixed flours increased up to certain point, with an increase of SS and BT at two studied moistures. In general, extruded mixed flours with 20% of soybean presented more EP than those with 10% of soybean, and both showed more EP than their controls. This way, extruded mixed flours with 10% of soybean were formulated in semiready white sauces, being evaluated sensorily. The results indicate that, the white sauce prepared with the mixed flour with 29% moisture and extruded at 150rpm and 120°C, showed better appearance and similar texture, although flavor was worse than that of 26% moisture and extruded at 150rpm and 130°C, being the first the most preferred by the untrained consumer-type panelists, when compared to the last and the controls. On the other hand, extruded mixed flours with 20% of soybean were formulated in semiready creamy soups, being submitted to the sensory analyses. The results showed that, the creamy soup prepared with the mixed flour with 26% moisture and extruded at 180rpm and 120°C, presented similar appearance and better texture, but worse flavor than that of 29% moisture and extruded at 150rpm and 130°C, being the first the most preferred by the untrained consumer-type panelists, when compared to the last and the controls.