| Resumo: |
Mixed vegetable powders – composed of purple sweet potato, red cabbage and beetroot at a 2:1:1 ratio – were incorporated with cereal base by an extrusion process to obtain a functional, ready-to-eat breakfast cereal. This study investigated the effects of mixed vegetable powder level (8, 12 and 16%), screw speed (300, 350 and 400 rpm) and feed moisture content (13, 15 and 17%) on the physical and functional properties of extrudates in breakfast cereal production using response surface methodology (RSM) and Box-Behnken experimental design. The results showed high correlation coefficients (R2 ) of multiple regression equations about the relationship among product responses and process variables, and no significant lack of fit (indicating a best-fit model). The optimum conditions were determined from the overlaid area found by superimposing the individual contour plots of responses. Correspondingly, the verification of results showed good agreement between the responses of experimental values at selected optimum conditions and the predicted values from regression equations.
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