Protein content maximization of vegetable paste by incorporation of whey through the linear programming: drying and rehydration evaluation

The vegetable paste was optimized by the protein content maximization through incorporation of whey using the linear programming, with linear restrictions functions. The enriched paste was dried in a spouted bed of cone-cylindrical geometry, at different conditions, and the dried powder products were analyzed by the functional, nutritional, bioactive, chemical, thermal and morphological properties and, also its rehydration characteristics were evaluated. The best results were found in the assay performed at inlet drying air temperature of 100 A degrees C and in paste solids concentration of 10% (w/w). In these drying conditions, the values were of protein solubility of 26.5 +/- 0.1% (w/w), water holding capacity 10.8 +/- 0.1 g g(-1), protein digestibility of 84.9 +/- 2.2% (w/w), total phenolic compounds 7.72 +/- 0.1 mg(EAG) g(sample)(-1), antioxidant activity of 75.7 +/- 0.2% of DPPH inhibition. The glass transition temperature was in range of 97.3 A degrees C, due to the lactose non-caramelization, this fact aided in the functionality of the bed. The powder morphology presented irregular and rough structure, with particles size lower than 100 mu m and, with a low crystallinity index (12.8%). The rehydration constant value was found as 16.5 min(-1), showing the rapidity with that the water diffused into the powder in the most suitable condition.