Formulation and optimization of foam mat dried grape bar

A five level four factors central composite rotatable design under response surface methodology was used to optimize process conditions of the foam mat drying process i.e. egg albumen (0%-12%), methyl cellulose (0.1%-0.5%), drying bed thickness (3-7 mm) and drying temperature (55-75°C) to develop grape bar with final moisture content of 14%±1% (dry-base). Contour and response graphs were generated and the effect of foaming parameters on the quality parameters namely drying time, color change, texture, non-enzymatic browning, total sugars (%), titratable acidity (%), protein (%) and overall acceptability (%) were studied. Significant regression models were established with the coefficient of determination, R (≥0.90). Optimization of process for grape bar was performed to result minimum drying time, color change, cutting force, non enzymatic browning and maximum overall acceptability and optimized process conditions were 5.51% egg albumen, 0.31% methyl cellulose, 4 mm drying bed thickness and 60°C drying temperature with desirability 0.74.