Effect of foaming duration, soy protein isolate and drying temperature on DPPH activity, color and solubility of foam-mat dried bottle gourd powder: optimization, characterization and storage study

The undertaken study was conducted to prepare bottle gourd juice powder using foam mat drying. The foam mat drying process parameters were optimized using response surface methodology with three parameters i.e. concentration of soy protein isolate, drying temperature and whipping time on the physico-chemical properties (responses) viz. yield, a* value, water solubility index and DPPH free radical scavenging activity was designed using three factors three level Box–Behnken design (BBD) of response surface design. The optimized conditions were obtained as 6.85 per cent concentration of soy protein isolate, 53.22 °C drying temperature and 3.36 min whipping time with desirability of 78.5 per cent. Under these optimized process parameters the values of responses were obtained as yield 11.69 per cent, a* value − 4.54, water solubility index 45.44 per cent and 41.83 per cent DPPH free radical scavenging activity. The optimised foam mat dried powder was than analysed for various physico-chemical properties, physical properties, bioactive constituents, surface morphology and molecular interactions. Surface morphology of the optimised powder releaved that the powder particles were porous and possessed flake-like structure. The sensory evaluation scores of reconstituted optimised foam mat dried powder were lower in comparison to raw bottle gourd juice in terms of overall acceptability. Aluminium laminate pouch was found to better preserve the physico-chemical quality attributes of the powders which highlight its potential use as a packaging material for the bottle gourd juice powder.

Graphical Abstract