Foaming process optimization, drying kinetics and quality of foam mat dried papaya pulp

Abstract

This study was performed to optimize the papaya pulp foaming process and determine the effect of drying conditions on the drying kinetics and the quality of the obtained powder. Thus, the one- factor-at-a-time experimental method, followed by 2 ^k full factorial design was implemented to determine the optimal conditions of the foaming process. The factors studied were egg white percentage (EW%), xanthan gum percentage (XG%), and whipping time (WT) which varied between 5-20%, 0-0.5%, and 5-20 min, respectively. The optimum conditions (EW% of 15%, XG% of 0.3% and WT of 15 min) for papaya foam expansion percentage (FE%) resulted in a foam with the highest FE% (275.64%) and desirability of 0.916. Foamed and non-foamed papaya pulp in thickness layers of 2-, 4- and 6-mm were dried at 60° and 80° C. Foaming papaya pulp reduced drying time at various layer thicknesses from 140-400 min to 60-160 min, and from 70-160 min to 30-100 min at 60° and 80° C, respectively. Foamed powder samples had the lowest dissolution times and hygroscopicity values; in addition, reconstituted solutions were lighter than non-foamed solutions. Ascorbic acid retention and total phenolic compound content was adversely affected by increased drying time. The obtained papaya powder was classified into six groups based on its quality parameters via hierarchical cluster analysis. In general, foam mat drying is a promising method for producing papaya pulp powder due to its high drying rates and better-quality product.

Keywords: Foam mat drying; Hierarchical cluster analysis; Optimization; Papaya pulp; Xanthan gum.