EFFECT OF FOAMING AGENT AND DRYING TEMPERATURE ON DRYING RATE AND QUALITY OF FOAM-MAT DRIED PAPAYA POWDER

Recently, foam-mat dryingis being considered a mild drying technique, requiring lowinvestment costs but being particularly highly effective. This drying method is very useful for liquid or semi-liquid food products that are highly viscous and easily changequalitiesby heat. Liquid or finely ground foods are foamed with the assistance of surfactants (foam-creatingand foam-stabilizingagentsare egg albuminand carboxymethyl cellulose, respectively), followed by drying of the foam with hot air. Box-Behnkendesign(BBD) of response surface methodology (RSM) was designed in this study, with 3 factors and 3 levels, including egg albumin content (6-10%), carboxymethyl cellulose (CMC) (0.1-0.5%) and drying temperature (50-70oC). The drying rate and beta-carotene content of foam and product, respectively, are the indicators observed in 18 experimental runs and 6 repetitions at the central point. Use targetsettings for each response based on high beta-carotene content and highest drying rate to produce a high-quality papaya powder product with the shortest drying time. The optimal and feasible experimental conditions for drying foam mats were achieved with albumin concentration, CMC and optimal drying temperature at 9.07%, 0.39% and 62oC, respectively. From these optimal conditions, the optimal values of drying rate and beta-carotene content were achieved as 3.41 g water/g dry matter/min and 37.95 mu g/g, respectively. This study has confirmed that foam drying is a feasible method to produce good quality papaya powder, the product maintains the natural color of the original material, low moisture (8.5%) and water activity(0.35), and high rehydration ratio (4.05) when drying at 62oC for 3 hours.