Foam mat drying of fig fruit: Optimization of foam composition and physicochemical properties of fig powder

摘要

In this study, we report an optimization study on fig foam composition and hot air/microwave-assisted foam mat drying (FMD) at different conditions to produce fig powder. The effects of foam composition on foam stability and capacity were evaluated. The optimum ratio of fig, egg white, carboxymethyl cellulose, and maltodextrin was determined as 52.9, 28.9, 0.8, and 17.4% (wt/wt), respectively, targeting maximum foam capacity and minimum drainage volume, that is, maximum foam stability. The effects of drying methods and their conditions were investigated on the drying rate of fig foam and physicochemical properties of fig powder. Moisture content, water activity, particle and bulk properties, and hydroxymethylfurfural and total phenolic contents of FMD fig powder were analyzed to understand the effect of drying methods and conditions on the physicochemical properties of fig powder. Practical applications Although fig fruit is generally dried as a whole, the ready-to-eat foods in the food market are mostly in powder form. That is why the powdering fig fruit by an appropriate drying method is essential. In this study, we report the foam mat-dried (FMD) fig fruit powder. The fig foam composition was optimized. The fig foam was dried through hot air and microwave separately. The results showed that the foam capacity and stability of the fig powder highly depend on the foam composition. Microwave drying method was found more efficient than the hot air in the sense of time. Besides, the higher foam thickness provided more hydroxymethylfurfural content in the fig powder. The drying method and conditions were found to be important to produce a high-quality FMD fig powder.