Drying characteristics of foamed alphonso mango pulp in a continuous type foam mat dryer

Abstract

Preliminary trials were conducted for foam mat drying of alphonso mango pulp using batch type cabinet dryer. From the trial, it was observed that the foamed mango pulp using egg albumen (10%) as foaming agent with methyl cellulose (0.5%) as stabilizing agent, dried at 60 °C with 1 mm foam thickness was found to be the best. For this foamed pulp, parameters such as viscosity (5.7 ± 0.06 Pa s), stickiness (18.9 ± 0.1 g force) and specific heat (3.66 ± 0.02 kJ/kg °C) values were determined. The drying study showed that the time required to dry the fresh (non-foamed) and foamed mango pulps were 75 and 35 min, respectively. Based on the preliminary drying results, a continuous type foam mat dryer (lab model) with a capacity of drying 2.5 kg/day of 8 h was developed to dry the mango pulps. The overall moisture diffusion in fresh and foam dried mango flakes was 5.3 and 9.7 × 10 −9 m 2/s, respectively. Based on the performance evaluation, it was found that foam dried flakes recorded higher heat utilization factor than non-foam dried flakes. Also from the quality analysis, it was observed that the changes were comparatively lower in foam dried flakes than in non-foam dried flakes using continuous type foam mat dryer.