MICROWAVE-ASSISTED FOAM MAT DRYING OF GUAVA PULP: DRYING KINETICS AND EFFECT ON QUALITY ATTRIBUTES

The present study investigated the drying kinetics and quality of microwave foam mat-dried guava powder using 8% egg albumin as the foaming agent. The foamed guava pulp was dried at microwave power of 480, 560, 640, 720 and 800W; foam thickness of 3, 5 and 7 mm; and inlet air temperature of 40 and 50C. Weight loss was used to estimate change in drying rate with respect to time. Reduction in drying time was observed with increase in microwave power and decrease in foam thickness. Powdered samples were analyzed for various physicochemical quality parameters viz. acidity, pH, total soluble solids (TSS), color change and ascorbic acid content. Statistical analysis using three-way analysis of variance revealed that sample of 5 mm foam thickness dried at 800W and 50C was the best with 0.3584% total acid, 3.98 pH, 14 min drying time, 8(o)Brix TSS, 3.263 color change and 154.762 mg/100 g ascorbic acid content.