Preparation of Papaya Powder under Foam-Mat Drying Technique using Egg Albumin as Foaming Agent

Abstract

Foam-mat drying of papaya pulp using egg albumin as foaming agent was investigated. The egg albumin was incorporated into papaya pulp at 5, 10, 15 and 20% (w/w) and whipped for 5, 10, 15 and 20 min in room temperature. Foam expansion, foam sta­bility and foam density were determined. The maximum stable foam formation was 125.62% at 15% egg albumin and whipping time of 15 min. The foam expansion was significantly influenced by levels of the egg albumin at (p≤0.01). Foam density was measured and expressed in g cm-3. The resulting foams were dried at air temperatures of 60, 65 and 70°C with foam thickness of 2, 4, 6 and 8 mm under air flow rate of 2.25 cu.m min-1. Lower drying temperature and higher foam thickness resulted in longer drying time. Biochemical and sensory properties of fresh papaya fruit and reconstituted juice from foam-mat dried papaya powder were determined. Biochemical analysis results showed a significant (p≤0.05) reduction in ascorbic acid, β-carotene and total sugars in the foamed papaya dried product at higher drying temperatures (65 and 70°C) and higher foam thickness (4, 6 and 8 mm) due to destruction at higher drying temperature and longer drying time. There was no significant change in other biochemi­cal constituents such as TSS, pH and acidity. The sensory attributes of reconstituted papaya powder juice showed a significant (p≤0.01) reduction in colour, flavor, taste and overall acceptability at higher temperature (65°C and 70°C) and significantly less as compared to fresh papaya juice. The papaya powder obtained from the foam thickness of 2 mm and dried at 60°C was found to be optimum to produce the foam-mat dried papaya powder.