Foam-mat Drying of Papaya (Carica Papaya L.) using Glycerol monostearate as Foaming Agent

Abstract

The study was carried out to production of papaya powder using glycerol mono-stearate as foaming agent under foam-mat drying technique. Foaming, drying, reconstitution, quality and sensory attributes of dried papaya powder were investigated. Foams were prepared from papaya pulp by adding different concentration of glycerol monostearate (1, 2, 3 and 4% w/w) at whipping time of 5, 10 and 15 min. The foam expansion was significantly influenced by pulp concentration and levels of the foaming agent at 1% level. The maximum stable foam formation was 90% at 3% glycerol monostearate with 9°Brix pulp concentration and whipping time of 10 min. The resulting foams were dried at air temperatures of 60, 65 and 70°C with foam thickness of 2, 4, 6 and 8 mm in a batch type cabinet dryer under air flow rate of 2.25 m³/min. 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, ?-carotene and total sugars in the foamed papaya dried product at higher foam thickness (6 and 8 mm) and temperature (65 and 70°C due to destruction at higher drying temperature and increasing time. There was no significant change in other biochemical constituents such as pH and acidity. The sensory attributes of papaya powder juice were significantly (P?0.01) influenced by drying temperature and was compared with fresh papaya juice. The papaya powder obtained from the foam thickness of 4 mm and dried at 60°C was found to be optimum to produce the foam-mat dried papaya powder.

Keywords: papaya pulp, glycerol monostearate, whipping, foam expansion, foam thickness, drying, moisture content