Quality Evaluation of Foam Dried Watermelon Flakes

Abstract

Watermelon is mostly eaten in fresh form due to its high moisture content which is responsible for its deterioration within a short time. Foam-mat drying of watermelon was carried out using a mechanical dryer. In the foam mat drying experiments, 10% egg albumen and 2% carboxyl methylcellulose were used as the foaming agent and stabilizing agent, respectively. Thin layer drying was carried out in the mechanical dryer under temperatures of 60 and 70C. Some nutritional qualities and chemical compositions of the watermelon were determined before and after drying. The result of the phytochemical properties revealed that the watermelon flakes have a high value of flavonoid content of 1.18±0.02 and 1.09±0.00 mg 100 g-1 with low terpenoid contents of 0.10±0.00 and 0.11±0.00 mg 100 g-1 for the sample dried using 60 and 70C respectively. High ferric ion reducing antioxidant power (FRAP) value of 38.73±0.90 and 41.25±0.90 mg g-1 with low lycopene value of 0.312±0.00 and 0.323±0.01 mg g-1 was observed for the antioxidant properties of watermelon dried at 60 and 70⁰C. The vitamin content shows that the flakes are highly rich in vitamin C (46.26±0.03 and 47.35±0.02 mg g-1 for 60 and 70C, respectively) and had a low vitamin B1 content (0.15±0.01 and 0.13±0.00 mg g-1 for drying temperature of 60 and 70C, respectively). Therefore, the results of the foam-dried watermelon flakes showed that the qualities of the watermelon were preserved during drying and safe for consumption.