Comparison of the nutritional, physico-chemical and anti-nutrient properties of freeze and hot air dried watermelon (citrullus lanatus) rind

Abstract

The preservation of food by drying is one of the most commonly used methods in the food processing industry. Watermelon belongs to the family of Cucurbitaceae. The processing of watermelon generates a large amount of waste in the form of rind, peel and seeds. The watermelon rind is an under-utilised waste generated after the consumption of the fruit. Watermelon rind contains Vitamin C, dietary fiber, citrulline, potassium, a small amount of Vitamin B-6. It is also known to contain a variety of bioactive compounds like cucurbitacin, triterpenes, sterols and alkaloid. The citrulline in watermelon rind gives it antioxidant effects that protect the body from free-radical damage. In this study efforts have been made to dry and preserve the watermelon rind by hot air drying and freeze drying technique. The water absorption capacity, rehydration ratio and the solubility of the freeze dried watermelon rind powder were found to be 11.42±0.6 (g/g), 9±0.8 (g/g) and 8±0.5% respectively. Hot air drying significantly reduced the water absorption capacity of the watermelon rind while it increased the water solubility and bulk density. The tannins, alkaloids and saponin content were found to be lesser in hot iar dried samples compared to freeze dried.