Bioactive Recovery from Watermelon Rind Waste Using Ultrasound-Assisted Extraction

Abstract In response to the imperative to address food waste and promote environmental sustainability, this study investigates the transformation of watermelon rind waste, an agrowaste, into a valuable resource. We extract polyphenols and antioxidants from freeze-dried watermelon rind (WMR) across four cultivars (Crimson Sweet, Black Prince, Black Chairman, and Sugar Baby) using ultrasound-assisted extraction (UAE). Solvent selection, based on a preliminary experiment, is optimized through response surface methodology (RSM), fine-tuning solvent concentration and sonication time. RSM effectively models our responses (R2> 0.90), confirming its suitability for optimization. Applying the optimized parameters (79.8% solvent concentration and 20 minutes of sonication) to various cultivars yields rich bioactive extracts. This optimization is vital for extracting polyphenols and antioxidants as sustainable alternatives to synthetic antioxidants, bolstering food stability. Watermelon rind also offers a distinct profile of fatty acids and phytosterols, ideal for diverse applications in food, pharmaceuticals, nutraceuticals, and industry. Practical Applications: Watermelon rinds are valuable sources of bioactive molecules with potential for pharmaceutical and nutraceutical applications. The application of ultrasound-assisted extraction (UAE) to retrieve polyphenols and antioxidants from watermelon rinds presents an ecofriendly and efficient approach with practical applications. Within the food industry, these compounds can serve as natural alternatives to synthetic antioxidants. By enhancing oxidative stability, the use of these bioactive compounds extends the shelf life of food items while improving their nutritional quality. Moreover, specific fatty acids and phytosterols in watermelon rinds open avenues in pharmaceuticals, nutraceuticals, and functional ingredients. These compounds can be integrated into dietary supplements and functional foods, promoting health among consumers. In summary, this study's optimized extraction methods yield bioactive compounds with practical value. These compounds enhance food quality and meet consumer preferences while driving innovation across various industries, from food production to pharmaceuticals and nutraceuticals.