Evaluation of drying and extraction parameters for the extraction yield of watermelon (Citrullus lanatus (Thunb.)) rind using statistical design experiment

Watermelon rind contributes about 30% of overall watermelon mass and is considered the most underutilized resource as it is usually discarded as waste. Watermelon rind resources have great potential economic value in various industries. Thus, utilizing the rind could decrease the amount of biological waste in the environment. Therefore, this study aims to determine the optimal conditions in extracting oven and dehydrator drying watermelon rind using a sonicator extraction procedure. Watermelon rind samples were evaluated using a one-factor-at-a-time (OFAT) evaluation to identify the most significant factor for the sonicator extraction time (0.5-3 hrs), ethanol concentration (20-100%), solvent-tosolid ratio (10:1-50:1 v/w), and sample drying time (24-48 hrs) parameters. The highest yield obtained for the oven drying sample was at one hr extraction time (15%), 100% ethanol concentration (12.5%), 30:1 v/w ratio (12%), and 48 hrs drying (9%). Meanwhile, the extraction yield of dehydrator drying sample was optimized at one hr of extraction time with 10% yield 100% of ethanol concentration with 15.4% yield, 40:1 v/w of solvent ratio with 14.7% yield, and 48 hrs of drying with 8% yield. The optimum extract yield of dehydrator drying sample could be further applied for cosmeceutical application as it produced higher yield compared to oven drying sample.