Model generation and process optimization of microwave-assisted aqueous extraction of anthocyanins from grape juice waste

Abstract

The microwave-assisted extraction of anthocyanins from grape juice waste was investigated in this study. The optimization was implemented using response surface methodology with Box–Behnken design and genetic algorithm (GA). Anthocyanins from grape juice waste were extracted under various microwave power (100–600 W), exposure time (1–5 min) and solvent/solid ratio (10–50 ml/g). The total monomeric anthocyanin yield was considered as the response for optimization experiments. The results indicated that the quadratic model was significant for the chosen response at p <.0001. The analysis of variance and response surface plots showed a significant interaction of all the selected independent variables over anthocyanin extraction process. The maximum anthocyanin yield of 1.31881 mg/g of grape juice waste was predicted by response surface methodology, and the prediction was improved to 1.32244 mg/g of grape juice waste by GA. A confirmatory experiment performed under optimum conditions showed anthocyanin yield of 1.3215 mg/g of grape juice waste. Hence, this model was successful in predicting anthocyanin extraction from grape juice waste under microwave-assisted extraction conditions. Practical application: Anthocyanin pigments find a broad range of implementation as food colorants, antioxidants, and anticancerous agents. The waste residue obtained during grape juice production and processing is also rich in anthocyanins and can be used as an alternative source for anthocyanin extraction. This study exploits the use of grape juice waste for anthocyanin extraction, and it can be the best way of waste management and cost reduction in grape juice production units. © 2016 Wiley Periodicals, Inc.