Optimizing the antioxidant biocompound recovery from peach waste extraction assisted by ultrasounds or microwaves

Abstract

The possibility to valorize peach juice waste, either frozen or air-dried, through microwave (MAE) and ultrasound assisted extraction (UAE) was evaluated. MAE power, UAE amplitude and time were optimized using a 22-factorial design. For frozen waste, optimal MAE (540W, 50s) and UAE (23%, 120s) processes gave extracts presenting analogous content (on 100g dry matter) of polyphenols (309-317mg GAE), flavonoids (94-120mg QE), anthocyanins (8-9mg CGE), and similar antioxidant activity (2.1-2.2mg TE). Extracts from dried waste resulted higher in polyphenols (630-670mg GAE) but lower in flavonoids (75-90mg QE), anthocyanins and vitamin C (not detectable). Although developing an energy density 2-fold higher than that of UAE, MAE more efficaciously extracted vitamin C (108mg/100gdm) and required half extraction time (50s). MAE would also be less impactful than UAE in terms of greenhouse gas emission and energy requirements on industrial scale. The industrial valorization of peach waste through the application of microwave or ultrasound assisted extraction requires quantitative data, able to encourage company interest and investment. This study not only identifies optimal MAE and UAE parameters to assist the extraction of peach waste bioactive compounds but also provides a preliminary estimation of the potential economic and environmental impact on an industrial scale of these technologies.