Evaluation of drying parameters and antioxidant activity of agro-industrial waste

Abstract

ABSTRACT Natural antioxidants are a research topic of increased attention due to the fact that some synthetic antioxidants are now suspected to be potentially harmful to human health. The biomass like mirabelle plum stones valorisation considered as agro-industrial residues seems to be a prospective way for new natural antioxidants. Therefore, an experimental study of sorption isotherm and drying kinetic and antioxidant activities of shell and kernel of mirabelle was carried out. The gravimetric method is used to determine adsorption and desorption isotherms. The experimental results were fitted by GAB and Owswin models. Moreover, a set of drying experiments were studied at five air temperatures (75, 85, 95, 105 and 110°C). Experimental drying curves were fitted with Page, single-term and two-term exponential models. It is found that exponential models are suitable for fruit stones drying. Moreover, the antioxidant activity of kernel extracts is evaluated using the methods of oxygen uptake method (OUI) and the scavenging of 2-2-diphenyl-1-picrylhydrazyl (DPPH) radical. The OUI measurement showed that the extracts had considerably high antioxidant activity (83–90%). The close correlation between DPPH and OUI assays is confirmed. Hence, the mirabelle kernel extracts can be used as effective natural antioxidant.