Effect of blanching on enzyme inactivation, physicochemical attributes and antioxidant capacity of hot-air dried pomegranate (Punica granatum l.) arils (cv. wonderful)

Blanch-assisted hot-air drying of pomegranate arils with blanching treatments 90^◦C for 30 s, 100^◦C for 60 s, and unblanched (control) arils were investigated. Effects of blanching on enzyme inactivation (polyphenol oxidase and peroxidse), colour, texture, and other qualities of dried arils were discussed. The hot-air drying conditions were 60^◦C, 19.6% relative humidity, and 1.0 m s⁻¹ air velocity. Results showed that blanching reduced enzyme activity by 76% and 68% for blanched arils treated at 90^◦C for 30 s and 100^◦C for 60 s, respectively, compared to unblanched arils. With regard to the total colour difference (TCD), unblanched arils were 20.9% and 16.6% higher than blanched arils treated at 90^◦C for 30 s and 100^◦C for 60 s, respectively. Furthermore, the total soluble solids (TSS) for unblanched aril increased significantly from 16.1 to 24.9^◦Brix after drying, followed by arils treated at 90^◦C for 30 s and 100^◦C for 60 s (21.4; 18.5^◦Brix), respectively. Among the blanching treatments, dried arils treated at 90^◦C for 30 s had the highest total anthocyanin content (28.6 mg C3gE/g DM), followed by 100^◦C for 60 s (24.8 mg C3gE/g DM). Similarly, dried arils treated at 90^◦C for 30 s had the highest radical scavenging activity (RSA) (32.1 mM TE/g DM) while the least was observed with unblanched arils (17.0 mM TE/g DM). Overall, the blanching treatment was more effective to maintain the quality attributes of pomegranate dried arils.