Comparison of antioxidant properties of dehydrated fruits and vegetables with different drying techniques

Abstract

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Present study was carried out to evaluate the effect of various dehydration techniques such as sun drying, solar drying, drying after freezing (Freeze for one hour followed by mechanical drying), vacuum drying and drying using lab scale air oven on retention of antioxidants in different fruit and vegetable powders, prepared from fruits such as Bael (Aegle marmelos), Palmyra (Borassus flabellifer) and vegetables; Pumpkin (Cucurbita maxima) and Hibiscus (Hibiscus rosasinensis). The major antioxidants present such as total phenolic content, P - carotene and total anthocyanin content were determined (n=3) in fruits and vegetables which were dehydrated by different drying methods. The retention of antioxidant activity was evaluated by conducting the DPPH scavenging activity using methanol as a solvent. The results were analyzed by complete randomized design using ANOVA (SAS statistical package) and mean separation was done by using Least Significant Difference (LSD) at a= 0.05. Higher retention of P - Carotene and total phenolic content was recorded in vacuum dried samples significantly (a< 0.05). Sun drying and solar drying were significantly affected on reduction of the retention of total phenols. Hibiscus powder contained higher level of anthocyanin; dehydrated beal, palmyra and pumpkin retained higher concentration of P -Carotene and total phenolic content by vacuum drying