Effects of Drying on Total Polyphenols Contents and Antioxidant Properties of Carica Papaya Leaves.

Papaya is widely grown in Malaysia and normally only the fruits are consumed. Other parts of the plant such as leaves, roots, bark, peel, seeds and pulp are also known to have medicinal properties and have been used to treat various diseases. Papaya leaves also contain flavonoids, alkaloids phenolic compounds and cynogenetic compounds as well as reported able to treat dengue fever.

Studies were carried out on drying of papaya leaves using hot air (60 °C, 70 °C and 80 °C), shade and freeze drying. Effective diffusivities were estimated ranging from 2.09 × 10^-12 to 2.18 × 10^-12 m² s^-1 from hot air drying which are within the order of magnitudes reported for most agricultural and food products. Activation energy to initiate drying showed relatively low value (2.11 kJ mol^-1 ) owing to the thin leave layer that eased moisture diffusion. In terms of total polyphenols contents and antioxidant activities, freeze-dried sample showed significantly higher (p<0.05) total polyphenols contents (2158 mg GAE 100g DW^-1 ) and antioxidant activities (ABTS = 571 mg TE 100g DW^-1 and DPPH = 215 μg mg^-1 ) as compared to hot air and shade dried samples.

Freeze dried sample retained the most total polyphenol contents and showed the highest antioxidant activities in both ABTS and DPPH antioxidant assays. Hot air and shade drying are not conducive in preserving the antioxidants owing to possible thermal degradation at elevated temperatures and oxidations under prolonged drying condition. This article is protected by copyright. All rights reserved.