EFFECT OF DRYING TEMPERATURE ON BIO-ACTIVE COMPONENTS AND PHYSICAL PROPERTIES OF LEMON PEEL

Abstract

The study was carried out to study the effect of drying on bio-active components and physical properties of lemon peel at different temperature. Lemon of variety “madrasi baramasi” brought from local market of Dharan, Sunsari was used for the preparation of lemon peel powder. The fruit was sorted, washed and peeled. Lemon peel was submitted to oven drying at 50℃, 60℃, 70℃ till moisture content reached 5% and the dried peel was grinded to make fine powder. Bio-active components (Antioxidant activity, Polyphenol content, Flavonoid content, Ascorbic acid, Tannin) and physiochemical analysis (Bulk density, Solubility, Oil absorption capacity and Swelling capacity) were measured on fresh (control) and dried samples. Drying lemon peel with the higher temperatures sharply increased the loss of bioactive components. The results showed that drying at 50°C indicated less reduction on bioactive component. Increase in temperature decreases the bioactive component, i.e., at 70℃ the TPC, TFC and antioxidant scavenging activity of lemon peel were found to be reduced by 31%, 61% and 26% respectively similarly, tannin and Ascorbic acid content were found to be reduced by 46% and 36% respectively. This study evaluated the physiochemical properties of peel powder which indicated that the increase in temperature increases bulk density, oil absorption capacity and swelling capacity but decreases solubility index. All analyzed samples showed that low temperature drying method is the best method for obtaining higher bioactive component.