Effect of storage temperature on antioxidant activities of Citrus medica L. var. limetta

Abstract

Citrus medica L. var. limetta is commonly known as citron or somsa in Thailand. It is a local fruit in Thailand. Its leaf and peel provide a unique aroma oil and flavour. The peel provides flavor and aroma in several Thai recipes. In addition, it is believed to have medicinal effect on sore throat, cough and sputum. In contrast to its wide applications, somsa is not widely utilised due to limited availability which leads to few studies of somsa. The objectives of this study were to study antioxidant activity in different parts of somsa (peel, segment, and seed) and to compare fresh with 3-months stored somsa as well as with other fruits from the Citrus genus. The methods of analysis were ferric reducing antioxidant power (FRAP), diphenyl-1-picrylhydrazyl (DPPH), and Folin-Ciocalteu assay (total phenolic compounds), respectively. The results showed that the antioxidant activity in all parts of stored somsa was increased. Peel of stored somsa increased from 5.86 to 11.12 µM TE g-1 in FRAP assay, segment of stored somsa increased from 2.91 to 34.09 µg GAE g-1 in TP and seed sample increased from 0.88 to 1.94 µM TE g-1 in DPPH. This indicated the occurrence of new compounds which exhibited antioxidant activities during storage showing by changes in color and flavor. Therefore, 3 months storage of somsa at elevated temperature could be an alternative way to increase antioxidant activities compared to fresh sample.