Valorization of ultraviolet-C (UV-C) dose validation in spices: Changes in phenolic contents and antioxidant activity during storage of UV-C-treated dried spices powder

Abstract

In this work, ultraviolet-C (UV-C) radiation was applied at dose levels of 0, 0.5, 1, 1.5 and 2.0 kJ.m–2 to evaluate changes on the antioxidant capacity of dried fennel seeds, chilli pepper, and coriander seeds powder during storage. The samples’ total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydra-zyl activity, and ferric-reducing antioxidant power (FRAP) were evaluated prior to and after storage for 6 and 12 months at 25°C and a relative humidity of 45%. The results showed that spices treated with UV-C doses had significantly greater content of TPC, TFC and FRAP during storage, compared to untreated samples. The validation of UV-C dose, as investigated by the partial least squares regression analysis, stated the most valid dose for each dried spice that improved its phenolic content and antioxidant activity prior to and after storage. These findings revealed that UV-C irradiation could help alleviate losses and sustain spices’ quality and shelf life as a postharvest treatment method.