Irradiation effects on color and functional properties of persimmon (Diospyros kaki L. folium) leaf extract and licorice (Glycyrrhiza Uralensis Fischer) root extract during storage

Abstract

Irradiation effects on color and functional properties of persimmon (Diospyros kaki L. folium) leaf extract and licorice (Glycyrrhiza Uralensis Fischer) root extract were studied. Persimmon leaf and licorice root extracts were irradiated using Co-60 gamma irradiator at 0 and 20 kGy absorbed dose and stored at 4degreesC or -20degreesC for 2 weeks. Tyrosinase inhibition effect (TIE) of both extracts was not different by 20 kGy-irradiation but reduced during storage. Electron donating ability (EDA) of the persimmon leaf extract was generally consistent, but that of licorice root extract was reduced by irradiation except for I week of storage. Both TIE and EDA of persimmon leaf extract were higher than that of licorice root. Hunter color L*-, a*-, and b*-values were changed, resulting in a desirable brighter color by irradiation. During storage, the bright yellow color of irradiated sample changed to brown gradually, and especially the changes in the refrigeration condition (4degreesC) was faster than frozen (-20degreesC). Results indicate that irradiation can be a useful method to produce value-added natural ingredients with functions such as persimmon leaf or licorice root for food or cosmetic industry in addition to elimination of microbial load. (C) 2003 Elsevier Science Ltd. All rights reserved.