Effect of gamma-irradiation on the phenolic acids of some Indian spices

Five commercially important spices, namely cinnamon, clove, cardamom, nutmeg and mace, were subjected to gamma-irradiation using a dose of 10 kGy, which is recommended for microbial decontamination. Various phenolic acids present in these spices were analysed by high-performance liquid chromatography (HPLC). In clove and nutmeg, quantitatively significant changes were noted in some of the phenolic acids upon irradiation. The content of gallic and syringic acids in irradiated clove increased by 2.2- and 4.4-fold respectively, whereas in irradiated nutmeg many of the phenolic acids showed wide increases and decreases in the range of two- to sixfold compared with the control samples. No qualitative and major quantitative changes were, however, observed in the phenolic acids of cinnamon, cardamom and mace upon irradiation. The possibility that gamma-radiation induced breakdown of tannins could be responsible for the changes in phenolic acids content of clove and nutmeg is discussed.