The influence of gamma radiation on the aflatoxigenic fungi, phenolics content and antioxidant activity of the green tea.

Abstract

The use of raw plants, including the green tea (Camelia sinensis), has been increasing in Brazil. Along with this increasing tea consuption, there are risks due to its unsuitable handling and storage, which points to the need of controlling possible contaminations. This could be achieved with the use of ionizing radiation. In this context, the present study aimed to evaluate the effect of gamma irradiation over the total phenolics amount, antioxidants and fungic activities of the green tea aqueous extract aiming its processing. Aliquots of the bulk samples have been analyzed before and after gamma irradiation (dosages of 0; 5; 7,5 and 10 kGy). The total phenolics content of the aqueous extracts was determined by using the Folin-Ciocalteu reagent having the catechin as the standard. Those same extracts were used to evaluate its abilitity of scavenging the free radical DPPH. The microbiological analysis were performed through irradiated samples and control. The results have allowed to check that different dosages of radiation (5; 7,5 e 10 kGy) did not induce significant differences on the content of total phenols and on the antioxidant capacity of the analyzed samples when compared to control. Also, it was also observed that the radiation may have had a catalytic effect on the oxidation of the DPPH and was effective on the microbiological control, even though it was not possible to kill the aflatoxigenic fungus.