Effectiveness of Irradiation Treatment in Eliminating E. coli O157:H7 and Salmonella in Dried Organic Herb Samples Intended for Use in Blended Tea

Blended tea with different herbs, seeds and dehydrated vegetable substances bring a world of flavours, aromas and colours to tea. Tea is usually made with dried tea leaves, or blended with other dried herbs and pouring boiling water over the leaves and letting them stay for a few minutes and then sip. This study was done to evaluate the microbial contamination of dried organic lemongrass, mint and jasmine samples intended to prepare flavoured tea and also to see the effect of gamma irradiation in inactivating microorganisms in dried organic herbs (lemongrass, mint and jasmine) samples intended to prepare flavoured tea. Presence of higher number of generic E. coli and pathogenic E. coli O157:H7 in dried organic lemongrass, mint, and jasmine samples, and blended tea samples were observed. No Salmonella was detected in dried lemongrass sample; however, presence of Salmonella was evident in mint and jasmine samples. Application of 2.0 kGy irradiation dose was able to successfully eliminate the pathogenic E. coli O157:H7 and Salmonella in lemongrass, mint and jasmine samples. In addition, the aerobic bacterial count was also reduced to <100 CFU/g in dried lemongrass or other tea samples. This finding suggested that application of 2.0 kGy dose of irradiation could successfully eliminate the pathogens and provide safe food with lower bacterial content compared to non-irradiated herbs for human consumption.