Evaluation of Microbiological Contamination of Black and Green Teas

Mateusz Ossowski,Jolanta Kr�L,Martyna Kasela,Piotr Maksym,Anna Malm,Lukasz Wlazlo,Bozena Nowakowicz-Debek

doi:10.19026/ajfst.17.6016

Abstract

The study aimed to determine the level of microbial contamination of black and green teas with different degrees of fragmentation. The microbiological analysis we conducted on 18 black and green teas available commercially on the market. Solutions were prepared from the weighed samples and then inoculated on sterile microbial media. Teas in bags proved to be the most polluted among the tested tea groups. Statistical analysis indicated significant differences in mycological contamination between black and green teas of various degrees of fragmentation. Green tea in bags manifested the highest fungal contamination - 9.3×103 CFU/g, significantly exceeding the other teas. Isolated fungi belonged to Aspergillus sp., Cryptococcus sp., Rhizopus sp., Mucor sp., Penicillium sp. and Cladosporium sp. The lowest number of fungi we observed in the group of green leaf teas -1.7×102 CFU/g. We recorded the most significant amount of Gram-positive bacteria in deciduous black tea - 1.8×103 CFU/g. The correlation between the degree of tea fragmentation and their microbial contamination has been demonstrated. Potentially pathogenic bacteria isolated from black and green tea can pose a threat to the health of consumers.

Highlights

The microflora of products with low water content, i.e., dried plants, is characterized by a wide variety of species in both qualitative and quantitative terms
The highest geometric mean value indicating the highest mycological contamination was obtained for green teas in bags - 9.3×103 CFU/g (3.97 log CFU/g)
The lowest fungi load among green teas were observed for green leaf teas - 1.7×102 CFU/g (2.24 log CFU/g)

Summary

Introduction

The microflora of products with low water content, i.e., dried plants, is characterized by a wide variety of species in both qualitative and quantitative terms. Having entered the gastrointestinal tract, potentially harmful microorganisms originating from soil or water, in direct contact with plants, may cause severe poisoning (Carraturo et al, 2018; European Medicines Agency (EMA), 2013; Stojanović et al, 2011; Omogbai and Ikenebomeh, 2013; Marin et al, 2013). Such biological hazards include mold producing dangerous mycotoxins. The same applies to the majority of toxins produced by bacteria (Carraturo et al, 2018; Marin et al, 2013; Quadros Rodrigues et al, 2014; Sobieraj-Garbiak and Drożdzyńska, 2015)

Methods

Results

Discussion

Conclusion