Abstract
The aim of this work was to assess the heavy metal presence and possible microbiological contamination in herbal teas. Evaluation of selected tea products was performed from Nitra locality during years 2009 - 2013. Microscopic filamentous fungi detection, bacteria such as Escherichia coli and Salmonella spp. were compared to requirements given in the Codex Alimentarius of Slovakia. The highest permissible limit for microscopic filamentous fungi was not exceeded (in 32 observed herbal tea samples). For incidence of Escherichia coli, 93 samples were investigated and for Salmonella spp., 91 herbal tea samples. No sample showed the presence of Salmonella spp., and at E. coli maximum permitted presence was detected below limit. Among chemical parameters, cadmium, lead and mercury content were monitored. The highest amount of lead and mercury was found in year 2012. In 2009, the highest cadmium content was found. The average content of lead in all 100 inspected herbal tea samples was 0.784 mg.kg-1 so all the samples met requirements defined in the legislation. The mean content of mercury (98 investigated herbal tea samples) was 0.0161 mg.kg-1 so all samples met the requirements as well. Average cadmium content was 0.1702 mg.kg-1 while the highest permitted limit for cadmium is 1.0 mg.kg-1. All herbal tea samples were in accordance with the legislation except one (white willow bark tea) with a very high content of cadmium (4.36 mg.kg-1).
Highlights
The tea is a product of plant origin, which is intended for preparing a beverage or prepared from such product
Herbal teas must meet requirements for maximum levels of microorganisms that are listed in the Codex Alimentarius of the Slovak Republic and there are clearly defined contents for Escherichia coli as well
We focused on determination of the chemical parameters, namely the determination of lead, cadmium and mercury in herbal teas and their mixtures for a period of five years
Summary
The tea is a product of plant origin, which is intended for preparing a beverage or prepared from such product. It is necessary to meet the legislative requirements for the production and import of tea, tea extracts and preparations thereof, for handling them and placing them on the market as is defined by the legislation. The composition of tea varies by variety, season, leaf age, climate and practices at harvest. Its chemical composition is a complex including carbohydrates, amino acids, proteins, alkaloids (caffeine, theophylline and theobromine), volatile compounds, polyphenols, minerals and trace elements (Bansal et al, 2013). The results of several studies show potential health benefits of tea, due to the consumption of tea. Multiple benefits are described, such as prevention of cancer and heart disease (Sang et al, 2011)
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