Microbiological quality of tea imported to Poland from Asia and South America

The quality of tea and its microbiological cleanness are influenced by the following factors, such as: the kind of soil, weather conditions, conditions of the storage and transportation. Koga et al. reported that on tea plantations, at the sour reaction of acid soil (pH<6) along with the decrease pH follows the set-back of the development of microorganisms. Also it was observed that along with the decrease of the contents of water in soil from 52.5% the quantity of microorganisms falls by half. Additionally, too long process of withering of tea leaves, their excessive exsiccation, the prolonged process of the classification and irregular passage of the packing and transport of the raw material can contribute to the development of microbes [1,2,3,4]. Samples of black tea from Argentina (12), China (12) and Indonesia (15) were selected for this study. The mesophilic total count was determined by Total Plate Count. The samples were incubated in the plates at 30⁰C±1⁰C for 48 hours. Count of yeast and moulds was determined in the media – Dichlorane Glycerol Agar (DG18). The samples were incubated in the plates at 25⁰C±1⁰C for 5 days. Results show that Total Plate Count contents in examined tea samples was highly diversified. It ranged from 1.54 log cfu/g to 5.59 log cfu/g. The highest quantities of microbiological contaminates were obtained from Argentinian teas – average 4.14±0.90 log cfu/g, whereas the lowest in Chinese teas – average 3.63±1.2 log cfu/g. This analysis did not show a significant influence of region of origin. It was found that yeasts and moulds in samples of tea were variable and dependent on the country of origin (ranged from 1.40 log cfu/g to 5.13 log cfu/g). The highest quantities of yeasts and moulds were determined in Argentinian teas – average 3.81±1.03 log cfu/g. This analysis showed a significant influence of country of origin.

This paper was financed from Republic of Poland scientific funds in the years 2005–2007, as a research project, within grant no. 2 P06T 031 29.

References: [1] Chou, C. et al. (1999) International Journal of Food Microbiology 48: 125–130. [2] Koga, K. et al. (2003) Journal of Bioscience and Bioengineering 5: 429–434. [3] Sanaka, S. et al. (2000) Journal of Bioscience and Bioengineering 1: 81–85. [4] Yam, T.S. et al. (1997) FEMS Microbiology Letters 152: 169–174.