How Clean Is Your Tea? Microbe Quality Across Regions

Jenn Hoskins
30th March, 2024

How Clean Is Your Tea? Microbe Quality Across Regions

Image Source: Natural Science News, 2024

Key Findings

  • In Sri Lanka, most teas meet local microbial safety standards
  • No E. coli or Salmonella found in any tea samples
  • Microbial counts in tea vary by geographic elevation
Tea is a beloved beverage enjoyed across the globe, and its quality is of paramount importance to consumers and producers alike. One aspect of quality that is often overlooked is the microbial content of tea. Microorganisms, including bacteria and fungi, can influence the flavor, safety, and shelf life of tea products. The Industrial Technology Institute in Sri Lanka has recently conducted a study[1] to evaluate the microbial quality of different tea grades from factories across various agro-climatic regions in Sri Lanka. This research is crucial as it addresses the potential health risks associated with microbial contamination in tea, an issue highlighted in earlier studies[2][3]. The Sri Lankan study assessed the microbial load, specifically the average plate count (APC), yeast and mold counts, and coliforms in various tea grades. The APC is a measure of the number of bacteria in a sample, while yeast and mold counts indicate the level of fungal contamination. Coliforms are a group of bacteria, including pathogens like E. coli, which can indicate fecal contamination and the potential presence of other harmful microorganisms. Remarkably, the study found that E. coli and Salmonella, which are serious foodborne pathogens, were not detected in any of the tea grades or composite samples. The research revealed that microbial counts varied significantly with geographic location. Tea samples from the mid-country elevation showed the highest bacterial counts, whereas those from the low-country elevation had higher yeast and mold counts. Despite these variations, over 70% of the tea samples met the Sri Lankan Tea Board's microbiological quality guidelines for black tea. The study's findings are consistent with previous research[2], which identified a range of fungi involved in the fermentation of Fuzhuan brick-tea, a unique microbial fermented tea. The dominant fungi found in the brick-tea, such as Eurotium and Aspergillus, are similar to those detected in the Sri Lankan tea samples, belonging to the phyla Ascomycota. Interestingly, the earlier study[2] also recognized the presence of beneficial fungi that contribute to the fermentation process and enhance tea quality. Another relevant study[3] conducted in Italy on commercially available black and green teas highlighted the risks of improper tea storage, which can lead to the growth of harmful bacteria and molds. This research found microbial loads in most tea samples, with a significant number exceeding the limits for safe consumption. The presence of ochratoxin A, a toxic compound produced by certain molds, was detected in many samples, raising concerns about consumer safety. The Sri Lankan study expands on these findings by providing insights into the microbiological quality of tea in relation to different production elevations. The research methods employed did not specifically look for ochratoxin A but focused on the overall microbial counts and the presence of harmful bacteria, which are critical for assessing tea safety. The results of the Sri Lankan study are significant as they offer a comprehensive overview of the microbial landscape of tea produced in different regions. The absence of E. coli and Salmonella in the samples is reassuring for both consumers and producers. However, the variability in microbial counts with geographic location suggests that environmental factors and production practices can influence the microbial quality of tea. The study also underscores the importance of maintaining stringent quality control measures across the tea industry to ensure the safety and quality of the final product. This research complements and builds upon previous studies[2][3] by providing a more in-depth analysis of the microbial content in tea and highlighting the need for targeted regulations and monitoring to safeguard consumer health.

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Main Study

1) Microbiological quality of different tea grades produced in diverse agro-climatic regions in Sri Lanka.

Published 30th March, 2024

Related Studies

2) Fungal community associated with fermentation and storage of Fuzhuan brick-tea.

3) Comparative assessment of the quality of commercial black and green tea using microbiology analyses.

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