Effects of Processing and Handling Operations on Microbial Load in Black and Green Teas during Tea Manufacture
Abstract
Tea (Camellia sinensis) is considered a low-risk food in terms of microbial contamination due to the way it is processed, packaged, and consumed. It is the most popular and widely consumed drink worldwide, second only to water. However, there are possibilities of microbial contamination along the value chain, and for this reason, care should be taken to eliminate them. The study investigated the microbial safety of tea along the processing line, providing insights into the diversity and quantity of microbes identified along the value chain. Tea processing steps are followed, and the microbial profile is assessed from green leaf reception up to the finished product, following stipulations in the ISO Kenyan Black Tea Standard. This research study addressed the gap in existing research regarding the microbial status of teas across several processing stages in Kenyan tea factories, encompassing leaf reception, withering, maceration, oxidation, drying, sorting and grading, packaging, and storage. The primary objective was to assess the microbial profile of teas along the processing line and recommend microbial quality control strategies aimed at minimising cross-contamination risks during and after tea processing as per KS EAS 65:2018. By identifying and quantifying microbial populations at each processing stage, this study aimed to contribute valuable insights that could inform the implementation of effective Good Manufacturing Practices and hygiene protocols to ensure the production of microbiologically safe teas for consumers. This study focused on both cut, tear, and curl (CTC) teas free from microbial contamination. Bacteria and fungi were isolated using Nutrient Agar (NA) and Potato Dextrose Agar (PDA), respectively. Escherichia coli and Staphylococcus spp. were isolated from tea, while Salmonella spp. was not detected. The yeast and mould detected were within the limits set in the standards. The findings show that even though there are set guidelines and standards for microbial control in tea processing, like HACCP and KEBS, the effectiveness of these control measures in various Kenyan tea factories is limited
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