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

Abstract

In Sri Lanka, several tea grades are produced in factories located in different agro-climatic regions within three geographical elevations. The study aimed to determine the microbial quality of different tea grades and composite tea samples obtained from factories situated at diverse locations. The average APC, yeast & mould counts and coliforms in different tea grades ranged from 3.4 × 103 to 2.0 × 104 cfu/g, 4.8 × 102 to 2.5 × 103 cfu/g and 0.005 to 3.9 × 101 Most Probable Number (MPN)/g respectively. The tea samples collected from different factories had mean values of APC and yeast & mould as 5.3 × 103±1.3 × 103 cfu/g and 9.7 × 102±1.9 × 102 cfu/g. Escherichia coli (E.coli) and Salmonella were not detected either in tea grades or in composite samples. The identified microorganisms in tea samples belong to phyla Firmicutes, Proteobacteria, Ascomycota, Basidiomycota and Zygomycota.The samples collected from the mid country elevation had the highest counts of APC and yeast & mould counts were high in the low country elevation. More than 70 % of the tested samples comply with the SLTB guidelines given for the microbiological quality of black tea. The distribution of bacterial, yeast and mould and coliform densities of tea were significantly variable with respect to geographic areas.

Keywords

• Black tea
• Tea grades
• Microbial quality
• Agro climatic regions
• Elevations