Quality of Ghana herbal tea: microflora and control measures

Abstract

The microflora of Ghanaian herbal tea comprising dried leaves of Cinnamon, Hibiscus and Citronella have been investigated under field and laboratory conditions. Fungal species isolated varied from one sample to another. Sixteen fungal species were isolated from Hibiscus, belonging to the genera Aspergillus, Cladosporium, Eurotium, Manoascus. Paecilomyces, Penicillium, Septodochium, Rhizopus and Syncephalastrum; thirteen fungal species belonging to the genera Aspergillus, Cladosporium, Emericella, Monoascus, Penicillium, Streptomyces, and Rhizopus were resident in Cinnamon tea while nine fungal species belonging to the genera Aspergillus, Cladosporium, Monoascus, Rhizopus and Syncephalastrum were encounted on Citronella tea. Aspergillus species (A. candidus, A. fumigatus, A. ochraceus, A. rubrum, A. terreus, A. wentii) predominated followed by Cladosporium (C. herbarium, C. cladosporioides, C. macrocarpon). Some potential pathogenic bacteria (Flavobacterium meningoseptium, Pseudomonas cepacia, P. paucimobolis and Xanthomonas maltophila were also encountered. Some of the aeromycoflora isolated from the farms from which the tea leaves were harvested (Aspergillus candidus, A. fumigatus, A. ochraceus, Cladosporium clasosporioides, C. herbarium, Penicillium digitatum, Syncephalastrum spp.) also infected the dry leaf samples. Gamma irradiation up to 5.0 KGy reduced the microbiological loads of the tea samples by 2-5 log cycles. A combination of low (£ 75% ERH) storage ERH and packaging material (brown paper and transparent polyphone) significantly lowered the moisture content of the dried tea samples and increased their shelf life. Practical implication of these findings are discussed and further studies suggested.




JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 3, July (1999) pp. 84-99