| dc.description.abstract | This study involved analysis of microbiological risk factors and their control
points in commercial black tea manufacture at Githambo tea factory. The specific
objectives were: 1) Determination of the levels of total viable counts, coliforms and
Staphylococcus aureus in the raw material (fresh green tea leaves) and at the
processing stages of withering, rolling, fermentation, firing/drying, sorting and
packing; 2) Determination of the quality of water used for cleaning and soaking of
oversized tea and its effects on total viable counts, coli forms and Staphylococcus
aureus; 3) Determination of the hygiene status of equipment surfaces and utensils
used in tea processing; and 4) Identification of the critical control points for identified
microbiological hazards.
Total viable counts (log of means/g) were highest at the reception (6.57),
reduced after drying (4.50) but increased at packing (4.64). Faecal coliform counts
(log mean MPN cells/g) increased from field (2.61) to maceration/rolling (3.49),
reduced at drying (2.32), and finally increased at packing (3.58). Staphylococcus
aureus counts (log of means/g) increased from the field (3.61), to the maximum at
withering (5.47), then reduced at ferme~tation (4.82) and further at drying (l.83), but
finally rose at packing (2.08). After drying, black tea underwent contamination in the
sorting and packing sections. The most contaminated (expressed as log of total viable
cells/em' ) factory equipments were scooping spades (4.47) and ball breakers (3.79)
while the interior surfaces packing paper sacks(1.33) were the cleanest surfaces and
were of expected microbiological quality (maximum of 102 cells/em"). The quality of
water used in the factory was not potable i.e. did not comply with requirements of the
Kenya Standard (KS 05-459) but this did not correlate with the microbiological
quality of black tea (P< 0.01). Grading of black tea significantly affected its level of
contamination (P< 0.05) with primary grades meeting the required microbiological
quality while secondary grades were non-compliant. Microbiological hazards were
therefore classified as risks posed by enteropathogenic microrganisms indicated by
the presence of faecal coliforms and pathogenic Staphylococcus aureus.
Drying/firing, sorting and packing processes were identified as a Critical Control
Points (CCPs) for both categories of hazards.
In order to enhance product safety, it is recommended that commercial tea
processors adopt HACCP as a food safety management system. There is need to
modify the tea processing machinery in order to eradicate tea spillages in all the
sections especially the dry tea section. Further research is recommended to establish
mechanisms of reduction Staphylococcus aureus by the fermentation process, effects
of the withering and fermentation conditions on the likelihood of enterotoxin
production by pathogenic Staphylococcus aureus and its fate after drying. There is a
further need to establish the microbiological quality status of tea in the Kenyan retail
market. | en |
