Microbiological conditions of tea [Camellia sinensis], 1
2002
Sawamura, S. (Ito-En Co. Ltd., Sagara, Shizuoka (Japan). Central Research Inst.) | Ito Nakano, E. | Kato, I.
The hygienic maintenance of food has become an increasingly important issue in recent years. This is true in the tea industry as well. In the present study, we investigated the amount of microorganisms in incoming lots of crude tea (green tea). Crude tea contains large amounts of microorganisms in comparison with oolong tea and black tea, ranging most frequently from 3 * 10E3 CFU /g to 1 * 10E4 CFU/ g. In oolong and black teas, the amount of microorganisms most frequently ranges below 3 * 10E2 CFU /g. Differences attributable to the crop year, harvesting season and a location of the plants have been neglected. We have found, however, a difference in the amount of microorganisms with two types of steaming machine: a net drum type and a conveyor type. The amount of microorganisms in crude tea from the conveyor type tends to be greater than that from the net drum type. We also investigated the quantity of microorganisms in the samples from each process stage of the plant. At the stage of fresh leaves, the amount of microorganisms in the tea sample was about 1 * 10E6 CFU/g. In tea processed in net drum type steaming machines, that was decreased to the range of 10E2-10E3 CFU/g. In tea processed in conveyor steamers, however, the amount was decreased to only 10E5 CFU/g. In late stage tea plants, the amount of microorganisms in the sample was increased, and the final amount of microorganisms in the crude tea was in the range of 10E2-10E4 CFU/g. It is presumed that two main causes on the large amounts of microorganisms in crude tea are the survival of these microorganisms in the steaming stage and the secondary contamination from late stage of plants.
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