Studies on the ‘fermentation’ of Ceylon tea

Abstract

THE production of CO2 during fermentation in the manufacture of black tea has been observed by previous workers [Evans, 1928, 1, 2; Bosscha & Brzeskowsky, 1916; Roberts, 1939]. Evans (Ceylon) found that tea leaf like most other plant materials had a respiratory quotient of 1.0 which, however, did not appreciably change during withering. While crushing had no effect on the R.Q. of fresh leaf it caused a marked decrea%e in the R.Q. of withered leaf, due to a very large increase in the 02 uptake associated with oxidation of polyphenols. This 02 uptake, which is initially very rapid, gradually falls off until the ratio C02/02 again approximates to unity. The volume of C02 produced during fermentation decreases only slightly with time, e.g. 40 g. of rolled leaf at 180, which produced 4-6 ml. in the 1st hr., still formed 3-8 ml. in the 7th. As a result of these obser- vations Evans [1928, 2] concluded that 'the respiratory process is upset when