Effects of Fermentation under Enriched Oxygen Atmosphere on Clonal Black Tea Aroma Complex

Enriching the atmosphere of fermenting “dhool” (macerated leaf) with oxygen led to faster production of some black tea volatile flavor compounds (VFC). There was a general rise in the total amounts of the VFC with long fermentation duration irrespective of whether it was done under enriched oxygen atmosphere or ambient air. The rise was, however faster under enriched oxygen atmosphere than under ambient air. The rise was also faster in the group I VFC than the group II VFC leading to a general decline in the Flavor Index with long fermentation durations. For every fermentation duration, the sum of group I VFC was higher under enriched oxygen atmosphere than under ambient air fermentation. Such variations were only marginal in the group II VFC. As a result, fermentation under enriched oxygen atmosphere reduced the aroma quality of black tea despite increasing the total amounts of VFC. Generally, the VFC which are oxidative products of amino acids and unsaturated fatty acids degradation increased with fermentation durations, while the major terpene alcohols declined under both ambient air and enriched oxygen atmosphere fermentation conditions.