So im reading this study (more looking at the graphs than reading)
"Study on the increase mechanism of the caffeine content during the fermentation of tea with microorganisms"
quote:
"molds fermentation increased the caffeine content, but yeasts fermentation decreased the caffeine content. Among the three molds in this study, Aspergillus niger van Tieghem has the most remarkable effect, and the caffeine content in dry green tea increased from an initial 3.47% to 9.63%.
the changes of caffeine and theophylline were of a similar trend. Possibly theophylline instead of theobromine is the precursor of caffeine in the living microorganisms."
endquote.
While they say green tea caffeine went from 3 to 9% - that is only at day 15, but at the end of the study - day 30 the caffeine content was just slightly above the starting point or even dropped significantly.
With "black tea" the results were more similar between the different microbes, and caffeine content increase in all of them somewhat linearly (unlike the green tea) from ~4.5% to 5% at 30 days.
...
is there any info on what more age (years) +/- microbes does to caffeine/theophylline in the tea? especially puerh?