Vietnamese Iced Coffee 11. Electronic Resources 8. List of Contributors 2. The Chemistry of Caffeine and related products 1. The variability in the amount of caffeine in a cup of coffee or tea is relatively large even if prepared by the same person using the same equipment and ingredients day after day.
Tea also contains two other alkaloids, theobromine and theophylline.
These last two relax the smooth muscles where caffeine stimulates the heart and respiratory systems. The effects of theobromine are, compared to caffeine and theophylline, relatively moderate. However, cocoa contains eight times more theophylline than caffeine. As well, caffeine has been shown to combine with other substances for added potency. Thus the effects of theobromine might be enhanced by the caffeine in chocolate.