Fact or Fiction? Chemicals in Tea
What do tea, bubbles in beer, and homeopathy have in common? Answer - recent highly technical papers by physicists and material scientists tackle these subjects and provide sophisticated insights on how these items function.1-3 My initial intent was to write a column including all three, showing how high-powered science was stepping into the fray. However, research on tea alone led to many side-tracks mostly regarding one of my favorite topics: multi-chemical foods and beverages. So, this month’s topic is tea. Beer and homeopathy will have to wait until some future date. Speaking of chemicals, tea, like many natural products, contains hundreds of compounds. Plants are capable of synthesizing tens to hundreds of thousands of primary and secondary metabolites with diverse biological properties and functions. To date, more than 7000 flavor volatiles have been identified and cataloged from foods and beverages.4 If someone offered you a cocktail of butanol, iso amyl alcohol, hexanol, phenyl ethanol, tannin, benzyl alcohol, caffeine, geraniol, quercetin, epigallocatechin-3-gallate and inorganic salts, would you take it? Or would you place it in a secure container and contact your friendly environmental activist for advice? If recent media coverage of environmentalists' concerns about our exposure to chemicals has left you feeling paranoid, then you might opt for the second option - or, as is more likely, you'd pour the mix down the drain and leave it for someone else to take care of.5 As a reader of this column, you wouldn't get alarmed but would drink the cocktail because you are clever enough to know that the mixture is nothing other than a cup of tea. However, there are more chemicals than just these. In the aroma of tea alone, some 467 compounds have been identified. Ivon Flament classifies these products into their functional groups or their heterocyclic structures and comes up with 18 distinct families. Table 1 lists these chemical classes while comparing tea to coffee (655 compounds) and cocoa (462 compounds).6 Table 1 - Partition of coffee, cocoa and tea flavor constituents into chemical classes.6 Number of identified compounds Functionality Coffee Cocoa Tea Hydrocarbons 50 39 37 Alcohols 20 25 46 Aldehydes 28 22 55 Ketones 70 24 57 Acids 20 51 71 Esters 29 58 55 Lactones 8 7 16 Phenols 42 6 19 Furans 99 19 9 Thiophenes 26 --- 1 Pyrroles 67 18 10 Oxazoles 27 15 2 Thiazoles 28 9 7 Pyridines 13 12 23 Pyrazines 79 94 22 Amines and N-containing products 24 45 18 Sulfides and S-containing products 16 10 5 Other compounds 9 8 14 Total 655 462 467 Featured Content Epner Technology Pays Tribute to Industry Legend Stephen Candiloro Jr.