Pu-erh: Compressed, microbial, semi-infinite in variety
Pu-erh teas are “different.” Most tea drinkers will never sample one in their lifetime or even know about them. Most pu-erh lovers will never exhaust the choices if they live to be a hundred – including trying ones even older than that.
They are by far the most complex of teas, in terms of variety, processing, taste characteristics, marketing, counterfeiting, pricing, brewing and history. You could go through this broad list and identify a pu-erh uniqueness in comparison to any other tea type. There’s one more to add in the form of a question: are pu-erhs different in their known impacts on health?
Yes, decidedly so, according to the consensual findings of scientific papers published in respected journals.
A 2012 study found 60 bioactive compounds and six bacteria strains in its sample of pu-erhs. The authors concluded that there is an accumulation of evidence for their contribution to cardio health, but no smoking gun. That accumulation of findings in lab studies of rats and mice has included improvements in blood pressure, triglycerides, cholesterol, obesity, diabetes and other “Bad For You” elements of serum lipid profiles. Such animal studies don’t necessarily transfer to human subjects where so many other factors come into play: bioavailability, toxicity, dosage, biogenetics, medications and side effects. There have been surprisingly few studies outside the lab and using human subjects.
But the lab research shows very clearly the active power and effectiveness of pu-erh’s microbial and bacterial agents. It’s not at all clear from the research how they work but why they work is very apparent: the highly “different” nature of the making of the tea.
The basics of pu-erh processing: A minimalist summary
The processing of pu-erhs fully oxidizes the original leaf – the equivalent of cutting an apple open so that it browns. In tea, oxidation breaks down cell walls and stimulates a wide range of enzymatic interactions between the leaf’s over 600 compounds and the air. The oxidation can be stopped by heating, affecting the retention of multiple polyphenols – flavonols, flavonoids and catechins. These affect taste, aroma, color and potential microbiological impacts on the body, and hence health. Basically, green tea is minimally oxidized, oolongs 20-80% and black teas fully so, with exceptions and variations in methods.
Pu-erhs are unique in that their bacteria continue to ferment over many years – 15 is still “young” – and there are ones that are over a century old, with claims of rare ones being made from leaf gathered from thousand year old bushes. They are wide-ranging in rich flavors, with descriptors like earthy, damp, and mushroomy. (The ones that are poorly made and matured have the scent of compost but a fine pu-erh reminds you of the forest floor during an autumn walk in the woods.)
Pile-fermentation: The Catalyst that Creates Shou Pu-erh
Compressed teas come in many forms: brick, bowl, bing, tuocha (birds nest), or pressed inside an orange or bamboo stem. They may be “raw” or“cooked.” These evolved historically on the basis of trade: storage, transportation and portage along the thousands of miles of the Tea Horse Road from the South West province of Yunnan, still the fabled home of pu-erhs, to Tibet, Nepal. Mongolia and even the Balkans, where they were used as a barter currency as late as the 1920s.
Pu-erhs are made from the same camellia sinensis bush as any other true tea: Japanese tiny sencha green leaf, wiry and curly Chinese and Taiwan oolongs, or Darjeeling long, thin tips. However, the best come from large broad leaf wild trees that have not been kept trimmed down, and laid out in rows. The processing is equally distinct from the mainstream of tea. The base tea is fully oxidized but does not kill off all the enzymes in the leaf. These continue to “ferment” over many years, creating the palette of flavors pu-erh is famed for. Basically, green and black teas are bacterially and microbially dead while pu-erh continues to live.
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