En Jie Rudd

How important is oxygen in Pu-erh's conversion?

We are all aware of the fact that the older a Pu-erh is, the better the quality. There are currently two options to acquire a well aged Pu-erh:

1. Buy it from a vendor, which is often expensive
2. Purchase young and store to age

The storage conditions are however crucial, they can make or break a tea. There are abundant theories out there speculating on the ideal conditions for a Pu-erh to age and convert: humidity, temperature and oxygen levels etc. There is however not so black and white when it comes to apply them in real life.

There has been an interesting article published recently about a an interesting experiment.

Method (www.puercn.com, Author: Yang Zhong Yue)

Four samples were created in 2013 using the same product, a fresh Jingmai (景迈) Gushu Pu-erh Maocha:

  • One vacuum sealed
  • One sealed, buy not vacuumed
  • One sealed, buy injected oxygen on a regular base
  • One natural open storage

All four samples were stored in a storage with a humidity machine for 4 years – the machine starts extracting extra humidity after it has exceeded 70%.


  • The vacuum sealed Pu-erh sample: The colour has converted nicely into golden red, aroma strong in both dry leaf and tea brew. The downside is that it is very bitter, the most bitter one of the four samples.
  • The sealed but not vacuumed sample: good colour – golden red; Good aroma, but slightly less than the vacuum sealed sample; Significant reduction in bitterness and astringency.
  • Oxygen injected sample: Colour gold, less red than the previous two; Aroma OK, but not as strong as previous two. Bitterness and astringency reduced, more than the vacuumed one, but similar to the non-oxygen injected one.
  • Natural open stored sample: Colour gold, similar to the oxygen injected one; Very little aroma remained; There is some reduction in bitterness and astringency, but not as much as the sealed non-vacuumed one.


  1. Vacuuming is good to keep the Pu-erh teas in their original state, eg sample keeping, but not for consumption purpose ageing.
  2. Oxygen did not appear to have significant impact on the Pu-erh tea’s conversion, illustrated by the results of the oxygen injection and the natural open storage sample.
  3. There has been an active and ongoing internal conversions regulated by the internal enzymes of the tea leaves under the sealed conditions, result in rather satisfactory reduction of bitterness and astringency and colour conversion, without losing the aroma as the open stored sample. 
  4. The author acknowledged that this comparison was only conducted 4 years after the storage, longer term differences of the storage impacts on the Pu-erh teas are yet to be studied. 


Top ripened Pu-erh tea a gamble than a prediction

Compared to most of the Chinese teas, green tea, white tea or black tea, ripened (Shou) Pu-erh tea is still in its infancy state – born in around 1975. ripened Pu-erh tea

Ripened Pu-erh’s ageing process is somewhat different from the traditional raw (Sheng) Pu-erh:

  • It is believed that ripened Pu-erh has less ageing potential, as the potential is overdrawn during their speed fermentation process called Ou-Dui.
  • On the other hand, the residual odours left from the Ou-Dui (acidic, fishy and mushroom smell) takes 2-3 years to evaporate

The combination the above results in a necessity of around 10 years to allow the ‘true colour’ of a ripened Pu-erh to reveal – the ‘bad stuff to disappear’ and the ‘good quality to come out’.

While being relatively new and lack of traditional wisdom to refer to, the Pu-erh masters are trying to draw some ‘road maps’ from the current available experiences while producing ‘new’ ripened Pu-erh tea for the future use.

Like all other teas, producing a premium quality ripened Pu-erh requires: 

  • The right original material – tea leaves
  • The right processing skills
  • The right storage conditions after their production

As the knowledge of processing ripened Pu-erh is being explored and accumulated and skills being fine-tuned, there is a consensus in the community that getting hold of a top end ripened (Shou) Pu-erh tea is more of a gamble than a prediction (可遇不可求).


The transformation of Chinese tea from a local produce to a modern luxury

buy Chinese teaWe have witnessed the traditional Chinese tea, green tea, white tea, Oolong tea, Pu-erh tea and all others transforming from a country folk’s staple food to a luxury item today during our life time from aspects more than one.

A bit of history

My grandmother was a classic villager resided in a small country village in the Fu-Jian Province, the tea country of China. Following are some of my memories of the tea consumption when I was growing up in her village.

My grandfather died when my grandmother was in her late 20’s. For a woman like her of that time in China without a husband, the alternative name was extreme poverty as women simply did not have ‘jobs’. For rich for poor, teas however companied her for all her life.

Like many other villagers of her time, the first thing she would do when she got up in the morning was to get ready for a pot of tea for after breakfast. The teas were mostly locally produced, in her case mostly green tea and Oolong tea, and purchased from the local market with all other local produces. Tea was a must have every day. When visitors dropped in without any warning (phones were not available), the first thing she did was to put the kettle on and get the teapot ready for a pot of tea to share. Tea was a way of everyday life, not just for the rich.
The costs of teas have sky rocketed since largely due to the increased demand, in China and worldwide. This increase of prices affects categories of all Chinese teas: green tea, white tea, yellow tea, Oolong tea, black tea and Pu-erh tea.

A Luxury for aspects more than one

Apart from the price increase, the is also another element of ‘out of reach’ that is much ignored, which is TIME. I have had so many inquiries for methods to: brew teas while customers are waiting; reduce tea temperature quickly so that the customer can consume immediately; tea bags suitable for those who are on the go and the list goes on. A crucial aspect of tea enjoyment with is sitting down, take time to share a pot of tea with families and friends over a chat, unnoticeably disappears into the history.

As a Chinese decedent who is proud of my inheritance, tea, not as a product but a culture, is one of the few that I wish we could turn the clock back a few decades. Off the treadmill of the modern life style and take time to enjoy a humble pot of tea like my grandmother’s generation did.

Additional note

Ironically, one of the reasons that the popularity of tea is rapidly increasing worldwide is their potential to combat ‘modern life style related health conditions’, such as cancers, cardio-vascular-diseases, overweight and diabetes etc. How much weight can the humble teas pull remains to be determined. This reminds me of a Chinese humour regarding our current lifestyle: the companies pay with money and we pay with our lives.


Pu-erh tea storage risks

Puer teaA big advantage of Pu-erh tea in comparison to other tea categories such as green tea, is its aging nature. There is not urgency to consume the tea while fresh as a tea naturally improves with ageing. The down side however is the risks of damage during the storage period. The following images surfaced during the recent cyclone/flood in Fang-Cun of Guang-Zhou (the tea trade capital of China): the street turned into a river of tea soup and tons of teas damaged. There is not available data on how much damage has been caused yet, but the sight is not looking good. 

A good aged raw (Sheng) Pu-erh or ripened (shou) Pu-erh would require at least good 10 years storage under optimal conditions. Many factors can affect the tea’s quality if not damaged completely. The sale price of tea is therefore: the original the purchasing cost, long term storage cost factoring the damaged stock along the way.

If global warming is affecting all aspects of human lives, tea industry is not excluded and Pu-erh tea is a vulnerable one. 

pu-erh tea


Tea water separation a strange but useful term

It is almost impossible to talk about a tea without water, from cultivation to the final stage of tea brewing.

The ‘tea water separation’ discussed here is however a different but meaningful concept.

The very reason that teas are delightful to sensors is because of the effects of their internal substances. The correct brewing methods maximise the extraction of these substances and their optimal concentration in the tea brew.

‘Tea water separation’ is a term used to describe the breakdown of this process. The impression is the ‘incomparability of the tea and water’.

Following are some of the causes to ‘tea water separation’ of Pu-erh teas:

Processing issues:

  1. jelena 4Tea leaves harvested during the raining season, Chinese term ‘水味’ (water taste)
  2. Short of rubbing during the processing. These causes the insufficient release of the internal substances for tea brew.
  3. Not steamed and compressed thoroughly during the processing. The ‘tea water separation’ phenomenon is especially prominent when new/young for these teas. 

Brewing method issues:

  1. Pu-erh tea requires 100-degree temperature hot water to brew the tea. The tea can taste ‘watery’ if the water temperature is not high enough.
  2. Insufficient ‘tea waking (醒茶)’ time. It takes normally 5-10 seconds for the tea leaves to be separated from each other when brewing compressed tea. A rush to serve the tea can cause the brew to taste ‘tea water separation’.
  3. Inadequate serving intervals can cause the tea internal substances to dissolve in the brews unevenly.
  4. Too many infusions from one serve of the tea leaves.


Subscribe to this RSS feed