In this third part of our series on Pu-erh tea we look into the fermentation in pu-erh tea a little closely and the changes it brings about in post-fermented teas.
Fermentation and Recipes
So what exactly causes the tea to ferment in pu-erh and what does that process do to the tea? We are often times asked this question. Also the question how kombucha is different than pu-erh often arises because kombucha is also a fermented form of tea.
The fermentation in pu-erh is initiated when the tea is steamed and compacted. Microorganisms start growing in the tea leaves due to the moisture trapped in the cake. These bacteria and fungi react with the chemicals in the tea, producing different flavors while also changing the chemical composition of the tea.
The fermentation that undergoes in the pu-erh tea is "solid state fermentation," as opposed to kombucha where the fermentation happens in a liquid triggered off by a symbiotic culture of bacteria and yeast (SCOBY). Aspergillus niger, a fungus, is the predominant microbe found in both sheng and shu pu erh. Aspergillus niger is considered to be a "industrial fungus" because it is also cultured to produce substances like citric acid, gluconic acid, high-fructose corn syrup, and pectinases. The latter is used for cider and wine clarification.
While Aspergillus niger is relatively found more in shu pu-erh, research has uncovered in sheng pu-erh a yet underdetermined species of Aspergillus fungus in higher concentration. Other microbial members included Penicillium, Rhizopus, Saccharomyces, Actinoplane, Streptomyces and Bacterium.
The 2016 study "The Microbiome and Metabolites in Fermented Pu-erh Tea as Revealed by High-Throughput Sequencing and Quantitative Multiplex Metabolite Analysis "* also had some interesting findings:
Traditionally, pu-erh specially the ripe variety is thought to be very good for digestion. People in Asia, where pu-erh is popular, often drink shu with rich food like dumplings. Also pu-erh fans believe that both varieties of the tea impart a benefit at a more psychic level - triggering off a "qi" effect, where a warm fuzzy sensation can be felt in various parts of your body. Some describe it as a kind of a high.
Another scientific study identified statins, popular medicine against coronary diseases, in pu-erh.
Pu-erh cakes come with a number printed on their wrapper. This number which is consists of 4 digits is called the "recipe." The first two numbers indicate the year, the third number leaf grade and the last number denotes the factory where it came from. For example our 2006 Feng Qing Raw Pu-erh Tea comes with recipe number 7813. This means the first production of this recipe took place in 1978. The grade of leaf used is 1 and it comes from factory number 3 or Xiaguan Tea Factory.
The most famous and sought after recipe number is 7542. A blend that started in 1975, with grade 4 leaves and made by factory number 2, which is Menghai tea factory.
There are 10 and more grades of leaf for making pu-erh. Although the higher grade means more larger and broken leaves, it is not a consistent system and does not reflect on the quality of the tea.
As for the factory and its corresponding numbers they run as below.
*The Microbiome and Metabolites in Fermented Pu-erh Tea as Revealed by High-Throughput Sequencing and Quantitative Multiplex Metabolite Analysis. - Yongjie Zhang, Ida Skaar, Michael Sulyok, Xingzhong Liu, Mingyong Rao,and John W. Taylor
**Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea. - Jeng KC1, Chen CS, Fang YP, Hou RC, Chen YS.
This is first of a 3 part series on Pu-erh tea.
Pu-erh is fermented and aged tea that comes in a compacted form. Produced exclusively in Yunnan, the South-Western province of China, the tea is produced in two broad styles - raw (sheng), and ripe (shu). Sheng pu-erh is left to ferment naturally, while the fermentation in ripe or shu pu-erh is done in controlled factory settings.