Puer microbial analysis
I might soon have access to a new technology that identifies microorganisms. I am curious about experimenting with it for testing puer tea.
I think it will be useful for detecting harmful organisms in funny smelling samples, and for fine tuning the aging process with regards to optimal humidity, for example.
It would also be interesting to check for microbial development after breaking up the tea and letting it breathe.
I am curious to hear other ideas.
I mentioned an interesting reference in a recent blog post on pu’er storage issues, just a bit technical though:
The Microbiome and Metabolites in Fermented Pu-erh Tea as Revealed by High-Throughput Sequencing and Quantitative Multiplex Metabolite Analysis.
http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0157847
mrmopar, I will update you if and when I start working with this.
John, Great article, particularly the part below is important. I have sometimes drank the first infusion. Now I know that its not just a taste issue.
that was interesting, and it gave some background and validity to the common claim that it doesn’t matter if you use a rinse for most types of teas but for pu’er, shou or aged sheng, you should. for occasional consumption taking in some extra toxins might not be a problem but for regular pu’er drinkers that could add up to a real issue.
The abstract talks about all of the toxins in the tea, but when you try to investigate the specific toxins mentioned, there is very little info to suggest there is a real hazard.
Part of the problem is that the data is based upon dry tea, and only a handful of the supposed toxins have more than 1 part per million. Most seem to be on the order of 10 parts per billion. Since we dilute the dry tea significantly when we steep, even if we assume that 100% of the toxins wind up in the tea, then if we produce 1 liter of tea from 10 mg of tea, then we’re at less than 1 part per billion in our drink. The one quantitative negative in the paper says that patulin is limited to 50 ppb in apple juice, but appears to be at something like 5 ppb in puerh. Many of the compounds seem to have positive (anti-fungal) applications.
So, I guess part of the conversation should be a clearer view of whether all of the fungi/bacteria/metabolites are beneficial or harmful.
I know that it has been claimed for years that ripe puerh has beneficial bacteria in it.
A lot of the fungi and bacteria that I looked up said they are very common in soil and on agricultural products. no indication of negative effects. Some claimed positive effects. The biggest negative seemed to be the products that they product (metabolites) some of which are said to be toxic.
Fantastic project, I would know the results too. :D
Thank you jon-in-siam for the link, it’s very interesting. :)
As linked in one of my posts (http://www.aguywithagaiwan.com/2016/08/21/compression-and-storage-why-it-matters/), you might want to check out this study: http://www.ncbi.nlm.nih.gov/pubmed/23973844
I would like to see a massive program where the microbial populations are inventoried for a large number of samples of raw teas of varying ages.
Have anyone else seen on webMD that it says the bacteria in Puerh actually produce natural lovastatin, and the older the tea,the more lovastatin there is? I thought that was interesting as it is one of the sites that seems more trustworthy than some others.
Yes, I’ve found this abstract a short time ago: http://www.ncbi.nlm.nih.gov/pubmed/23587710
This may be interesting but isn’t useful. The therapeutic dose of lovastatin is 20 mg and the paper measured tenths of micrograms per gram of tea.
I will not pretend to be scientifically minded but I do see the intrigue in finding out the microbial values of teas such as Puer.
As people have mentioned it will change very much per Puer depending on it’s storage. Either way it will be interesting to see exactly what we are drinking.
My husband is allergic to quite a few types of aspergillus which puts a stop to his fermented tea drinking. I just don’t want to risk giving him the wrong thing. Wiki talks about Aspergillus Niger being used as the microbial agent used in Puer when previous studies have found it to be Aspergillus Luchuensis instead. https://en.wikipedia.org/wiki/Fermented_tea
My point in being from a health point of view it’s always better to know what you find. This is why I am looking forward to seeing your results.
I know it is a Chinese theory that ripe puerh has probiotics and that these probiotics can actually survive the boiling water to in theory do you some good. It was my gastroenterologist view that they could not survive boiling water.
We considered this too, that boiling water should kill any living aspergillus present. Though I suppose without testing it I may not be positive.
Anyone who has ever gotten sick from badly fermented ripe puerh can tell you that some bacteria can survive the boiling water.
@AllanK, there would also be the mechanism where toxic stuff accumulates in the leaf and is there whether the microbes are dead or not.
Seems a good time to check back in about all this.
Related to aardvarkcheeselog’s last comment, that is my understanding, that the toxins accumulating are the issue, not the live microbe agents that caused those to develop. Because of this only a rinse would reduce those toxins, to an extent that would be easy to determine by testing but not so easy to determine otherwise, but killing the actual microbes may or may not be a concern.
Related to Kittylovestea’s comment, I did mention the same point in that pu’er storage post, but I didn’t add much beyond a brief mention of the WebMD description that a compound used as a medicine is found in pu’er tea. It was interesting since this may be the kind of evidence that’s missing from current tea health claims being perfectly valid but not easy to justify. This may be atypical since a drug-related compound is in the tea, and for other claims and benefits unusual types of dietary supplements, trace components, may be present, but that could be a more difficult case for establishing beneficial cause and effect.
That blog post and the WebMD link (which is a bit sparse, with most of that subject covered in a short citation here):
http://teaintheancientworld.blogspot.com/2016/09/puer-storage-and-fermentation.html
There is interest in using pu-erh tea for lowering cholesterol because, unlike other teas, it contains small amounts of a chemical called lovastatin. Lovastatin is a prescription medicine used for lowering cholesterol.
Just my two cents: here in HK, I’ve been taught to rinse pu erh twice. In Kunming, a dealer even rinsed fresh maocha twice. The Hong Kong Government itself also advocates rinsing all teas to reduce pesticide residues. I rinse ALL Chinese teas at least once.
Login or sign up to leave a comment.