sobota 29. června 2013

Mold under miscoscope

Due to exceptional kindness of Ondra Novák, I acquired some microscopic photos of molds (white spots on wetter tea and aspergillus crystatum from Fu brick). Actually, I wanted to post the photos of the former (the white spots) to back up my earlier statement that it is mold (and to refute the statement of certain other people). Some photos were composed from Z-stacks using Combine ZP, if you're interested in the source photos, just ask me - but the depth of field is really small so one does not see that much from that.

White spots first:
Unfortunately, I drank almost all of tea with coating I had, therefore I had to use a tea which has been only mildly wet stored and had only a couple of white spots. The magnification is a bit limited by the dry objective used, but it should be sufficient nevertheless:

a stem

... and a closeup

The only other thing that the white spots could have been was probably crystals of minerals (sort of like efflorescence) - and the white matter is obviously not crystals (at this magnification level, they would be entirely obvious). It totally looks like puffs of mold hyphae.

I wonder what sort of mold it is. It might be some acremonium, maybe (which also plays its role in shu puerh). Anyway, I'm currently searching for a lab which could perform the analysis.

Aspergillus Crystatum
How does our good friend, found, e.g., in Fu bricks, look like? 

The microworld is entirely amazing - is it not?

7 komentářů:

  1. What idiot told you its no mold? Great photos btw.

    1. Hello Phil,
      well, owner of one local store wrote on his site how the white coating on wetter stored tea is by no means mold...

  2. All health, non-moldy puerh has a lot of fungi which have potential to develop mold (under improper storage or under pile fermentation). And mold generally is not a microscopic structure. So it's rather paradoxical that you have to use a microscope to see "mold".

    Most molds are of comparable sizes as the "golden flowers" (which are not molds), yet photos show a huge difference between the first group of microbes and the golden flowers.

    Whatever conclusion you draw, your photos are great illustrations of tea microbes. And it helps to read about the life history of fungi from a textbook.

    1. Hello Gingko!
      Well, it rather depends on what you call a unit of mold. I had some spent tea leaves that developed mold and the single hyphae were about as large/thin as those of the white flecks on stems/white coating.

      E.g., acremonia tend to grow in the form of single hyphae and therefore can look like a very thin spider web - while it can cover large surface, it sometimes also produces light coating rather than obvious puddles.

      I think that the white flecks/coating on wetter stored pu do not need a microscope - but to show that it is composed of filaments and not, e.g., crystals, a microscope is useful.

      The definition of mold is rather loose, but as far as I know, one of the most common is something like "a fungus that grows in the form of hyphae" - i.e., a mold does not have to have these fruiting bodies to be a mold (that could be sort of like to say that a tree that's not blooming is not a tree...). This white stuff has hyphae, thus, imho, it is mold. I might try feeding it a bit to see how it develops. Or I may just take it to a lab for analysis...

      Anyway, I don't have an issue with that white stuff - there is plenty of molds that are all right and this one is probably one of them (and if a tea is rinsed, it will be washed away anyway).

      Thanks for your comments, the discussion is much appreciated!

    2. Jakub, when people use the word "mold", there is usually a negative connotation. I agree the definition of mold is rather vague and varies case by case. But with your definition of mold, you may have to call most good aged puerh "moldy", and will have to spend extra time to tell people "moldy puerh" is healthy. That doesn't sound very convenient.
      My definition of mold would be based on blooming/sporulation of fungi (often accompanied with toxin production). So I would think moldy puerh is always bad.

    3. Ah, I guess that it really depends... I agree that molds generally have negative connotations, however, in cheese, people got used to them.

      Well, in that article in Art of tea, they demonstrated that pretty much all puerh (even young) contains mold/fungi... I think that the better the people get used to that, the better.

      For me, it is important whether the fungi are visible by naked eye - the white coating is visible, therefore I consider it to be a mold...

      According to your definition, I agree that I'd throw moldy pu out.

  3. This is not a tea fungus, but tells the story of life cycle:

    The molds are the "fruiting bodies" which can be seen with naked eyes from 10 meters away most of the time and usually contains spores that can fly off in a blow. Your first groups of photos show the stages well before the fruiting bodies, and if an aged puerh doesn't have them, then it's not a puerh...

    The golden flowers are specialized structure that don't contain spores and similar to the two stages before fruiting bodies.

    For better illustrations and explanations, I recommend Campbell Biology. You can buy an older edition for $1 on amazon, and it tells you a lot more about biology than many other more expensive ways.