I am new here and mentioned a few things in the welcome center, this post in a continuation of that. So if you want a little background on how this post appeared the thread that started it is here http://homedistiller.org/forum/viewtopi ... 27&t=52488.
By request I have been asked to keep this at a level that most people can grasp, I will do my best but equally if anybody wants more in depth information I will supply links etc to papers that should give you all the information you want.
First a quick introduction for those that dont read the 'Hi I am new here threads'
I am a scientist that works in Biotechnology, my professional and personal research at the moment is based around yeast. I dont drink however and my interest in my personal research revolves around getting yeast to make other things besides Ethanol, currently most of my effort is based around getting them to produce Isoamyl Alcohol.
I cant do it all in a single post so I will just keep adding to this thread. Two things first though, some information I use might come from current research I am being paid to do, therefore I will be unable to use anything I have yet to publish in the public domain, where possible I will supply an alternative reference though.
The other thing is I also have a fully equipped laboratory at home as well as work, so if anyone wants certain experiments doing etc shout up and we will get it done. I have access to a well equipped Electronics,Chemistry and biotechnology Labs so most things should be possible. I also have a Gas Chromatograph and mass spectrometer both at home and work so analyzing results will be done using more than the dip finger and taste test
. While we do have the ability to DNA test strains this is expensive both time and reagent wise so it isnt something i will do doing routinely, but I do hope that if I get sent some interesting samples then I will do a DNA profile.So what are yeast? what do they do? how do they do it? and where do they come from? Lets start from there.
Yeast are single celled organisms they belong to a order known as eukaryote, this just means its has cells with bits in called organelles (yes over simplified at this point), Most people view yeast as just a kind of bag that takes things in and turns stuff out, the inner workings are way more complex, as we go on we will delve deep inside the yeast cell so we can fully understand how and why it makes you a drink. The following picture is of a typical Eukaryotic cell, dont fret over all the bits yet as and when needed we can refer back to it.
So what do yeast do? Well there sole aim is to live and reproduce, if you answered make booze your wrong, not all yeast make alcohol and even those that can dont always, in fact it couldnt care less what comes out of it, in that respect its no different from you and I. we pay more attention to what we ingest and trying to reproduce than we ever do worrying about whats coming out of us. Its important you wipe from your minds the notion that yeast actually want to make you alcohol, they dont care what they make, and what they make depends on what the take in, now at this point it would be easy to say what they eat, or consume. But there are different ways that yeast ingest products.
We say products because in reality not everything yeast ingest is of use to it and some are very much not healthy for them. At this point I am going to say that when I use the term yeast I am talking specifically about Saccharomyces cerevisiae more commonly known as bakers yeast................Yes sorry to disappoint some but the most common yeast you all use (including most Turbo yeasts) is Saccharomyces cerevisiae and this is plain old simple bakers yeast, yes there are different strains and later when we get into genetics I will explain some of this, but on the whole when you hear or read people talking about wine yeasts or beer yeasts, or maybe trying out bakers yeast, they are in fact all exactly the same organism.
Ok so your back from taking a stiff drink at this shocking news, better get the bottle ready again..............Yeast are not the only organism thats involved in making your drink :O..........Knowing that last statement will lead to trouble for some I will at this point offer some proof. The following is a rough flow chart of the most common organisms you will find in the majority of brewing situation, not all ferment, but as we will see later all cells (except two types of human cell) Respire, all respiration produces a by product, so like it or not each and every one of these organisms if present will be 'respiring' (in science terms) or taking a shit (in other terms) in your brew.
Some of the by products you might notice in taste or smell others you may well not notice at all, but all of then will have some effect.
The reason all affect what you produce is simple.........some organisms will be producing products that some of the others are using to make there products, This is the true art form of brewing, the ability to balance the process to obtain results that you find pleasant.
Bokulich NA, Bamforth CW. The Microbiology of Malting and Brewing. Microbiology and Molecular Biology Reviews : MMBR 2013;77(2):157-172. doi:10.1128/MMBR.00060-12.
If anyone wants a copy of the paper the PID is PMCID: PMC3668669
That will do for part1, I will stop at this point in case anyone wants deeper explanation or clarification, I will then continue later
PART 2
So before we go down the deep dark rabbit hole of detail lets take a look at where these beasts occur in the natural world, its probably a good idea to narrow this down a little and look specifically at two areas in particular, Vine yards and orchards. Although much of the following will equally apply to your gardens and hedgerows and the fruits found therein.
I do not have citations as yet that I can use for this section, I will come back and cite papers you can access for free once I have found them, I appologise for this. I had wrongly assumed that seeing as much research had been conducted in this field there would be freely available information, in turns out all the references I have used for this section come from sources such as journals that you need to pay for, or from work that is not for public publication! There will be many sources however I can cite and post links to papers you can down load freely, I just need to come back after digging them up.
So there we are at home with a freshly prepared plate of agar agar with all the correct nutrients in and perfectly sterile, we open the lid and place the petri dish down on a surface for an hour. Then proudly we place the lid on the petri dish TAPE around the outside and place UPSIDE DOWN [ You do ALL place your petri dishes tapped and UPSIDE down dont you?] in our environmental chamber (or incubator,or warm cupboard, or anywhere else that will give us the temperature we require).
If you an old hand in microbio labs jump this bit
With yeast and when using petri dishes it is GOOD and normal practice to place the plate UPSIDE DOWN in the chamber, if its a wild plate (a plate that you have allowed to self inoculate, then it is ESSENTIAL you tape around the edge and seal it. please note a single strip all the way around will suffice, there will be those that scoff at this, however none will be able to show you a paper or book that advocates any other way. So why upside down? Normally you will be plateing up in order to isolate a single colony or colonies of yeast or other organisms, unless you use very high end chambers etc its highly likely you get condensation form on your plate, it dosnt always . But to be on the safe side we store most plates upside down so any condensation formed dosnt run into colonies on the plate and spread them into others, it also helps keep the colonies fresher. So why when air plating do you seal the agar plate? Actualy on a personal level when dealing with any culture or organism I have not directly handled and know beyond reasonable doubt to be pure, I seal ALL plates. Although considered a little over the top when dealing with say culture to culture plating, I have been unfortunate enough to witness what can happen with bad practice So the reason we seal all air plates?
- air plate.jpg (8.37 KiB) Viewed 9051 times
NO yeast plate is worth risk, if you see anything that dosnt look right, or anything you cant identify, then safely destroy the plate and leave the seal intact (we will go through how to kill plates without a autoclave later).
Not everybody dies that messes with unknown microbes, but please take the time to learn a few things so you dont become one of the few that do die.
NEXT section I will go into the main route for yeast to get onto fruit etc, and no air is not it! sorry to have to leave it here but work calls.
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So where do our little friends live when there isnt fruit around? Where do they go and keep warm in the winter?
I have asked this at several talks I have to give at brewing conventions etc, it never ceases to amaze me how many people in the industry will tell you BEES. When I get home tonight I wil attach 2 papers that show you will not find yeast under normal circumstances in Beehives, in fact Bees hate yeast! Its bad news for a bive hive full of sugar to yeast show up. Talk to a beekeeper about propolis and they moan how it takes them ages to clean off a hive that hasnt been opened in a while. They moan about how the bees put it all around the gaps and especially around the brood chamber.
Then you ask them what do Bees make propolis for anyway? Some will instantly answer its just there kind of glue, I have had its a draught excluder (nearly close), and some simply shrug and tell you its the bees way of keeping you out. Propolis is wonderful stuff, in the laboratory I have spent hours taking this stuff apart chemically. Truly amazing properties, it also cost the bees a great deal of energy to produce, more so even than wax. So in a wild situation say in a hollow tree, you will find it all around the outside of the main cone, its also used to connect the cone along its side. This stuff is a anti microbial power house! very sticky at first then it begins to harden as more microbes are ingested on it. Yeast if you ever manage to find any in a Bee hive are always on the propolis being chemically digested.
So anyway No yeast dosnt live in beehives, no one truly knows how bees dont manage to pick up the spores from fruit etc but some how it just dosnt stick to them, all other modes are covered by the bee super glue, so how do we know bees dont get yeast on them? Because if thy did then you would find it in there gut, the main method it would be taken off from them is by grooming, this leads to organisms that get attached to bees are often found in there gut.
Apart from keeping and dissecting many bees myself (varroa research) I have searched the literature thoroughly and can find no reference to yeast in a bees gut. I will attach a paper that details how propolis deals with yeast, also as a side note bee keepers sto moaning about it when you tell them what it does.
So we know where its not so where is it? Wasp or more precisely social wasps are where they stay during the winter (the majority, there are other minor sources), this leads to a remarkable evolutionary..........................................TBC
Welcome...and teach away.
