Seeking natural source of yeast nutrient

[TimT]

Superstock - boil to kill the wild yeasts. Though this may not matter either - stronger yeasts will almost always dominate. Perhaps boil as a precautionary measure.

 

[sp0rk]

I know it's not strictly a "nutrient" for the yeast, but have you tried or considered adding a minute amount of olive oil?

https://www.google.com.au/webhp?tab=ww&ei=6afLUovlJ8WBlQXb8oHgBw&ved=0CBUQ1S4#q=olive+oil+yeast+starter

Seems to be lots of homebrewers claiming that it improves fermentaion in one way or another, meets your criteria for being a readily accessibly, common ingredient. The biggest issue I see with it is being able to accurately measure a small enough quantity of it for ~ 20L of wort.

The amount you need is less than a bee's wiener
I've done it a few times, I heat sterilize a pin, let it cool and then scrape it inside the neck of the bottle
This gets the tiniest coating and then I give it a stir in the starter
It does work for me, but I've been too lazy to do it for my last few brews
The theory/SCIENCE! is that yeast turns oxygen into unsaturated fatty acids, which helps yeast grow and create cell walls, olive oil contains oleic acid, which does the same thing (apparently)
I've got a few beers and ciders planned for the next few months, so I might give it a try again soon

 

[TimT]

As far as I understand sufficient FAN should be provided from malt in an AG brew.

Cool, so this suggests that one way of storing up yeast nutrient, especially for meads and other non-grape wines, etc, would be simply by taking a small portion of your wort before adding hops/flavourings etc. Maybe freeze it. Of course the question is, why wouldn't you want to keep it all for the beer, but my guess is it wouldn't have to be much. (It's all a bit speculative).

In answer to your last question Carniebrew, no not really - the product you suggest is just a variant product on the other ones you can get at brew stores. I'm looking for a common product you can just find around your home, or in the garden.

I take Galbrew's point about beer making being not entirely natural, and therefore buying yeast nutrient to give the yeast optimal performance is a simple and easy solution - but for my brewing I'd like to also have the option of just using, for instance, sultanas or raisins. The science is still very vague to me - but the responses on this thread have given me more of an idea of my options. Thanks everyone! I'll keep this thread open in case anymore helpful and creative solutions for using yeast nutrient come through!

 

[TimT]

This all suggests to me what I'd suspected already - that older methods of brewing, in which pots full of a sweet ale wort or wine must were left out to catch a wild yeast, and then were considered to contain that yeast in subsequent years - may have had something to them. If you don't clean out the pot thoroughly, then dormant and dead yeast cells will hang around, providing zinc for later colonies. And if you make beer in a pot or barrel one year, then some yeast nutrients inherent in wort will stay in the vessel, waiting for the next brew to come along.

(Only makes sense if you don't clean the vessels thoroughly of course, which is, er, somewhat antithetical to modern practices Though if you have a barrel you're never going to be able to sterilise the lot anyway and I wouldn't be surprised if even in modern times brewers who use barrels just refill their barrel with another wort or must straight after they empty it, so the young and vigorous yeast cultures take over where the older yeast cultures left off.)

 

[O'Henry]

I don't think storing a small portion of the wort would be enough. You would need more than that. For some reason I have it in the back of my mind that 60% or more should have enough FAN, but the number may be more. The less malt you have the more likely you are to run into FAN problems, esp when the malt isn't great for FAN.

Lager malt usually has a higher FAN spec, I'm guessing due to the typical use of adjuncts with it.

 

[superstock]

Superstock - boil to kill the wild yeasts. Though this may not matter either - stronger yeasts will almost always dominate. Perhaps boil as a precautionary measure.

Don't know what boiling would do to the nutrients in the dried grape. Have only ever used commercial yeast nutrient in beer and raisins as described previously in meads and ciders.

 

[GalBrew]

Keep in mind that while servo from White Labs are dead yeast, they were pre loaded with zinc, which is why they are zinc rich. The other problem you have is the bioavailability of you nutrient of choice. For example there is plenty of nitrogen in the air, but this cannot be used by yeast, hence the need for FAN, which can be metabolised by yeast.

 

[TimT]

I wonder a bit about the boiling too Superstock, though given that others recommend throwing yeast nutrient into the boil anyway maybe FAN isn't particularly affected by a boil.

 

[TimT]

So a method could be -
boil wort or must, maybe add a tiny bit of vegemite or old yeast to the boil so the yeast dies but the nutrients remain
get a few raisins, not that many, maybe chop them up to expose flesh and so the bits of raisin can be dispersed throughout the wort or must (though some of the ginger beer starter recipes I've seen just recommend throwing them in whole) (note here I am assuming that the yeast you want to ferment your brew will be so healthy and vigorous it will overwhelm any wild yeast living on your raisins)
chuck into the fermentation vessel along with yeast, add the wort or must, aerating if necessary
seal and let it have a yeast party.

If beer: quite possible you could skip most of these steps. If making a wine, (provided it's a non-grape wine) follow these steps to ensure the yeast gets enough to eat.

 

[superstock]

I wonder a bit about the boiling too Superstock, though given that others recommend throwing yeast nutrient into the boil anyway maybe FAN isn't particularly affected by a boil.

Commercial yeast nutrients are concentrated chemical salts, ignoring the dead yeast type, and as such are probably not affected by the boiling. But use too much and you can affect the taste. Natural nutrients are less concentrated and so you need more of it by volume but it is almost impossible to overdose, although I imagine large volumes may add flavour. Also if you put the raisins in whole, the yeast have to wait until the skin becomes permeable before they can access the nutrients. This may inhibit the yeasts growth.
My personal feeling is s/h yeast in the boil for beer, raisins,tea and lemon juice in ciders and meads.
I've never had a problem using raisins straight from the packet. There is an opened packet in the cupboard presently which if contaminated would be going off after the heat and humidity we've had lately and it's not.

 

[TimT]

Just as follow up to this - I'd been wondering what the odd yeast-looking clouds were in my latest brew, a yarrow and raspberry leaf saison. Several small round pale yellow blobs hovering at the top when all the rest of the foam had pretty much cleared up. I'd noticed them yesterday morning and was starting to get a tad worried this morning - I was thinking, 'hmmm, did any of the herbs I put in during the boil accidentally get into the fermenter?' Or even worse - 'is it an infection?'

And then it hit me.

Small. Round. Pale yellow. Blobs.

They're the bloody raisins I put in. The yeast is living on them in happy yeasty colonies!

I'm a nong, but a happy nong