Wild yeasts

[Andy Hamilton]

Just written this for my "booze for free" book and thought, as the discussion has come up on here before, I'd share it and see if anyone had any comments.

It is possible to not use yeast in a recipe, that is it is possible to rely on wild yeasts which are omnipresent in our atmosphere. Many wine makers in the old world won’t add any yeast. They crush the grapes get the juice and let the wild yeasts get on with it. Each year they take the grape skins and place them as a mulch around the vines. Over time this changes the natural mix of wild yeasts in the area, favouring the Saccharomyces strain above all else. This has taken centuries and the hope of booze maker to have the same happen in their back garden in Romford in just a couple of years is hopeful at best. Reliance on wild yeast isn’t like going to a loud packed nightclub in the hope of finding a future long term partner. It might happen but the chance will be truly serendipitous.

However, whenever I make non-alcoholic champagnes wild yeast do seem to take hold very quickly and work very well. For the champagnes it doesn’t matter so much that the yeast “eats” all the sugar as the only reaction you are looking is it eating some and therfore getting some carbonation and many yeasts do that.

[gregorach]

Wild yeasts are all very well if you're not worried about minor details like flavour or clarity...

Mind you, I'm seriously considering buying a decent microscope to take my yeast-wrangling to the next level, so you might not want to listen to me.

[grahamhobbs]

Don't know about home brewing in England, but I do about wine making in France au Paysan, ie. how the locals do it. If I suggested adding yeast to their grapes, they would look at me as an English simpleton and say mon dieu, non, non, non, pas de tout. No ordinary french person would dream of adding yeast to their grapes.

As for putting the grape skins around the vines, I've never seen or heard of this, it sounds like an old wives tale. If anything the skins and stalks, called marc, are sent of to be distilled into eau de vie (in some areas also called marc). Otherwise they are used as compost, not that there is much, perhaps 5 to 10 barrow loads, from an acre vinyard.

The yeast on grapes is naturally occuring, you don't have to do anything, it is just there. True you can get different strains and obviously some commercial wine makers play around with them, but ordinary small producers don't, they use what comes naturally.

[gregorach]

Wine is sufficiently alcoholic that you can get away all sorts. I'm a brewer, so I tend to be a good deal more careful about such matters, and I maintain a small library of different yeast strains with distinct characteristics.

I know sod-all about traditional French wine-making, but I do sometimes wonder how much yeast really comes from the grapes, and how much comes from the vessels...

Mind you, they'll drink bloody anything over there.

[oldjerry]

Chuck grape skins on the soil? Are you kidding?........GRAPPA.

[grahamhobbs]

I know sod-all about traditional French wine-making, but I do sometimes wonder how much yeast really comes from the grapes, and how much comes from the vessels...

Mind you, they'll drink bloody anything over there.

It's true your average french paysan will drink anything (much like a lot of our home brewers). It is the custom in France for your host to pour the glasses of wine but for them to left on the table for several minutes before he indicates it's time to drink. I used to think charitably that this was to allow the wine to breath, but I noticed that the worst the wine was the longer it was left, everyone dreading when they were going to have to drink it - some wine can be as rough as scrumpy.

Although wine made on the farm in France, can be made in the most unimagineable conditions ( a cross between a coal cellar and a garden shed), they do usually try to sterilise their 'vessels' before commencing the fermentation of the grapes - so don't think the yeast comes from the vessels. Again I think there is a lot of mystic built up about these things, like the terrior, by the big producers to exagerate the uniquness of their wine. The big name wine growing areas are by the big rivers of France, simply because that was the best place for transport, not the uniqueness of their soils.

[gregorach]

Although wine made on the farm in France, can be made in the most unimagineable conditions ( a cross between a coal cellar and a garden shed), they do usually try to sterilise their 'vessels' before commencing the fermentation of the grapes

Emphasis on the word "try". You can't sterilise anything without an autoclave, and if the Scottish Amateur Winemakers are anything to go by, their sanitation practices probably leave a lot to be desired... As I said earlier, the higher alcohol content of wine can hide a lot of bad practice. There's also plenty of opportunity for environmental exposure if you're not using closed fermentors and transferring using aseptic techniques.

I'm not saying the yeast doesn't come from the grapes, but I'd love to see the results of a proper microbiological investigation of the matter. Relying on native yeast can be very hit-and-miss.

[MKG]

It doesn't matter a damn WHY local yeast populations are as they are. The point is, and Andy's quite correct in this, that they have taken centuries to develop. I am not going to be able to depend upon a decent wine yeast floating by, or even a decent cider yeast, merely because I don't live in an area with a long-standing tradition of making zoob-juice. Having said that, you'll always get a yeast and it will make an attempt to digest all of the sugar in whatever you're making. Some yeasts do that better than others and, more importantly, some are much better at it under anaerobic conditions - the conditions which force yeast to convert sugar to alcohol as a major by-product.

So why risk getting one of the less suitable yeasts (with consequent incomplete fermentation or even, god forbid, less alcohol) when it's so easy to take advantage of the centuries-old populations by popping down to the local homebrew shop? Obviously, if you already live in one of the "good" yeast areas, don't bother - but only if you're making the brew of the area. Don't expect fantastic wine yeasts in Devon. Don't expect brilliant French cider yeasts unless you live around Normandy.

And I haven't mentioned various other micro-organisms, several of which are quite capable of fermenting a sugar solution but not necessarily into anything safe for humans to drink. They're always around too. By inoculating your potential booze with yeast, you massively increase the chances of swamping out any potential harmful infection. Go the wild yeast route in an unsuitable area, and it's quite likely to be the other way around.

Mike

[grahamhobbs]

Gregorach, everything you say is true, although I think you are emphasising how bad practices allow bad yeasts/bacteria into the wine, whereas I was merely countering the idea, in this country, that you must add yeast to grapes to make wine. Also I think it is a myth that you need to rely on yeasts built up over centuries on the cobwebs hanging from the old beams, they're on the grapes. I've seen perfectly good wine made in plastic dustbins in modern garages without adding yeast.

Obviously if you are investing heavily in a comercial wine making business, this may be a bit hit and miss, but it is how the vast majority on wine is traditionally made in France, whether in peoples garages, barns or on small commercial vineyards.

My experience in 'farmyard' wine is that the best wine comes, not so much the conditions of the fermentation stage but where it is stored afterwards - you can't beat the even temperature of a deep cellar. Talk to any frenchman, what is important when considering a house - they'll enthuse if it has a good 'cave'.

[gregorach]

Yeah, well, I'm a brewer rather than a winemaker, so the conditions of the fermentation stage are absolutely vital to me... Also, wine starts out at a significantly lower pH / higher acidity that barley wort, so it's much less hospitable to spoilage organisms. Having tasted some of the last SAW beer competition entries, I can tell you that winemakers must get away with inferior sanitation standards - every single one was infected with something. I've never tasted the like before, and I hope never to again!