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Low Intervention wines?

That’s what I understood. But week before last I attended via Zoom a presentation by Matt Wengel who is winemaker for Lemelson Vineyards in Oregon (TWS stock one of their Pinot Noirs.)

Matt’s talk was titled ‘Let’s talk about Wine Microbiology – The Hidden Warfront’. It was supported by lab reports on the amount of microbes present in his wine. At the beginning the natural yeast on the grapes and brought in from in the vineyard were in the majority - but left to their own Matt said they wouldn’t make more than 4% abv.

The winemaking yeast numbers grew and killed off the wild yeasts. Where do the winemaking yeasts come from? Matt couldn’t answer the question whether a brand new winery could make wine with introducing a wine yeast. Subsequent years spontaneous fermentation could happen as that initial yeast was in the winery fabric.

Matt said that if he went to other wineries, he introduced yeast from Lemelson’s as it was on his person and vice versa. “I’m covered in it” he said.

He was flatly denied that yeasts on grape skins and in the vineyard could make wine.

I’m not a scientist, but this guy has studied the matter, has the laboratory reports which he showed us, and makes his living from that knowledge.

Re commercially bought yeasts: wineries claiming they use natural yeasts can be buying commercially and still be telling the truth. The yeasts are natural, and naturally propagated and dried as opposed to genetically modified.

In the case above, where did those yeasts come from? Could be spontaneous fermentation, i.e. they didn’t inoculate but the yeast could come from the fabric of the winery a descendent of past years fermentations, I don’t know how old it is, or where the old demi-muids came from - or how old the concrete tanks are.

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One thing that I’ve liked in “natural wines” that I’ve also occasionally found in other wine (e.g Weinert Cabernet Sauvignon or Chateau Musar) is the feeling that the wine is almost vaporising in my mouth if a take a small sip. I want to call it “petrol-y”, but I think people use that to refer to the actual taste of some rieslings. Maybe I’d call it “solvent-y” Does anyone know what that sensation is and what it’s called?

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Peter
The world of yeast is a deep and complicated one. But broadly, wild yests such as Candida and Kloeckera start the fermentation and do their work but adding different aromas etc. Yes, they are weak and die out because they have difficulty surviving in an alcohol environment above 4%abv. There is another yeast (of which there are different strains ) called Saccharomyces cerevisiae which is a dominant strain, does exist in the wild, and it takes over and carries on fermenting until dryness. But SC can also be cultured in a lab.
I suspect that I have over simplified the process, but basically of there is enough SC that exists on say the grape skin, that will multiply very rapidly in the fermentation process and take over at 4%. But there is no guarantee SC will always be present so the maker may have to add a cultured version of it.
I am not sure I have explained that very well (I am not a chemist) but I will ask a friend of wine who is a winemaker and a chemist by training.

As I say, I am not a scientist. Matt Wengel doesn’t think so, and his lab reports didn’t show so on his grapes.

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@peterm
[I presume in the quote from your post that Matt said he couldn’t answer whether a brand new winery could make wine WITHOUT introducing a ‘wine yeast’ - viz Saccharomyces cerevisiae. ]

If I may try to add to Andrew’s comments and try to bring sense to it all:
1/ Essentially, to make wine that has 11, 12, …15% alcohol you need active S.cerevisiae in at least the second half and latter stages of fermentation as it is the species of yeast that can withstand up to about 23% alcohol before dying off. Albeit most grape musts will not have enough sugar to take it up to 23% even when ‘fermented to dryness’.
2/ There isn’t much (if any) S.cerevisiae in most vineyards (and on the skins of grapes); but there will generally be plenty in the fabric of an established long running winery which will adequately ‘infect’ the must during fermentation. Hence Matt’s hesitation as to whether an absolutely brand new winery built on a greenfield site would be able to produce a ‘normal’ wine of 11-15% alcohol. But once it has had a few successful fermentations to 10+ % alc (thanks to S.cerevisiae - wherever it was first introduced from) then the aerosols from the fermenting must will have plastered the walls, equipment etc with S.cerev. for the next year.
3/ Wild yeast species and strains (of which there may be up to 20-30 types) ferment slowly and all die out at between 4-6% alcohol. If S.cerevisiae is injected into the must at the beginning or early stage of the fermentation it will rapidly out compete the wild yeasts (if any) and dominate the fermentation.
4/ The mix of yeasts you have in your vineyard overwinter in the soil and, in my view may account for a substantial part of the ‘terrior’ differences so prized and advertised and attributed to various rocks, clay, geographical slope etc, but never spoken of. Still that is another story. Your competitors can’t buy your land/domaine but … they could replicate your yeast mix if they knew…

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That looks about right to me. Just a few points…

I am sure you need special yeasts strains to get above 18%, but a bit of googling suggests they do seem to be variants of S.cerevisiae.

Even if there is little S.cerevisia initially I believe it can still eventually take over a fermentation and ferment to dryness, but depending on temperature, and maybe other factors, the fermentation may stick.

I haven’t seen any studies on this, but sometimes marc is used as a fertiliser on vineyard soil, and I do wonder to what extent this causes “terroir yeasts” to be ousted by “winery yeasts”. (There is a more general point that even the most organic of commercial vineyards are far from being natural environments - they are created by man, with the natural vegetation essentially replaced by monoculture, and sometimes even blasted out of the landscape to create a reasonably flat area.)

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Alfredo Maestro – Consuelo 2018
Kamara Winery – Stalisma White 2019

and so it came to pass that the wines above were opened and the Alfredo Maestro was an improvement on the first but nothing of note.

Last night however we had the Retsina which was very good. Medium-ish body with a dainty tickle of pine and some lovely apricot flavours.

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