Yeast Making

[wadewood]

Great thread and history lesson. I was surprised at how much difference the yeast makes in taste, until about 6 months ago. A local micro brewery here in Houston, St. Arnold's, recently started a new series of limited beers. They are taking their standard products and are changing the yeast only. They are calling this series Movable Yeast - My link

So far, they have released 2 batches. #2 - Altared Amber We've matched our Amber Ale wort with Belgian Trappist yeast to create a hybrid style – Belgian American Amber Ale. Belgian Trappist yeast has clove and spice phenolics with a hint of banana and we think the spice works well with the caramel malt and hops of the Amber Ale.” #1 - Weedwacker A variation of Saint Arnold's best-selling Fancy Lawnmower. All other ingredients remain the same, but the new beer will be fermented with a Bavarian hefeweizen yeast.

I have had both side by side with normal version and the difference is amazing.

[JohnD]

That's a great sensory comparison to be able to make. Some of the things yeast make that are most interesting in terms of flavor are esters.

Ethyl hexanoate: banana/pineapple flavor and aroma: ester of ethanol and hexanoic acid commonly found in grain spirits

Isoamyl acetate: banana flavor and aroma: another common ester of isoamyl alcohol with acetic acid

Propyl acetate: pear/raspberry: propanol and acetic

There are tons of these. A brewery near us makes a Belgian style beer that used to be made with a traditional Belgian yeast. They let that yeast go and are now using a standard brewing yeast and adding acetic and citric acid to make up for the lost flavor. It's a shame. I would love to use that original yeast for a spirit. The beer was amazing.

[JohninWV]

We actually make our vodka from a bourbon mash....and funny, our bourbon is actually made from a bourbon mash too.

The only changes are the yeast and of course the distillation. There's obviously a huge difference in the way they taste once you take the vodka to 190, but it's still a very different product even as low wines.

While not quite the difference in beer mentioned above (because nobody but us ever tastes it) it's cool to note the differences only when changing yeasts. With the exact same grain recipe, I can tell a huge difference in aroma alone.

[cowdery]

Woodford Reserve has an experimental series called the Masters Collection. One of their most interesting experiments was making a sweet mash bourbon. It was interesting because they did everything the same -- including using the same yeast they always use -- they just didn't use any backset. The result was a very different flavor. So this is the same yeast in a slightly different medium that produced a completely different set of flavors.

This is why I continue to be appalled by Bill Owen's recommendation that microdistillers shouldn't ferment but should instead buy wash from a brewery. As I wrote here, there is a difference between a "distiller" and a "still operator."

[Sherman]

there is a difference between a "distiller" and a "still operator."

When I went to their Bourbon Academy last spring, They were doing a wheat and a rye. Same conditions you stated. same yeast, but a proven lacto inoculation. It was a non-distinctive mash of either. But they are marketing it as. the "best there ever was" It was ok for mash but I think it is going to be mostly barrel.

Chris was a bit put off that I thought it was "usual"

Marketing will fix it all though. I prefer Bernheim wheat.

Parker Beam selected some good barrels of that.

[Collin]

Thanks guys, this topic has been really interesting, and has inspired me to look into yeast production a lot more. Here at Harvest Spirits we have been using dried yeast with pretty good results -- but I would love to see what types of yeast are on the apples out in our orchards. Looks like its time to start more experiments.

[cowdery]

Maybe someone can explain this to me. Craig Beam, at Heaven Hill, told me once how they used to make their yeast for production. They started with a yeast mash which they made like this. First they boiled hops in spring water, added cracked malt, and mixed it all up with an electric mixer. Then they covered it with burlap and let it sit for about three hours before adding yeast from the dona jug. The next day they added that to the yeast tanks with fresh whiskey mash, producing enough yeast to set their fermenters with.

My questions are: does that sound about right? (I may have misunderstood him) And what are the hops for?

Booker Noe told me once that Jim Beam's yeast mash recipe included hops and sulfur. Was he pulling my leg? (Booker would do that.) What's the sulfur for?

[Denver Distiller]

They both have antiseptic properties. It's to encourage yeast growth, and discourage bacterial activity.

[JohnD]

Hops and sulfur are both used as preservatives that yeast can tolerate. They're probably controlling microbial populations but allowing yeast to proliferate. Hops were originally included in beers for their preservative properties and sulfur is used in wine making all the time.

I'm wondering why they let it sit for 3 hours if they were going to inoculate it with cultured yeast anyway. Allowing some wild yeast to get in there first?

[Sherman]

Hops and sulfur are both used as preservatives that yeast can tolerate. They're probably controlling microbial populations but allowing yeast to proliferate. Hops were originally included in beers for their preservative properties and sulfur is used in wine making all the time.

I'm wondering why they let it sit for 3 hours if they were going to inoculate it with cultured yeast anyway. Allowing some wild yeast to get in there first?

More than likely to let a bit of the sulfur gas off like you would for a wine must.

[delaware_phoenix]

Remember that hops and sulfur are not instantaneous bactericides, they may want a little time to work before adding the yeast.

Is there any particular form of sulfur that would be better than elemental powder?

[JohnD]

We've used sodium metabisulfate powder, which becomes sulfer dioxide once introduced to the wine.

I didn't realized that about the hops.

[Sherman]

According to a lot of sources, it was common practice just to burn sulfur over the grape must or whiskey mash. The liquid absorbs the sulfur dioxide quite readily.

Of course that was before there were alternatives.

[JohnD]

Back to the backset discussion, I found a paper that looked at different %s of backset as mashing water. It found that backset had a negative effect on alpha and beta amylase activity but a positive effect on limit dextrinase. They thought effects were due mainly to pH changes because limit dextrinase was most active between 4.0-4.4 which is low for the other enzymes. They looked at backset addition to malt mash and 90%wheat mash and found that the backset lowered the pH in the malt mash much more than in the wheat (wheat mash buffered the pH change much more effectively).

In the malt mash, acceptable enzyme activity was only maintained when 5% of mash water was backset. In the wheat mash as much as 40% backset as mash water still had little effect on enzyme activity.

[cowdery]

Around 20% seems to be typical in Kentucky. Some only add it to the fermenters while others add it at the mashing stage and even to the yeast mash.

[JohnD]

I'm not sure whether I'm mixing terms or those British fellows are. The study referred to taking spent mash after distillation and using it to lower pH in the next fermentation. They call that backset. Denver described that as sour mashing. I think these terms are used differently across the pond, and most of the academic work I'm reading comes from that side.

[cowdery]

'Backset' and 'sour mash' are the exact same thing. Distillers in Kentucky use the terms interchangeably. They also call it 'slopping back.' 'Stillage' is another common term for the same stuff. In fact, I would say distillers in Kentucky use the terms 'backset' and 'slop' most of the time. They only call it 'sour mash' for the tourists.

[Sudzie]

This was a great read. Thanks to everyone that posted such useful info. Now it's time to grow some of the little buggers.

[rumfarmer]

I have isolated a very interesting strain of saccharomyces here in Hawaii and I have been experimenting with it for several months now. The yeast was taken from a local source and the most robust yeast was isolated out and propagated by a local laboratory doing other food science research. Our paths accidentally crossed, and now I fully intend to us this yeast to make a true and pure Hawaiian cane rum. I keep live cultures in the refrigerator and simply activate and reactivate using fresh cane juice as a starter. So far, this yeast has outperformed every commercial yeast I have tried both in alcohol and heat tolerance. Best of all, it has a great flavor profile. Clean and floral. I have an exclusive license for its use, but I haven't tried it on a commercial scale yet. Biggest tests have been 5 gallon. I plan on doing a 50 gallon test in the next month or so while I wait for my final permits and inspections for the distillery.

[Rob]

Just read through this and wanted to give some insight into the idea of terroir with regards to yeast.

In 2009, two high profile papers in the journal Nature published global genome data on the yeast species Saccharomyces cerevisiae. This gave interesting insight into whether or not trait variations in S. cerevisiae are due to population structure (ie lineage) or source environment (ie terroir). A 2011 PLOS Genetics paper titled “Trait Variation in Yeast is Defined by Population History” concluded that trait variation (trait variation leads to different flavors) is largely defined by which lineage the strain belongs to vs. the source environment that the yeast was isolated. Up until 2012, there were five known lineages of the yeast S. cerevisiae: European, Sake, Malaysian, North American, and West African. A yeast belonging to the European lineage does not mean that it was isolated in Europe. It just means that genetically it groups into the lineage that was declared European by the researchers that proposed these concepts years ago (same is true for the other lineages). In fact, most of the brewing, distilling, and winemaking strains that are used in the western world today, including America, are from the European lineage. Even more, yeast from this lineage have been isolated in China. How yeast from the same lineage can be isolated in such varying areas is still a topic of debate, but human activity such as trade and travel is one proposed reason.

The point being, most yeast that are used in Kentucky, Scotland, America, etc. are proposed to be of the same lineage – European. So, it’s not so much that Kentucky and Tennessee have the perfect environments to harbor whiskey-making yeast. The data seems to show, as Sherman pointed out, that as colonist moved from Europe to New England and then down into Kentucky and Tennessee, they brought with them (unknowingly or knowingly) yeast capable of fermenting a grain mash. Therefore, as people moved west, the same would be true – they took with them yeast from the European lineage. And this idea seems very plausible when you consider the fact that most wild yeast isolated from California vineyards are of the European lineage. In fact, the standard S. cerevisiae lab strain (S. cerevisiae is a model organism for research…it was the first sequenced eukaryotic organism) was originally isolated from a fig in a California vineyard, and is of the European lineage.

As a side note, all of the strains discovered so far that group within the North American lineage can’t metabolize maltose. If the yeast can’t metabolize maltose, it fails as a suitable beer or whiskey yeast.

Currently, we are sequencing the necessary genomic regions of our proprietary yeast – isolated from a Texas ranch – to determine which lineage it groups.

Finally, while a strain’s lineage may be the principal driving factor for trait variation, data from a 2011 paper in PLOS One shows that strains of the same lineage can form sub-groups with metabolic discrimination based on the different ecological niches they inhabit (ie oak tree vs. vineyard grape; distillery vs. brewery).

In other words, lineage is most influential in determining trait variation within S. cerevisiae. However, the ecological niche that the strain inhabited (or had recently inhabited) when it was captured will also affect trait variation, just to a lesser degree.