Maltose experiment

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Stibnut
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Maltose experiment

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I found a bottle containing 385 g of fairly pure maltose on eBay for $25 from a guy who sells old unwanted chemical bottles. I snapped it up and did an experiment to see how well four different yeast strains metabolize maltose when it's the only available sugar.

The four yeasts were EC-1118, K1V-1116, Red Star DADY, and Fleischmann active baker’s yeast. I made up about 2.2 L of a wash containing the maltose, 2 g of Fermaid K, and 25 mL of a nutrient/buffer solution containing ammonium, calcium, magnesium, and zinc chlorides along with citric acid and potassium citrate as buffering agents for a pH of about 5.2 to start. It also contains glucose, but the amount added was not enough to affect the results much. The OG of the wash was 1.072.

I distributed about 850 mL of this wash to each of two 1 L bottles for the EC and K1V. The rest went to two little 250 mL bottles for the DADY and baker’s yeast. I pitched 2 g of each yeast in the larger bottles and 0.5 g in the smaller ones without rehydration.

Here are the results:

Image

It’s kind of interesting to see a situation where EC-1118 is the laggard, blown out of the water by DADY and bread yeast. It makes sense to me, given that maltose is the most common sugar in wort and DADY is a beer yeast while EC and K1V are wine yeasts which haven’t been selected for their ability to metabolize maltose. Still, even EC was able to ferment to semi-dryness by the time I ended the experiment and added them to a sugar wash for distilling, and it was still going slowly but surely.

I’m surprised that baker’s yeast did so much better than K1V given that K1V is supposed to have some ability to metabolize maltotriose, which isn’t a common wine yeast trait. I assumed that would come with a much better ability to use maltose too, but it looks like the effect is pretty modest - only enough to outpace EC a little.
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Chauncey
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Re: Maltose experiment

Post by Chauncey »

Pretty interesting experiment. You should try it with some other sugars to see how each of those 4 act as well.
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Stibnut
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Re: Maltose experiment

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The thought has certainly crossed my mind. The one I'd most like to try is maltotriose, but that is prohibitively expensive. I've done both sucrose and glucose with all four of them at different times, although not as a dedicated experiment. I didn't see any real difference in fermentation speed between them although I haven't analyzed it as closely.

I would imagine fructose would produce similar results to glucose, given that sucrose does and it is made up of a glucose and a fructose, but maybe it's worth a shot. Also, perhaps galactose or trehalose might be interesting - seems most yeasts can metabolize those to some degree or another. Any other ideas?
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NZChris
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Re: Maltose experiment

Post by NZChris »

Very interesting. Thanks for doing that.

I'd like to see how the same yeasts behave with grape must. Would EC-1118 still be the laggard?
Stibnut
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Re: Maltose experiment

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To clarify what I said above, glucose and sucrose produce nearly identical results to each other but not to maltose at all. EC-1118 is the fastest, K1V and DADY are slightly slower, and baker's yeast is slightly slower than that, if memory serves me right. But I've never put all four in the same conditions at the same time before, and usually I push the OG up to the 1.090 - 1.100 range because I've found this works fine without producing more off odors, at least for my usual workhorses EC, K1V, and DADY which are all bred to handle it.

Sometime soon I should try using either sucrose or glucose/dextrose to create identical washes with OGs around the 1.072 I used for this one. When I get around to it, I'll post here.

As for grape must, I imagine that EC-1118 would be very fast given that it's designed for quick, neutral wine fermentation. I've made wine a couple of times but have shied away from it just because of its reputation for fermenting too clean without much flavor. Might be worth a shot especially for brandy though.
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Chauncey
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Re: Maltose experiment

Post by Chauncey »

Definitely following this thread, if you can dig up any result data from your past experiments thatd be cool.

Makes it sound like ec 1118 would make for better sugar washes or at least quicker ones if i read that right.

It is a slow yeast over all

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Brew bama
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Re: Maltose experiment

Post by Brew bama »

Have you considered using a Saccharomyces cerevisiae var. diastaticus?

They can hydrolyze dextrins into fermentable sugars so they attenuate more fully.

Several Saison strains are var. diastaticus which is why they’re so dry.
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Re: Maltose experiment

Post by Stibnut »

Chauncey wrote: Wed Jul 29, 2020 11:23 pm Definitely following this thread, if you can dig up any result data from your past experiments thatd be cool.

Makes it sound like ec 1118 would make for better sugar washes or at least quicker ones if i read that right.

It is a slow yeast over all

Im drunk ill report back
Yeah, EC-1118 is excellent for sugar washes, rum washes, wine, mead...anything really where the only sugars present are glucose, fructose, and sucrose. It goes through those sugars at lightning speed and can stand quite high osmotic stress (early)/ABV (late) without producing noticeably more off odors, given adequate nutrients.

I once managed to get it to ferment a wash with an OG of 1.129 down to 1.001 without noticing any worse odors than one that I had started at 1.089 under otherwise identical conditions. Starting it that high is still a bad idea from an efficiency perspective because it took far longer and crapped out without quite eating all the sugar, but I think 19% ABV without off-odors is pretty impressive.

However, it evidently sucks at eating maltose and can't do anything with maltotriose, so it would have slow and poor attenuation for any kind of beer including whiskey mash. The thread about EC-1118 has some people reporting great results and others saying it's kind of slow and crappy, and I'd guess that a major factor is the sugar composition of what they're trying to ferment.

edit to add: I do have a fair amount of data about what I've tried over the past few months. Before the maltose experiment I never really tried different yeast strains under otherwise identical conditions - typically I messed with several variables at once - but it still might be interesting. I'll see what I can dig up this weekend.
Brew bama wrote: Thu Jul 30, 2020 12:29 pm Have you considered using a Saccharomyces cerevisiae var. diastaticus?

They can hydrolyze dextrins into fermentable sugars so they attenuate more fully.

Several Saison strains are var. diastaticus which is why they’re so dry.
That's an excellent idea! It's one that has sort of crossed my mind but I haven't tried yet. I did buy a few containers of Chinese maltose syrup, which is a rice malt extract, to see how different yeasts handled it. I should get my hands on a diastaticus strain and try it out.
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