Tuesday, 21 July 2020

The price of yeast in 1913 and the mystery of M.F.

One of the advantages of brewing beer is that you end up with more yeast than you started with. Great if you need yeast for the next brew. Even better if you find you have more yeast than you need, because you can sell it on. To bakers, or distillers.

After fermentation is complete and the beer has been pumped off, the residual gunk remaining in a tank can itself be collected. Brewery yeast is typically a slurry which still contains some valuable beer. So you can give the yeast a good squeeze and the resulting liquid gained can be mixed with ullage and sugar to make brown ale and sweet stout.

The dry matter remaining is what “pressed yeast” refers to in the document below, which is a page from a notebook displayed at a Glasgow University Archive Services event in 2018 (which might give you an idea how far behind I am with blog posts). The date is 1913, which is handy. As there is a beer mentioned called XXP, I’m assuming the notebook is from William Younger. For the purposes of this post it doesn’t really matter.

One press = 25 cwt. = 13 Hhds [hogsheads] Distillery Yeast
Average price for Country = 17/6 p Hhd
do for Town  = 7/6 "
Price of Pressed Yeast to B.S. Co Greenock = 45/- p Ton less 14/9 for Carriage
Therefore £1·16·4 = £4·17·6 = £11·7·6

Thirteen hogsheads is a shedload of yeast. I did say you got more back than you started with.

The buyer of the yeast looks like “B S Co”, but if what I think is an S is actually an ampersand, it might be Blair & Co’s distillery in Greenock, which changed its name to Greenock Distillery after the war.

Why was the selling price of yeast so much higher in the country?

I am not sure what the calculation in the last line is for, and since it is expressed mathematically incorrectly I wouldn’t like to speculate.

The second half of the page seems to be notes on an experiment.

The experiment consists of setting up two kilderkins (18-gallon casks), to which one had a mysterious substance “M.F.” added and the other didn’t. It appears to have had the effect of inhibiting fermentation.

Two kils XXP set up; one with & one without M.F. The kil without M.F. started working first (about 12 hrs before the other). Both kept brisk for fully a fortnight, being tried at spile every morning. After that the cask without M.F. began to cool down while kil with M.F. was still brisk at 3 weeks. Samples then drawn showed the kil with M.F. much brisker with good creamy head.

Two kils stout one with & one without. The kil with M.F. 24 hours later in starting working.

“Working” here means fermentation and “brisk” means well carbonated.

Any ideas as to what M.F. was are very welcome.


  1. Hi ,
    Could the MF be a blend of Malt Extract and Finings ??

    1. Wouldn't malt extract cause a faster start to fermentation rather than a slower one?

  2. William Younger wasn't the only brewery with a beer called XXP. Both Lorimer & Clark and Drybrough produced one at various points.

  3. I have had it suggested that M.F. might stand for Maize Flakes, though personally I am not convinced – either that Younger (presuming it was them) would be motivated to switch to flakes from the much cheaper grits, or that substituting flakes would have such a dramatic effect on the progress of fermentation.