Thursday, February 07, 2008

converting malt/beer ratios to original gravities: the beer historian's conundrum

One of my favorite blogs, Shut up About Barclay Perkins, is mostly about the history of beer and brewing. Ron Pattinson posts some really great stuff from primary sources (where he gets it all I have no idea) and I think this semester I might have my beer class (which I should have been preparing for instead of writing this post) read some of when we talk about the Porter Revolution. Maybe.

Today Dr. Pattinson posts some recipes from A Cyclopaedia of Six Thousand Practical Receipts, and Collateral Information by Arnold James Cooley (1854). It was common practice before the widespread acceptance of the hydrometer (or saccharometer) to express the strength of a beer in terms of how much malt was used to make it. This makes sense considering the fact that alcoholic strength depends mainly on how much sugar the yeast have to convert to alcohol and how much sugar depends on how much starch you have from the grain.

But there are other things that effect the alcoholic strength of a beer and this is what makes using malt/beer ratios problematic. The quality of the grain, how the mash is conducted (temperature for instance), the moisture content of the grain, how the fermentation is conducted (temperature for instance), what kind of yeast is used etc. all influence the strength of a beer. So the malt/beer ratios can be pretty variable indicators of beer strength.

But historians of beer and brewing have little choice but to make do with this system because it's all we have. And to get an idea of how strong these beers were it's helpful to try and convert the malt/beer ratios into original gravities, into figures that represent the density of the wort prior to fermentation. Because the density of wort is influenced primarily by the amount of sugar in the wort, it is a good indicator of how strong the beer can be. Of course you have to take into account how the fermentation it conducted etc. but original gravity is a much better indicator of the potential strength of a beer than is malt/beer ratios.

And it's the way we speak about the strength of beer today so it's something we can wrap our heads around pretty easily.

So let's get down to the brass tacks, as it were. Dr. Pattinson intimates that Cooley had no idea what he was talking about for several reasons, but the one I latched onto was the fact that he thinks Cooley got the malt/beer ratios wrong.

For the "Ale, Burton" Cooley says a barrel and a half of beer (48 gallons) was drawn from a quarter of malt (64 gallons of malt). Pattinson says this would result in an OG of over 1400. This is very, very strong. With today's technology you could probably make a 16% abv beer from that wort. In the 1850s, they probably would be able to coax that wort down to a final gravity of at most 1040, probably lower, making a beer of over 13% abv.

Similarly, in his description of "Ale, Dorchester" Cooley says they drew two barrels (64 gallons) from one quarter of malt. Pattinson claims this would give an OG of 1100. Again, this is very strong. This wort would likely make a +10% abv beer.

I think Pattinson might be overshooting a bit.

In her wonderful book Country House Brewing in England, 1500-1900 Pamela Sambrook says that October Beer (the strongest brewed in the English country house) would typically be a barrel drawn from ("well over" in some cases) one quarter of malt (more than eight and a half bushels). And I doubt this brew had an OG over 1140 and therefore a FG probably over 1050 FGs probably go higher the farther back in history you go). And by Pattinson's conversions a quarter of malt would make a barrel of beer with an OG probably over 1180, extremely strong.

Similarly, the "Ales" that were commonly brewed in these country houses were made by drawing one barrel from usually four bushels of malt, or half a quarter, or two barrels from one quarter (p.117). And this brew was meant for regular consumption (at least by the families, at least before ~1700) so I doubt it had an OG of 1100. Because regular consumption of a beer over 10% abv would make you drizunk like you wouldn't belizeve.

Moreover, entire guile small beer in both Sambrook and Ellis is about five barrels from a quarter (Sambrook p.121), which by Pattinson's calculations would probably be around 1040, too strong to adequately quench the field laborer's thirst without making him fall down wasted betwixt the rows. I'm thinking small and table beer had OGs around 1020.

Ellis gives similar numbers in The London and Country Brewer for strong ale as well.

In Bennett's Ale, Beer, and Brewsters she claims that on Lady Clare's estate in the 14th century they were brewing almost 500 gallons of ale per week, drawing two barrels from each quarter (p.18). On Pattinson's conversion, that's a shit ton of 1100 OG ale to be brewing every week. And a lot of very strong ale to drink considering Bennett says that in an average household a person would drink about 1/4 gallon of ale every day (p.19). A drunken household indeed.

I suppose I would just be interested in knowing how Pattinson does his conversion and the justification for it because it doesn't square with what I know from the primary and secondary literature on the subject. I've built this nice little house of historical beer strengths and with one wave of his hand Pattinson threaten's to blow it off like so much fart in the wind.


Ron Pattinson said...

How do I work out the gravities from the amount of malt used per barrel? Exactly the same way Victorian brewers did.

The sugar yield from malt was usually expressed in pounds per quarter. It's the amount of extract that will give you that OG spread over a barrel. The standard amount was 80 pounds per quarter for pale malt (about 54 for brown malt). That means you would get 36 gallons of wort with a gravity of 80 pounds per barrel. To get the OG in specific gravity, you multiply it by 2.77 and add 1000. So

80 X 2.77 = 221.6 + 1000 = 1221.6

I know that figure is reliable, because I've seen it on so many brewing logs. They always include the yield expressed this way.

Standard-strength commercial beers (Like Porter) were usually brewed four barrels to the quarter, or 20 pounds per barrel (1055º).

A barrel and a half to a quarter is a huge gravity. But I'm inclined to believe it, because the Edinburgh Ale is about right at 1100º. In "Scottish Ale Brewer" (1847) there are tables of Scotch Ales analysed in the 1830's. The highest OG is 1133.5.

My information comes from old brewing manuals and old brewing records. There are almost complete sets of brewing records for three of the large London Porter breweries (Whitbread, Barclay Perkins and Truman) for the period 1805 - 1970 in the London Metropolitan Archives. It's a wonderful resource.

Daddy said...

Did I ever tell you about the time we all took turns on Pamela Sambrook out behind the country house?

Talk about trub.

Matthew D Dunn said...

Thanks Ron. Yes, assuming 80lbs per barrel extract (Richardson's original number was 82 for "good malt"), I calculate an original gravity for a 36 gallon barrel to be 1.268 (doing it the long way, first correcting the volume to 1000 liters and the weights to kilograms).

Surely the sources I mentioned were not coming close to 80 pounds per barrel extract. Certainly not the brewers on Lady Clare's estate in the 1300s at least. And probably not any of the private brewers either. All the sources I cite were likely not employing thermometers very often if at all, whereas after Richardson's work on saccharometry, using thermometers and saccharometers was the norm and extracts likely increased proportionately.

Ron Pattinson said...

Yes, someone brewing with more primitive equipment, no thermometer and darker malt would get a much worse yield.

I'm never quite sure what figures to use when calculating gravities of beers before Richardson. In reality, it was probably pretty variable. I doubt they ever got more than 60 pounds per quarter.

Yield was lower when brewing high-gravity beer. Whitbread 1914: SS and SSS 89.2 pounds per quarter; Porter and LS 94.6.

Ryan (Beer) said...

What lautering method is considered when calculating those numbers?

Wasn't it more common for the English, of that time period, to batch sparge and parti gyle their beers. If the malt ratio is calcuated based on using 100% of the extracted liquor for a single beer, then I would agree those OG numbers are really out there. However, if the grain to barrel ratio was intended for 2 to 3 beers made with 1st, 2nd, and 3rd runnings then the stock ale created from the 1st runnings would be considerably lower (potentially around 1.080).

Matthew D Dunn said...


pretty sure all English brewers at the time were employing what we might call the parti gyle method. Sparging was a Scottish thing. Maybe continental too? And the extract was a volume-relative measure, it was per barrel, so sparging would get more sugar total from a single mash, but less per barrel of wort. Also, the second and third beers would be made by infusing the grains with more water after the wort for the first beer was all run off, and actually conducting what they called a second mash (rather than just for the purpose of rinsing the sugars from the grains as we know we do now when we add more water). In other words, they probably didn't draw more than one wort from one mash.

And Ron is right with his numbers. The standard extract for "good barley" was 82 pounds per barrel after Richardson developed (after Benjamin Martin actually) "saccharometry" or the use of hydrometry to determine the strengths of worts and beers. What this means is that a quarter of good barley (a volumetric measure of 64 gallons) when mashed to make a barrel of wort, would add 82 pounds to the weight of that 36 gallon barrel, the weight would be the "saccharine matter" extracted from the malt.

So it's easy then to convert that to specific gravity as specific gravity is just the ratio of the weight of a cubic meter of the liquid in question (wort) to the weight of a cubic meter of water.

However, the numbers I cite in the original post would make much weaker beers because they were using much more "primitive" methods. No thermometers so that meant a rough malting and mashing. Generally worse quality control.

And regardless we don't know how much "saccharine matter" good malt yielded before Richardson (Martin actually) because there was no way to measure it and no "theory of worts" to tell us what a measurement would even mean anyway!

Anonymous said...

I thought I was a wine nerd. This is intense

Ron Pattinson said...

English breweries usually had 3 or 4 worts which were then blended to make any number of different gravity worts. Because it was illegal to add water, Victorian brewers were adept at mixing worts to hit exactly the gravity they wanted.

Most of the really strong beers I've seen in brewing logs used all the worts or all but the weakest. Before 1850 the last wort was often used for small or table beer. Later table beer doesn't seem to have been as popular. Sometimes the last wort was added in another brew.

I'm pretty sure that the first wort had a higher gravity than 1080.

Here's an example from 1880 (Whitbread KK):

wort 1: 118 bareels @ 41.1 (1114º)
wort 2: 133 bareels @ 15.2 (1042º)
combined wort: 251 barrels @ 27.5 (1076º)
return wort: 200 barrels at 2.4 (1007º)