Today's numbers are to demonstrate the sudden change in the degree of attenuation of Guinness around 1950. Is this when "Irish Dry Stout" was born?
In 1950, the degree of attenuation of Guinness shot up from around 74% to 84%. This must have had a huge impact on the taste and body of the beer. It also sharply differentiated Guinness from English Stouts, which were rarely more than 75% attenuated.
This is just a WAG, but Guinness was still a bottle-conditioned product, and the attenuation would be changing from the moment it was bottled as secondary fermentation went on in the bottle ... I wonder if, up to circa 1950, they were sending it out "younger" and with less condition as it left the brewery gate, allowing it a longer time "in trade" to mature, but after 1950 or so they kept the bottles back in the brewery longer before releasing them, so that more secondary fermentation had gone on before they hit the pubs and the attenuation was lower when they first hit the shelves?
ReplyDeleteIf that were the case, providing the punters were drinking it at the same "age" the wouldn't have noticed any difference, but Whitbread was perhaps testng "early release" bottles up to 1950, and finding lower attenuation because the bottles weren't that aged, and then testing "later release" bottles after 1950 and finding the attenuation figure was greater because the bottles were older and had seen more secondary fermentation ...
A very good point, Zythophile. Some of the samples were indeed from Whitbread's bottling stores. But that applies to both pre- and post 1950.
ReplyDeleteThe samples come from a wide range of sources: their own bottling stores, ones bottled by other brewers and even ones exported to Belgium. As you would expect with a living beer, the FG's vary, but there's a very clear line at 1950. Before that attenuation is always below 80%, after it always above.
Pre-1950, the FG is in the range 1010-1016, post-1950 1005-1009. I don't think secondary conditioning can account for a difference of 11ยบ (between the highest pre 1950 and the lowest post 1950).
Ron - I looked back both your Nov. 8th (07) post and Zenthophile's and the discourse was about when Guinness started using Roasted Barley in place of Roasted Malt and it appears to coincide rather well with the drop in FG. The Early 1950’s is a good birth date for the Dry Stout, a change in both grist and gravity are very strong indicators.
ReplyDeleteHappy New Year
Thank you for such a nice Blog.
Cheers
Jim
Dang, there goes another beery myth... Splendid job, Ron, again !
ReplyDeleteI expect 11 degrees of attenuation in the bottle would cause a very carbonated beer.
ReplyDeleteI would have thought the beer was fermented out completely, primed and then bottled. Recording the 'FG' of a beer that hasn't reached 'final' gravity would a tad useless.
ReplyDeleteWas there a change in the excise regime? (Sir Stafford Cripps was, as you remember, the chancellor at the time). Obviously, if it were financially advantageous to lower original gravs, and final gravs, then most breweries would do the same.
Fascinating stuff as usual.
Fatman, you're probably right about how the beer was handled. Not all the samples are from Whitbread's bottling stores.
ReplyDeleteWell, recording the FG from Guinness does tell Whitbread something. Remember that they had their own Extra Stout that seems very similar to Guinness. Measuring the FG would tell them Guinness's racking gravity.
These are the tax rates (per standard barrel) for the period:
1948 173s 9d
1949 218s 4d
1950 198s 5d
1951 200s 2d
1952 197s 4d
1953 195s 7d
1954 196s 11d
1955 198s 5d
Wobbling around, tax was. But cutting OG and raising the level of attenuation was common, in response to tax rises.
Annoyingly, I have no Guinness sample from 1949, when the tax jumped. I suspect it may be responsible.
Off topic, but I'm interested in how the first Guinness Draught was under 4%. Teething troubles, or a deliberate experiment?
ReplyDeleteWould I be right in assuming that all the product here was coming out of Park Royal?
Beer Nut, I assume it was deliberately brewed to that strength. I seem to remember that in my youth Draught Guinness was weaker than bottled Guinness and a tad under 4% ABV. Not sure what it is today.
ReplyDeleteIt's hard to say where the Guinness was brewed. The Export Stout has to come from Dublin, as it was never brewed at Park Royal. As Whitbread were based in London, chances are the samples from their bottling stores came from Park Royal. I wouldn't be so sure about any other samples. Though, for the most part, Northern breweries got their Guinness from Dublin and Southern ones from London, it wasn't always quite that simple. Not all the Gravity Book entries specify the bottler. It's possible some of the bottled samples came from the North of England.