Acidity in Porter

I do occasionally read other blogs. Zythophile's in particular. A post of his last week got me thinking. About acidity in Porter.

What train of thought did it wave goodbye to from the platform? Simple. That maybe I should take a look at the analyses I have. The ones that give acidity. So that's what I did. Just now. The results are intriguing. Now I just have to summon up the energy to tell you about them. It's Sunday and the Yorkshire puddings are already in the oven. I'll have to be quick.

First, an explanation about how I've selected these samples. It wasn't a complicated process. I just sorted on the acidity column. My beautiful table contains all the examples with an acidity of greater than 0.12%. (Most British beers in the 20th century had acidity of 0.04 to 0.06%.) An arbitrary cut-off point, mostly decided on to keep the table to a reasonable length.

For purposes of comparison, 3 analyses of Lambik in the late 19th century gave acidity percentages of 1.06, 1.11, 1.16.

Acidity of Porter and Stout
Year	Brewer	Country	Beer	Style	Acidity	FG	OG	Colour	ABV	attenuation
1929	Hammerton	UK	Oatmeal Stout	Stout	0.12	1015.7	1049.4		4.36	68.22%
1929	Hoare	UK	Stout	Stout	0.12	1010.9	1052.1		5.37	79.08%
1947	Raggett	UK	Stout	Stout	0.12	1012.1	1040.4	1 + 18.5	3.67	70.05%
1948	Guinness	Ireland	Extra Stout	Stout	0.12	1012	1047.2	1 + 6.5	4.57	74.58%
1948	Taylor Walker	UK	Nourishing Stout	Stout	0.12	1008.4	1031.6	1 + 17.5	3.01	73.42%
1958	Guinness	Ireland	Foreign Extra Stout	Stout	0.12	1015.9	1074.4	250	7.65	78.63%
1933	Barclay Perkins	UK	Stout	Stout	0.13	1013.9	1052		4.95	73.27%
1940	Whitakers Halifax	UK	Milk Stout	Stout	0.13	1021.7	1058.8	1 + 21	4.80	63.10%
1899	Unknown	USA	American Porter	Porter	0.14	1011.43	1053.49		5.24	77.74%
1931	Hoare	UK	Stout	Stout	0.14	1012.6	1054.2		5.41	76.75%
1951	JW Lees & Co Ltd	UK	Archer Stout	Stout	0.14	1009.6	1041.7		4.17	76.98%
1953	Brickwoods	UK	Black Bricky	Stout	0.14	1015.1	1045.7	1 + 12	3.96	66.96%
1887	Unknown	UK	English Stout	Stout	0.15	1014.38	1074.72		7.66	79.63%
1950	Tennent Ltd	UK	Milk Stout (Export)	Stout	0.16	1020	1063.2	1 + 17	5.60	68.35%
1950	Unknown	UK	Imperial Stout	Stout	0.16	1017	1066.8	1 + 19	6.49	74.55%
1900	Unknown	Canada	Canadian Porter	Porter	0.16	1015.57	1057.97		5.46	72.03%
1897	Unknown	USA	American Porter	Porter	0.17	1026.36	1073.88		6.11	62.72%
1952	Leicester Brewing & Malting Co.	UK	Milk Stout	Stout	0.17	1010.2	1044.2	1 + 15.5	4.42	76.92%
1955	Worthington	UK	Imperial Stout (White Shield)	Stout	0.17	1017.3	1078.2	325	7.97	77.88%
1870	Hoare	UK	Porter	Porter	0.18	1012.99	1052.42		5.13	75.22%
1870	Whitbread	UK	Porter	Porter	0.18	1014.04	1054.11		5.21	74.05%
1953	Guinness	Ireland	Extra Stout	Stout	0.18	1002.8	1046.3	1 + 8	5.70	93.95%
1879	Unknown, Dublin	Ireland	Dublin Single Stout	Stout	0.22	1023.94	1061.75		6.15	59.82%
1870	Guinness	Ireland	Extra Stout	Stout	0.24	1015.51	1078.06		8.20	80.13%
1870	Truman	UK	Porter	Porter	0.24	1013.16	1051.33		4.96	74.36%
1901	Guinness	Ireland	Extra Foreign Stout, white label	Stout	0.24	1013.20	1074.98		7.86	81.34%
1882	Unknown, Dublin	Ireland	Dublin Stout	Stout	0.25	1028.38	1096.75		8.48	68.80%
1870	Berlin	Germany	Porter	Porter	0.34	1020.7	1077.85	40	7.46	71.97%
1955	Bass	UK	Imperial Stout	Stout	0.34	1018.4	1078.8	375	7.90	76.65%
1879	Unknown, Dublin	Ireland	Dublin Double Stout	Stout	0.36	1011.24	1085.68		9.04	85.94%
1890	Haake & Co., Bremen	Germany	Porter	Porter	0.45	1041.3	1089.3		6.18	53.75%
1884	Barclay Perkins	UK	Double Brown Stout	Stout	0.46	1015.57	1077.45		7.50	78.70%
1950	Artois Brewery	Belgium	Extra Stout	Stout	0.47	1018.1	1058	1 + 16.5	5.17	68.79%
1932	Guinness	Ireland	Extra Stout (bottled by John Martin, Antwerp)	Stout	0.77	1014.4	1057		5.54	74.74%
Sources:
Whitbread Gravity Book
Wahl & Henius, pages 823-830
A dictionary of chemistry and the allied branches of other sciences, Volume 6 by Henry Watts, 1872, page 256
"Theory and Practice of the Preparation of Malt and the Fabrication of Beer" Julius E. Thausing, Anton Schwartz and A.H. Bauer, Philadelphia 1882, pages 748-751
"Handbuch der chemischen technologie" by Otto Dammer, Rudolf Kaiser, 1896, pages 696-697

Surprisingly, both the most acidic examples are from the 20th century. Guinness is well represented. Not such a surprise, given their production methods.

Dinner's ready. Do-it-yourself analysis time, I'm afraid.