Acid

Acid. In particular, acid in beer. It's another area where there's been a great deal of speculation and precious few facts. I'd like to add a few of the latter.

Many contemporary sources tell us of the tartness of Porter and other aged beers in the 19th century. But was this sourness caused by lactic or acetic acid? You may remember my posts last week based on "Food and its adulterations" (by Arthur Hill Hassall, published 1855). The author remarked upon the sourness of Porter and said that it came from lactic acid, the quantity of acetic acid present being negligible.

Here's confirmation of that from a slightly later date, around 1900. My source this time is "A hand-book of industrial organic chemistry adapted for the use of manufacturers, chemists, and all interested in the utilization of organic materials in the industrial arts" by Samuel Philip Sadtler, 1908, page 197. They don't give books snappy titles like that any more. Just as well.

In every case but one (Scotch export, bitter) the acetic acid content is far lower than the lactic acid content. As might have been expected, Dublin XXX Stout has the greatest lactic acid content.



To be fair, when these analyses were perfromed long ageing was out of fashion. I suspect that, had they been done half a century earlier, the level of acidity in the British beers would have been higher.