In a 1928 Guide to Guinness Brewery published by the brewery, which recently became available in full view on Google Books, this statement is made at p. 46:
The discovery of roasted malt as a flavouring material about the year 1800 was responsible for converting the “Brown Ale” previously manufactured into the “Porter” or “Stout” of today.
If one takes a literal approach to porter history, as one should who is concerned with the record and accuracy, this statement is inaccurate – as far as that goes.
Brown ale, and porter made from brown malt, are not the same thing and Guinness made both ale and London-style brown porter in the late 1700s. These data are well-known to students of beer history. The colour was certainly in many cases shared, but porter was more bitter and meant to keep longer. So roasted malt did not coincide with the development in Ireland, or anywhere, of porter.
Yet, something very similar to the above quotation was stated in the Irish Section of a Handbook prepared for the 1887 Royal Jubilee Exhibition in Manchester:
The discovery of patent or roasted malt as colouring and flavouring material had transformed the Irish trade chiefly into a porter trade.
Black malt is an almost carbonized form of malt patented in 1817 by Daniel Wheeler who used a coffee drum-type apparatus.
1887 is rather closer to porter’s origins than 1928. So what’s going on here? The Handbook’s statement follows its acknowledgment of “brown ale” as the historical Irish type. The statement is then made that before roast malt appeared London porter was still being imported to Dublin and Cork. It was competing with Guinness’s stab at the style.
Were the authors – in the first case, Guinness itself – just spinning a yarn of marketing blab, or were they driving at a larger point, that black malt really “made” Irish porter?
What they were driving at IMO is that the early use of roasted or black malt by Guinness was a keynote development for its beer that made it different from London-style porter. London’s porter, as many authorities state, used in the 1800s varying combinations of pale malt, brown or amber malt, and black malt.*
Some breweries in England by then did use only pale malt and black malt a la Guinness, or for some brews, but Guinness was pre-eminently associated with black malt usage. The author of a Guinness history, David Hughes, insists on the importance for Guinness of black malt, see his remarks in his 2006 study A Bottle of Guinness, under “Brewing From 1801”. He notes that porter production at St. James Gate relied very early on pale and black malt only, with some use of amber malt as well for keeping, superior, and foreign stout, not for the staple draught form in other words. Hughes speculates that the amber was used to assist stability, i.e., in beers kept long or exported, not (as I read him or his 1880s grist table) for the staple porter including town and country porter.
According to the American beer writer Kim Winship, writing originally in 1987 and citing Stan Corran’s A History of Brewing (1975), Guinness started to use black malt even before Daniel Wheeler patented it. He cites the year as 1815, which is “about the year 1800” for practical purposes. Know-how and practical innovation often develop simultaneously in different places and usually precede legal recognition in the form of patents and other intellectual property.
Use of roasted or black malt in the staple Irish beer to replace brown or amber malt had to lend a particular flavour as 1800s commentary noted, often a liquorice taste even without use of real liquorice.** The percentage of black malt or, today, perhaps roasted (unmalted) barley, will be relatively low in the mash but the “colouring” and acerbic taste conveyed are disproportionate in their effect.
Beers made in the earlier (1800s) London manner had, when fresh, a more caramelised or luscious taste than the Guinness style,*** as well as often being less intensely black. These early London beers were probably more smoky as well but this is difficult to pinpoint viz. the Irish competition at this juncture of time.
As an example of an essential distinction between the two types I recall Vaux Jubilee Porter as made by Fred Koch in Dunkirk, NY in the 1980s, a recipe supplied by the northern English brewer, Vaux, that owned Fred Koch. The beer was dark reddish-brown and of the taste I’ve noted for London style, quite different to Guinness.**** Many craft stouts, in contrast, hew to the Guinness model, probably under influence of that beer from the 1980s when craft brewing started to spread.
In this sense, the 1928 and 1887 statements are interesting. They seek credibly IMO to mark a dividing point between the older brown beers and the almost black, very roasty Guinness stout that appeared possibly even before Wheeler’s patent. Whether ale or brown porter, it was all brown stuff to the citizen reading the Guide or Handbook…
Had Guinness continued to make a copy of London porter as it started to do in the late 1700s before roasted malt was known, it would likely not have achieved the eminence it did, especially in England which after all was the home of porter.
In modern terms, we would call it brand differentiation, or such was the end result. That is what the guide and handbook writers were trying to explain to, need I stress, a non-technical audience.
*See Martyn Cornell’s Amber, Gold and Black, viz. continued use mid-1800s of brown malt in England while the Irish had given it up (or for practical, domestic purposes they did, and see later in the century, 1888, Frank Faulkner in England writing that in Dublin only pale malt and black malt are used in mashing (at 261)).
**See pg. 331 in Britannica.
*** See London, Vol. 4, viz the “balmy” character of a “crack” London porter vs. the “sub-acid” and “brisk” character of Guinness stout. This comparison was between extra stout sold in England, bottled there from casks shipped from Dublin, and mild London porter. To be fair, draught porter in Ireland had a milder character and probably resembled the best mild London porter more closely, but Guinness was always recognized by British commentators including technical ones for a distinctive product, e.g., Tizard in 1846. I attribute that in good measure to its mash bill, mainly reliant on pale and roast malt from 1815. The use of highly roasted black malt vs. still-smoky brown malt, in connection too with a correspondingly greater amount of pale malt, may have resulted in a milder, creamy pint, in particular.
****Per Howard Hillman’s 1983 Gourmet Guide to Beer: “A regional brew from Dunkirk, New York. Deep tea-brown tinged with orangy-red. Malty nose. Smooth bittersweet palate. Relatively thin-bodied, mellow and short-finished for a porter”. Some porter is still made like this, I think most reading have had examples.