Martin, any thoughts on the origin or the rumor?
It was a reasonable assumption.
Guinness was long known to deliver their dark Guinness Flavor Extract to their other breweries, so everyone knew that this was an important component. The thing that I believe confused the typical homebrewer was that people thought that Dublin water was very hard and alkaline. While that is true in some parts of the city, its not true in the part that the St James Gate brewery is. Their water runs off the granitic Wicklow Mountains and it is almost devoid of mineralization and alkalinity.
Mixing roast barley with a highly alkaline water would not result in a very low pH wort. But mixing roast barley with what amounts to RO or distilled water, results in a wort pH that hovers around 4.5. If you assumed that the Guinness water source was alkaline, you would have to assume that there was some sort of souring action in order for that dark extract to have a low pH. But the reality is that their process and result is much simpler than that. Guinness' recipe of barley malt, raw barley, and roast barley create a very complimentary flavor when the pH of the overall beer is depressed by that GFE addition. They do mash the pale components in a separate mash and combine the worts later.
The simple work-around for brewing an excellent dry stout is to use RO water and hold the roast barley out of the main mash. You then add the ground roast barley at the end of the mash where it adds the color and drives the wort pH down. It is a very effective technique and I and many others have found it to produce a very authentic result.
Topic: The Beerery's Sauegut Reactor (Read 6619 times)
