A Funny Thing Happened on the Way to the Brewery…

Recently I have been pontificating about water chemistry, and I was preparing a post about how I deal with my water when I brew dark beers.  It was all going to center around adjusting the carbonate levels to achieve the correct level of residual alkalinity.  Coincidentally, I had been planning a brewing experiment relating to brewing dark beers, namely, evaluating methods of mashing with dark grains.  It is funny how sometimes reality comes up, slaps you in the face, and proceeds to show you how ignorant you are.
Let’s talk about the experiment.  Mashing involves mixing the crushed grains with water in order to make magic happen, that is, enzymes breaking down long chains of sugar molecules (starch) into little munchy bits that your yeast can gobble up in the process of making ethanol and carbon dioxide. How efficiently this magic happens depends on many things, but the brewer is mostly concerned with the temperature and pH of the mash. Managing temperature is pretty easy, but the pH is a little more complicated, as the grain and the water chemistry both affect the pH. All things being the same (and when does THAT ever happen?), dark grains will tend to lower the pH of the mash. And depending on the nature of your water this may or may not be a problem. Consider Dublin, the home of the classic example of dark beer, the Dry Irish Stout. Dublin water has very high levels of alkalinity, which is to say it reacts with acids in order to prevent the pH from dropping too much. Now where I live the alkalinity of the water is maybe a third or less of Dublin, so in theory if I wish to make a good dark beer I should add something to the water to increase alkalinity. That something is carbonate, either in the form of calcium carbonate (chalk) or sodium bicarbonate (baking soda).
But there is another way. Dark roasted grains do not have any long chains of sugar left to break up, so having them in the mash is somewhat irrelevant. Some brewers choose to not add the dark grains until after the mashing of the base malts is done. Doing this removes the necessity of adding any minerals to your mash, because once the mash is done the pH is largely irrelevant (not to say that the pH of wort and subsequent beer is totally unimportant, but as pH affects mashing enzymes it is).
To take the experiment one step further, some brewers actually cold steep their grains. What is this? Well, you add the dark grains to cold water and let them sit and steep for a longer period of time than a normal mash (overnight?), and then remove the liquid and add it to the wort. Why? well, I have heard the claim that dark grains that are cold steeped have better flavor, such as less harshness.
So I was all prepared to do a three way experiment: brew a dry stout using the “normal” method of adding carbonates to the mash, brew a second adding the dark grains after mashing, and third batch, cold steeping the grains and adding the liquor from that to the wort. And so I set off to demonstrate my knowledge of water chemistry…

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