Acidification of Mashing and Sparging Water

From "water, a comprehensive guide for brewers"

Many brewers acidify their sparge water and/or mash water. At the beginning of the sparge, the mash pH should be at the target and the buffering conditions within the mash should be at full strength. As the sparging water rinses the bed, the sugars and buffers are rinsed away and the pH shifts towards the pH of the sparging water. If the sparging water is alkaline, the mash pH will rise, and the extraction of tannins, silicates and ash from the malt husks is more likely as it approaches a pH of 5.8. These compounds can ruin the taste of an otherwise well-brewed beer. The easy solution is to stop sparging when the pH hits 5.8, or when the specific gravity falls below 1.008, and top up the kettle with hot liquor alone. This will only cause a small drop in efficiency while preventing significant off-flavors in the beer.

However, an ounce of prevention is worth a pound of cure, as they say. The better solution is to acidify the sparge water to a pH in the mash target range, which should effectively prevent the pH of the mash from rising above 5.8; although as discussed in Chapter 5, the DI pH of the base malts may pull it higher. The rise in mash pH at the end of the sparge is more common to lower-gravity paler styles where the buffering systems in the mash are weaker and/or more dilute. It can also occur in low-gravity darker styles where the melanoidin concentration (a buffer) is actually low despite the high color wort.

Jim Mellem of Sierra Nevada Brewing Co. presented the following data (Table 13) at the MBAA South & Southeast Technical in 2010. In the presentation, "Water Quality From a Craft Brewer's Perspective," he showed results from experiments they had conducted to compare their standard operating procedure of phosphoric acid acidi fication of all brewing water, with doubling the amount of calcium salts normally added to the mash and boil, as appropriate to the beer recipe.

Pale ale beers were brewed on a 10 barrel pilot system, each condition brewed twice to fill 20 barrel fermentors. To summarize the findings, the mash pH of all three conditions was within acceptable parameters, as was the extract yield and general parameters of the beers. The most Significant difference between the trials was the last-runnings lauter pH, for the doubled calcium level without acidification. The pH for standard which rose to 5.91 for the standard salts without acidification, and 5.83 only rose to 5.56 at the end of sparging. In triangle testing, 38 trained Procedure condition (brewing liquor acidified to 5.7 by inline injection) Panelists determined that there was a statistically significant difference in taste between the three conditions (α=0.05) with regard to astringency.