Quick 'N Dirty Tech Tues: Mash Thickness, Pt. 1

Mash thickness is defined as the ratio of volume of water to the amount of grain in your mash. Here in the US, it is typically expressed as quarts (of water) per pound (of grain), or qt./lb. Mash thicknesses can run the gamut from .75 quarts/lb. to 1.3 quarts/lb.+. You may have wondered what sort of impact your mash thickness can have on the resultant beer. Today I'm going to do a short entry on that topic to help you further customize your brews and get exactly what you want out of your end product.

Different thicknesses primarily affect the types of sugars that are produced during the mash. (If you need a quick primer on what to expect of worts of different sugar compositions, look here.)

Here's a quick practical rundown of what you can expect from a thick and thin mashes, respectively. Thick mashes tend to produce a higher proportion of dextrins, which lend a fullness and sweetness to the finished beer.[1] Noonan writes, "A thick mash (less than three-tenths of a gallon of water per pound of malt) induces the greatest overall extraction. A much thinner mash increases the proportion of maltose, and thus wort attenuation."[2] For reference, 3/10 of a gallon is 38.4 fluid ounces, or 1.2 quarts.

Bottom line: A thicker mash will typically result in a more dextrinous wort. A thinner mash, on the other hand, will typically result in a thinner, more highly attenuated wort. As far as numbers are concerned, less than 1 qt/lb. would probably be considered thick. Likewise, more than 1.5 qt./lb. would probably be considered on the thin side.

You'll just have to wait around for Part 2 to learn about the mechanisms responsible for this difference.

References:

[1] Noonan, Gregory New Brewing Lager Beer (Brewers Publications, 1996) pg. 140-1
[2] Ibid.