This week I cover water to grain ratios used during mashing and how it affects the mash and ultimately your finished beer.
What is the Water to Grain Ratio?
Water to grain ratio refers to the volume of water used per unit of grains mixed during the mash. In English units, this is typically measured in quarts per pound, while in metric it is liters per kilogram. To convert from quarts per pound to liters per kilograms the conversion rate is 1 qt/lb=2.336 liters/kg or if going the other way, 1 l/kg = 0.428 qt/lb. For this discussion we are primarily concerned with the water/grist ratio during the main conversion step of the mash, as this is where the mash enzymes are most active.
The typical range of water to grain ratio used depends on the type of mash you are doing. For a conventional mash where you have a sizeable separate sparge step, thicker ratios in the 1.25-2.0 qt/lb (2.9-4.6 l/kg) are often used. If you are using an all-in-one, brew-in-a-bag, no-sparge or decoction mash the water/grain ratio can run much higher in the 2.5-3+ qt/lb (5.8-7+ l/kg) range as all of the water is added up front. Water to grain ratios lower than 1.0 qt/lb (2.33 l/kg) are hard to achieve as the mash can be too thick and difficult to properly mash in. It can also result in a stuck sparge.
Effects of the Water to Grain Ratio
The use of more water in the mash will slightly increase the activity and effectiveness of the major mash enzymes. This will result in the enzymes breaking starches into shorter sugar chains which are more fermentable. This will give you beer with a slightly thinner finished body, and slightly higher alcohol level as compared to the same beer mashed in a thicker mash.
This effect was noticed by many Brew-in-a-bag (BIAB) brewers when they switched from traditional mash-sparge systems to BIAB systems which typically use a full volume of water in the mash. You can of course compensate if needed in many ways for the higher enzyme activity by adjusting the body of the beer using grains, mash temperature or other techniques. However, this is only an issue if targeting a higher body beer. Using a higher water/grain ratio is nothing new as Central European brewers have been using the decoction method for hundreds of years with high water/grain ratios.
A secondary concern with higher water/grain issues is managing the pH of the mash. Since water sources are generally alkaline, using more water in a given mash will raise the pH of the mash versus a comparable thick mash. So if you are using a system with a high water/grain ratio you need to manage your mash pH and consider adding an acid like lactic acid when mashing in to achieve a proper mash pH in the 5.2-5.6 range. BeerSmith has tools to help you calculate the amount of acid needed. This is often a concern with lighter colored beers as darker grains are more acidic and therefore do a better job achieving the proper pH range.
A final concern when setting your water/grain ratio is the volume of your mash tun when brewing high gravity beers. The issue is that often one may need to lower the water/grain ratio to get as much grains into the mash tun as possible. If you use too high a water/grain issue with a lot of grain, you may exceed the volume of the mash tun.
Adjusting the Water/Grain Ratio in BeerSmith
I often get the question of how to change the water/grain ratio in BeerSmith. The water/grain ratio is part of a given mash profile so when you pick a mash profile in a recipe it will apply the water/grain ratio to the recipe and calculate the water needed for your mash. Each mash step has its own water/grain ratio which is needed since many people infuse hot water to raise the mash temperature between steps (called an infusion step).
As a result each step in the mash has its own water/grain ratio. So to adjust the water/grain ratio for a given step, go to the Mash tab in the recipe and simply double click on the step you want to change. Then enter the desired water/grain ratio and BeerSmith will recalculate the water needed.
I should mention the above technique only works for a conventional mash where you have a separate sparge step. For BIAB and no-sparge mash profiles, BeerSmith will instead estimate the total water needed for your beer based on your batch volume and losses and will then include the full volume of water in the mash.
I hope you enjoyed this week’s article on water to grain ratios in the mash. Thanks for joining me on the BeerSmith Home Brewing Blog. If you want to take the guesswork out of brewing, please try my BeerSmith recipe software from BeerSmith.com. Be sure to sign up for my newsletter or my podcast (also on itunes and youtube) for more great tips on homebrewing.
