When calculating the percent hydration of a bread, does one include all of the solid ingredients, or just the flours?
Percentage in baker's math refers to the relative percentage compared to the flours, which are always 100%. This TFL site has a good primer here. For example, if you have 1000 grams of flour (all flours combined) and 600 grams of water, it would be 60% hydration (600/1000). All other ingredients are calculated similarly. So, if in the previous example you also used 20 grams of salt, it would be 2%. When all percentages are added together, it will add up to more than 100%.
Thanks Brad--but my question goes a bit deeper. In addition to 1000g of flour, I add 200g of 5-grain cereal, 57g of oat bran and 30g of flax seed. For this bread I use 680g of water. So is my percent hydration 680/1000 (=68%) or 680/1287 (=53%)?
If you have access to Hamelman's "Bread," he gives percentages and hydration with good detail. For example, his Five Grain Levain recipe, which uses a grain soaker, lists 3 flours that total 100%. The grains are not included in the calculation, so he follows the rule that everything is calculated on the basis of the total flour. However, this recipe lists 98% hydration, which does include the water that is used in the soaker and mostly absorbed by the grains. He does not include the water from the levain in the calculation for hydration. I'm sure there are other ways to do it and other books often show their preferred calculation. I think the most common use for baker's percentages is to help scale recipes to larger or smaller batches, so I think if you find a method that works for you and stick to it, you should be fine.
Thank you Brad--I think your advice 'if it works, just stick with it' is good. I've tried increasing the amount of water in this particular bread--up to 70% hydration based on the total of flour + grains--and it loses i'ts structure and flavor. This is a fairly heavy bread. I often use 75% hydration with other breads that I make (without added grains) and have no trouble with those.
I don't have an exact answer for you as I'm not sure if there is an accepted procedure here. Personally I think the added grain should be counted in some way, as it will definitely want to take up some water which otherwise would be available for the flour. When I write formulae for these type of products I tend to list 2 % hydrations; one based on the total flour only, and the other based on flour plus other grains. It can get even more complicated if you use a soaker with those grains!
I saw a post on Bakers % from davidg618 just recently with liks provided by proth to the BBGA site area discussing methodology of formulae presentation. Here is the link to the post and thread, it's worth a good look through.