Designing a recipe using potatoes

I have a good (cheap!) source of potatoes and would like to try brewing with some.  I am somewhat hooked on BeerSmith and would like to know what to use from the ingredient list to approximate my spuds.  Or.....where to get all the info I need to add spuds to the program.

Ooh I'm looking forward to this thread... I did a sweet potato saison once before my beersmith days.  It was headed in the right direction but didn't hit FG - with autumn approaching it may be time to give it another shot

I am actually mostly interested in plain old white potatoes right now.........but with Fall coming up SPs will be plentiful so info about them would be great too!    I was hoping that the latest upgrade of BS would have a greater ingredient list.  I guess you can't put everything on it..............

Here is something I came across with a quick google search:

http://www.reddit.com/r/Homebrewing/comments/1cvbo0/no_grain_sweet_potato_beer_test_1/


-It seems potatoes have no absorption and in fact add water to the mash.

-They are tough to access all the starch. Perhaps mashing them up good in a food processor as well as doing a double mash where you drain the original mash liquid (to preserve enzymes) then boil the potatoes to release the starches, cool, and then re-add the original enzymes to finish them off. Even then only figure the Potential to be 1.020

-It seems they have enough enzymes to self convert

I think one of Papizan's books talks a little about using potatoes.

Potatoes as a fermentable are quite compatible with all grain brewing.

First, pick a starchy variety, rather than a waxy type. The latter will work, but the starchy varieties work faster and more completely. 

Potatoes add distinct sulfur related aromas and flavors to beer. Somewhere between "fresh turned earth" and "French Fry." In other words, the beer is gonna taste like a potato.

The starch in a potato is pretty similar to malt. It gelatinizes (the phase where it's available to enzymes) at a low temperature of 140F. Similar to malt, the amylase enzymes will work from 140 to 150 F. Used with high diastatic power malt, you can go as high as 50% of the grist.

How you prep the potato is pretty wide open. Just grating it and adding it raw to a mash is simple and works. You can also bake, boil and smash it or run it through a ricer. Using potato flakes is another possibility with the advantage of being gelatinized, consistent and dry weight.

The Russet varieties have the highest specific gravity, especially ones that have been allowed to mature in the ground. Most varieties will lose a little of their water weight if stored in a dry room. Just be aware that gravity can change from potato to potato and even one end of the spud to the other. 

BeerSmith want to calculate the gravity based on one pound of soluble dry weight diluted into one gallon of water. Most potatoes have about 15 to 25% dry matter (basically starch), which is in the 1.070 to 1.080 range. You then have to take that number and divide it by the weight of a gallon of water (8.3 lbs).

80 / 8.3 = 9.6 or a potential of 1.0096

The water contribution of potatoes isn't trivial. If they're in the 20% solids range, then they're 80% water. At that level, 5 lbs of spuds can contribute about a half gallon of water

Potatoes are one of my favorite foods. I like them fried, boiled, mashed, roasted, baked, chipped, sautéed and every other way you can think of. I like potato vodka. I didn't know you can make them into beer.

What hops would you use. I'd guess fuggles would be good for bittering and bobek for aroma. I don't think a citrusy hop would work with potatoes but I'll stand corrected.

This is an interesting thread. I might have a go if it works.