Sweet Potato Lager

[aslander]

Wanted to run this by everyone to get their thoughts. I based this recipe off of the Pumpkin Ale recipe I came up with a few months ago that was fantastic (8.5%). The 6 gallons of pumpkin ale I made is mostly gone and my wife drank the majority of it, so I wanted to make something similar, but more refreshing. My goal was to base it off the pumpkin ale recipe, lower the gravity of it down to 6% (not counting what I get out of the sweet potato), use less spice, and use a lager yeast. Here is the recipe that I came up with:

Batch Size (fermenter): 5.75 gal
Bottling Volume: 5.25 gal
Estimated OG: 1.059 SG
Estimated Color: 8.1 SRM
Estimated IBU: 30.4 IBUs
Brewhouse Efficiency: 70.00 %
Est Mash Efficiency: 73.0 %
Boil Time: 60 Minutes

Ingredients:
------------
Amt Name Type # %/IBU
10 lbs Pale Malt, Maris Otter (3.0 SRM) 76.9 %
2 lbs Munich Malt (9.0 SRM) 15.4 %
8.0 oz Caramel/Crystal Malt - 20L (20.0 SRM) 3.8 %
8.0 oz Victory Malt (25.0 SRM) 3.8 %
8.00 lb Roasted Sweet Potato (Mash 60.0 mins)
0.75 oz Magnum [11.90 %] - Boil 60.0 min 27.9 IBUs
0.75 oz Saaz [2.90 %] - Boil 10.0 min 2.5 IBUs
1.00 tbsp Pumpkin Pie Spice (Boil 5.0 mins)
1.0 L SafLager West European Lager (DCL/Fermen

According to some research papers I found, the optimal range for starch conversion in yams to be 60-100c for alpha amylase and 70-75c for beta-amylase. I plan to grate the sweet potato, use an appropriate amount of water to cover the gratings, raise that to 160F and let it sit for an hour or so to convert the starches as much as possible. Then, I have different ideas that I'm not sure what I want to do. I could either squeeze the crap out of the bag to get as much sugary liquid out of it... or my other idea is to puree it all in a blender and then add it to the mash. Hopefully by pureeing it, I would maximize the conversion of the remaining starches when I mash in, without creating a stuck sparge from it being too gooey.

Thoughts?

 

[durbanguy]

I have done two very similar brews to the one you are planning and they turned out great.

The first one i grated the sweet potato and i ended up with a stuck mash.....a very bad stuck mash...the beer however turned out great. I used 04 yeast.

The second brew i sliced the potato into thin slices and this worked very well with no stuck mash. I fermented with a larger yeast and it turned out nice and crisp. i also reduced the spice in this batch and everyone who had tasted both preferred this one. The sweet potato flavor was quiet prominent.

I can remember my recipe off hand but i recall using 8kgs of potatoes and i had a gravity of 1040 after i had mashed the potatoes on there own.

Good luck and let us know how it all turns out.

 

[aslander]

I have done two very similar brews to the one you are planning and they turned out great.

The first one i grated the sweet potato and i ended up with a stuck mash.....a very bad stuck mash...the beer however turned out great. I used 04 yeast.

The second brew i sliced the potato into thin slices and this worked very well with no stuck mash. I fermented with a larger yeast and it turned out nice and crisp. i also reduced the spice in this batch and everyone who had tasted both preferred this one. The sweet potato flavor was quiet prominent.

I can remember my recipe off hand but i recall using 8kgs of potatoes and i had a gravity of 1040 after i had mashed the potatoes on there own.

Good luck and let us know how it all turns out.

Thanks for the response. Both times you tried this, you mashed the potatoes separately? After your response I'm thinking the grating would be best and to use a BIAB bag and do it in the kettle instead of my mashtun, so I don't get a stuck sparge like you mentioned.

Also, do you remember your water volume that you got the 1040 OG with? I'll be using half the amount of sweet potatoes, but adding 20 gravity points to a 5 gallon batch means I should rethink my grain bill because I dont want a 10% beer