Bagels too dense
I've been learning about sourdough bread baking, and yesterday I decided to try my hand at sourdough bagels. I used the adaptation to Peter Reinhard's NY bagel recipe for making sourdough bagels. This recipe is all over the internet, here is an example:
I used the same sourdough starter that I've been using to make bread (the SF starter from sourdo.com) to make the sponge, and the sponge was very active by the time I mixed it in with the dough. I Used KA bread flour.
One possible issue was that I might have overworked the dough. I mixed for 15 minutes with my KA Artisan stand mixer (325 watts). This seemed like a long time, and really worked my mixer. It was struggling, and got very hot.
After mixing the dough and forming the bagels, I did the "float test", and they did float. Then I proofed overnight in a 38 degree fridge.
To boil, I added baking soda and honey to the water (a mix I found on another site). The water was very foamy, and it was difficult to see the bagels in order to flip them. I haven't seen any recipes that mention this issue... They boiled for about a minute a side, maybe a little more.
The bagels looked fine when they came out of the oven. After cooling on a rack, I froze half of them and put the other half in a plastic bag. I didn't eat any until today. When I took one of the bagels out to toast today, I could swear that they had shrunk. Is that possible? I didn't measure them, but I remember thinking that they were large looking bagels when they came out of the oven, and today they looked small. Anyway, they were a bit disappointing. Too dense, almost like they were stale. And they looked like they might be undercooked. I did cook them at 500 for 25 mins, as per the recipe. Maybe next time I will use my thermapen to test doneness before taking them from the oven.
Anyway, any suggestions as to how to make them come out better, why they are too dense? Anyone ever hear of shrinking bagels? Did I overwork the dough? Were they undercooked?
Also, why does this recipe have you supplement the sourdough culture with yeast? And does it matter what kind of yeast I use? The recipe doesn't specify. I used ADY. Should I have used IDY?