I brewed a winter warmer last December. Added 2lbs maple syrup to the boil at the 5min mark to flameout. No decernable maple flavor, however there was a lot going on with this beer. I believe I weighed in at about 6% abv, but the beer wasn't as dried out as I expected. I'm attaching the recipe below.
Based on my very limited experience I would say adding maple syrup to the boil is going to react much like adding brown sugar to the boil, which is to say you'll be drying out the beer and boosting the abv. I don't think that adding maple syrup to the boil will add any unfermentables to the wort, thereby imparting flavor.
Winter Warmer 10 Gal
All Grain Recipe
Submitted By: kennymac (Private) (Share)
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Brewer: Paul Houseworth
Batch Size: 10.00 gal Style: Christmas/Winter Specialty Spice Beer (21B)
Boil Size: 11.66 gal Style Guide: BJCP 2008
Color: 24.2 SRM Equipment: Ken's Brew Equipment
Bitterness: 27.3 IBUs Boil Time: 60 min
Est OG: 1.056 (13.8° P) Mash Profile: Single Infusion, Full Body, Batch Sparge
Est FG: 1.012 SG (3.2° P) Fermentation: My House
ABV: 5.8% Taste Rating: 30.0
Ingredients Amount Name Type #
14 lbs Pale Malt (2 Row) US (2.0 SRM) Grain 1
2 lbs Brown Malt (65.0 SRM) Grain 2
2 lbs Caramunich Malt (56.0 SRM) Grain 3
2 lbs Caravienne Malt (22.0 SRM) Grain 4
1 lbs 2.7 oz Special B Malt (180.0 SRM) Grain 5
1.5 oz Northern Brewer [8.0%] - Boil 60 min Hops 6
0.50 Propane (Boil 60 min) Misc 7
2.00 tsp Irish Moss (Boil 10 min) Misc 8
1.0 oz Goldings, East Kent [5.0%] - Boil 10 min Hops 9
3.00 oz Cinnamon Stick (Boil 5 min) Misc 10
2.00 tsp Nutmeg (Boil 5 min) Misc 11
2 lbs Maple Syrup [Boil for 5 min] (35.0 SRM) Grain 12
1.0 oz Goldings, East Kent [5.0%] - Boil 2 min Hops 13
0.5 oz Northern Brewer [8.0%] - Boil 2 min Hops 14
2 pkgs Octoberfest Lager Blend (Wyeast Labs #2633) Yeast 15