Tuesday, December 13, 2011

Brewing for Yeast Propogation

Yeast is, far and away, the most important part of the brewing process. Yeast is so important that sometimes I will plan my brewing process around making my yeast happy. Just last weekend, I brewed up a Scottish 70/- Ale (a session-strength ale) for the express purpose of building up enough yeast from the slurry to give me a nice cake for brewing up the beer I really want to brew (a Black IPA).

When you know you need to brew a batch to build up a ton of healthy yeast, the best thing you can do is to brew up a low-gravity beer. Since I wanted to build up a propagator of Wyeast 1450 Denny's Favorite 50 yeast (an American-style ale yeast), I made a 2L stir-plate starter, and then pitched that starter into a 1.036 wort of Scottish 70/- wort. Why a Scottish 70 schilling ale? Because I was tired of brewing bitters. Ad I had never brewed this style before. And it's not the worst style to try to win a medal with. Also, a key part of this style is the long boil. So I gave the beer 120 min of boiling and did a pretty classic British base malt and Roasted Barley recipe, with just a pinch of crystal malt. Here's the recipe:

Campbell's Heavy 70/-
Style: 9B-Scottish And Irish Ale-Scottish Heavy 70/-

Recipe Overview

Wort Volume Before Boil: 9.50 US gals
Wort Volume After Boil: 6.25 US gals
Volume Transferred: 5.75 US gals
Volume At Pitching: 5.75 US gals
Final Batch Volume: 5.20 US gals
Expected Pre-Boil Gravity: 1.024 SG
Expected OG: 1.037 SG
Expected FG: 1.010 SG
Expected ABV: 3.5 %
Expected ABW: 2.7 %
Expected IBU (using Tinseth): 19.9
Expected Color: 10.8 SRM
Apparent Attenuation: 71.4 %
Mash Efficiency: 84.0 %
Boil Duration: 125.0 mins
Fermentation Temperature: 60 degF

UK Pale Ale Malt (Maris Otter) 7lb 0oz (94.9 %) In Mash/Steeped
UK Medium Crystal (120EBC) 4.00 oz (3.4 %) In Mash/Steeped
UK Roasted Barley 2.00 oz (1.7 %) In Mash/Steeped

US Ultra (9.0 % alpha) 20 g Bagged Whole Hops used 60 Min From End

Other Ingredients

Yeast: Wyeast 1450-Denny's Favorite 50

Mash at 156 degF for 60 mins

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