A Robust Porter for Christmas

I spent a while thinking about what to brew for the holidays. I’m in a big debate with myself now on whether to drive back to Iowa for Christmas or to fly, and I’m leaning towards driving. If I do I want to bring a nice warming winter beer with me. A porter seemed like the right style for Christmas.

I made this recipe up myself, based on the style notes for a robust porter and the grain and hops schedules for several porter kits. I took a little from several places and then on a whim swapped out a big chunk of the base malt for Maris Otter malt instead.







I made yeast starter on Saturday September 29. I used the standard starter guide: 700 mL of water, boiled, 1/2 cup dry malt extract, 15 minute boil, cool, and pitch. Swirled by hand a few times through the night. The yeast itself had a strong smell, I don’t know if that’s particular to Wyeast 1098. It was pretty flocculant, and I had a nice yeast layer on the bottom of the flask before starting the brew.


I started the brew process around 9:30 am by preheating the mash tun with hot water and heating the mash water to 170 F.

To keep my sparge volume below 12 quarts (a limitation of my available pots) I used a water to grain ratio of 1.80 qt/lb, with a target mash temperature of 152 F

Mash-in was at 10:15 am. I waited 5 minutes for the temperature to stabilize, then took a reading. The temperature of the mash at the center of the tun was about 153-154 F. At the edge of the tun it was closer to 149 F. At 40 minutes the temperature was still at 152 F in the center of the mash tun. The temperature was above 150 F at the end of the hour long mash.

I stirred the mash at 20 and 40 minutes, and at 60 minutes the mash was stirred again, allowed to settle, and then recirculated and drained starting at 11:30 am. I had to recirculate about 4 quarts of wort before it ran clear. I finished the sparge at 12:20 pm.

Once that was complete I started the boil. The mash and sparge water calculations from iBrewMaster were good, and I had what appeared to be just the right amount of wort come out. I extracted a sample to measure the boil gravity.


The starting boil gravity was 1.056.

Because I’m constantly worried about having too little beer at the end of the process I added a little water to the boil along the way to keep the volume up. I worried about diluting the final result, and in the end I did have about a quart more clean wort than I needed, but it doesn’t seem to have harmed anything. Assuming a 70% mash efficiency the calculator I used estimated an OG of around 1.060, but experience with my setup shows I either get higher efficiencies than that or my hydrometer is wrong.

I ended up adding the remaining Willamette and Cascade hops at the 10 minute mark just to use them. They weren’t in the original plan but the packages were 1 ounce each. This may add another 4 or 5 IBUs to the beer, but it should still be within the style guidelines.

Measurements and fermentation

The measured original gravity was 1.066 at 78 F (1.067 at 68 F). That’s higher than expected. I think I get better yields from my system than my current set of calculators estimates. I’ll have to adjust my mash profiles. It might be prudent to check my hydrometer as well. If it’s reading high then the rest of my calculations are wrong.

Style: Robust Porter
Type: All Grain
Boil Size: 6.73 Gal
Batch Size: 5.00 Gal
Calories: 210
IBU’s: 47.59
Color: 27.1 SRM

Right now the calendar estimates this beer will be ready to drink in mid December, perfect for Christmas.

— Steve

Posted on 30 September 2012