Homebrewing: Robust Porter Brew-Along Day 11
Our robust porter looks about the same today as it did a few days ago, and there really isn't a lot of activity under the surface anymore. It should condition for a couple weeks to ensure that fermentation is 100% complete, and to let the flavors meld together.
Today, take a sample using a sanitized auto-syphon racking cane to check your beer's gravity and give it a taste. Taking a taste earlier in the process wouldn't have given us a good impression of the final flavor, because the yeast hadn't completely finished cleaning up all the byproducts of fermentation.
If your sample has a little bit of a sulfur aroma, don't worry about it too much. Some yeast will produce unpleasant aromas, but they eventually break down and disperse. After the beer has conditioned in the bottles for a couple of weeks none of the sulfur smell should remain. My porter sample had a strong smell of dark fruit and cocoa powder. The beer was flat (we haven't carbonated yet!), but the flavors of burnt toffee and chocolate came through in a really pleasant way.
There may be a little alcohol bite in the flavor, but this should dissipate after bottling. There will still be some changes to the flavor as it sits for awhile, but the base flavors of your beer are already shining through.
How to Determine the Alcohol Content of Your Beer
The gravity reading I took today showed a Final Gravity (abbreviated FG) of 1.019. The FG is measured after fermentation is complete. This was a little higher than the 1.015 that I expected, but it's close enough. On our brew day, the first gravity reading was 1.064. This measurement is referred to as the Original Gravity (OG). With these two values, we can determine the approximate alcohol content of the beer.
A formula to estimate the ABV is simply (OG - FG) * 131.25. Using this formula, we get an approximate ABV of 5.9% for our robust porter. There are complex formulas that will give a more accurate calculation. I frequently use the formulas that are built into website calculators, such as this one, to get a more refined value. Using an online calculator gives an ABV of 6.0%, which is very close to our estimation.
Next week we'll be checking our gravity one more time—if it's the same as today then we'll be bottling this beer next Friday. Check back then!
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