We had planned on bottling our beer this past weekend and then starting our next batch…..a Black Saison. After reading a bit more about bottling, we have decided to wait one more week. Although our beer has quit bubbling, it appears as though fermentation should be given at least two weeks. We don’t want to risk having our first batch explode in their bottles! The beer will remain in the bathroom.
Using a hydrometer, we did check the specific gravity of our beers at this point. Let me share with you what I have learned about the specific gravity of beer.
The original gravity (O.G.) is the specific gravity of the wort before fermentation begins. Wort is the liquid extracted from the mashing process. It contains the sugars that will be fermented. The O.G. depends on the sugar content of the wort.
The final gravity (F.G.) is the specific gravity measured at completion of fermentation. This is basically a measure of how much sugar is left after fermentation.
For a beer to fit within a certain style, both its O.G. and F.G. must fall within determined ranges. For instance, the O.G. for our IPA recipe should fall at 1.062. We took our measurement before the beer was put into our two carboys to ferment. Luckily, our beer measured just at 1.062 (whew…..so far, so good)! The F.G. of our American IPA could measure as low as 1.003 or as high as 1.020.
The size of the gap between the O.G. and F.G. can be used to calculate the alcohol content of the beer.
We have brewed two batches of an American IPA, one with an American yeast and one with an English Ale yeast.
We used the following utensils to remove a sample from each carboy. The long rod (the beer thief) is dipped into the opening of the carboy to remove a sample. The sample is put into the plastic beaker. The hydrometer is then placed into the liquid.
At this point, the specific gravity of the batch with American yeast is 1.017. The specific gravity of the batch with the English yeast is 1.02.
Using an online calculator, I input my O.G. and F.G. numbers to calculate the alcohol content:
American yeast: 6% by volume; English yeast: 5.6% by volume.
I did give both samples a try. Without any carbonation, the beer was a little flat but the flavors tasted great! We will definitely be bottling next weekend.