Apparent vs. real attenuation?

[arborman]

Whats the difference between apparent attenuation vs. real attenuation?

I am ready to transfer my Pliney The Elder clone to Keg, and took my final gravity, which came out to 1.016. In beersmith, it says my apparent attenuation is 77.7%, but real attenuation is 63.7%.

I did not quite hit my FG that I was targeting, and the beer came out to approximately 7.9%. I was kinda shooting for 8-8.5%.

I used whitelabs 001 cal ale yeast, with a nice starter. BTW, the beer tasted EXCELLENT!

 

[billl]

Apparent attenuation is what is measured in brewing. It is just a measure of the density of the finished product vs the original wort.

This isn't the actual attenuation because alcohol is lighter than water, so the FG reading isn't just a measure of how much sugar is left. It is a mix of sugar and the difference between the densities of alcohol and water. So, the actual amount of sugar left in a 1.010 isn't 10 points. It is 10 points plus some amount for the lighter alcohol.

 

[arborman]

Got it, thank you! Is this a number that anyone pays attention to, or are the gravity readings more important?

 

[mike024]

Got it, thank you! Is this a number that anyone pays attention to, or are the gravity readings more important?

I use it so that I know how well my yeasties are. The 001 has an attenuation max of 80%. Meaning that your yeast will only turn about 80% of your sugars to alcohol. If you are near the top end you know that you did a great job of keeping your yeast happy and healthy during fermentation. I just did an IIPA with 001 and had 79% apparent attenuation on a 1.098 extract. My FG was 1.020. I know that I did everything about as good as I could have and want to duplicate the process on my next batch.

 

[arborman]

I use it so that I know how well my yeasties are. The 001 has an attenuation max of 80%. Meaning that your yeast will only turn about 80% of your sugars to alcohol. If you are near the top end you know that you did a great job of keeping your yeast happy and healthy during fermentation. I just did an IIPA with 001 and had 79% apparent attenuation on a 1.098 extract. My FG was 1.020. I know that I did everything about as good as I could have and want to duplicate the process on my next batch.

Wow, that's going to be one strong IPA! Makes the 2IPA I just kegged look like child's play!

 

[mike024]

Wow, that's going to be one strong IPA! Makes the 2IPA I just kegged look like child's play!

Yeah it is from a socal brewery. Iron Fist. I got the recipe from the brew master there. I have to tweak it a bit because I overshot the ABV. The actual brew is a 9.6% percent double IPA. Mine came out to about 10.4%. It is definitely crazy big.