Does adding coffee to secondary change SG?

[Horseshoot]

Hey gang, I brewed a Porter from an extract kit with specialty grains. The corrected OG was 1.045. After 16 days, I racked over to secondary onto 4oz of my own home roasted ground coffee. My hydrometer was broken (found it to be broken just as I was about to use it) and so I have no reading then. Today, I took a reading (as I want to bottle in a few days) and the corrected SG was 1.020. The FG expected for this kit was supposed to be around 1.011. (The expected OG for this kit was about 1.044, so I hit that pretty much.)

So, my question is this: Is it possible that the coffee being added (but not fermentable) add to the SG? Would this throw off my ability to calculate the ABV? Or, did my fermentation simply stop there? Or maybe it hasn't stopped?

I tasted the sample, and it was incredibly smooth. I don't mind session beers, but a porter with an ABV of a little over 3% seems kind of sad.

Any thoughts? Thanks, Mike

 

[Horseshoot]

I wanted to add that the racking over to secondary happened 2 weeks ago. The beer was brewed 30 days ago. Thanks.

 

[rudu81]

I would say that your beer finished at 1.020. Presuming that you had it at optimal temps for your yeast, 30 days fermenting should have done it and cleaned up. Adding beans shouldn't change your gravity by any perceptible amount as they won't absorb that much of your beer. For my coffee stout I cold brewed 2qt of coffee with 4 oz of grounds, so for that volume I had an effect, albeit a small one.

 

[Horseshoot]

Thanks for the response. I suspect the yeast that came with the kit, was not that good. If I had it to do over, I would use different yeast. I kept good temps throughout. I think it just is what it is. I'll bottle it soon (after a couple readings confirm it to be steady) and just enjoy it as is.

 

[SKMO]

So, my question is this: Is it possible that the coffee being added (but not fermentable) add to the SG?

Dry coffee grounds are going to have virtually zero effect on gravity.

 

[FensterBos]

When I first started brewing kit beers I would buy separate yeast and usually hit my marks.
Regarding coffee beers, I steep the grounds in a quart of water and then add it at flame out so my measurements are constant to instructions. I haven't missed my mark doing it that way.....yet.

 

[SoonerDoc]

Dry coffee grounds are going to have virtually zero effect on gravity.

Are you sure? I would think it would. (I really don't know.)

 

[bonzombiekitty]

Are you sure? I would think it would. (I really don't know.)

No, it shouldn't have much of an effect.

Think of it this way: 4oz of sugar would completely dissolve, so all of that sugar would contribute to an increase in gravity. 4 oz of sugar would mean a minuscule increase in gravity in 5 gallons of water. 4oz of corn sugar in 5gal of water is an SG of 1.002 according to the hopville calculator.

Now, consider that with 4oz of coffee grounds, most of that will not dissolve. So you're ending up with an even tinier increase in gravity. It won't be noticeable at all for our purposes.

 

[SoonerDoc]

No, it shouldn't have much of an effect.

Think of it this way: 4oz of sugar would completely dissolve, so all of that sugar would contribute to an increase in gravity. 4 oz of sugar would mean a minuscule increase in gravity in 5 gallons of water. 4oz of corn sugar in 5gal of water is an SG of 1.002 according to the hopville calculator.

Now, consider that with 4oz of coffee grounds, most of that will not dissolve. So you're ending up with an even tinier increase in gravity. It won't be noticeable at all for our purposes.

Makes sense. I was thinking more along the lines of could it change gravity, not should it. Coffee grounds will change the SG, just not an appreciable amount. Got it.