Thoughts on FG and ABV - Pineapple IPA

[dkwolf]

My brew club is doing a "Wort Transformation Challenge" type competition - we got together and brewed a 10 gal batch of a base pale ale, and then anyone participating took a gallon home to do as we pleased with yeast, dry-hopping, and any other additions. I decided to try a pineapple IPA. Left it sit in primary for just over a week, then racked to secondary, and added two and a half cans of pineapple and about 1/2-3/4 oz of dried, whole leaf hops. It's been in secondary for about two weeks now, and I'm probably going to check FG tonight and make a decision about bottling.

My question is, I know the OG of the wort (1.048, if I remember correctly - don't have it written down here at work). But FG isn't really going to help me calculate ABV, as I added a metric crap-ton of fermentable sugars in the secondary with the pineapple (I added all of the fruit, plus the juices from all cans. I wanted the pineapple to really come through.)

Am I correct in thinking OG/FG isn't going to really help me in determining ABV? I guess I maybe should have checked gravity before and after adding the fruit, but I didn't, so..

(And I fully realize that my fruit and hop additions may have been way off base for any known recipe, but I figured what the hell - it's a 1 gallon batch, good opportunity to wing it and see what happens.)

 

[m00ps]

For a rough OG addition estimation from the pineapple, I would look up the nutritions facts and figure out how much sugar (grams) it contains in total. Plug that (as cane sugar) into a brewing software for your 1gal batch size and there ya go

 

[Calder]

As Moops says, using the sugar content on the cans will get you a reasonable estimate. Add that to your original recipe, and up the volume to where ever it ended up at.

I think the nutrition information on food is only an estimate and can vary widely; I've had apple juice that said it should have given me a 1.048 cider, but was actually 1.060. I think the number is just an average.

If you have a refractometer, you can take FG with both a refractometer and an hydrometer, and from those two numbers, you can back-calculate an estimate of OG.