How to figure FG with a fruit beer

[gbob]

So, we laid down a Loganberry Hefe this week. If you don't know what a Loganberry is, it's a Western New York thing. The point is, we made the Hefe and it had an OG of 1.058. We racked it on top of 2 pounds of loganberry extract. When it comes time to bottle it and we check the gravity reading, how would we be able to calculate the alcohol content? It seems to me that the OG/FG calculation wouldn't account for the sugars in the fruit. Is there some chart we can use to work it out, or will we be drinking blind?

[ziggy]

Did you take any other gravity readings? If you had a pre-racking onto berry extract reading and a post-racking onto berry reading you could figure it out. If not you could figure that even if the loganberries were pure sugar and you added 2 lbs that would be and 18 point increase in gravity which if fermented out completely would give you 2.3%. So you could just calculate from OG and FG then add 2.3 to find what the absolute maximum abv that it could be.

[Pseudolus.]

There are some lists of estimated sugar content. I think I've seen them more in mead/fruit wine type places. You won't be able to know perfectly to the last .01% ABV what you have, but you can get pretty close. Unless you're using some crazy amount of fruit in there the large majority of your sugar is going to come from the malt, anyway, so the portion you'll have to estimate won't be the biggest factor.

[Pseudolus.]

Might this be helpful? http://www.honeycreek.us/sug_acid.php

[gbob]

Thanks folks. Good stuff.

Hmmm...should have taken a gravity reading before and after racking it over the fruit. Lesson learned.

In all fairness, I'm not a big fruit beer guy. I'm already married, but my brewing partner is single and looking for the perfect panty dropper.

[NickelCityMike]

I took a reading when I racked it onto the fruit. 1.024 after 6 days in primary. The fruit was 2# of loganberry puree (ingredients: loganberries, cane sugar, lemon juice). It's been sitting in the glass secondary for 10 days now.

I've got a picture of it after 12 hours on the fruit with a high purple krauzen. I'll have to post it when I get home later tonight.

[TapItGood]

Tell me more about the Loganberry.

[baltobrewer]

Tell me more about the Loganberry.

Well, he was always a quiet berry, kept to himself, mostly. He tried to fit in with the hip crowd, but his natural shyness tended to sideline him.....he usually just hung out with his friend boysen, who was also shy...

Never mind, I'm an idiot.