Citric Acid, What is it Good For?

Well I posted a while ao asking about the effects of adding grapefruit or another citrus fruit to secondary fermentation. People seemed to be cautiously optimistic, although there certainly were concerns about citric acid. Someone suggested it might kill the yeast. I was in my LHBS yesterday picking up ingredients and noticed they sell bottles of citric acid! What is that used for? How much is it used? In what quantities? I figure if reasonable amounts of CA are healthy in a brew, I might just go forward with the Grapefruit IPA.

Also on a side note, what is the procedure for adding fruit in secondary. Some seem to like to boil it with water and then add it, others, to freeze it. Also, how is it removed? Do I re-rack my beer? Thanks!
-Ben

I don't have a clue as to the effects of citric acid but since you'll be using a ton of hops anyway, Cascade would definitely impart a citusy aroma.

Citric acid is used in Winemaking and Meadmaking. I have not heard of anyone using it in ales/lagers.

It is a fairly common addition to meads, however.

citric acid does not interfere with fermentation - i made a hard lemonade clone with frozen concentrated lemonade which included citric acid and it fermented great for over a month

Well, that's the go-ahead I needed. Onward towards the Grape-fruit IPA!
-Ben

I remember reading somewhere that it's used in small amounts to invert sugar.

Carne de Perro said:

I remember reading somewhere that it's used in small amounts to invert sugar.

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True! The acid helps with the process. I squeeze of lemon works just as well.

I think I'd just boil some grapefruit juice a couple minutes, cool and add to the secondary or at bottling/kegging.

Would the rind of the grapefruit give you the flavor you are looking for? With oranges, there's a lot more flavor in the rind (just the outer, colored layer of the peel) than in the juice; wondering if the same holds true with grapefruit.

You raise an interesting question...

the_bird said:

Would the rind of the grapefruit give you the flavor you are looking for? With oranges, there's a lot more flavor in the rind (just the outer, colored layer of the peel) than in the juice; wondering if the same holds true with grapefruit.

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Yes it would, all citrus fruits have oil glands in their skin that hold the flavor. As you mentioned though stay away from the white pith.

I also read in Dave Miller's Homebrewing Guide that the pH in wort can be low enough to convert table sugar to invert sugar if added early enough to the boil.

Well I was really looking forward to adding a pound of so of crushed grapefruit flesh to my secondary fermentor. However, now I'm thinking of just using cleaned rines. Is there really any danger in adding grapefruit flesh? It's so tasty!
-Ben

Concidering how acid the flesh is I doubt it. You might want to rethink using the flesh though, unless you want a really acidic beer. Citrus flavors are mostly in the skin (they're soaked in alcohol to make extract), the flesh has a much lower concentration.