racemic acid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A form of tartaric acid, C₄H₆O₆, that is composed of equal portions of dextrorotatory and levorotatory components, is not optically active, and is sometimes found in grape juice during the making of wine.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry an equal mixture of the d- and l- forms of tartaric acid found in grape juice; the isomers can be separated via crystallization

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the optically inactive form of tartaric acid that is often found in grape juice