racemic acid

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An optically inactive form of tartaric acid, C₄H₆O₆, that can be separated into dextrorotatory and levorotatory components and is sometimes found in grape juice during the making of wine.

Wiktionary

1. n. 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

WordNet 3.0

1. n. the optically inactive form of tartaric acid that is often found in grape juice