I used fresh garlic in my pickles and it turned blue. Why?
Garlic contains sulfur compounds which may react with copper to form copper sulfate, a blue or blue-green compound. The amount of copper needed for this reaction is very small and is frequently found in normal water supplies. Use the pickles but discard the garlic.
Also, garlic bulbs that have not been properly cured before marketing or bulbs that have been refrigerated will turn green or blue-green. Storing garlic bulbs for 32 days at or above 70-80 degrees F. before use will prevent formation of green or blue-green pigments.
Caution: Old-time recipes often called for the addition
of copper pennies or bluestone to give pickles a vivid
green color. This is not recommended because a large
amount of copper is toxic.
Source: Dr. Gerald Kuhn, Penn State, May 1987.
Last update: Tuesday, May 05, 2009