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Canning -- Pickled and Fermented Foods

What is bluestone?

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Bluestone (copper sulfate) is also called blue vitro. It was used in pickling years ago to impart a bright green color to the pickled cucumbers. The copper reacted with chlorophyll to form a blue-green pigment. Because high levels of copper are toxic, the addition of copper to any product is not recommended.

PREPARED BY: Angela M. Fraser, Ph.D., Associate Professor/Food Safety Specialist, and Carolyn J. Lackey, Ph.D., R.D., L.D.N., Professor/Food and Nutrition Specialist, North Carolina State University (August 2004)

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