Michigan State University Extension
Preserving Food Safely - 01600734
10/13/97

### BLUESTONE IN PICKLING

        Some  old  pickle recipes call for a  bluestone  to  be

    added
    to the pickling brine to give the pickles a blue-green

    color.
     Bluestone  is  copper  sulfate  and is also known as

    blue
    vitro.   In earlier days,  pickles were usually made in

    metal
     pans containing copper.   They turned a bright  blue-

    green
     as  the copper ions  interacted with the  chlorophyll

    molecules
     in the pickle.   A similar color was  sought  for

    pickles
    brined in enameled pan or crocks, and it wasn't long

    before
     copper sulfate,  or bluestone,  was found to do  the

    job.
      Since  high  levels  of copper can  produce  toxicity

    symptoms
    in humans,  particularly gastrointestinal problems,

    the
     use  of copper sulfate in pickling should  be  avoided.

    Since
     its  only  function  is  to  color  the pickles,  the

    bluestone
     can be simply eliminated from the recipe  without

    affecting
    the overall quality of the final product.

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