RE: Bluing King Crab

From: West Coast Fisheries Corp., Bruce (westcoastfish@hotmail.com)
Date: Fri May 19 2006 - 10:31:11 PDT

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    Gregg, I would suggest looking into re-cooking Frozen King Crab and chilling
    and freezing quickly to see if this would stop the bluing. Also...years ago
    I heard that absorbic acid may work.

    Bruce Levy
    West Coast Fisheries Corp.
    email: westcoastfish@hotmail.com
    tel. (206)232-0719 fax (206)230-9197

    ----Original Message Follows----
    From: "Gregg Morrow" <greggmorrow@comcast.net>
    To: <seafood@ucdavis.edu>
    Subject: Bluing King Crab
    Date: Fri, 19 May 2006 06:58:23 -0700

    none StationeryHello,

    I am looking for a good explanation for what stops bluing in King Crab.

    I understand that crab blood gets its blue color from the oxygen-carrying
    respiratory protein hemocyanin, and that there are a number of theories as
    to how cooking controls the ability of the blood to turn blue.

    I am curious as to how cooking the crab to a certain temperature for a
    minimum time, stops the bluing process.

    Does cooking disrupts the molecular structure of the hemocyanin?

    Does cooking destroy or de-activate an oxidative enzyme naturally found in
    the blood?

    Occasionally, we have observed slight amounts of bluing in the external
    surfaces shoulder and attribute this to improper bleeding and washing during
    the butchering process. Extensive thaw tests of these crab sections show
    that the crab is properly cooked and no bluing is found elsewhere within the
    section. I believe that blood from a freshly butchered section will turn
    blue when it is exposed to air and that you can not cook the blue away.

    I have also observed in crab sections that were purposely undercooked, how
    the bluing process is slowed by maintaining a deep frozen temperature
    (colder than 0°F). Portions of this same undercooked crab maintained at
    warmer temperatures 40°-45°F will show significant signs of bluing (from the
    shoulder to the dactylus) within a very short period of time. This would
    seem to support the idea of an oxidative enzyme that has its ability
    diminished by the cold temperature.

    Does the molting cycle of the crab have any factor?

    Thank you,

    Gregg Morrow



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