Dr. Sonja Koukel of the UAF Cooperative Extension Service

The following column originally appeared in the Sept. 30-Oct. 6, 2009, issue of Capital City Weekly and was made available to the Sitka Local Foods Network site. This column runs monthly.

More on Home Canning Seafood: Crab and Shrimp

By Dr. Sonja Koukel, PhD
Health, Home & Family Development Program
UAF Cooperative Extension Service

For the Aug. 5 Capital City Weekly issue, I submitted an article focusing on home canning seafood, specifically crab and geoducks. I was pleased to receive an e-mail from a reader asking for more information. As many of you may have had the same questions I’m sharing my responses here.

To refresh: In the article, I provided the guideline for freezing crab as that is the best preservation method for this food. Experts recommend boiling the live crab for five minutes -– at which time the crab is considered “cooked.”

Our reader asked two questions.

The first:

“Please let me know if this [recommended time] is a misprint. All the people I know who cook crab heat water in a crab cooking vessel until the water boils, then they boil the crab a minimum of 15 minutes before cooling it. I have often wondered if the 15-minute boiling period is too long, but have always deferred to the locals with crab experience. What is the critical issue in crab cooking?”

The second question:

“When cooking shrimp, on the other hand, the accepted practice seems to be: put the critters in a pot, bring the water to boil, then remove the shrimp when they float to the surface, which does not take very long.”

My responses to these two questions follow.

Dear Capital City Weekly Reader,

In regards to your questions, I did some further research over the weekend on the topics of cooking crab and shrimp. Here is what I found.

Crab:

The University of Alaska Fairbanks Cooperative Extension Service uses the University of Georgia Extension publication, “So Easy to Preserve,” as the main resource for home canning and food preservation information. Much of the information in this publication is based on the USDA, “Complete Guide to Home Canning,” as well as research from Extension Services across the US. In fact, Alaska Cooperative Extension is represented in the publication for the processing times for canning fish in quart jars (Kristy Long, Foods Specialist UAF CES).

For more information, I resourced other Extension websites and found a variety of cooking times for preparing crab for freezing. Oregon State University Extension publication, “home freezing of seafood” (PNW0586), recommends the following for whole crab: [after preparing crab] Cook in boiling salt water (2-4 Tbsp. per gallon, according to your taste preference) for 12-15 minutes. If the back is left intact, add 10 minutes to the cooking time. Add 2-3 minutes to the cooking time if the water doesn’t boil within a few minutes after adding the crab.

This from the Sea Grant Extension Program, UC Davis, “Freezing Seafood at Home”: You can either freeze crabmeat in the shell or as picked crabmeat. Cook crab before freezing to prevent discoloration of the crabmeat. Drop live crabs into enough boiling water to cover the crabs. Cover and return water to a boil. Boil for about 25 minutes. Remove crabs from boiling water and cool them immediately in cold water. Let crabs cool for several minutes and then drain.

One purpose served by boiling the crab prior to freezing is that the process makes the meat easier to remove from the shell. As far as food safety, boiling will kill any parasites and/or bacteria that contribute to the decay of the shellfish. My sources claim that this is done after one minute in the boiling water. A celebrity chef wrote on his website that the cooking time for crab is not based on food safety but on the product being undercooked, cooked, and overcooked. A good guideline for cooking crab is to check the color of the shell. When the crab is done, the shell turns an orange/red color.

Something to take into consideration when looking at information on the Internet, many sources group all types of crab into one category. On the East Coast, most crab will be Maryland blue crab which are smaller than the Dungeness crab normally consumed in the Northwest. Just keep in mind that you have a safe and easy to handle product when the crab is boiled at least five minutes prior to freezing.

Now, the reply to the shrimp question.

The Sea Grant Extension Program, University of Delaware, instructs cooking the live shrimp just to the point of being done (the flesh turns from translucent to opaque). The cooking method you describe — putting live shrimp in a pot of boiling water and removing when they float to the top — is right on. If you were to time this procedure you probably will find that it takes approximately 3-5 minutes to boil one pound of medium sized shrimp.

I appreciate input from readers and welcome all suggestions, inquiries, and ideas. Please contact me via email: sdkoukel@alaska.edu or phone: 907-796-6221.

Sonja Koukel, PhD, is an assistant professor in the Health, Home & Family Development Program for the Juneau District office of the UAF Cooperative Extension Service. Reach her at sdkoukel@alaska.edu or 907-796-6221.