Judy, cooking fish can be challenging because of the variety of degrees of doneness and textures they present. It's always a matter of personal preference. However the choice of 132F is a little below the acceptable doneness cooking temperature for most North Americans, except of course for those who dwell along the left coast.
Cooking from from the frozen state introduces another layer of challenge to your cooking and potentially compounds cooking errors. Your researched time of an additional 15 minutes for frozen fish is only about right for 1/4-inch thick filets. I've never seen Alaskan Cod cut so thin. It's usually cut steak-like, an inch or more thick.
You might want to reconsider your research sources to have more reliable information. Please share them as a helpful warning to your Community.
In spite of your claim to have cooked those cod fillets you present evidence to the contrary. In the cat's experience "Chewy and spongy" doesn't describe cooked fish.
To help you discover the requested corrections to your technique we need you to disclose the following pertinent details one always considers before SV cooking:
- filet thickness?
- desired texture of the cooked product as in soft or firm?
- And did you preheat the water to 132F?
The 45 minutes cooking time for frozen fish filets is about right for half inch thick filets. Were yours any thicker?
FYI, Pasteurization cooking times for frozen 1" thick fish filets require about 1 3/4 hours and about 4 1/4 hours for 1 1/2-inch thick filets.
And now for a few words on food safety.
Judy you were wise to purchase frozen cod which removes the risk of ingesting live parasites if you chose not to Pasteurize fresh fish. Raw inshore fish filets should always be examined for parasites, usually in the form of little white worms which you certainly don't want to have setting up housekeeping in your gut.
Here is your new trusted SV fish cooking resource: