I am sure the processed foods are fine - just be sure to watch that they don't get spoiled - anything with a big dose of omega3 or similar will decompose incredibly fast if it is exposed to heat and humidity. I have been feeding my tanks the following for several years now and I would recommend it to anyone -
Take a big blender - you might want to get a blender just for this purpose because the faint odour of fish will stick around no matter how many times you wash it out.
Put in a bunch of shelled shrimp, squid tubes, couple of sheets of nori, small amount of shelled oysters or clams, and, if you have a proper fish shop nearby, try and get a hold of a bunch of egg sacs from the gutted fish - these are absolutely the bees knees. If you want to use packaged roe/caviar instead, as with the clams and oysters, make sure you are just getting the meat rather than 'meat in oil' or 'meat in brine' or some other processed variety. Add a small amount of plain gelatine (1-2 teaspoons or less!) and whatever vitamin mix you want to use. Mix this in the blender until the contents are reasonably smooth with small floaty chunks. Pour the mix out into icecube trays, wait a few minutes to give the gelatine a chance to settle, then put it in the freezer. You don't need much gelatine, mainly this is to hold it together for just a minute or two after the cubes are left out to defrost - otherwise the mashed paste will get loose too quickly and just turn into dissolved organics in the water.
I have never had a fish that has not gone mad beserk pushing other fish out of the way to get at this stuff. If you put a cube in a cup of tank water first and slosh it around it is also fantastic coral food - I suck it up in a large bore syringe and squirt it at corals.
The big advantages of doing it this way is that you always know exactly what is in it and can vary the mix depending on what you want the fish to get more of, you are paying about fourteen trillion times less per ounce than packaged food, and you know it is fresh.