Fish balls aren't bouncy and fall apart easily

Question

So I tried making fish balls using the recipe at https://thishungrykitten.com/2013/11/14/homemade-chinese-fish-balls-the-way-they-should-be-made/ and I don't think I did anything wrong, but the result is certainly not what I had been hoping for or what was described. Specifically, the fish balls fell apart extremely easily (basically dissolved in very lightly boiling water) and weren't bouncy (the only fish balls I've had have been frozen fish balls from the local asian market used in hot pot). So I'll just describe what I did and ask what I may have done wrong.

I went to Walmart and got 2 pounds of frozen cod fillets, with the bones and skin already removed. I kept them in the freezer for a few days (under a week). After thawing the cod in the sink for an hour or two, I took 3 of the fillets (relatively small, total weight between all 3 probably around a pound) and chopped them into 1-inch cubes. Then I put them in the food processor and turned it on for 2 minutes. I removed them, added 1/4 tsp salt and some black pepper (since I didn't have any white pepper) and started throwing the paste (into a metal bowl so that it wouldn't go flying everywhere). I slammed it probably around 100 times in there, then added a tablespoon of corn starch (with a little water), mixed it in, shaped a fishball, and put it into some very lightly boiling water. The water quickly turned a cloudy white and started foaming, and when I tried to scoop it back up it slipped through the slots of the spoon and dissolved entirely. I tried to thicken up the paste and help it hold together by adding more corn starch, but every time it just dissolved rapidly. Eventually I switched to deep frying, where it managed to stay together, but when I bit into the ball it wasn't bouncy at all.

In addition to asking a general "what did I do wrong / what should I have done?", I have some specific questions:

• Can frozen fish be used for fish balls? I understand the recipes all call for fresh fish, but my search-engine-fu has failed to tell me whether frozen fish is an acceptable substitute (I live in Nebraska, "fresh saltwater fish" as a requirement has some logistical difficulties)
• Does it work to use cod for fish balls?
• Do properly-made fish balls have issues with falling apart during cooking?
• Roughly how hard should fish paste be slammed (I wasn't exactly going pitching speed, just "toss across the room speed", if that makes sense)? Are there effective alternatives to slamming?

Answer 1

The most likely cause was this part:

slammed it probably around 100 times in there, then added a tablespoon of corn starch (with a little water), mixed it in, shaped a fishball, and put it into some very lightly boiling water.

You need to blend the water with the fish paste thoroughly. What I do is I dump all ingredients into the food processor and blend for about eight to ten minutes, excluding the time taken to scrape down the sides, or until the paste becomes a little elastic. When you push it with a finger tip and release, there is a little resistance.

There is no need to slam the fish paste at all.

For bounciness, add either baking powder or egg white. In my case, I add 1g of baking powder per 100g of fish. Alternatively, 0.4g of baking powder and 5g of egg white.

Also, add at least 44-50g of ice-cold water and 1g of potato starch. Commercial fish balls contain even more water for more bounciness.

Answer 2

There's no need to bounce the mixture by hand. Chinese chefs nowadays use food processors, and that works just fine (and saves a lot of time as well). Also, frozen fish is perfectly fine since that's what most Chinese chefs use nowadays. I see no problem with cod in particular; I sure have eaten cod balls somewhere.

If your fish balls aren't bouncy and dissolve easily, then there's a problem with the precipitation of proteins, which is the chemical process that leads to bouncy fish balls that don't fall apart. There might be several things going wrong here:

• not enough salt added. The purpose of adding salt is such that the proteins in the fish will precipitate and form a gelatinous substance, which is exactly what you want. Depending on the type of fish, maybe 1g of salt isn't enough. You have to make sure that your mixture is gelatinous enough (i.e., sticks on your hands).
• not enough protein. If there's not enough protein in your fish, then there won't be enough protein precipitating. In this case, you want to add some extra protein in the form of egg whites. There's no need to add baking powder. Since egg whites are pretty neutral in terms of taste, you can just add 1-2 egg whites at the beginning.
• the mixture gets too hot. You have to frequently add iced water to the mixture while mixing the fish mixture; otherwise the protein in the mixture will degenerate.

So, make sure you have enough salt, add some egg whites to the mixture (put it in together with the starch), and add iced water to the food processor frequently. This way you will likely be fine.

Not part of the question, but Chinese chefs often add to the mixture some cooking liquor and ginger-infused water to tone down the fishiness of the fish.