Have you ever taken frozen fish balls out for cooking after a while, only to find that after thawing and cooking, they have a greasy, meaty smell? Are the balls no longer fresh? Or were they stored incorrectly?

What should I do if frozen food is no longer fresh?

Causes of WOF (Warmed-Over Flavor)

Freezing raw food in the freezer can slow oxidation, but if frozen for too long, the ice crystals formed can pierce the cell membranes. Cooking them again will still produce WOF (Warmed-Over Flavor). Thawing them at room temperature, exposing the food to a large amount of air, will accelerate oxidation.

Although already cooked ingredients, such as fish balls, will still develop WOF after being frozen for a long time, the maximum temperature for cooking fish ball soup is 100 degrees Celsius, which is the same as boiling water. The heating time is slow and the temperature is low. The WOF is amplified over and over again, resulting in fish balls with a high WOF and a strange, smelly flavor.

How to Preserve the Freshness of Frozen Foods

Take fish balls as an example. Follow these steps to keep fish ball soup fresh and flavorful.

• Step 1:
  Thaw the frozen fish balls in salt water. To reduce oxidation during the thawing process, soak them in 1% salt water.
• Step 2:
  Dice the thawed fish balls. Heat oil in a pan and stir-fry over high heat. Then add the diced fish balls to the soup.

This way, the fish balls retain their freshness and are enhanced with the fragrant aroma of stir-frying. Sprinkle with a little chopped green onion (or celery, coriander, or chives). Your family will probably all say, “Mom’s fish ball soup is the best.”

Or, prepare the fish balls before freezing them. Be present at the hot pot at the fish ball stall. As soon as the fish balls are removed from the scalding pot, ask the owner to immediately bag them in heat-resistant plastic bags. Tie the bags tightly to extend the fish balls’ shelf life.

However, if you miss the opportunity to remove the fish balls from the pan and leave them exposed to the air, this trick will fail.