The main reason is that the soup tastes cold when you eat it. If you don’t have a refrigerator, just heat it up after eating and it won’t spoil.

It is possible;

The flesh tissue (not the melon flesh) around the winter melon seeds has not been picked or not cleaned cleanly. The flesh tissue of melons (same for cucumbers) will be there. It will become sour when cooked at high temperatures. The more seeds (older) the more sour it will be. However, it does not deteriorate, it just affects the taste of the whole dish.

Winter melon itself has a light sour taste.

There are two types of winter melon. One is called human winter melon, which tastes sour. The other is called rice winter melon, which does not taste sour. The sour taste of boiled winter melon does not mean that the winter melon is bad. Remember When cooking winter melon, don't always stir it with a spoon. When the soup is cooked, just season it. The heart of winter melon will become sour when cooked, so just remove the heart and wait until it is ready to serve. Add salt and it will definitely not turn sour. It does not mean that the pot has not been cleaned or that the winter melon has gone bad.

It is normal for the sour taste of winter melon.

To solve this problem, you can first Blanch the winter melon in boiling water, take it out and make soup, and there will be no sour taste.

Normal winter melon has no sour taste without adding vinegar. The sour one is because your pot has not been cleaned, and the other is that the winter melon has gone bad. It is inedible.

Do not add soy sauce, so that it will not have much sour taste. In addition, winter melon soup made overnight will also have a sour taste!

Did you add soy sauce? Soy sauce The color of the winter melon slices will become darker and the taste will become sour.

Maybe the winter melon has gone bad, or it has been cooked for too long

Did you add salt when cooking? You should wait until the melon is ripe before adding salt!

Good winter melon will not have a sour taste. A sour taste means that the winter melon has gone bad.