Why Food (Soup) Get Sour

Over the years, humans have invented different strategies to prevent food from getting sour. With more knowledge about the process, the solution is not easy. However, we may be able to reduce the number of incidents if we understand the mechanism behind sour food.

Sour soup

What Is Sour

Sour is one of the five basic tastes, and tasting sour indicates the presence of an acid in food, such as citric or lactic acid. While sourness can be a warning sign of spoiled or rotten food, many sour foods are perfectly safe and healthy to eat.

Why Food Get Sour

The major cause of sour food is bacteria releasing waste in food. This happens when the food is not properly preserved. When the food is well preserved, touching the food with bare hands can introduce bacteria into the food that can lead to sour taste. Different foods have different methods of storage to prevent sour taste.

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How To Prevent Sour Food By Warming

Cooking food is one way of preventing sour taste. Cooking food is not a means of sterilization. It only kills bacteria in the food. The dead bacteria can no longer release waste in the food.

Unfortunately, cooking food does not kill the spores. These spores can hatch to become active bacteria after some time.

To prevent these new bacteria from releasing their waste in the food, it is recommended that the food is warm again. The warming kills the bacteria again but not the spores. So this process must be repeated.

The frequency of warming is determined by many factors. Watery foods provide a suitable environment for bacteria growth. Hence they should be warm more frequently. Personal observation of it at a 12 hours interval.

The above is only effective when the food is properly warm. The temperature must be above 100°C. The steam must be allowed to escape the pot. This allows the food to retain heat longer than when the pot is closed immediately after warming.

After getting cool, the pot should be covered. The cover reduces the number of bacteria that falls into the pot from the environment. This prevents further degradation. Failure to warm it properly will only result in sour food within hours.

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Oily food doesn't provide a suitable environment for bacteria growth. So the foods can survive without frequent warming. Some have stayed 24 hours without losing taste.

Preventing Sour Food By Refrigeration

Storing food in the fridge is another method of preventing sour food. The fridge provides an uncomfortable environment for the bacteria to thrive. At -40°C, the activity of the spore is reduced. They may remain dormant for up to 4 days. After this, they may become active and make the food go sour. This is true of airtight fridges.

Some fridge cannot even provide this safety. When bacteria find a little vent into the fridge, they may attack the food before they succumb to the temperature. This frequent attack will over time render the food sour. To prevent this, the food should be wrapped in a nylon and placed in an airtight container inside the fridge.

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It is thought that the airtight bacteria prevent bacteria from gaining access to the food. Another school of thought is that lack of oxygen renders most bacteria useless. This second reason seems logical as some bacteria defutenly are in the food but now inactive.

For storage in the fridge to be effective, the food must be properly warmed and allowed to cool. Storing hot food in the fridge will make the food spoil. The heat from the food will heat up inside of the fridge and provide the suitable environment for bacterial degradation. The food must be allowed to cool down and transferred without touching the food.