Science of freezing food

Once in a while, we all need to store our food in the refrigerator, whether you’re making ahead meal planner or just can’t stand to see leftovers go to waste. Frozen foods are continuing to become more and more popular as time goes.

This is not a surprise as It is one of the easiest ways to preserve food and not to mention its convenience to preserve the food’s nutrition value. They’re basically a machine for stopping time by freezing things! Plus, it’s much easier to make homemade food if all the ingredients are ready to hand. But are you making the most out of your freezer? Does freezing provide the nutritional value that combats fresh foods?

For you to preserve high-quality goods/foods, you need to understand how the whole freezing process works.

Science of Freezing

Generally, the act of freezing delays spoilage and keeps foods safe by preventing micro-organism from growing and slowing down the enzyme activity that causes food to go bad. But lets’ get into details of how all that happens.

First of all, you need to understand that liquids(water)freezes differently compared to foods. When ice crystals form during the process of water freezing, there’s actually a very low amount of heat produced. The water’s temperature remains 320F as ice crystals grow and the temperature suddenly drops as the ice crystals cool. Now, foods are much more complex than water and are made of mixture of many substances hence their freeing point going lower than the freezing point of water.

The act of freezing food products is basically just the process of freezing the water present in the food substance. Water and other chemical substance found in the plant cells generally make up 90% of the food products.

When the food is put in the refrigerator, the water in those cells freezes, the ice crystals rupture, changing the physical appearance of the food, especially for those products that are consumed raw. For example, tomatoes and celery will be much softer and thawed while you’ll barely notice the difference in fruits.

As ice crystals form within the food, a slow temperature drop occurs. The drop in the temperature then goes faster as the crystals cool inside the food.

Different food freezes differently and how a food freezes depends on factors like:

  • The amount of water present
  • Amount of sugar
  • The muscle tissue of air in the food

The speed at which the food freezes affects the quality of food. This means that foods that freeze faster have improved quality. Let me explain why this happens.

The size of the crystals that form depends on the speed at which the food is freezing in that, faster freezing foods have smaller crystal made and the slower freezing food, have larger crystal formed. The smaller crystals do less damage to cell walls compared to the larger ones which punch through cell membranes. As a result, the food with large ice crystals thaws and have more dripping due to the loss of liquid.

However, even small crystals can become unstable and grow to form large crystals overtime. This happens during the defrosting period in which the food thaws slightly, allowing the ice crystals to grow and rupture more cells when they refreeze again. This freeze-thaw cycle will repeat each time the freezer door is opened, allowing heat to enter the freezer. This can be seen in the freeze-thaw cycle in frost-free freezers. To prevent this, a chest type freezer would be ideal as it reduces heat loss that occurs when opening the door because warm air rises.

Does freezing food kill all its nutrients?

I’m sure you’ve heard people talk all about the benefits of fresh foods and how frozen food is the enemy. But are they correct? Does freezing really kill all or even some of the food’s nutrients?

The truth is that freezing doesn’t actually kill the nutrients but are just as good as fresh foods, if not better. Let me explain. All the freezing does is to stop the spoiling process right in its track. The act in itself has very little effect on the food’s nutrients.

Vitamin C can be lost when you immerse some fruits or vegetables in boiling water before freezing to inactivate enzymes and yeasts that would continue to cause food spoilage even in the freezer. Despite that, the frozen fruits/vegetables are in peak conditions throughout and might even be higher in nutrients than the fresh ones.

Fresh foods can take some days to be sorted, transported, and distributed to stores during which vitamins (fruits and vegetables can lose up to 15% of vitamin C daily at room temperature) and minerals can be slowly lost from the food. While in freezing, there’s barely any nutrients lost.

If you want to know more about fresh versus frozen food you may want to watch this!