UNSPLASH
Have you ever wondered how your favourite pizza, vegetables, or even ice cream stays fresh in the freezer for months?
Freezing food is like hitting the pause button on a video game. It stops most bacteria from growing, which are the tiny creatures that can make food go bad or make you sick. When food is frozen, the water inside it turns into ice. Since bacteria need liquid water to grow, ice stops them in their tracks!
When you put food in your freezer, it cools down until it reaches 0°C. However, to ensure that all the bacteria growth stops, the temperature needs to go even lower, to about -18°C. At this super cold temperature, the molecules in the food slow down, making it almost impossible for bacteria to multiply.
When food freezes, small ice crystals form inside it. The speed of freezing is key here: the faster the food freezes, the smaller the ice crystals. Smaller ice crystals are much better because they cause less damage to the food’s cells. This means when you defrost the food, it still looks and tastes fresh.
In big factories, food is frozen super quickly with special equipment, which is much faster than how ice cream freezes in your home freezer. This process is called flash freezing.
Not all foods freeze well. Fruits and vegetables with high water content can become mushy when thawed. That's because the large ice crystals can break the cell walls, causing the food to lose its firm texture.
However, many foods are perfect for freezing, like bread, meat, and cooked dishes. Scientists are always finding new ways to freeze different types of food so that they keep their taste and nutritional value after being frozen.
So, the next time you enjoy a scoop of frozen strawberries or a slice of pizza from the freezer, remember the cool science that made it possible.