Why do some foods freeze well and others don’t?



Why do some foods freeze well and others don’t?

In: Biology


Sometime it is how you freeze it. Normal freezers produce larger ice crystals and will turn veggies and fruit into mush when thawed. Those large ice crystals basically puncture cell walls and the water pours out when thawed. Imagine a bunch of ziplock bags full of water and those are the cell walls. Then the tip of a knife is an ice crystal and poke a bag and watch the water pour out. Now to get around this you need extreme cold. Liquid nitrogen works. You can freeze a strawberry with that and then thaw it and it will have pretty much the same texture. Why because at extreme colds ice crystals have less time to form and are smaller not every cell wall gets cut open.

The different contents of items may have different freezing points, plus some contents may want to separate naturally.

Ice cream is a great example. If you leave it out to melt, the fats and the water will separate (just like oil and water). They will still separate when frozen, but much more slowly. This is why if you leave ice cream in the freezer for too long, the fats and water separate more and more, and you have two frozen parts instead of a nice mix – the frozen milk fats (the goopy stuff) and frozen water (the ice crystals).

There are similar dynamics at play with many items. When the moisture wants to freeze in something like bread, it separates out and freezes on it’s own, this means less moisture is left inside the bread making it hard and dry, and ice accumulates outside of the bread – AKA, freezer burn.

Largely depends on the water content of that food. If the water content is high (for example raw fruits) they will typically not freeze well – tend to become mushy when thawed. Why they become mushy – I am not fully clear – but it may have to do with water expanding upon freezing and damaging cell structures in the food.

Foods which have very little water content – freeze very well. For example – partially dehydrated / sun dried fruits, partially cooked / pre cooked foods like french fries etc. They do not turn **as mushy** as the watery foods.