I recently had to throw away a small jar of eggs that I had frozen just before I left for a holiday and did not have time to cook. The glass jar had cracked in the freezer.
It seems so basic, yet I do it again and again: use glass containers without thinking, and wrappings that fail to keep out moisture and vapour. I also forget to label my containers so that I have to guess at its contents. Often I defrost whatever it is and just cook it.
But if you are taking the trouble to freeze your food, it makes sense to know the following few rules.
Not every container or wrapper is suitable. You cannot use just any old plastic bag, like the one that your bread came in, to store stuff in the freezer. They have to be labelled freezer safe.
Containers need to protect against moisture and vapour to prevent freezer burn and oxidation by blocking oxygen, which can cause meat to go rancid and fruit and vegetables to lose their nutrients.
You need sturdy, rigid containers like plastic boxes and glass jars as well as flexible containers such as freezer bags and aluminium foil. Freezer bags, cheap and flexible, can be used for almost anything.
As for plastic containers, opt for good quality ones and choose the right sizes for the food to be frozen so that there is no excess air in the container. They should also be able to go from the freezer to the microwave oven. Do not use regular waxed paper, plastic wrap or plastic bags. And, as I found out, glass jars can crack, if they are not meant for the freezer.