Freezing is where storage containers earn their keep and where a few properties of freezing itself catch people out.
Leave Headspace
The first rule. Water expands as it freezes, and food containing water expands with it.
A container filled to the brim will have its lid forced off, its seal deformed or, with glass, its walls stressed. Leaving a gap of an inch or so at the top absorbs the expansion.
Liquids need more headspace than solids, because there is more water to expand.
Freeze Fast, Freeze Flat
- Faster freezing produces smaller ice crystals and less cell damage
- Shallow containers freeze faster than deep ones
- Flat packages also thaw faster and stack better
- Which matters for safety, since slow thawing is the risk
- And for space, which is always short in a freezer
Ranges offering several capacities within one stacking system, of the kind at mysnapware.com, make portioning into shallow containers practical rather than a compromise.
Cool It First
The food safety step that gets rushed. Hot food cooling slowly spends hours in the range where bacteria multiply fastest.
Divide into shallow containers to cool quickly, and get food refrigerated within about two hours before it goes to the freezer.
Do not put a large hot mass straight into a freezer, since it raises the temperature of everything around it.
Glass in the Freezer
Tempered glass tolerates freezing and it is not immune to thermal shock in the other direction.
A dish taken from the freezer straight into a hot oven is the classic failure. Let it stand, or move it to a refrigerator first.
Leave more headspace with glass than with plastic, since glass will not flex to accommodate expansion.
Label Everything
Contents, date and portion size, on the lid or on tape.
Frozen food is safe indefinitely at a proper freezer temperature and declines in quality, so the date is what lets you use things in order rather than discovering a mystery in a year.
Freezer Temperature
Around minus eighteen degrees Celsius, or zero Fahrenheit, is the target.
A freezer running warmer than that shortens quality life substantially, and most people have never checked.
Thawing
In a refrigerator, in cold water changed regularly, or in a microwave followed immediately by cooking.
Not on a worktop, where the outside sits in the danger range for hours.
Do Not Refreeze Raw Food
Once thawed, cook it before it goes back.
