Can my freezer be too cold?

Question

The FDA recommends a freezer temperature of 0˚F (-18˚C). Warmer temperatures risk bacterial growth and quality problems. But what are the reasons not to set the freezer colder? My Bosch freezer can be set as low as -8˚F (-22˚C).

The only downsides I can see are increased electricity usage, increased thaw times during food preparation, and more wear on the freezer compressor. But advantages include colder ice cubes and faster freeze times for new items. Are there any other reasons not to set my freezer to the coldest setting?

Answer 1

One possible consideration is that some frozen desserts (most notably ice creams and sorbets) can be very difficult to scoop if your freezer is too cold. Optimal serving temperature for ice cream is between about 5 & 10°F (-15°C & -12°C); colder freezers may result in difficult scooping and/or needing to leave the ice cream out to thaw.

The proposed advantage of "colder ice cubes" is relatively small, because the vast majority of heat absorption by ice (in a drink, say) is due to it thawing. To put some numbers on it, every gram of frozen ice absorbs about 2.1 joules of heat energy when it warms up by 1°C. In contrast, that same gram of ice absorbs 335 joules of heat energy when it thaws into liquid water. If you run the numbers, this means that ice at -22°C will only absorb 2-3% more heat from your drinks than ice at -18°C.

Answer 2

There is little reason, aside from the obvious ones you already mention, to avoid the coldest setting. You might be concerned with scoop-ability of some frozen desserts, but that probably will not be too much of an issue for store-bought products, which are often stabilized for texture. Also, these can be removed in advance to temper.

The Institute for Food Resources at the University of Nebraska-Lincoln, states that "most foods will maintain good quality longer if the freezer temperature is -10°F to -20°F."

The Ohio State extension states, "the colder the better."

Freezer burn is not caused by cold temperatures. It is dehydration that occurs from poor or improper packaging. It is not unsafe, but usually not pleasant.

Most modern freezers control potential ice build up. So, that is usually not an issue either. However, some chest freezers might need the occasional, manual defrost. This would be the case regardless of your set temperature.

Answer 3

Two minor considerations (but still is an answer)

• Even if your freezer can be set as low as -22, it is good to have some safety margin in regard to the freezer longevity.

Most machines don't like being operated at their extreme settings and they are much safer by operating somewhat off the extreme. Both energy consumption and wear are expected to double or triple (an educated guess, it can be even more) between -18 and -22.

Random failure modes like cracking or breaking internal doors or drawers or frost build-up inside the insulating foam are also much more probable.

• You don't gain much more storage time at -22, compared to -18. I am yet to see something gone bad when stored at -18, even after years of storage. Yes, textures somewhat change, but in regard to textures, the colder is not the better anyway.

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When it is good to crank your freezer lower, even all the way down to its possible minimum temperature?

• Unreliable electricity
• Frequent opening

These both get the temperature temporarily higher than the setting. Whatever the reason is, you will have some time until the temperature climbs above the acceptable values.

(Modern freezers automatically react to the frequent opening by lowering the temperature)

Answer 4

There are two things that can happen if the freezer is too cold for extended periods of time:

• You'll get more ice build-up (especially with frequent use) and
• The food inside will have more freezer burn than expected

Note that some more modern freezers have a "quick freeze" setting that drops the freezer temperature for a few hours and then returns it to "normal", as there are no problems with having a lower freezer temperature for a couple of hours, most issues will happen after an extended period of time with too low temperature

Answer 5

I assume you mean standalone freezer, not refrigerator+freezer combo.

There is no reason to not use the lowest temperature setting, except the obvious wear of the machine. The advantage of this is that food may keep a bit longer. The temperature within freezer is not uniform - it will be a bit warmer near the door. Depending on which location the manufacturer used for measuring, and inaccuracies of thermostat, it may vary slightly. Many food I see has label saying something like -10C: two weeks, -18 C: until expiry date. So to be extra sure it never exceeds the -18 C, just dial in couple extra degrees.

Regarding the disadvantage of thaw times - use fridge and the built-in freezer it has. The food you know you will be using soon - a week, a day - just keep it in fridge's freezer. It has higher temperature, so the food will not be as rock frozen. Whenever you use stuff from fridge, bring new ones from the freezer. I do that with ice cream - fresh from freezer, it can bend spoons, but in fridge freezer, its nice and soft. In case you need to get something thawed out now - microwaves are great for that.

Alternatively, you can rearrange things in freezer slightly - move the stuff that you want absolutely rock solid frozen deep inside, and keep the stuff you want not-as-much-frozen near the door.