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Energy Efficiency

Canning or Freezing?

Each method of food storage has its advantages and drawbacks

One of the joys of summer is growing and picking the fruits and vegetables we’ve grown in the garden. But when it comes to preserving the bounty, there is one timeless question: Which is better, canning or freezing?

The answer is: It depends—on variables like preference, time, space and the type of food. But there are other variables that perhaps are worth mentioning, too.

Which has a smaller energy footprint?

Canning involves boiling jars of food to sterilize and seal them, requiring a one-shot—though considerable—burst of energy use. Freezing food requires a long-term consumption of continuous electricity, and the longer you store the food, the more it costs.

A 1980 academic study published in the Journal of Food Science calculated the energy use for processing and storing 50 pounds of vegetables. The study determined that freezing them for six months used about three times as much energy as canning them.

However, it’s hard to extrapolate this information to today’s numbers. New freezers use a third of the electricity used by freezers in 1980, while electricity costs about 2½ times as much as it did then. The numbers also vary significantly depending on whether the freezer is full or not. Also, chest freezers are twice as efficient as uprights, so the difference can greatly affect electricity use.

A more recent analysis concludes that freezing uses 15 times as much electricity and costs four times as much per pound as canning, once the cost of the equipment is factored in.

Which method has a smaller physical footprint?

Another source, The Natural Canning Resource Book, made a couple of relevant points about the issue besides energy use.

Availability of resources is an important factor in the equation: If you often deal with outages or other power disruptions, canned food keeps a lot better than thawed-and-refrozen food. If you live in a small space, or if you’re a renter rather than an owner, it’s a lot easier to store and move canned food than it is to store and move a freezer.

Finally, the issue of taste: The Journal of Food Science study found that people preferred the taste of frozen food over canned by a huge margin. Whatever method you use, the end result is that you want people to eat it and like it.