Freezer mathematics

Back in 1998, food scientists at Colorado University worked out whether it's worth the time to process and freeze vegetables, including the cost of buying and running a freezer.

Their calculations were for a new 450 litre chest freezer with a 240kg capacity and a 20-year lifespan. They assumed it would always be full for best energy efficiency. They also included the cost of containers, repairs, maintenance, savings on fuel (fewer trips to the supermarket), and even the interest on the purchase cost.

The cost: around NZ$1.40 per kilogram of food (converted from USD and adjusted for inflation).