Freezing is a relatively cost-effective way to preserve nutrients and taste, but unfortunately it comes with a big energy and carbon emissions price tag. Researchers now propose a fundamentally new way to freeze foods that could cut global energy consumption by as much as 6.5 billion kilowatt-hours a year. This 4.59 billion kg carbon emission reduction can be compared to removing about 1 million cars from the road.
Also, the technique substantially improves food quality and can preserve fresh and otherwise delicate food products for longer than conventional freezing methods.
The method that Cristina Bilbao-Sainz, a research food technologist with the U.S. Department of Agriculture, mechanical engineer Boris Rubinsky at the University of California, Berkeley and their colleagues have reported is based on a strategy that Rubinsky’s team devised for transporting organs for transplant patients.
Called isochoric freezing, the technique relies on storing foods in a sealed, rigid container made of hard plastic or metal that is filled with a liquid such as water, and placing it in a freezer. Conventional freezing involves exposing food to the air and freezing it solid at sub-zero temperatures, the new method does not turn food into solid ice.
Instead, only about 10% of the volume of water in the container is frozen, and the pressure inside the chamber keeps the ice from continually expanding. “Energy savings come from not having to freeze foods completely solid, which uses a huge amount of energy,” Bilbao-Sainz told anthropocenemagazine.org.
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