Scientists from the U.S. Department of Agriculture's Agricultural Research Service (ARS) and the University of California (UC)-Berkeley suggest that a new food freezing technique could save energy, reduce carbon emissions and improve the quality of frozen foods.

The technique, called isochoric freezing, stores food in sealed, rigid containers — typically composed of plastic or metal — and entirely filled with water or another liquid. Once filled, the food is immersed in the liquid and placed in a freezer.

While conventional food freezing exposes food to the air, freezing it solid at temperatures under 32° F, the isochoric freezing method preserves the food without turning it into solid ice. This is due to food being entirely submerged in the liquid ahead of freezing, thereby preventing ice crystallization — which is a common threat to food quality.

In addition to improving the quality of frozen foods, the team of scientists suggest that an energy savings is a likely result of isochoric freezing because freezing foods completely solid demands a significant amount of energy as do cold storage protocols like quick freezing, which is commonly used to help avoid ice crystal formation.

"A complete change over to this new method of food freezing worldwide could cut energy use by as much as 6.5 billion kilowatt-hours each year while reducing the carbon emissions that go along with generating that power by 4.6 billion kg, the equivalent of removing roughly one million cars from roads," said ARS research food technologist Cristina Bilbao-Sainz.

The team of scientists believe that the process could enable the freezing of commonly difficult to preserve foods like tomatoes, cherries and potatoes. Additionally, the researchers report that microbial contaminants are destroyed with isochoric freezing.

Originally developed to cryopreserve tissues and organs for transplants by a UC-Berkeley biomedical engineer, isochoric freezing could potentially be used for other applications such as medicine, biology and space travel.

The study, Analysis of global energy savings in the frozen food industry made possible by transitioning from conventional isobaric freezing to isochoric freezing, appears in the journal Renewable and Sustainable Energy Reviews.

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