Freezing preserves food. We know this. But anyone who has tried freezing a banana or a tomato would be equipped to argue otherwise. When you freeze most fruit and vegetables, the water in the cells crystallizes, slicing through the delicate tissues, turning your produce to mush. It’s a problem for the preservation of other biological materials as well, including organs for transplant. “If you want to keep something forever, you need to store it at cryogenic temperatures, but ice kills biological tissues,” mechanical engineering Professor Boris Rubinsky told Berkeley Engineer recently.
So, he wondered, “How do we get cryogenic temperatures without the ice?” The answer, he and his team at his Bio-Thermal Laboratory discovered, was to limit the volume in a process called isochoric preservation. If water is cooled within a sealed airtight container, and thus not allowed to expand, it can reach subfreezing temperatures without turning to ice.
The technique, first theorized by Rubinsky in 2005, is now being used for such diverse applications as organ preservation and the vitrification of endangered corals with the hopes of restoring the species at a later date. Isochoric freezing could also help the planet in other, more immediate ways. In 2021, Rubinsky’s team calculated that freezing foods under isochoric conditions rather than conventional methods could cut energy use by nearly 6.5 billion kilowatt hours annually. In terms of carbon emissions, it would be roughly equal to taking a million gas cars off the road.
