Science Friday

New Cold Storage Method Solves Freezer Burn—And Saves Energy

Have you ever pulled a long-anticipated pint of ice cream out of the freezer, only to find the strawberries crunchy and the normally creamy substance chalky and caked with ice? Freezer burn, a phenomenon caused by water in food crystallizing into ice inside the ice cream or fruit or meat during freezing, is a menace to taste buds, a driver of food waste, and even damages some of the nutritional benefits of food. And it’s always a risk as long as food preservation relies on very cold temperatures. Even flash-freezing, which works much faster, can still create small ice crystals.

But United States Department of Agriculture (USDA) food scientists, working with a team at the University of California-Berkeley, have a method that could help solve this problem. Normal food freezing, called isobaric, keeps food at whatever pressure the surrounding air is. But what if you change that? Isochoric freezing, the new method, adds pressure to the food while lowering temperature, so the food becomes cold enough to preserve without its moisture turning into ice. No ice means no freezer burn. And, potentially, a much lower energy footprint for the commercial food industry: up to billions fewer kilowatt-hours, according to recent research.

Ira talks to USDA food technologist Cristina Bilbao-Sainz and mechanical engineer Matthew Powell-Palm about how pressure and temperature can be manipulated to make food last longer, and hopefully taste better. Plus, the challenges of turning a good idea into a widespread technology.

When chef Jeremy Umansky grows a batch of Aspergillus oryzae, a cultured mold also known as koji, in a tray of rice, he says he’s “bewitched” by its fluffy white texture and tantalizing floral smells. When professional mechanical engineer and koji explorer Rich Shih thinks about the versatility of koji, from traditional Japanese sake to cured meats, he says, “It blows my mind.”

Koji-inoculated starches are crucial in centuries-old Asian foods like soy sauce and miso—and, now, inspiring new and creative twists from modern culinary minds. And Shih and Umansky, the two food fanatics, have written a new book describing the near-magical workings of the fungus, which, like other molds, uses enzymes to break starches, fats, and proteins down into food for itself. It just so happens that, in the process, it’s making our food tastier. 

You can grow koji on grains, vegetables, and other starchy foods, and make sauces, pastes, alcohols, and vinegars. Even cure meats. Umansky and Shih say the possibilities are endless—and they have the koji pastrami and umami popcorn to prove it.

Cheese lovers, you can thank microbes for the flavorful funk of Camembert cheese and the perforated pattern of Swiss. According to microbiologist Rachel Dutton, one gram of cheese rind is home to 10 billion bacterial and fungal cells. Dutton describes our favorite cheese-microbe pairings and explains why the cheese rind is ripe for teaching us about the basic interactions of bacteria.

A few years ago, Chris Hoff was making himself some plum wine. He had a nice big plum tree in the apartment he was renting in San Francisco, and it had been a plentiful year. During the process he came across a beautiful, simple sound that made him get out his recording gear. It came from his little metal funnel.

Each time Hoff poured liquid through his funnel to fill a bottle, it made this pleasant rising arpeggio of bubbles. When the pitch reached its height, the bottle was filled, and Hoff moved on to the next one. He liked it so much that he grabbed his small handheld recorder and captured the sound.

This simple, everyday sound is the result of a complex interaction of the liquid, bottle, air, and funnel. While water pours down through the funnel, air is being forced out of the bottle and up through the liquid, where it makes a bubble on the surface and then pops. As the level of liquid decreases in the funnel, the pitch of the popping bubbles rises.

Read more at sciencefriday.com.