Focus on Frozen Food: Food Quality and Safety Concerns

In 2019, the campaign achieved more than 700 million impressions through influencer marketing, media outreach, strategic partnerships, and social media efforts on the NFRA’s Easy Home Meals consumer channels and EasyHomeMeals.com, Henderson mentions.

Freezing Technique in Development

A novel technique called isochoric freezing holds promise for use in food manufacturing and preservation, according to its developer, Boris Rubinsky, PhD, a professor of biomedical and mechanical engineering at the University of California, Berkeley.

Dr. Rubinsky first published the thermodynamic principles of isochoric cryopreservation in 2005 in the journal Cryobiology. His initial research focuses on using isochoric freezing for human cells and tissues, and organs destined for transplantation. Collaborating with USDA since 2017, Dr. Rubinsky and other scientists have shown that freezing various foods under certain isochoric conditions results in products with quality superior to those preserved by conventional freezing.

Typically, food is frozen under isobaric conditions, which means a constant atmospheric pressure when temperature and volume vary in tandem, Dr. Rubinsky relates. “Within such a system, an unrestricted volume of water or the total water content within a given solid mass of food will freeze almost completely when held at a temperature below its freezing point,” he explains.

With isochoric freezing, a food product is immersed in an isotonic solution inside a closed chamber so that the volume remains constant during freezing, Dr. Rubinsky elaborates. “The chamber is then gradually cooled down to a preset freezing temperature,” he says. “Once the temperature reaches the freezing point of the solution, ice starts forming and growing in size, generating hydrostatic pressure inside the closed chamber until the system reaches a new thermodynamic equilibrium at the preset freezing temperature. At this point, a two-phase system exists, with an unfrozen liquid portion and a frozen solid portion.”

The most notable benefit of isochoric freezing, Dr. Rubinsky says, is that food can be safely preserved without ice crystal formation if it remains in the liquid portion of the system. To date, the technique has been successfully demonstrated with studies on cherries, tomatoes, potatoes, and tilapia, Dr. Rubinsky reports. “Additional foods that could benefit from the process include berries and leafy greens, which deteriorate after traditional freezing and thawing,” he points out. “Moreover, isochoric freezing of bacteria in solutions at minus 15 degrees Fahrenheit for 24 hours has resulted in a seven-log reduction of Lm and Salmonella typhimurium.”

“Energy savings is another benefit of isochoric freezing,” Dr. Rubinsky adds. “Our research shows that an isochoric system requires up to 70 percent less energy compared to conventional freezing.”

Another game-changing breakthrough is on the horizon. “Our current research includes freezing for 3D printing of food—cryoprinting,” Dr. Rubinsky says. “That will have a major impact on the food industry worldwide. One day, in the foreseeable future, instead of first making a food product and then freezing it, we will be able to freeze a food product as it’s being made, courtesy of cryoprinting.”