We’re so deep into the growing season here, it’s almost hard to believe that the local berries, corn, peppers, broccoli (and on and on!) will ever end. But when winter comes, as it always does, we’ll return to using frozen fruits and vegetables from our trusty bulk bags buried deep in the freezer. (Which are just as healthy as fresh, science has confirmed!) The only downside to dipping into this hoard is dealing with freezer burn, that state of cold dehydration that leaves too-long-frozen food mushy, shriveled, and gross-tasting.
But science has now found a solution, based on a natural process, in which animals in extremely cold environments make a type of internal antifreeze out of proteins to prevent themselves from freezing entirely solid. (Similarly to these carp we profiled a few years ago.) A team from the University of Tennessee has recently refined the method of using peptides—broken up bits of proteins—to slow ice crystal growth in frozen foods, thus reducing freezer burn As the previous version used peptides derived from animal sources, this variation is key for vegetarian and vegan consumers.
“The team generated peptides from a commercially available soy protein isolate powder by exposing it to three different hydrolyzing enzymes: alcalase, pancreatin and trypsin. Each resulting mixture of peptides was also separated by size into multiple fractions.
All of the mixtures slowed ice growth in tests, but the ones produced from alcalase and trypsin were better inhibitors than those from pancreatin. For all three enzymes, most of the activity came from the fraction with the largest peptides. The large-size fractions also ended up including some smaller peptides, which on their own didn’t keep ice crystals from growing; however, the team showed that these small compounds boosted the activity.”
The researchers are keen to apply their findings to vegetarian and vegan frozen items, to increase their shelf-life—and their long term flavour. I’m a huge fan of both! It may be too late for that bag of peas I’ve had rattling around in the back of my freezer for a couple seasons… But, once I enjoy this growing season to the last drop, I look forward to replacing it with an ice-proof version, and tasting the difference!