Destination Sublimation (The Basics of Freeze-Drying)

As a kid growing up in the 60s, I have fond memories surrounding the USA’s first lunar landing, especially all the crazy-fun space drinks and snacks that came along with it, like Tang, Pillsbury Food Sticks and astronaut ice-cream. Although Tang and the food sticks were kinda gross, the astronaut-ice cream was the stuff of magic. It was light as a feather, crispy and didn’t melt at room temperature. Best of all, it looked just like a regular old slice of ice cream. Behold the brainy beauty of freeze-drying.

When OuttaMyKitchen! dog treats were initially developed, they were dehydrated, not baked. While both are perfectly reasonable cooking methods, the shelf-life of the finished product is limited. And, for customers and retailers alike, the shelf-life of real food, like OMK’s yummy dog treats, is a valid and important concern. After conducting some research into methods of food preservation, freeze-drying was clearly the optimal means of retaining freshness of foods without altering their appearance or nutritive value.

What makes freeze-drying so special? How is it different from dehydrating? While dehydrating use circulating heat to remove moisture by evaporation, which changes it from liquid to a gas, freeze-drying employs sublimation, whereby ice (water’s solid form) is directly transformed to its water vapor (water’s gaseous form). This transformation is a function of atmospheric pressure. At sea level, ice will melt into water before evaporating. When pressure becomes sub-atmospheric (like inside a vacuum), that same ice will sublimate directly into water vapor as it heats, bypassing the liquid phase entirely, removing water nearly completely. In freeze-drying, this is achieved by creating a vacuum, which lowers the atmospheric pressure by sucking out air. So, in short, a freeze-dryer consists of freezing and heating elements and a vacuum pump. It’s a time consuming process that cannot be rushed; each batch of treats requires 24-27 hours to dry.

Freeze-dried foods are light and crispy and look exactly the same as they did before being processed. It’s sort of Willy Wonka-esque. A strawberry looks (and tastes) exactly like a strawberry, only it’s dry, crunchy and much lighter in weight. OuttaMyKitchen’s freeze-dried treats have a pleasing tendercrisp texture, much like that of shortbread. They can be easily snapped into smaller pieces for training or for smaller dogs. Same great flavor, new texture and extended shelf-life…what’s not to love? Oh, I almost forgot to mention, they’re now grain-free!

SteveBaxter, commandeering the freeze-dryer cart.

SteveBaxter, commandeering the freeze-dryer cart.