By George Harvey
There are lots of ways to preserve food. In ancient times, meats and fish were smoked, and vegetables and cheese were lacto-fermented. In the Middle Ages, freshly caught ocean fish was packed in salt and sold weeks or months later in Alpine towns. More recently, canning, freezing, and refrigeration came into being. None of these systems is perfect, but all have their uses.
Perhaps the oldest system of preservation is drying, but about seventy years ago, that old technology was updated by being combined with freezing. In freeze drying, foods are taken to about 40° below zero (the point where Celsius and Fahrenheit are the same), and then subjected to an intense vacuum. With this combination of conditions, the ice in the food is removed through sublimation, a type of evaporation in which a solid changes to a gas without going through a liquid stage.
Freeze drying is a very superior food preservation system. This is partly because the food has not been heated in the preservation process. Heat-sensitive nutrition is undamaged, and these include many vitamins and enzymes. Also undamaged are flavors. Without water in the food, and if it is placed in an oxygen-free environment, most foods can be stored for twenty-five years without noticeable loss of quality.
About seven years ago Dan Neville, of Salt Lake City, was considering freeze drying at home and started looking for suitable equipment. He found the least expensive freeze dryer on the market had a steep price tag of $24,000. Rather than seeing this as a hindrance, however, he saw it as an opportunity. He started work on plans for a freeze dryer for ordinary people.
Three years ago, Neville’s company, Harvest Right, began selling freeze dryers for the home at the surprisingly low price of $3,495, with even lower prices during the sales that occasionally happen. The units can dry seven to ten pounds of food in about 24 hours. The process uses quite a lot of electricity, but we should remember that when food is packed in a Mylar bag with a small oxygen absorber, it can retain fresh flavor and nutrition for many years without any further use of power.
Almost any kind of food can be freeze dried. This includes not just meat, fish, and poultry, but nearly any vegetable, eggs, cheese, and even avocados. Raw foods, cooked foods, and whole packaged dinners can be freeze dried. When I asked Neville what sorts of foods could not be prepared this way, he gave me a single example. “You can’t freeze dry peanut butter,” he said, “because there isn’t any water in it.”
I had the really good luck to be able to try a variety of foods that were freeze dried in a Harvest Right machine. Among them were summer squash, tomatoes, strawberries, grapes, apple slices, yogurt drops, and cheesecake. Freeze-dried cheesecake was delicious, and I was amazed. The quality of the foods ranged from extremely good to better than that.
This was not merely my own opinion. It was the opinion of Chubbs the Cat. Normally, when he sees me eating something he thinks he would like, he takes a seat next to me and speaks patiently but insistently. When a yogurt drop fell to the floor and he tasted it, he immediately climbed all over me in a mad hunt for more. Others who tasted the freeze-dried food were more polite, but also agreed on quality.
I asked Neville whether living organisms can survive freeze drying, thinking the process might kill pathogens in uncooked food. He responded, “Some customers tell us they have been able to freeze dry cheese cultures or seeds for later use successfully.” Now, that is an impressive retention of quality.
The amount of food in a batch and the power needed to process make freeze dryers attractive to groups of people, such as members of a co-operative or church. Certainly, Harvest Right’s freeze dryer seems ideal for an individual with a large garden.
Freeze drying certainly beats walking around town looking for cars with open windows in which you can leave excess zucchini. Instead, you can continue to rehydrate and cook the zucchini whenever you want through subsequent years and devote the garden space to other things, which you can also freeze dry. And it can be, and stay, as healthful as you grow it.
Harvest Right’s web site is harvestright.com.