In traditional belief, fruit is the best when it is fresh, and once it has been processed, there is very little nutrition left. Even if the dried fruit still preserves dietary fiber and minerals, are the vitamins and other healthy ingredients still preserved? Is this freeze-dried fruit a hoax? Is it really nutritious? Should it be considered a healthy food?
SIAL China believes that, in fact, if eating fresh fruit is not available, or not enough, or if there are other concerns, it can use freeze-dried fruit to supplement fruit nutrition. Of course, it's also quite delicious as a snack.
The so-called freeze-dried fruits are made through vacuum freeze-drying process. Vacuum freezing equipment first freezes the fruit to a low temperature of -30 to -40 degrees Celsius, so that the food is covered with many tiny ice crystals. Then it pumps out the air and lowers the air pressure. The water vapor that the ice crystals sublimate into is also pumped off constantly, so the ice-gas balance tends to facilitate water vaporisation. In this way, the ice crystals in the food keep turning into water vapor at low temperatures. After dozens of hours, the food becomes dry. Because the ice crystals turn directly into vapor and quietly leave the food matrix without passing through the liquid water state, it leaves a lot of voids inside the food, which makes it crunchy to eat.
Vacuuming solves the problem that nutrients such as vitamin C, vitamin A, vitamin E and folic acid, as well as antioxidant components such as anthocyanins, flavonoids and carotenoids, are easily oxidized during processing. Low-temperature freezing on the other hand solves the problem that vitamins such as vitamin C, vitamin B1 and folic acid and health ingredients such as anthocyanins and thioglycosides vanish in heat. At the same time, because there is no cooking, there is no loss of vitamin C, a variety of B vitamins and water-soluble health ingredients such as anthocyanins, flavonoids, chlorogenic acid, etc. Also, because deep-frying is avoided, there is no problem of fat-soluble health ingredients such as carotenoids, vitamin K and other fat-soluble health ingredients dissolved in oil loss; and because it is sufficiently dry to inhibit the growth of microorganisms, there is no need to add preservatives.
However, SIAL China said that because of the many voids inside, vacuum freeze-dried food is very susceptible to moisture absorption. Foods with a porous structure will also oxidize faster if left at room temperature for a long time and exposed to oxygen. Therefore, freeze-dried foods are usually placed in vacuum-filled, nitrogen-filled packages that protect them from light and oxygen. They should be eaten up as fast as possible after the package is opened.
