Solidify drying is a procedure to safeguard nourishment, while holding every one of the supplements and flavors. This procedure is extremely effective, however has its downsides also.
Science has made storage and preservation of food very easy. It is now possible to carry frozen food, and quickly heat it before consuming. Ready-to-eat meals are an instant hit, as they have saved our efforts and time.
It is also a huge advantage for astronauts, hikers, and campers; they don’t have to carry excess loads or worry about food spoiling. It has also helped to preserve certain seasonal fruits, and make them available all year around.
Two very commonly used procedures to preserve food are dehydration and freeze-drying. This Buzzle write-up describes the process of freeze-drying, or lyophilization, and lists its advantages and disadvantages.
What is Freeze-drying?
It is a process in which food is first flash frozen, and then placed in a vacuum. The food to be freeze dried can be cooked or raw. When it is placed in a vacuum, all the ice sublimes; thus the moisture is removed. Almost 98% of the moisture is removed, which significantly reduces the weight of the food. Then, the food is sealed properly and stored. Freeze-drying is not restricted to food only; it is also used to store pharmaceutics like vaccines or other injections.
Commonly freeze-dried foods
Instant coffee is the most popular freeze-dried food. Vegetables in soup packets or fruits in noodles are usually freeze dried. Herbs, spices, food-flavorings, fruits, and meat can be freeze dried as well. Astronauts eat freeze-dried food, when in space. Many campers and hikers prefer to carry it as well.
✔ Since all the moisture is removed from the food, its weight decreases making it easier to carry or transport.
✔ All the nutrients and flavors are retained when food is freeze dried. Even the aroma is not lost.
✔ The food does not shrink or its texture does not change when it is freeze dried. This makes it a better option than dehydration.
✔ Since, the ice sublimes, it leaves small pockets in food. Thus, when the food is reheated, it hydrates evenly all over. It takes only 10 minutes to rehydrate.
✔ It has a very long shelf life and can be quickly rehydrate as well. This makes it ideal for backpackers or hikers to carry.
✔ Freeze-dried foods can stay edible for up to 25 years if unopened. Fruits or ice creams can be eaten without hydrating them. This makes it a very convenient food option.
✘ The biggest disadvantage of freeze-drying is its cost. It is extremely costly, and may not be cost-effective for certain foods.
✘ The equipment required to freeze-dry foods is very costly, and obviously it’s not possible to freeze-dry food at home.
✘ Not all foods can be freeze dried, some may get spoiled when freeze dried; others may need pretreatment to retain color or flavor.
✘ Additives may be used when freeze-drying food.
✘ Canning or dehydration is cost-efficient compared to freeze-drying.
✘ Along with the water, other liquids like vinegar can sublimate, leading to spoilage of food or change in taste in some cases.
✘ Airtight and moisture-control storage is absolutely necessary to ensure that the food does not spoil. Even slight exposure to humidity can easily spoil the food.
✘ Dehydrated food is more common, freeze-dried food may not be easily available everywhere.
Freeze-drying food has many advantages and is very useful. The other disadvantages are minor, only the cost factor can be a problem for most people.