Freeze drying is a lately developed approach of preserving food stuffs. It requires the freezing of the meals, then removing most of the foods moisture inside a vacuum, and lastly sealing the food in air-tight storage. Freeze dried foods can be transported at normal temperatures, stored for really extended periods of time, and be eaten with minimum preparation. As soon as prepared to consume, freeze-dried foods appear and taste the similar as the original, organic merchandise.
Freeze-dried meals was developed in the course of Planet War II as a process of preserving blood for battlefield injuries, without the need of needing refrigeration or damaging the organic nature of the plasma. The technology was later applied to food merchandise just after the end of the war. Coffee was 1 of the initial freeze-dried goods to be developed on a huge scale. Quite a few fruits, vegetables, meats, eggs, and foods are freeze-dried.
Freeze-dried food has lots of benefits. Because as significantly as 98% of the water content has been removed, the food is incredibly lightweight, which reduces the expense of shipping. This also tends to make it popular with any one that has to carry their meals with them. Mainly because it calls for no refrigeration, shipping and storage fees are minimal. Freeze-dried meals is also relatively clean, as the dehydration process makes it virtually not possible for yeast and dangerous bacteria to survive the process. Finally, considering that the physical structure of the meals is not altered during the freeze-dried course of action, the food retains much of its colour and flavor when it is prepared by adding water. This tends to make it far far more appealing to men and women, than meals preserved by other solutions.
1 of the major disadvantages of freeze-dried food is its expense. The equipment needed for this approach is high priced, and the procedure itself is time consuming and labor intensive. These charges are normally passed on to the consumer, which makes freeze-dried food very high-priced when compared to other techniques of food preservation such as canning or freezing.
Raw Supplies
Some foods are exceptionally nicely-suited to the freeze-drying course of action. Liquids, thin portions of meat, and modest fruits and vegetables can be freeze dried easily. Coffee is the most frequent freeze-dried liquid. Chunks or slices of shrimp, crab, lobster, beef, and chicken can be freeze-dried. They are normally mixed with vegetables as component of soups or primary course entrees. Nearly all fruits and vegetables can be freeze-dried, which includes beans, corn, peas, tomatoes, berries, lemons, oranges, and pineapples. Even items like olives and water chestnuts can be processed this way.
Thick portions of meat and larger, whole vegetables and fruits can not be freeze dried with any accomplishment. With several other foods, it is basically not economical to preserve them by freeze drying.
The Manufacturing Course of action
A freeze-drying processing facility is generally a massive plant with modern day equipment. Its meals-handling regions have to be approved by the United States Department of Agriculture, and the business and its staff ought to adhere to government regulatory procedures. The plant may well incorporate a receiving and storage location for raw foods that arrive at the plant in bulk a meals cooking location for those foods that must be cooked prior to processing a substantial location with quite a few big freezing and drying chambers and a packaging region. The facility might also incorporate a research region exactly where improved solutions of freeze-drying foods are developed, and a test kitchen exactly where new preparation procedures to enhance the final taste, top quality, and texture of the meals are attempted. Some plants are dedicated to freeze-drying only one particular product like freeze-dried coffee. Other people process a wide variety of meats, vegetables, and fruits. Nonfood goods such as chemicals and pharmaceuticals are ordinarily processed in separate plants from meals goods.
The freeze-drying procedure varies in the details of temperatures, occasions, pressures, and intermediate actions from 1 meals to one more. The following is a generalized description of the method with various particular exceptions noted.
Testing and preparation
The food is first checked for contamination and purity. Fruits, meats, and some other edibles are tested for bacterial counts and spoilage. A great deal of the function of the plant is dependent on the harvest season for every food. In January, for example, the plant would be processing celery, olives, lemons, oranges, and pineapples. In July, it would method green beans, peas, and strawberries, among other folks.
Some kinds of meals, like seafood and meats, will have to be cooked before freeze drying. They are normally purchased currently cut into little pieces. If they have not been pre-cooked and frozen, these foods are placed in significant, industrial-sized kettles and properly cooked. Fruits and vegetables are usually bought already cut, pitted, and peeled. These foods are just washed with sprays of water. Some vegetables, like peas and corn, are swiftly scalded, or blanched, ahead of freezing. Coffee is purchased as a pre-brewed concentrated liquid. Mainly because the aroma of coffee is critical to shoppers, a smaller amount of coffee bean oil might be added to the liquid. In contrast to the water, the oil is not removed through the drying method.
Freezing
The food pieces are spread out on flat, metal trays which are stacked 20 to 30 higher in slots in a wheeled cart. With meals that has been pre-cooked and frozen, the trays are pre-chilled to avert partial thawing in the course of handling. With liquids like coffee, the pre-brewed coffee is poured into shallow pans. The carts are wheeled into a large, walk-in coldroom where the temperature can be as low as -40F (-40C). In this particularly cold temperature, the meals is quickly frozen. There are usually a dozen or a lot more coldrooms in operation, and the carts are kept there until it is time to move them into the drying chamber.
Drying
The carts are wheeled out of the coldroom and into a vacuum drying chamber. In the case of liquids like coffee, the frozen coffee is initially ground up into little particles in a low-temperature grinder. freeze dried food drying chamber is a large, lengthy, horizontal cylinder with semi-elliptical ends. One particular finish is hinged to open and close. When the trays of frozen meals pieces are inside, the chamber is closed and sealed. In a substantial plant, there may be 20 to 30 drying chambers in operation at any time.
The drying process requires a method known as sublimation. In sublimation, a solid material is forced to modify state into a gaseous material without having ever becoming a liquid. In the case of freezedried meals, the strong ice crystals trapped in the frozen meals pieces are forced to modify into water vapor without ever becoming liquid water. In the drying chamber, this is accomplished by evacuating the air with a vacuum pump to lower the pressure to about .036 psi (.0025 bar). The temperature of the food is raised to about one hundred degrees by direct conduction through the bottom of the trays, radiation from heat lamps, or microwave heating. When the chamber is evacuated of air, the stress is beneath the threshold at which water can simultaneously exist in a strong, liquid, and gaseous (vapor) state. This threshold is known as the triple point of water. When the pressure falls under this point, the heat causes the ice crystals trapped in the frozen pieces of food to change directly to water vapor. The vapor is drawn off and condensed inside the chamber leaving the food behind. The dried meals is filled with tiny voids, like a sponge, where the ice crystals were once present. Not only does this make it a lot easier for the food to reabsorb water when it is prepared for consumption, but the dried food retains its original size and shape. The time for this drying process varies. Freeze-dried liquids make take only about four hours to prepare, even though semi-solids and solids like soup and sliced meats may perhaps take 12 hours or additional.
