Freeze-drying is a complicated process of preserving fresh or already-cooked food by detatching as much as 98% of the food's moisture, leaving intact the food's texture, flavor, aroma and nutritional value.
The process requires that the fresh or cooked food be quickly frozen at temperatures only -50°C. The frozen food is then placed right into a vacuum chamber. This vacuum chamber lowers the pressure, and raises the temperature to almost 0°C.
At this specific temperature and fat freeze singapore, the ice crystals in the foodstuff evaporate into water vapor, bypassing water's liquid form, through an activity called sublimation.
This technique preserves the cell structure and nutritional content of the foodstuff, producing a product that, when rehydrated, very closely resembles the original food.
The process also prevents the water from being reabsorbed by the foodstuff and thus decreases its weight significantly.
Most foodstuffs such as fruits, vegetables and meats are well-suited to freeze-drying, and can be utilized for long-term food storage and preservation.
The Process of Dehydration
Dehydrating food is just a food preservation method which has been used for centuries. Native Americans dehydrated their buffalo kills in their hunting camps to create it safer to transport. Pemmican (a dehydrated concoction of buffalo meat combined with fat and berries) was a selection of most of the nomadic North American tribes. This low-heat dehydration process involved either air drying (with nearby campfires), or sun drying strips of meat on drying racks.
Dehydrators are a modern method for slowly removing the moisture from food without actually cooking it. A problem of dehydration could be the limited level of food which can be dried at one time. The positive aspect of dehydration is that this technique of processing for food storage could be easily done at home.
How Do These Two Methods Affect the Food?
Freeze-dried foods preserve a lot of the original color, shape, aroma and freshness of fruits, vegetables and meats. Freeze-dried food does not usually contain additives or preservatives, therefore it remains true to its original form. And the appearance, texture and flavor of the foodstuff remains after re-hydration.
Unlike low-heat dehydration, freeze-drying allows for the preservation of pre-cooked meals, including recipes such as soups, stews, stroganoff, and the like. An obvious benefit is that since the meal was prepared in its entirety just before freeze-drying, all that's necessary to accomplish is merely add water, then heat for a couple minutes in order to create sumptuous meals.
Rehydrating freeze-dried food takes just a few momemts, by just adding boiling water. Some foods, like many fruits and vegetables, need no re-hydration before eating.