Lyophilisation removes moisture from the product while retaining original characteristics like the aroma, color, texture, taste and most importantly preserving all nutritional values of the product. The products are required to undergo a cycle. The raw products are first cleaned with pure water many times before being placed in the Deep Freezer which will bring down its temperature. After about eight hours of Deep freezing the products are kept in the trays in the Vacuum Freeze Drier to undergo a cycle of another eight hours.
The moisture will be removed from the product within this cycle and the products will become completely dry with only about 4% moisture remaining at the end of the cycle. The vacuum dried products are removed from the Drier and sent to the CIP room. This is a total bacteria free room where the products are prepared by cutting, sizing, pulverizing etc as the need may be before it is sent for packing.
The freeze dried products can be stored at a room temperature for a long time. It retains its original flavor, color and texture and the nutritional values. Because the entire moisture content is removed the products become very light in weight.
For use the freeze dried products after opened from the packing will regain its original taste, shape, and color once it is mixed with water. There are examples where the products have remained fresh even after several decades. Technical details are available at our Knowledge Centre.
The raw products received from the known sources are first washed with purified water. Then the products are treated as per requirements like peeling, slicing etc. Then the product is again washed with ultrapure water to remove all unrequired particles, dust etc.
Then the products are placed in a Deep Freezer for a pre-decided time at a temperature of around -300 C. The products are now cooled and ready to be placed in the Machine called Freeze Dryer.
At the end of the operation, the final residual water content in the product is extremely low, around 1% to 4%.
Properties of freeze-dried products
If a freeze-dried substance is sealed to prevent the reabsorption of moisture, the substance may be stored at room temperature without refrigeration, and be protected against spoilage for many years. Preservation is possible because the greatly reduced water content inhibits the action of microorganisms and enzymes that would normally spoil or degrade the substance.
Freeze-drying also causes less damage to the substance than other dehydration methods using higher temperatures. Freeze-drying does not usually cause shrinkage or toughening of the material being dried. In addition, flavors, smells and nutritional content generally remain unchanged, making the process popular for preserving food. H
Freeze-dried products can be rehydrated (reconstituted) much more quickly and easily because the process leaves microscopic pores. The pores are created by the ice crystals that sublimate, leaving gaps or pores in their place.
Benefits of Freeze Dried Food
Freeze Dried products are not dehydrated products as people believe. There is a significant difference between the terms ‘dehydrated’ and’ freeze-dried’.
Freeze-drying is a proven and the most successful method of preserving food.
To preserve foods, the moisture contained within must be removed through a process called lyophilization (Freeze Drying). Usually in any food Micro-organisms (like bacteria) will thrive and feed, leading to food decomposition, mold growth, and inedibility. Dehydrating and freeze-drying are the two more commonly used practices to do this.
‘Freeze-drying’ is a modern process. Food is placed on large racks inside a vacuum chamber where the temperature is lowered to below freezing, and then slowly raised. The water in the food transforms from a solid state to a gas, thereby maintaining the food’s structure and preserving its all-important nutrients. Freeze-drying removes about 98-99% moisture content. The lower the moisture content, the longer the shelf life.
Freeze-dried foods can be stored for the longest time…
Most dehydrated products, like dried fruits, vegetables, powders and TVP (soy protein), have a shelf life of about 15-20 years. Dehydrated items like honey, salt, sugar, hard wheat and oats have a 30-year shelf life – sometimes longer. Freeze-dried fruits, vegetables, just-add-water meals and real meats have a longer average shelf life of approximately 25-30-years. Freeze-dried food can be stored at a wide range of temperatures without the food or packaging being affected – the food remains fresh for many years.
Freeze-drying retains the nutritional value of the fresh product, as well as its fresh flavor and color…
Freeze-drying is akin to keeping the food in a state of suspended animation and so once rehydrated the food is as fresh and nutritious as it was the moment it was frozen.
Freeze-drying makes food more palatable…
Freeze-dried food when exposed to water (moisture) or when you put them in your mouth become soft and fresh with the original taste and aroma.
Freeze-drying significantly reduces the weight of food…
Lyophilisation removes about 98% of a food’s water content and so the weight of that food is reduced by as much as 90%. For people having to carry their own food for days or months at a time, this is a huge benefit. Freeze-dried foods weigh a lot less than dehydrated foods, important for most of our customers who take part in long-haul endurance events where food weight and package size are crucial planning factors.
Freeze-drying is faster to prepare…
With freeze-dried foods you just need to add water – hot or cold will do (up to 5-8 minutes usually), As a general rule of thumb, dehydrated foods cost less than freeze-dried ones. However, the difference in price should be weighed up carefully against the marked nutritional benefits, weight, taste, and storability of freeze-dried. Happy eating!