What’s Lyophilization or Freeze Drying?
Lyophilization is the process of freeze drying, with many other names such as vacuum freeze drying, sublimation drying, lyophilization, liofilizador, they are synonymous. Typically used to remove water inside (of the materials) by sublimation process, meanwhile maximum protect the raw material original appearances and characteristics.
Freeze dried and lyophilized products could storage in room temperature and lasting 3 to 20 years, specially fit perishable materials.
Picture of water triple point, we could very easy understand freeze drying principle:
How it works? Freeze drying and lyophilization process.
Simply speaking, the process by freezing raw material very quickly, subjecting it to a vacuum and removes moisture in ice type. there are 3 main steps/stages in the process:
1, Freezing stage
Thoroughly freezing the raw material to solid phase, could be done in a Freeze Dryer Lyophilizer (if shelves with freezing function) or in one deep freezer. The keys of freezing is find out raw material’s eutectic point and make sure freezer temperature is lower than that, freezing stage is the insurance of dried products’ physical shape.
Some material, especially fluid, the freezing stage may also involve annealing treatment(rapid freezing cause large ice crystals, proper raise its temperature allow ice crystal grow), which could help protect cells from broken as well as short the drying time.
2, Primary drying.
Primary drying mainly remove water by sublimation, in this stage, water in solid phase sublimate to vapor and move to ice condenser, freezing on condenser coils surface, in this stage >95% water have removed.
In this stage gradually and proper increase the shelves temperature could speed up the sublimation, but too much energy supply may cause glass transition.
3, Secondary drying.
Secondary drying process could remove the adsorption water, in this stage need higher temperature and vacuum, after secondary drying, the shelves could reduce temperature and prepare harvest.
Using field.
Almost all material could success lyophilization after research its freeze drying curve and choose the right Lyophilizer.
Commonly, food, pharmaceutical, biological, diary, documents, plants etc. have dry by this way a long time, drying technology are also known in global market.
Freeze drying recipes.
For now, freeze drying equipment introduce intelligent controller, the freeze drying process achieve full automatic, integral data record system also help a lot, in recipes create, storage, modify, data check and system working status display etc.
Freeze drying recipe is one of the most important thing before start batch production, since the process cost more money than other dryer method, because of the slow drying rate arising from inefficient heat transfer, Higher lyophilizer equipment investment and operating costs.
Freeze drying curve, Freeze Dryer recipes (Cycle optimization) is, therefore, crucial, especially for food products produced on a large scale, where the cost factor increases significantly with time spent in the freeze dryer. A fully optimized freeze dryer recipe uses only the energy and time required, resulting in shorter process time and higher product throughput. Most importantly, it ensures optimum product quality and consistency between batches.
So, continue study freeze drying data and improve freeze drying curve is one part of daily work, this is may take months to years.
Why Freeze Drying?
Freeze drying method is irreplaceable in dehydration industry, its protective to material physical and chemical characters is all other drying method cannot compare: well keep raw material original shape, guarantee bacteria live rate, remain nutrition etc., minimum the damage to material, we can say the only difference between original and dried products is water!
Freezing raw material below -20C and dried under vacuum, Shape/nutrition/color/flavor all is very close to fresh, even the dried products is better than fresh material in some aspects, such as light weight, easy transport, no special storage temperature request but can last up to 25years.
Freeze dried food with its unique advantage, is very popular in activities like hiking, climbing, adventure, aerospace, meeting nutritional requirement and variety supply.
Exclusive features: Original shape/color/taste/nutrition that could compare fresh, light weight, storage in room temperature up to 5years, excellent rehydration.
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In Pharmaceutical/Biological Area
Freezing raw material and dried in minus temperature, biological activities stop and to a dormant state, after add solvent could quick wake on, freeze dried technology guarantee bacteria live rate and ensure its effectiveness.
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