Freeze drying/lyophilization definition:
Lyophilization is the process of freeze drying, with many other names such as vacuum freeze drying, sublimation drying, lyophilization, liofilizador, they are synonymous. It’s a dehydration way typically use to remove water from materials by sublimation process (working by frozen the material and then reduce surround pressure allow solid water direct vapor to gas, and escape out of raw material structure).
Freeze dried features, benefit and advantage:
The freezing process and dried in vacuum, dried products well keep its original shape, almost all nutrition remained because of only water removed, dried products with spongy internal formed by water escape and microchannel leave, thus could rapid rehydrate by add water or solvents, we could say freeze drying is the most perfect way to dry products that have minimum damage to raw material or lossless drying.
Most freeze dried products could storage in room temperature and lasting up to ten years.
For perishable products like season fruit, seafood, meals etc. lyophilization is one of the best choice to storage.
Principle and water phase:
Freeze drying/lyophilization works based on water triple point, which showed:
Freeze drying steps:
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.
Freeze drying recipe and optimization:
Almost all material could success lyophilization after research its freeze drying recipe.
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.
Freeze dryer features and select:
Lab Freeze Dryer
- Bench top, removable drying house (vertical cylindrical cover made by acrylic), removable shelves, 0.12m2 trays area, -55C condenser with 4L/24hrs capacity, Shelves without heating function.
- Top manual stoppering, flask holder, dry vacuum pump, -80C condenser, AISI316 condenser optional.
- Mainly use for lab investigation, small volume sample drying test.
BFD Pilot Freeze Dryer
- Floor type, acrylic see-through drying house door, internal or external ice condenser, shelves with heating and freezing function, external vacuum pump, up to 1.2m2 shelves area, 15L/24hrs vapor collect capacity.
- Suit lab or small-scale production.
LYO Pilot Freeze Dryer
- CGMP/FDA grade freeze dryer, fit rigorous research center or professional lab, all-in-one structure, up to 1.2m2 shelves area, 16L condenser capacity.
Tray Freeze Dryer
- AISI304 or 316 material for all parts, special design for bulk loading, accept raw material in fluid or mixture type like liquid pharmacy, chemical mixture, viscous fluid etc.
- Up to 50m2 shelves area or 500L condenser capacity.
Stopper Freeze Dryer
- Include all tray freeze dryer features, also accept raw material drying and capping in vials or bottles under vacuum condition.
- The range lyophilizer shelves area up to 20m2, CIP,SIP and special configurations accept.
Food Freeze Dryer (Al Alloy)
- Most hot sale and popular freeze dryers for edible products. stainless steel drying chamber, Radiation heating shelves and trays made of aluminum alloy, larger model material loading and harvest assist by overhead monorail and trolleys.
- Shelves area up to 200m2 or 2500L.
Food Freeze Dryer (S/S)
- Mainly use in fluid food area, Similar with tray freeze dryer, but drying house adopt inexpensive cylindrical shape.
- Up to 50m2 shelves area or 500L condenser capacity.
Food Freeze Drying Plant
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