Freeze drying involve multi-specialty, and they have delicate relations between. A small change may cause different freeze drying time or freeze dried quality. Here are some points you need pay attention to when do freeze drying:
- Freezing stage: raw product needs thoroughly frozen before move to freeze dryer. It’s the key also is the fundamental of freeze drying.
- Raw product pre-treatment: If its bulk material with loose structure, like solid, blocks or particles, better make them similar size and evenly load to each tray. For liquid or pasta product, make sure each tray with same loading and total water in trays < condenser capacity.
- Oily food not drying well. High sugar high fat contain product not drying well.
- While sublimation, program various steps and gradually give energy to shelves, too much energy may burn raw product.
- Cubed or sliced product have larger surface area than whole pieces, sublimation speed is higher.
- Various kinds product load into one tray or freeze dryer, may have odor taint problem. As well, different product drying time different, may waste energy.
- Use liners in trays is a good ideal to avoid sticky.
- For a product that you don’t have freeze drying recipe, contact your freeze dryer supplier is a good idea. Since they have many installations and tests, provide you the best/fully optimized drying recipe is really easy. But for you, will benefit really a lot.
- Regarding the loading capacity, total water in raw product should less than condenser capacity. We recommend raw product loading volume equals condenser capacity, for example:
FD50 condenser capacity 50kgs/24hrs, 100kgs total, we recommend you load 50kgs raw material, and Maximum load <75kgs.
Since freeze drying, the product drying start from top layer to bottom layer, that means, the thicker raw product in trays, the longer drying time will take, and, with the ice thickness increase in vapor collect coils, heat exchange efficient reduced, more energy is needed to collect vapor. So, proper product loading can help you save cost.