For freeze-dried fruits, berries, meat cubes and plant slices, the proportion of intact whole products determines selling price. Fine broken fragments can only be sold at discounted prices as secondary materials. Many manufacturers only optimize sorting and screening equipment, ignoring the fragmentation formed inside the freeze dryer.
Excessively fast sublimation is one common cause. Rapid escape of ice vapor forms internal stress inside material tissue. After drying, the product becomes overly crisp and easily broken during transferring. Properly extending sublimation time or lowering heating rate can ease internal stress and improve structural toughness.
Material loading thickness cannot be ignored. Overly thick stacking leads to uneven drying. The outer layer is excessively dry while the inner layer is insufficient. Uneven moisture distribution causes inconsistent hardness, which greatly increases fragmentation risk during vibration and transportation. Each raw material has a recommended stacking thickness range.
Pressure fluctuation inside the chamber also produces impact on material structure. Frequent and drastic vacuum adjustment will cause unstable steam migration. We suggest adopting slow gradient adjustment mode during the transition from sublimation stage to desorption drying stage.
In addition to process adjustment, matching soft buffer trays and gentle conveying equipment after discharging can avoid mechanical collision damage. Combining process optimization and hardware improvement is the most effective way to control overall breakage rate.
Stable low fragmentation rate helps factories supply high-grade whole freeze-dried products continuously, meet overseas brand buyers' appearance standards and obtain better unit sales profit.
