Why does coffee concentrate collapse when freeze-dried
Are some coffee concentrates loose and intact after freeze-drying, while others shrink and collapse? The key lies not only in the formula, but also in the temperature control of the freeze dryer - once the surface temperature exceeds the critical value, the particle structure will collapse instantly. The success or failure of freeze-dried coffee lies in every detail of temperature control.
Why do some coffee concentrates form loose and intact particles after being processed by a freeze dryer, while others shrink, collapse, or even clump? This is not only related to the solid content of the coffee concentrate, but also affected by freezing conditions, material temperature, and vacuum environment.
Coffee concentrate contains sugars, organic acids, and other soluble solids. After entering the freeze dryer, the water gradually freezes to form ice crystals, and the remaining solutes concentrate between the ice crystals. During a drying process, ice crystals sublime and leave pores. If the material temperature exceeds the critical temperature that its structure can withstand, the concentrate that originally supported the pores may soften and collapse, causing coffee particles to shrink and affecting their appearance and internal structure.
A study on coffee freeze-drying in the Journal of Food Engineering found that for experimental samples containing only water-soluble components, surface collapse is prone to occur when the surface temperature exceeds the maximum freezing concentration state glass transition temperature minus 3 ℃. This indicates that the temperature control of the freeze dryer cannot only rely on the set values at the dashboard level, but also needs to pay attention to the temperature changes of the materials.
For the industrial production of freeze-dried coffee, freeze-drying machines cannot only meet the dehydration requirements, but also need to balance aroma protection and batch quality. The CQ-HFD series food freeze dryer has uniform plate temperature control, stable vacuum system, cold trap water capture, and freeze-drying process formula management functions. It can adjust the freeze-drying parameters of the freeze dryer according to the characteristics of coffee concentrate, reduce the risk of collapse caused by improper temperature control, and provide a complete set of freeze-drying equipment support for the large-scale production of high-quality freeze-dried coffee. The CQ-HFD series freeze dryer can also be used for solid beverages such as freeze-dried tea powder, freeze-dried fruit and vegetable powder, freeze-dried milk powder, etc.