Laboratory suspension freeze concentration (Lab SFC) followed by a simple centrifugal procedure for separation

Suspension freeze concentration (SFC) is a low temperature technology which has a promising prospect in food and bioproducts industry. In SFC, the dispersed ice crystals are made in aqueous fluid and become bigger in sizes after ripening, are then separated from the mother liquor to achieve ice removal. A laboratory device of 2 L capacity integrating ice nucleation and ripening in one pot has been investigated in this study. Centrifugation is then applied to the whole slurry (in contrast to a tightly packed ice phase in previous studies) to separate the liquid out, which simplifies greatly the SFC process. This procedure was successfully used to concentrate sucrose solution from 10oBrix (wt%) to 17.6oBrix (wt%). For the first time, Scanning Electron Microscopy (SEM) was used to look at the microscopic distribution of sucrose attached and partly included in the ice particles. The solute loss (sucrose inclusion in the ice phase) was further reduced to only 0.6oBrix (wt%) by partially melting the particle phase. The yield of solute reached to about 97% in one go of about 2 hours. Agitation, partial ice melting, etc., were also examined in the current work. Similarly, the solid contents of orange juice, skim milk and the red wine can be concentrated to similar levels in runs of about 1.5 hours. This work has shown that this laboratory scale device is nice and simple for concentrating small amounts of practical aqueous liquids. The centrifuge as it is adopted here is also simple to operate and the whole procedure shows great promise for practical applications.