CONTACT NUCLEATION OF ICE IN FLUID DAIRY-PRODUCTS

For freeze concentration processes involving suspension crystallizers, contact (secondary) nucleation of ice crystals may be an important mechanism of formation of nuclei. The critical subcooling required before stable secondary nucleiform is an important design parameter for such freeze concentration systems. Critical subcooling for secondary nucleation of ice in aqueous sugar solutions and fluid dairy products were determined using two experimental techniques. The method of observation (experimental technique), type of solution studied and its concentration were found to affect the critical subcooling temperature. Of all the components in these solutions, whey protein was the main factor in determining critical subcooling temperature. Critical subcooling increased linearly with whey protein content.