MILK STERILIZATION USING MEMBRANES

Abstract

ABSTRACT Hydrophilic polyvinylidenefluoride microfiltration membranes were used for milk sterilization, i.e., to remove bacteria, spores, yeast, molds and somatic cells from milk, while allowing the other milk components to pass through and be retained in the milk. Sterilization is used for enhancing the quality, safety and shelf life of milk and dairy products. The aim of this research was determination of microfiltration ability for milk sterilization, investigation of the effects of affecting parameter and to establish a rational for removal mechanism of undesired species. The influence of transmembrane pressure, temperature, cross‐flow velocity and presence of fat globules on membrane performance were elucidated. The microfiltration mechanism was studied for both whole and skim milks. For whole milk (3.5–4% fat), the profiles indicated that at the beginning of filtration, standard blocking is the dominant mechanism. Over time the bacteria, fat and casein micelles filled the pores and formed a cake layer on the membrane surface. For skim milk (0.05–0.5% fat) the profiles indicated three model, standard blocking, intermediate blocking and cake deposition. This was proved using scanning electron microscopy. PRACTICAL APPLICATIONSThe practical application of the current research is utilization of microfiltration membrane instead of other techniques including heat processes for milk sterilization. The proposed procedure increases the milk shelf life, savethe valuable nutrients and removes all hazardous ingredients including spores and enzymes.