Mesoscale aggregation of rennet gels in LT and UHT milk

Abstract

We investigated the mesoscale aggregation in rennet gels of low-temperature pasteurized milk (LT) and ultra-high temperature (UHT) treated milk in terms of image analysis methods. In the viscoelastic measurements, both milk types showed qualitatively similar gelation behavior and comparable storage modulus at lower pH. However, image analysis revealed that UHT milk formed large aggregation structures of fat globules after gelation, which was not observed in LT milk. Heat treatment causes complex formations between casein micelles and whey proteins, as well as between fat globules and both whey proteins and casein micelles. These interactions alter the fundamental building components of milk gel, resulting in large-scale aggregation of fat globules.