Emulsification of milk fat and skimmed milk curds – Effect of temperature on rheological properties and structure of emulsion gels at different length scales

Abstract

There is a need to develop innovative cheese processes to meet consumer demands and improve production efficiency. In this study, rennet skimmed milk curds (SMC), and butter were emulsified using a thermo-mechanical process at temperatures between 70 and 90 °C. The composition, rheological properties, and microstructure of the emulsion gels were analysed up to 2 weeks of storage. Confocal laser scanning microscopy (CLSM), Small angle X-Ray Scattering (SAXS) and Low-Field Nuclear Magnetic Resonance (LF-NMR) were used to understand the gel structure. The results demonstrated that the thermo-mechanical process developed was successful in creating stable emulsion gel at 85 °C. Temperatures exceeding 85 °C led to water and fat loss, reduced fat droplet size, leading to a more compact protein network. Emulsion gels behaved as weak solid viscoelastic materials and tan δ decreased at temperature >85 °C. Lower temperatures (70 °C) lead to oiling off and incomplete gel network formation.