Effect of Homogenisation on Selected Properties of the Emulsion Phase of Pasteurised Milk

The study examined the effect of single-stage and two-stage homogenisation on the size of fat globules, the content of free fatty acids (FFAs), and the fatty acid profile of pasteurised milk immediately after processing and during storage. Both types of homogenisation reduced the size of fat globules. Two-stage homogenisation resulted in a uniform fat globule size, whereas one-stage homogenisation led to greater heterogeneity in fat globule size and the presence of large particles in milk. The increase in FFA content after homogenisation and storage is indicative of lipolysis. Single-stage and two-stage homogenisation induced an increase in FFA content, compared with non-homogenised milk. Two-stage homogenisation led to greater changes in the FFA content of milk, whereas single-stage homogenisation induced more pronounced lipolytic changes in milk during storage. No significant changes were observed in the composition of most fatty acids. The fatty acid profile and the proportions of saturated (SFAs) and unsaturated fatty acids (UFAs) remained stable in most samples. The proportion of SFAs increased (70.03%) and the proportion of UFAs decreased (29.97%) only in milk subjected to two-stage homogenisation, which increased the SFA/UFA ratio from 2.27 (before storage) to 2.34 (after storage).