Influence of hybrid lactose-permeate standardisation on the physicochemical and functional properties of skim milk and concentrates

Standardisation of protein content is important in ensuring consistent composition and functionality of dairy powders, especially those made from a seasonal milk supply. This study investigated the effects of hybrid standardisation media, composed of lactose and permeate mixtures, on the physicochemical and functional properties of skim milk concentrates. The protein content target was 3.5 %, using five different permeate:lactose (P:L) ratios: 100P, 75P:25L, 50P:50L, 25P:75L, and 100L (at 8 % total solids (TS)), followed by evaporation to 52 % TS. Results showed that higher P:L ratios led to higher viscosity of skim milk concentrates and enhanced the heat stability of protein-standardised milk at pH in the ranges 6.4–6.7 and 7.0–7.2. Mineral analysis reflected higher concentrations of calcium, phosphorous, and trace minerals for higher P:L ratios, contributing to higher buffering capacity, increased micellar hydration and larger particle size post-evaporation. These findings demonstrate the potential of hybrid standardisation media to optimise processing conditions in milk powder production, balancing enhanced heat stability and viscosity development of milk concentrates.