The effect of high-pressure homogenisation on the physicochemical properties of milk acidified using different acidulants

This study investigates the effects of high-pressure homogenisation (HPH) on the physicochemical properties of acidified milk at pH 5.50, using glucono-delta-lactone (GDL), lactic acid (LA), or citric acid (CA) as acidulants. HPH treatment did not significantly influence serum ionic calcium ([Ca²⁺]) of milk at native pH, however induced a large reduction on CA-acidified milk (0.96 mM; 19.5 %), followed by LA (0.52 mM; 7.78 %) and GDL-acidified milk (0.36 mM; 6.53 %). A decrease of apparent viscosity observed after HPH for GDL and LA was associated with an increase in casein micelles size for GDL and LA samples, while the CA sample was largely unchanged. Caseins are partitioned in the serum phase due to acidification, with the former being further re-assembly after HPH processing. Compared with CA, GDL and LA results in a more significant reduction of individual casein size in the serum phase with a reduction of 46.6–38.3 % for κ-casein, 50.4–62.0 % for α-casein and 31.3–36.5 % for β-casein after HPH process. The information provided in this study shows the potential to modulate the physicochemical properties (i.e., viscosity reduction, [Ca²⁺], particle size) and, thus, the functionality of acidified milk to be used in manufacturing dairy products.