Among the calcium hydroxycarboxylates important for cheese quality, D-lactobionate [Ksp = (7.0 ± 0.3) × 10(-3) mol(3) L(-3)] and L-lactate [Ksp = (5.8 ± 0.2) × 10(-3) mol(3) L(-3)] were found more soluble than D-gluconate [Ksp = (7.1 ± 0.2) × 10(-4) mol(3) L(-3)], as indicated by the solubility products determined electrochemically for aqueous 1.0 M NaCl at 25.0 °C. Still, solubility of calcium L-lactate increases by 45% in the presence of 0.50 M sodium D-gluconate and by 37% in the presence of 0.50 M sodium D-lactobionate, while solubility of calcium D-gluconate increases by 66 and 85% in the presence of 0.50 M sodium L-lactate and 0.50 M sodium D-lactobionate, respectively, as determined by complexometric titration. Sodium L-lactate and sodium D-gluconate have only little influence on solubility of calcium D-lactobionate. The increased solubility is described quantitatively by calcium binding to D-gluconate (K1 = 14 ± 3 mol(-1) L) in 1.0 M NaCl at 25 °C, D-lactobionate (K1 = 11 ± 2 mol(-1) L), and L-lactate (K1 = 8 ± 2 mol(-1) L), as indicated by the association constants determined electrochemically. In mixed hydroxycarboxylate solutions, calcium binding is quantitatively described by the geometric mean of the individual association constants for both aqueous 1.0 and 0.20 M NaCl, indicating a 1:1 stoichiometry for complex formation.

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Low-molecular-weight (LMW) emulsifiers are used to promote controlled destabilization in many dairy-type emulsions in order to obtain stable foams in whippable products. The relation between fat globule aggregation induced by three LMW emulsifiers, lactic acid ester of monoglyceride (LACTEM), saturated monoglyceride (GMS), and unsaturated monoglyceride (GMU) and their effect on interfacial protein displacement was investigated. It was found that protein displacement by LMW emulsifiers was not necessary for fat globule aggregation in emulsions, and conversely fat globule aggregation was not necessarily accompanied by protein displacement. The three LMW emulsifiers had very different effects on emulsions. LACTEM induced shear instability of emulsions, which was accompanied by protein displacement. High stability was characteristic for emulsions with GMS where protein was displaced from the interface. Emulsions containing GMU were semisolid, but only low concentrations of protein were detected in the separated serum phase. The effects of LACTEM, GMS, and GMU may be explained by three different mechanisms involving formation of interfacial α-gel, pickering stabilization and increased exposure of bound casein to the water phase. The latter may facilitate partial coalescence. Stabilizing hydrocolloids did not have any effect on the LMW emulsifiers' ability to induce protein displacement.

Oil-in-water emulsions were made with five different triglyceride fats ranging from completely liquid oil to solid. Regardless of the type of dispersed fat, all emulsions were non-aggregated and had low viscosity when stabilized only by caseinate. Presence of lactic acid ester of monoglyceride (LACTEM) and unsaturated monoglyceride (GMU) caused solidification of emulsions made with fat with intermediate solid fat content (SFC), due to fat globule aggregation. The hardest and most compact fat globule network was obtained for emulsions based on hydrogenated palm kernel oil (HPKO). Although palm kernel oil (PKO) and palm oil (PO) resembled HPKO in terms of fatty acid (FA) composition and SFC, a lower strength of the fat globule network was obtained for emulsions based on PKO and PO. The dispersed fat phase should have intermediate SFC (simultaneous presence of liquid and solid fat) in order to induce fat globule aggregation in emulsions. This was demonstrated by emulsions made with either rapeseed oil (RO) and fully hydrogenated palm oil (FHPO), which remained stable and pourable despite the presence of LACTEM and GMU. Practical applications: This study emphasizes the important role of fat on the texture of O/Wemulsions. This knowledge is vital for the industry in order to control or avoid fat globule aggregation. For manufacturers striving for partial coalescence of emulsions to occur, it is necessary to use low-molecularweight emulsifiers and fat with intermediate solid fat content.