In order to design and to adapt equipments for food processing, it is essential to know thermophysical properties. Once temperature and composition affects these properties, models based in such factors are important for further calculation. In this work, density and dynamic viscosity of bovine milk, probably the most processed food fluid in the world, were determined within large ranges of temperature and major constituents (moisture, fat, lactose, protein and minerals), based on typical processing values. Density varied from (962.01 to 1100.45) kg/m3 and dynamic viscosity varied from (0.60 to 63.70) mPa∙s. Temperature and moisture content negatively affected both properties, while lactose, protein and minerals contents positively affected them. An increase in fat content reduced density and increased dynamic viscosity. Experimental density data were fitted to the simplest multiple linear model and dynamic viscosity data were fitted to a multiple type Arrehnius’ model, obtaining good agreement.

Liquid−liquid equilibrium data and phase diagrams of new aqueous two-phase systems (ATPS's), composed of water + sodium hydroxide + poly(ethylene glycol) (PEG) of molar masses (1450, 4000, or 10 000) g•mol −1 , were determined at (288.2, 298.2, and 308.2) K. The effects of temperature and PEG molar mass on the equilibrium data were studied. It was found that an increase in temperature caused the expansion of the two-phase region and increased the slope and the length of the tie line. It was also observed that binodal curves shifted toward the origin with the increase in PEG molar mass.

Experimental equilibrium data were obtained for aqueous two-phase systems composed of polyethylene glycol 400 g·mol–1 + sodium phosphate, and polyethylene glycol 400 g·mol–1 + sodium citrate, at T = (298.2, 308.2 and 318.2) K. For the system formed by sodium phosphate, at the studied range, the temperature effect on the position of the binodal curves was not relevant. For the system composed of sodium citrate, the temperature increase caused an expansion of the biphasic region. The efficacy of the salts in inducing phase segregation follows the order sodium phosphate > sodium citrate at temperatures of (298.2 and 308.2) K. Energy interaction parameters for the NRTL and UNIQUAC models were estimated, and the mean deviations between experimental and calculated compositions were 0.46 % and 0.32 %, respectively. These results show that both models, NRTL and UNIQUAC, are able to represent the phase behavior of polymer–salt aqueous two-phase systems evaluated.

Peptides inhibiting the activity of angiotensin converting enzyme (ACE) were obtained by trypsin-catalyzed hydrolysis of bovine milk casein, performed at 37°C, during 1, 2, 5, 8 and 24h. Results of in vitro inhibitory activity ranged between 13.4% and 78.5%. The highest ACE inhibitory activity was evidenced for hydrolysates obtained after 2h of reaction. Aqueous two-phase systems (ATPS) formed by polyethylene glycol of 1500gmol (PEG 1500)+sodium phosphate or potassium phosphates were produced and evaluated, in terms of partition coefficients (K) and extraction yields (y), to recovery the casein hydrolysates at room temperature. In ATPS containing sodium phosphate, the peptides showed a slightly greater affinity toward the bottom salt-rich phase (0.1≤K≤0.9; 5.7%≤y≤47%). In the case of ATPS containing potassium phosphates, these molecules showed substantially greater affinity toward the top polymer-rich phase (137≤K≤266; y≥99%). These results point out extraction using PEG 1500/potassium phosphate ATPS is an efficient technique to recover casein hydrolysates containing ACE inhibitors peptides. Outlined data will be helpful in integrating such unit operation to larger scale processes.