TY - JOUR

T1 - Heat induced interactions in whey protein depleted milk concentrates

T2 - Comparison of ultrafiltration and microfiltration

AU - Coşkun, Özgenur

AU - Raak, Norbert

AU - Corredig, Milena

N1 - Funding Information: This work was funded by the Danish Milk Levy Fund . The support of Arla Food Amba and the Center for Innovative Food (CiFOOD) at Aarhus University is also greatly acknowledged. Data were generated through accessing the research infrastructure at Aarhus University, including FOODHAY (Food and Health Open Innovation Laboratory, Danish Roadmap for Research Infrastructure). Special thanks goes to Hanne Søndergaard Møller (Aarhus University, Aarhus, Denmark) for assistance in the analytical work. Publisher Copyright: © 2022 The Authors

PY - 2023/4

Y1 - 2023/4

N2 - The physical and chemical changes of 4x milk concentrates prepared by ultrafiltration (UF) and microfiltration (MF) combined with diafiltration were studied after heating in situ to 85 °C and subsequent cooling. Skim milk (1x) was analyzed as control. The concentrates had comparable pH, colloidal casein and colloidal calcium and phosphate, but differed in whey proteins and serum calcium and phosphate, allowing investigating the effect of soluble phase composition on viscosity changes and protein aggregation during heating. In heated samples, there was a decrease in the apparent diameter of the protein particles, as well as a decrease in bulk viscosity compared to unheated concentrates. On the other hand, the turbidity increased. Particles’ diffusivity measured by diffusive wave spectroscopy was slower in UF concentrate compared to the MF counterpart, both before and after heating, demonstrating the effect of protein aggregates in the soluble phase in changing the bulk properties of the concentrates. In this work, by comparing 4x MF and UF fresh concentrates with reduced calcium, and with similar processing history, it was demonstrated that the presence of whey proteins drives casein dissociation. MF concentrates showed increased heat stability compared to UF concentrates, with lower viscosity after heating. It was also observed that cooling kinetics affect the dissociation of caseins in heated skim milk. A fine control of diafiltration for ions and whey protein depletion is critical for control of the technological quality of the concentrates.

AB - The physical and chemical changes of 4x milk concentrates prepared by ultrafiltration (UF) and microfiltration (MF) combined with diafiltration were studied after heating in situ to 85 °C and subsequent cooling. Skim milk (1x) was analyzed as control. The concentrates had comparable pH, colloidal casein and colloidal calcium and phosphate, but differed in whey proteins and serum calcium and phosphate, allowing investigating the effect of soluble phase composition on viscosity changes and protein aggregation during heating. In heated samples, there was a decrease in the apparent diameter of the protein particles, as well as a decrease in bulk viscosity compared to unheated concentrates. On the other hand, the turbidity increased. Particles’ diffusivity measured by diffusive wave spectroscopy was slower in UF concentrate compared to the MF counterpart, both before and after heating, demonstrating the effect of protein aggregates in the soluble phase in changing the bulk properties of the concentrates. In this work, by comparing 4x MF and UF fresh concentrates with reduced calcium, and with similar processing history, it was demonstrated that the presence of whey proteins drives casein dissociation. MF concentrates showed increased heat stability compared to UF concentrates, with lower viscosity after heating. It was also observed that cooling kinetics affect the dissociation of caseins in heated skim milk. A fine control of diafiltration for ions and whey protein depletion is critical for control of the technological quality of the concentrates.

KW - Casein micelles

KW - Membrane filtration

KW - Viscosity

KW - Whey protein depletion

U2 - 10.1016/j.foodhyd.2022.108354

DO - 10.1016/j.foodhyd.2022.108354

M3 - Journal article

AN - SCOPUS:85143150806

VL - 137

JO - Food Hydrocolloids

JF - Food Hydrocolloids

SN - 0268-005X

M1 - 108354

ER -