TY - JOUR

T1 - The effect of milk fat content on microstructure and rheological properties of rennet casein gel emulsions

AU - Lorenzen, Mikkel

AU - van den Berg, Frans W.J.

AU - Lillevang, Søren K.

AU - Ahrné, Lilia

N1 - Funding Information: The authors would like to thank Ulf Andersen from Arla Food Amba Denmark for a kind and helpful discussion in the preparation of the LF-NMR experiments. Additionally, thanks to the Centre for Advanced Bioimaging (CAB) at the University of Copenhagen for support with CSLM. This project has received funding from Danish Dairy Rationalisation Fund (DDRF) and Arla Foods as part of the platform for Sustainable Dairy Processing. Publisher Copyright: © 2023 The Authors

PY - 2024

Y1 - 2024

N2 - Cheese is described as an emulsion gel, in which the dispersed phase comprises milk fat globules while the continuous phase consists of a casein gel network. By embedding fat into the casein network, it is possible to tailor the viscoelastic and physiochemical properties of casein emulsion gels and design customized cheese products. In this study, we incorporated 0.1, 7, 11, and 18% (w/w) milk fat in casein gels made from renneted skimmed milk curd and investigated its effect on microstructure, rheological properties, and melting behavior of the gels. Confocal laser scanning microscopy images revealed the presence of larger fat globules and serum pockets in samples with a fat content >11%, which also led to a more porous protein gel network structure. A higher proportion of water with high mobility, observed by low-field nuclear magnetic resonance, confirmed the presence of more or larger serum pockets in gels with the highest fat content. Rheological analysis showed that casein gels exhibited a behavior typical of weak solid viscoelastic materials. Increasing fat content increased gels strength, as revealed by a rise in storage modulus, but made them more susceptible to deformation. The gel-sol transition temperature increased from 65.5 ± 0.7 to 71.9 ± 0.2 °C with increased fat content due to the relatively lower moisture content in gels with a fat content >11%. The results obtained provided a better understanding of the possibility to modulate structural and rheological properties of casein emulsion gels emulsified with milk fat.

AB - Cheese is described as an emulsion gel, in which the dispersed phase comprises milk fat globules while the continuous phase consists of a casein gel network. By embedding fat into the casein network, it is possible to tailor the viscoelastic and physiochemical properties of casein emulsion gels and design customized cheese products. In this study, we incorporated 0.1, 7, 11, and 18% (w/w) milk fat in casein gels made from renneted skimmed milk curd and investigated its effect on microstructure, rheological properties, and melting behavior of the gels. Confocal laser scanning microscopy images revealed the presence of larger fat globules and serum pockets in samples with a fat content >11%, which also led to a more porous protein gel network structure. A higher proportion of water with high mobility, observed by low-field nuclear magnetic resonance, confirmed the presence of more or larger serum pockets in gels with the highest fat content. Rheological analysis showed that casein gels exhibited a behavior typical of weak solid viscoelastic materials. Increasing fat content increased gels strength, as revealed by a rise in storage modulus, but made them more susceptible to deformation. The gel-sol transition temperature increased from 65.5 ± 0.7 to 71.9 ± 0.2 °C with increased fat content due to the relatively lower moisture content in gels with a fat content >11%. The results obtained provided a better understanding of the possibility to modulate structural and rheological properties of casein emulsion gels emulsified with milk fat.

KW - casein emulsion gel

KW - Gel-sol transition temperature

KW - Skimmed milk curd

KW - Viscoelastic properties

U2 - 10.1016/j.foodhyd.2023.109243

DO - 10.1016/j.foodhyd.2023.109243

M3 - Journal article

AN - SCOPUS:85170429537

VL - 146

JO - Food Hydrocolloids

JF - Food Hydrocolloids

SN - 0268-005X

IS - Part A

M1 - 109243

ER -