Improved heat stability of recombined evaporated milk emulsions upon addition of phospholipid enriched dairy by-products

Over the last decades, milk fat globule membrane (MFGM) fragments have gained a considerable attention for their beneficial technological and nutritional properties due to the presence of proteins and phospholipids. During butter production, the MFGM is ruptured and a great amount of membrane material migrates to the aqueous fraction, known as buttermilk. Its high phospholipid concentration attributes a very interesting functionality to buttermilk.As it has been shown before that phospholipid addition may improve the heat stability of concentrated dairy emulsions during sterilization, the effect of two phospholipid enriched dairy by-products on the heat stability of recombined evaporated milk emulsions was investigated. To that end, a cream residue powder (CRP) originating from the production of butter oil from dairy cream, as well as a sweet buttermilk powder (SBP) have been used to reduce the undesirable changes taking place during intense heating of concentrated milk. Samples were prepared containing CRP or SBP in different concentrations (0–6 %) and were heated for multiple time intervals at sterilization conditions (121 °C). Both phospholipid enriched dairy by-products could largely reduce the pronounced viscosity increase as well as the increase in particle size observed upon intensive thermal treatment. Whereas the stabilizing effect of both products was directly proportional to their concentration, still the effect of CRP was more pronounced as compared to SBP: the addition of the maximum concentration (6%) of both products resulted in a similar particle size distribution and viscosity as compared to the original emulsion before heating, while a lower concentration of CRP (4%) also had a significant heat stabilizing effect. Whereas the difference in effectiveness could be probably related to the phospholipid content of both dairy ingredients, still it has to be kept in mind that these two ingredients not only differed in this aspect. Determination of the protein load revealed that phospholipid enriched dairy by-products reduced the increase in surface protein load upon sterilization, which points toward a reduced heat-induced interaction between the dairy proteins.Overall, our experiments revealed that phospholipid enriched dairy by-products have interesting functional properties and largely improve the heat stability of recombined evaporated milk emulsions. For the two products considered, their effect seemed to be related to their phospholipid content.

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