Microstructure and Material Properties of Milk Fat Systems During Temperature Fluctuations

作者：Buldo Patrizia; Andersen Ulf; Wiking Lars^*

来源：Food Biophysics, 2013, 8(4): 262-272.

DOI：10.1007/s11483-013-9299-y

• Emulsion
• Milk fat globule
• Crystallization
• Temperature fluctuations
• Rheology

Microstructure and material properties of milk fat systems containing different amount of milk fat globules and different emulsion types were studied towards the effects of temperature fluctuations stress. The three systems were (i) an emulsion based on anhydrous milk fat (AMF) consisting of crystals dispersed in liquid oil, (ii) butter which is a water in oil emulsion consisting of a continuous crystal network with partially disrupted fat globules interrupted by intact fat globules and water droplets, and (iii) freeze-dried cream which is an oil in water emulsion consisting of concentrated milk fat globules. The microstructure of the systems was observed by confocal laser scanning microscopy and linked to their material properties by large and small deformation rheology techniques. Different rheological techniques were used to characterize the material descriptors. The crystallization behavior was studied by thermal analysis and pulsed nuclear magnetic resonance. The freeze-dried cream was characterized as the softest, more elastic, and less stiff when compared to butter and AMF. Temperature fluctuations led to drastic material consolidation in butter as a consequence of flocculation of fat globules and formation of a more dense crystal network with stronger bonds. Only after several temperature fluctuations, material consolidation was observed in AMF, whereas no significant changes in material properties were observed in the freeze-dried cream. The intact fat globules decrease the hardness and stiffness, whereas the amount and type of contact points between crystal clusters of the dispersed crystal phase contribute to increase hardness, stiffness, and brittleness of the systems.

• 出版日期2013-12