Native fat globules of different sizes selected from raw milk: thermal and structural behavior.
The aim of this study was to characterize differences in the thermal and structural behavior between different sized native milk fat globules. A novel microfiltration process permits the selection of native small fat globules (SFG, 1-3 microm) and large fat globules (LFG, >5 microm) in raw milk, that were analyzed by X-ray diffraction (XRD) coupled to differential scanning calorimetry (DSC). There were no major differences in triglyceride crystalline structures between SFG and LFG, after eliminating thermal history and the influence of cooling rates. The three main 3L and 2L crystalline structures appearing under slow cooling existed regardless of globule size. The supercooling increased for the SFG, mainly due to heterogeneous nucleation in winter milk, and also to compositional variations in spring milk. Differences appeared regarding stabilized crystalline forms at 20 degrees C and subsequent cooling: the SFG contained less 2L triglyceride structures than the LFG. These results can be important in dairy manufactures using tempering periods.
Michalski
Marie-Caroline
MC
Science et Technologie du Lait et de l'OEuf, UMR INRA 1253, 65 rue de Saint-Brieuc, 35042 Rennes Cedex, France. mcmichal@labtechno.roazhon.inra.fr
Ollivon
Michel
M
Briard
Valérie
V
Leconte
Nadine
N
Lopez
Christelle
C
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D005227:Fatty Acids / Q000737:chemistry; D006017:Glycolipids / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry*; D066292:Lipid Droplets; D008892:Milk / Q000737:chemistry*; D010316:Particle Size; D013696:Temperature; D014961:X-Ray Diffraction
D005227:Fatty Acids; D006017:Glycolipids; D006023:Glycoproteins; C110367:milk fat globule