Transmission electron microscopy of milkfat globules in the low‐density lipid fraction of swiss cheese whey

Abstract

A low-density lipid fraction (LDLF) was recovered from Swiss cheese whey (SCW) residual lipids by highspeed centrifugation. The present study was conducted to determine the microstructural properties of the extremely smallsized milkfat globules (MFG) in LDLF by: (i) freeze-fracture transmission electron microscopy (FF-TEM) and (ii) thin-section TEM (TS-TEM). FF-TEM results revealed that MFG in LDLF were ≤1 µm in size and were embedded in what appeared to be a smooth, protein-like matrix. The MFG in FF-TEM specimens exhibited either planarly cleaved fractions with smooth cores or peripherally cleaved fractions with surface laminations. TS-TEM results revealed that the MFG in LDLF were dispersed in an aggregated nonlipid matrix. JAOCS 75, 745-747 (1998). FIG. 3. Surface laminations on a peripherally fractured MFG in LDLF by the FF-TEM method. For abbreviations see Figure 1. FIG. 4. MFG and matrix materials in LDLF by the thin-section TEM method. (1) MFG; (2) casein submicelles or aggregated matrix materials; (3) MFG membrane; and (4) ruptured MFG membrane. For abbreviations see Figure 1.