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Role of the fat globule membrane in the autoxidation of milk fat
Abstract
The fat globules in milk are surrounded by a membrane, approximately 7.6 nm in thickness, which contains proteins, lipids and other minor components. Although the total amount of the fat globule membrane is very small, it plays an important role in the quality of milk and dairy products. The purpose of this study was to examine the role of the components of the membrane, separately and in combination, on the oxidation of milk and milk fat. Such examinations were carried out by measuring atmospheric oxygen consumption and the disappearance of unsaturated fatty acids. In general, the results indicate that the milk fat globule membrane contains both antioxidative and oxidative components. The influence of the membrane on the oxidation of milk and dairy products depends largely on a delicate balance between two opposing factors. Such balance is governed by a number of parameters including the composition of the membrane, temperature, the presence or absence of water, pH, metal ions, and other minor components. Effects of individual phospholipids and amino acids on the milk fat oxidation were also conducted. At 50$\sp\circ$C, dipalmitoyl phosphatidyl ethanolamine (DPE) and dipalmitoyl phosphatidyl choline (DPC) inhibited milk fat oxidation in the dry system while accelerating it in the aqueous system. DPE was more effective than DPC. All amino acids tested protected milk fat against oxidation. Amino, sulfhydryl, phenol indole groups in the side chain were found to be responsible for the antioxidative activity of amino acids and proteins. The freeze-dried lysine. HCL and alanine.HCL promoted milk fat oxidation while the corresponding control amino acids inhibited it. An understanding of the mechanisms involved, and the processing conditions which influence inhibition and/or acceleration, would be of significant value in the control of oxidative reactions in milk, dairy products and other food systems.
Subject Area
Food Science
Recommended Citation
Chen, Zhen-Yu, "Role of the fat globule membrane in the autoxidation of milk fat" (1990). Doctoral Dissertations Available from Proquest. AAI9022671.
https://scholarworks.umass.edu/dissertations/AAI9022671