Date of Award

7-2011

Degree Name

MS in Agriculture - Dairy Products Technology

Department

Dairy Science

Advisor

Rafael Jiménez-Flores

Abstract

ABSTRACT

Effects of Milk Processing on the Milk Fat Globule Membrane Constituents

Xiomara E. Elías-Argote

The milk fat globule membrane (MFGM) is avidly studied by many groups of scientists around the world due to its unprecedented nutritional and functional properties; however, limited research has been performed on the effects of milk processing on the chemical changes of the MFGM. Thus, this study highlights the changes that lipids and proteins undergo from the time milk leaves cow’s udders. Cooling (4 °C) was included along with subsequent pasteurization by different traditional thermal processes and cold pasteurization by pulse light ultra violet treatment. Cooling milk to 4 °C had a measureable effect on the MFGM composition, resulting in protein alterations, particularly to butyrophilin and adipophilin. Thermal treatments disturbed the native structures of molecules and increased the adsorption of milk and whey proteins on the globules, especially a-lactalbumin and b-lactoglobulin. As the heat intensity increased, the aggregation of fat globules became more pronounced due to protein interactions. Intrinsic MFGM proteins also varied in relative abundance during the processing steps. The concentrations of polar lipids did not change during processing, with the exception of phosphatidylserine, which decreased during the cooling and thermal treatments. Cold pasteurization (UV treatment) had a minimal effect on fat globules and MFGM proteins. Since the MFGM promises to deliver nutritional effects and more when included in food products, currently HTST pasteurization was shown to be the best method to process milk and obtain MFGM isolates for further supplementation.