The milk fat globule membrane, a major component in buttermilk, contains many complex lipids known to be involved in a variety of biological processes. Phospholipids, including sphingolipids, exhibit antioxidative, anticarcinogenic, and antiatherogenic properties and have essential roles in numerous cell functions. Filtration coupled with supercritical fluid extraction (SFE) may provide a method of concentrating these nutritionally valuable lipids into a novel ingredient. The objective of this dissertation was to evaluate the SFE process as a method to enrich polar lipids in buttermilk powder.

The first part of this dissertation involved the optimization of the SFE treatment for buttermilk powder. Pressure and temperature treatment factors were assessed as were the role of matrix powder additions. The parameters at 350 bar and 50°C displayed enhanced extraction efficiency of triacylglycerol removal with minimal disruption to other buttermilk components. The addition of diatomaceous earth, Teflon^® beads and physical vibration were shown to help reduce total lipid by 86%, 78% and 70%, respectively.

The second part of the study was to apply the optimized SFE treatment to two different sources of buttermilk powder, regular and whey cream, also passed through two different filtration modes prior to drying. The buttermilk powders were compared in terms of lipid extraction efficiency and by assessing compositional differences of initial and final products, as well as the lipids extracted from the powder. After three extractions, SFE processing reduced the total fat, namely non-polar lipids, by 38 55% and phospholipids were concentrated by a 5-fold factor in the powders. Specific molecular fatty acid combinations on the sphingosine backbone of sphingomyelin from the treated buttermilk powder were characterized to show unique composition.

Finally, the thermal stability of ultrafiltrated whey cream buttermilk powder prior to and following SFE treatment was observed. Salt as well as pH levels were adjusted in the reconstituted powders and protein agglomeration upon heating was assessed. Results showed that in comparison to whey protein isolate, the SFE process enhances thermal stability by reducing protein aggregation, indicating the processed whey cream buttermilk powder to be a unique product with an interesting thermal profile and composition.

Filtration followed by supercritical fluid extraction processing is an effective tool for enriching bioactive lipids in both sweet and whey cream buttermilk powder, opening the potential for novel food ingredients.