The isolation and concentration of phospholipids from various dairy by-products
There has been great interest in the phospholipids (PLs) found in dairy products because of their health and functional properties. The isolation and concentration of these PLs has been a significant research area in recent years. Dairy by-products contain higher concentrations of PLs compared to raw milk, which make them an economic feedstock for PLs concentration. Technologies that produce isolated lipid fractions with elevated PLs concentrations have yet to be obtained and are a priority for the United States dairy industry. This dissertation summarizes methods used to isolate and concentrate PLs from various dairy by-products. The technologies utilized in these studies provide a means for the dairy industry to utilize dairy by-products more effectively and provide methodologies appropriate for industry scale-up. The end goal of this research is the production of an isolated dairy lecithin with a PLs concentration greater than 50%. The simultaneous texturization and extraction of PLs (STEP) method, modified from the method used for egg yolk, which utilized ethanol, was shown to be an effective and efficient way to produce a dairy PLs concentrate from whey protein phospholipid concentrate. The use of food grade surfactants was shown to be effective in improving the PLs distribution to buttermilk, which is a by-product with potential for PLs utilization, during cream churning. Both zinc acetate and calcium acetate were effective for precipitating the total lipid and PLs found in the beta stream and an additional ethanol extraction has great potential for producing valuable lipid fractions. The use of solvent fractionation was shown to be an effective way to concentrate PLs from the lipid fraction isolated from the beta stream and produced a dairy lecithin. An investigation into the oxidative stability of whey protein phospholipid concentrate lipid fraction suggests that powdered and liquid forms of industrial WPPC were oxidized.
All of these studies provided insight into PLs isolation and concentration methods, along with giving an understanding of the oxidative stability of dairy by-products lipid fractions. The end goal of this research was obtained with an effective means to produce a dairy lecithin that can be utilized in various food and consumer applications.