Partial enrichment of phospholipids by enzymatic hydrolysis and membrane filtration of whey protein phospholipid concentrate.

Whey protein phospholipid concentrate (WPPC) contains high amounts of phospholipids (PL; 4.5 ± 1%) but there is interest in further enriching the PL content for nutritional and functional applications. Chemical methods were unsuccessful in separating PL from proteins due to the presence of protein-fat aggregates. Instead, we explored hydrolysis of the proteins to peptides with the objective of removing peptides, thereby concentrating the PL fraction. We used microfiltration (MF) with a pore size of 0.1 µm to help reduce protein/peptide retention. Hydrolyzing proteins should facilitate passage of low molecular weight peptides through the MF membrane, while concentrating fat and PL in the MF retentate. Bench-top experiments were performed to select the proteolytic enzyme that resulted in the most extensive hydrolysis of proteins in WPPC from among 5 different commercial proteases. Sodium dodecyl sulfate-PAGE analysis was performed to measure the extent of protein hydrolysis over a period of 4 h. Alcalase enzyme was found to exhibit the highest proteolytic activity at conditions of pH 8 and temperature 55°C. The intensity of major protein bands (milkfat globule membrane proteins, caseins, ß-lactoglobulin) in WPPC decreased in sodium dodecyl sulfate-PAGE profiles as hydrolysis progressed, along with the appearance of low molecular weight bands. Pilot-scale MF production, coupled with diafiltration (DF), of the hydrolyzed sample aided in the removal of peptides that caused an ~18% reduction in protein content with the final retentate having a total PL content of 9.3% dry basis (db) with protein and fat contents at approximately 43.8 ± 0.4% (db) and 48.9 ± 1.2% (db), respectively. The MF permeate had minimal fat content, indicating that there was no transmission of lipids or PL through the membrane during the MF/DF process. Confocal laser scanning microscopy and particle size analysis of enzyme hydrolyzed solution revealed that protein aggregates were still present after 1 h of hydrolysis. Complete removal of proteins and peptides was not achieved by this process, suggesting that a combination of enzymes would be needed for further hydrolysis of protein aggregates in WPPC solution to further enrich the PL content.

A study of various chemical pretreatments to fractionate lipids from whey protein phospholipid concentrate.

Dairy-derived lipids such as phospholipids (PL) have been gaining interest due to their functional and nutritional properties. Our research goal was to develop a separation process (nonsolvent based) to produce an enriched dairy lipid fraction from whey protein phospholipid concentrate (WPPC). Various chemical pretreatments (i.e., adjustment of pH, calcium, or temperature) were applied to rehydrated commercial WPPC solutions. These treatments were done on a bench-top scale to aid in the precipitation of proteins or PL. The chemically treated solutions were centrifuged and fractionated into the following 3 layers: (1) top fat layer, (2) supernatant in the middle zone, and (3) sediment at the bottom of the centrifuge tubes. The thickness and size of the layers varied with the treatment parameters. Compositional analysis of each layer showed that the proteins, fat, and PL always appeared to fractionate in similar proportions. The proteins in each layer were characterized using sodium dodecyl sulfate-PAGE under reducing and nonreducing conditions. Different proteins including whey proteins, caseins, and milk fat globule membrane proteins and lipoproteins were identified, and no specific type of protein had an affinity for either the top or bottom layer. All types of proteins were present in each of the layers after centrifugation, and there were no major differences in fractionation of the proteins between layers with respect to the chemical treatment applied. The microstructure of protein and fat in WPPC was investigated using confocal laser scanning microscopy. Dual staining of the rehydrated WPPC solution with Fast Green FCF (proteins) and Nile Red (lipids) showed the presence of very large protein aggregates that varied in size from 20 to 150 µm, with fat trapped within these aggregates. The confocal laser scanning microscopy images of liquid WPPC revealed fine strands of a weak protein network surrounding the fat globules. This indicated that there were specific interactions between the proteins, as well as between the fat and proteins in WPPC. Sodium dodecyl sulfate treatment was performed to understand the nature of the interactions between protein and fat. We found that about 35% of the fat present in WPPC was in the form of free fat, which was only physically entrapped within the protein aggregates. The remaining fat had some form of association with the proteins in WPPC. Other fractionation techniques would be needed to obtain an enriched dairy lipid fraction.

Composition and functionality of whey protein phospholipid concentrate and delactosed permeate.

Whey protein phospholipid concentrate (WPPC) and delactosed permeate (DLP) are 2 coproducts of cheese whey processing that are currently underused. Past research has shown that WPPC and DLP can be used together as a functional dairy ingredient in foods such as ice cream, soup, and caramel. However, the scope of the research has been limited to 1 WPPC supplier. The objective of this research was to fully characterize a range of WPPC. Four WPPC samples and 1 DLP sample were analyzed for chemical composition and functionality. This analysis showed that WPPC composition was highly variable between suppliers and lots. In addition, the functionality of the WPPC varies depending on the supplier and testing pH, and cannot be correlated with fat or protein content because of differences in processing. The addition of DLP to WPPC affects functionality. In general, WPPC has a high water-holding capacity, is relatively heat stable, has low foamability, and does not aid in emulsion stability. The gel strength and texture are highly dependent on the amount of protein. To be able to use these 2 dairy products, the composition and functionality must be fully understood.

Whey protein phospholipid concentrate and delactosed permeate: Applications in caramel, ice cream, and cake.

Whey protein phospholipid concentrate (WPPC) and delactosed permeate (DLP) are 2 coproducts of cheese whey processing that are currently underutilized. Past research has shown that WPPC and DLP can be used together as a functional dairy ingredient in foods such as ice cream, soup, and caramel. However, the scope of the research has been limited to a single WPPC supplier. The variability of the composition and functionality of WPPC was previously studied. The objective of this research was to expand on the previous study and examine the potential applications of WPPC and DLP blends in foods. In ice cream, WPPC was added as a natural emulsifier to replace synthetic emulsifiers. The WPPC decreased the amount of partially coalesced fat and increased the drip-through rate. In caramel, DLP and WPPC replaced sweetened condensed skim milk and lecithin. Cold flow increased significantly, and hardness and stickiness decreased. In cake, DLP and WPPC were added as a total replacement of eggs, with no change in yield, color, or texture. Overall, WPPC and DLP can be utilized as functional dairy ingredients at a lower cost in ice cream and cake but not in chewy caramel.