Whey protein fibrils: a new approach to modify the functionality of milk protein concentrate and nonfat dry milk

Abstract

Milk-derived ingredients such as milk protein concentrate (MPC) and isolate are the preferred choice to provide nutritional and functional benefits in a wide range of dairy and food products. Milk proteins provide nutritional benefits by providing several essential amino acids. Besides nutrition, milk proteins also provide several functional properties such as thickening, gelling, emulsification, and foaming. These functional properties can be further enhanced by altering protein configuration and protein-protein interactions between milk proteins that can open doors for new product applications. Among several techniques, fibrillation is a technique that converts globular proteins such as whey proteins into a fibrillar form. Compared to globular proteins, fibrillar proteins have a higher aspect ratio (due to a few nanometers diameter and few microns length), which consequently provide improved functionality in terms of thickening, gelation, emulsification, foaming, and interfacial properties. As a first step, milk-derived whey proteins were selectively converted into fibrils and mixed with micellar casein, keeping the casein to whey protein ratio (80:20) to develop fibrillated model MPC (F-MPC) in liquid form. This F-MPC showed the presence of fibrils and consequently resulted in significantly (P<0.05) higher viscosity at a 5% (w/w) protein level. Acid gels prepared using F-MPC also resulted in firmer gels compared to control MPC. To further increase the convenience, liquid F-MPC was spray dried to produce in powder form. The F-MPC powder was reconstituted to 5% protein and confirmed the presence of fibrils using transmission electron microscopy. Further, reconstituted F-MPC showed enhanced viscosity, emulsification capacity, foaming capacity and stability, and lower surface and interfacial tension compared to control MPC. In a different study, nonfat dry milk (NDM) containing whey protein fibrils was also developed using microfiltration and ultrafiltration to yield fibrillated skim milk which was spray dried to get fibrillated NDM. Reconstituted fibrillated NDM (10% w/w) total solids also showed improved viscosity, emulsification, and foaming capacity. Therefore, it could be said that selective fibrillation of whey proteins can enhance the functionality of milk protein powders that can impart functionality to a range of dairy products. These fibrillated ingredients can aid in reducing the use of non-dairy ingredients and can be termed as clean-label ingredients.