Staff PhD

Whey protein fractions – Minimizing oxidation

Bente Marianne Jensen

Background

Whey proteins exist as by-products from manufacturing of cheese and caseinate. Through the last decades, the whey proteins have developed into high value products with many applications in the food industry. This is mainly because of their good functional properties as regards the nutritious as well as physical chemical (water binding, emulsifying and foaming) properties.

Whey protein fractions contain a varying amount of fat with an overrepresentation of phospholipids, which are typically more unsaturated than milk fat in general. Thus the whey is more exposed to oxidation and hence development of off-flavour components and toxic substances. Also milk proteins are oxidized, which influences the structure of the proteins. In addition secondary lipid oxidation products and lactose react with the milk proteins, likewise causing structural changes. The structural changes are expected to influence the functional properties of the ingredients.

Aim

The aim of the PhD project is to understand the mechanisms responsible for oxidation of lipids and proteins in the whey fraction plus the mechanisms responsible for the lactylation of proteins, and through this knowledge to propose a strategy for optimal processing and storage of powder products, including use of antioxidants.

The hypothesis is that oxidation in fat and proteins develop synchronously. Furthermore, it is hypothesized that the reduction of lipid oxidation can reduce oxidation of proteins and that use of antioxidants can reduce oxidation and thereby prolong shelf life.

Research Outline

The first phase in the project is to describe the oxidation course and the lactylation processes within the different whey powders during storage under realistic circumstances. This will, among other methods, be done by measuring free radicals using ESR, secondary volatile oxidation products with GC-MS and maillard reaction products with LC-MS. In addition changes in functionality will be analyzed with rheological measurements and the powders will be evaluated sensorically.

In the second phase, when the oxidation course is characterized, the use of antioxidants and other possible improvements in the production procedure are investigated. This is done in model systems with accelerated oxidation using the most informative analytical methods from phase one.

In the third phase possible solutions from phase two are tested in pilot-plant-scale, stored under realistic circumstances, analyzed and evaluated sensorically.