PhD defence by Mads Emil Bjørlie

Principal supervisor

• Professor Charlotte Jacobsen

Co-supervisors

• Senior Researcher Ann-Dorit Moltke Sørensen
• Senior Researcher Betül Yesiltas Svensson

Examiners

• Associate Professor Aberham Heilu Feyissa, DTU Food
• Professor Karin Schwarz, University of Kiel
• Associate Professor Mahesha Manjunatha Poojary, University of Copenhagen

Chairperson at defence

• Senior Researcher Grethe Hyldig, DTU Food

Resume
One of the main causes of food spoilage is lipid oxidation, a process that makes food go rancid. Lipid oxidation is accelerated by metal ions, which can enter food from raw materials or during processing. To combat this, special antioxidants called metal chelators are used by food producers. These molecules bind to metal ions, preventing them from initiating and propagating lipid oxidation.

Ethylenediaminetetraacetic acid (EDTA) is a synthetic metal chelator widely used in the food industry to protect food products from metal-catalyzed lipid oxidation. Although EDTA is approved as a food additive by the European Food Safety Authority, increasing consumer demand for natural ingredients and clean-label products has led to a heightened interest in finding alternatives to EDTA. Furthermore, traditional methods for identifying new metal-chelating antioxidants are often non-specific and time-consuming.

This PhD project had two main goals: to find a potential replacement for EDTA and to develop faster and more specific screening methods to identify peptides and protein hydrolysates with metal-chelating activity. Several techniques, both established and new, were evaluated and adapted for use in acidic environments similar to many food products. Additionally, storage experiments were conducted using simple emulsions and mayonnaise to ensure that the laboratory results would be relevant in real-world applications.

Each technique offered its own advantages and disadvantages, and the results were generally qualitative, highlighting the need for further refinement. Although a direct replacement for EDTA was not discovered, the findings and insights from this research are expected to contribute significantly to the ongoing search for effective natural chelators and enhance the understanding of antioxidant mechanisms.