23 September 2019

New professor of food chemistry investigates how to secure healthy and sustainable food for the future

New Professor of food chemistry

When raw materials are processed into meals and food products in both private kitchens and in the food industry, a large number of chemical reactions take place in e.g. fats and proteins. These changes typically have an impact on both the quality and nutritional value of the food and Marianne Nissen Lund is working to uncover these chemical reactions as a new professor of food chemistry in the Department of Food Science at the University of Copenhagen (UCPH FOOD).

Marianne Nissen Lund is a professor of food chemistry at UCPH FOOD, where she, among other things, investigates dairy foods. Picture Claus Boesen.

Marianne Nissen Lund will thus take over from her mentor and former PhD supervisor, professor Leif Skibsted, also UCPH FOOD, who established the food chemistry field in Denmark. However, Leif Skibsted will maintain his affiliation with UCPH FOOD, but from October as professor emeritus.

Will continue the food chemistry tradition in Denmark

“My goal is to continue and develop the food chemistry field in Denmark. It was at the old KVL (Royal Veterinary and Agricultural University of Denmark, which merged with the University of Copenhagen in 2007 Ed.) that food chemistry with Leif Skibsted was started up and it is something we are known for. It has expanded, so today there are also people at Aarhus University and DTU working with different types of food chemistry,” says Marianne Nissen Lund.

According to the new professor of food chemistry, we still lack some knowledge about how industrial food processing and storage affect human health.

“In order for us to work that out, we need to figure out how to map the changes that are taking place with the various food components at the molecular level. For example, proteins are an important part of our diet and they undergo many different changes during processing and storage,” explains Marianne Nissen Lund.

“My research looks at what happens when proteins in food come in contact with oxygen from the air. This contact typically occurs when you process foods and it affects the quality of the food – this applies to taste and possibly health in some cases,” says Marianne Nissen Lund.

One of the chemical reactions most familiar to consumers is the browning effect that occurs when you roast your meat or toast your bread. Many people in Denmark are probably aware of the official dietary guidelines regarding meat, which recommends not roasting or grilling the meat until the crust is burnt. It is here the unhealthy browning effect or among researchers – the Maillard reactions – occurs. The browning effect is one of the many chemical reactions that Marianne Nissen Lund and her research team are working with. An example of her research concerns Maillard reactions in long-life UHT-treated milk. The milk is typically microbiologically stable and thus safe to drink, but you would still not want to drink it after prolonged storage.

“You give the milk a more intense heat treatment, so that bacteria cannot grow in it. But the chemical Maillard reactions still limit its shelf life. The milk will taste different if it is stored for too long, plus it turns brown,” explains Marianne Nissen Lund.

Close collaboration with industry

Marianne Nissen Lund has a longstanding collaboration with the Danish food and ingredient industry, which already started during her master thesis, where she worked with Arla Foods to understand the chemical mechanisms of the initial reaction in precisely these Maillard reactions, which occur between proteins and sugar in food.

“When we know the mechanisms, we can control the reactions and develop new strategies for how we can avoid the reactions that are undesirable. And the close collaboration with the industry is also vital for implementing the solutions we develop in real life,” says Marianne Nissen Lund.  

After the thesis project, the business collaboration has expanded to include Novozymes, Arla Foods Ingredients, various Danish microbreweries and the Danish Meat Research Institute.

These days, sustainability is an important part of food chemistry research.

“We want to make sure that food remains fresh and healthy for as long as possible, as it can help to reduce food waste. Today, a variety of methods are used to prolong shelf life and you can have products, like the UHT-treated milk, that are microbiologically very stable, but they will always change chemically and physically if you use methods to kill bacteria, like salting, drying or harsh heat treatments. For example, if you have produced too much milk, it can be made into powdered milk, which keeps even longer than the UHT-treated milk. Again, this impacts the taste,” explains Marianne Nissen Lund.

Food chemistry is observed in molecules

As mentioned, food chemistry is about understanding the changes that foods undergo when they are processed, right down to the molecular level. Before professor Leif Skibsted established the field of food chemistry, a “cook and look” approach was used to examine what happened during food processing. In other words, you followed a recipe and observed the results. But understanding what is actually happening at the molecular level and being able to see what impact the changes are having on both food quality and health is the domain of food chemistry.

“We need the basic chemical understanding of foods when we are working with new, sustainable products. If, for example, you want to replace meat proteins with plant proteins, then the proteins in plants will behave very differently from the proteins in meat during processing. The diversity of proteins will affect the final quality of the product – for example, the texture, how the product changes during storage, as well as the nutritional value of the product,” says Marianne Nissen Lund.

New methods for characterising proteins

When you want to study the chemical reactions in a food at a molecular level and understand the underlying chemical mechanisms, you need to build model systems.

“This is typically a combination of studying individual components or a combination of components in model systems and the finished food. And then we try to relate the knowledge we obtain from the model systems to what happens in the food. The food is typically so complex that it can be difficult to get a precise understanding of what is happening at the molecular level. But you cannot only study model systems, because then you would not be able to relate the results to food quality, including, for example, how a food tastes or what the texture is like,” explains Marianne Nissen Lund, who emphasises that food chemistry research requires broad collaborations across research fields.

“At UCPH FOOD, we have really good prerequisites for collaborating broadly, as we already have many different competencies, both in chemometrics, which is an advanced form of data analysis, analytical technology, food microbiology and sensory science,” says Marianne Nissen Lund, who already has research collaborations across the entire department.

“In order to say something about how important a chemical modification in proteins is for health, you also need to know how much of this chemical modification is formed. If something is present in a very small concentration, it may not be harmful to health, while it may be harmful if, conversely, it is present in a large concentration,” explains Marianne Nissen Lund and continues:

“In the research group I lead, we have developed a wide range of analytical techniques to measure exactly how much of some very specific chemical modifications in proteins are formed during processing and storage, while the Chemometrics and Analytical Technology section is working with food analysis from a much more holistic approach. By combining the two approaches to investigate our food, we will be able to get much more information,” says Marianne Nissen Lund.

The group also collaborates with other researchers at the university, including  the Department of Biomedical Sciences, where Marianne Nissen Lund is also partly employed, and Department of Veterinary and Animal Science, with international researchers, and not least, the food and ingredient industry.

Marianne Nissen Lund will hold her inaugural lecture as Professor of food chemistry at Department of Food Science at University of Copenhagen (UCPH FOOD) on 27 September 2019. (See invitation in the box)