More efficient and sustainable: how to get the most out of plants

Only one-quarter of the crops’ dry weight ends up in food for human consumption. The remaining three-quarters are used in animal feed or end up as a residue in the food processing industry. The latter, in particular, leaves room for more efficiency, as many nutrients are now wasted. In the beer brewing industry, for example, it is more efficient to extract only the parts of the barley grain that are needed. Separating the required components of the crop can be done through dry fractionation – a process that uses no water but air and electricity instead. Starch is obtained from potatoes through wet fractionation. The residues of this process are currently not used to their full potential.

Jean-Paul Vincken, a professor of Food Chemistry, leads the Sustainable Plant Fractionation project. ‘You can extract starch from a potato. The remaining juice is packed with proteins and other components. These proteins are particularly useful in the production of other foodstuffs. During processing, the components contained in the juice react to oxygen, which causes them to change’, Vincken explains. These changes negatively affect the potato protein.

Recipe for new ingredients

Two issues result from the reaction of potato residues with oxygen: brown colouration and an unpleasant flavour in the final products. ‘We are now investigating whether we can reduce the oxygen in the process, thus preventing these two reactions. Alternatively, we could slow the reactions down by processing the potato under lower temperatures’, says Vincken. He knows that the food industry is receptive to this idea, but many questions remain.

A total of eight chair groups in the domains of food sciences and biomolecular sciences collaborate to study new processing methods and products. The groups collaborate closely in pairs. The other collaborations are somewhat looser. ‘It is currently an archipelago with a few bridges, but I hope to increase the number of connections’, Vincken states.

Structure at the most detailed level

Vincken maintains intensive contact with the Physics and Physical Chemistry of Foods group. This group studies the microstructure of known and new ingredients. A critical issue is whether components such as potato protein will retain their original properties if a crop is processed by a different method.

Erik van der Linden explains that the most efficient way to obtain an ingredient depends on the material and its properties. He studies how materials are made up on a scale of 1/10 to 1/100 of a millimetre. ‘These properties affect the amount and quality of the proteins and further processing, such as brewing. Moreover, the microstructure may impact how the body digests food. Knowledge about such tiny structures, from crop to cell, is necessary.’

Digestion

How does a new processing method affect the number of fibres, vitamins and minerals? That was largely unknown. The Food Quality Design and Microbiology groups are therefore studying digestion using the SHIME model, which mimics the digestive process in the stomach, small intestine and the three parts of the large intestine.

Intestinal bacteria that are naturally present in that part of the intestines are also present in the model. Thus, researchers investigate how new ingredients are digested and how this affects our health.

Processing with limited oxygen and at low temperatures raises another question. What if the product contains dangerous substances or bacteria that were neutralised through the heat? ‘We already know which of these substances and micro-organisms occur in potatoes and barley, but not whether traces thereof remain after a more cautious processing method’, says Hans Bouwmeester, an associate professor of Toxicology. In collaboration with Heidy den Besten, a personal professor of Food Microbiology, he maps possible risks. ‘Without animal testing, but using human cells in a laboratory, data from literature and computer models to translate the findings to the human body as a whole.’

Stimulating collaboration

Vincken brings researchers from all eight groups together three times per year to share knowledge. The researchers also find their way to each other in between these moments. Van der Linden: ‘We sometimes provide others with advice. And new collaborations may develop.’ Bouwmeester adds: ‘And before you know it, new ideas for future projects pop up.’

The business sector is also involved, because it is there that ingredients are used. Vincken: ‘We are currently working with potatoes and barley, but the knowledge is relevant to process many more plant crops in a more sustainable manner.’