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Thinking of Van Gogh’s painting ‘The Potato Eaters’, you probably don’t immediately picture a perfectly healthy family gathered around the table. The diet in the nineteenth century was monotonous and living conditions were harsh. Yet potatoes are very much an important raw material for healthy food ingredients. Avebe, a producer of potato starch and proteins, continuously innovates through the development of healthier food ingredients based on potato starch. Marc Laus, Technology Officer Product & Applications at the company, indicates that Avebe wants to make existing processes greener whilst also expanding its product portfolio of healthy starch products. ‘By changing the structure of starch, you can give it different functionalities,’ says Laus. ‘Certain starch variations become suitable as thickening or gelling agents, for instance, and provide a good texture to a food product. It can also give food properties such as resistance to moisture loss during freezing or thawing, or no loss of quality when heated.’
Certain starch variations also have a positive effect on gut health, as they digest slowly and thereby keep blood sugar levels stable. Many starch variations are currently produced using chemical reactions: cross-linking, oxidation, the addition of carboxyl groups, or the addition of side groups. Or physically, by heating the starch or applying pressure. ‘These are developments that have been ongoing since the 1960s — in short, a field that has been fully explored,’ explains Laus. ‘We believe that enzymatic processes can impart different functionalities to starch without the need for chemical processes.’ In this way, Avebe aims to develop variants that have a positive effect on health whilst simultaneously providing good texture to food products.
‘By changing the structure of starch, you can give it different functionalities’
Marc Laus
Enzymatic processes also have a smaller ecological footprint, Laus explains. ‘With enzymatic processes, there is no need to flush waste water streams. This allows us to reduce water consumption.’ Energy consumption in bio-catalysed processes is likewise lower, as these take place at room temperature and normal pressure. Avebe already produces a number of products in this way, and through this the company is able to expand its sustainable product portfolio.
The starting point of the project lies in finding the right enzymes for starch conversions. Since August, Avebe has been collaborating with UMCG and CarbExplore Research on the FIBERS project (Functional Ingredients by Enzymatic Redesign of Starch). The parties have received over €1.4 million in European funding from the Just Transition Fund to carry out the work. The first part of the project concerns the development and production of new starch variants using enzymes. This is where the expertise of CarbExplore Research comes into play. This innovative company identifies and selects specific carbohydrate-modifying enzymes.
Marcel van der Sluis, Chief Business Officer of CarbExplore Research, explains that the use of enzymes opens up a wealth of possibilities. ‘With enzymes, you look at starch in a different way. You have access to a different toolbox than with chemical conversions, which means you can also achieve different functionalities.’ This includes, for example, the digestibility of starch variants, he continues: ‘Starch consists of two biopolymers, amylose and amylopectin. Both are built from glucose monomers linked together via rapidly digestible bonds. By using glucanotransferase enzymes, you can alter the glucose bonds in starch so that it digests more slowly. This has a positive effect on health.’ The research in FIBERS also focuses on finding new structures that impart texture to food products.
The researchers’ first challenge is to find the enzyme that can carry out precisely these reactions and remains stable under process conditions. Van der Sluis: ‘It is known that glucanotransferase enzymes can modify starch structure. This class of enzymes therefore forms the starting point of the search.’ Whereas this search was once a time-consuming task, researchers today can make use of digital tools. ‘We search genome databases for specific DNA sequences of bacteria that could potentially produce this type of enzyme. This allows us to make a selection of enzymes that we wish to test experimentally for the reactions.’
‘With enzymes, you have access to a different toolbox than with chemical conversions’
Marcel van der Sluis
For several years now, modelling software such as AlphaFold has been accelerating experiments, says Van der Sluis. ‘We can use it to rapidly acquire knowledge about the three-dimensional structure of enzymes. With that, we try to understand how an enzyme works. Modelling also enables us to determine which parts of the enzymes are not required to catalyse the process. By making the enzyme smaller, we can produce it more easily.’
After an initial selection from a large number of candidate enzymes, Avebe will investigate the two or three most promising enzymes further. The company will examine their activity and selectivity, and determine which starch variations can be produced. ‘We then look at exactly what properties these variations have in terms of texture; resistance to food processing conditions such as heat, moisture, and pressure, among other things,’ Laus explains. ‘This area of biocatalysis is still largely unexplored. The functionalisation of starch using enzymes is relatively new.’ Avebe currently has two products in its portfolio that are produced using enzymes. ‘That means there is a world of possibilities.’
On the other side of the coin, the consortium will screen the starch derivatives formed for their potential positive effects on health. Paul de Vos, Professor of Immunoendocrinology at UMCG, is involved in FIBERS. ‘Research into the health effects of starch products is still in its infancy,’ he says. ‘We know that so-called retrograded starch has the same function as dietary fibre. Starch in this crystalline form adheres to the intestinal wall and leads to slower digestion.’
This effect also occurs when you allow cooked potatoes to cool, De Vos explains. ‘During cooking, the indigestible starch in raw potatoes is converted into starch that our bodies can digest. As the potatoes cool, the starch converts back to its resistant crystalline form and becomes indigestible by human enzymes in the gut. The starch consequently reaches the large intestine, where it forms an important food source for the gut flora. The gut flora use it to produce substances that are beneficial for our immune system, metabolism, and mental health.’
The old saying “you are what you eat” certainly has a scientific basis. Gut health is closely linked to mental health, De Vos explains: ‘There is an important neural pathway between the gut and the brain. In the early part of the large intestine, substances are produced that appear to have an effect on minor inflammations in the brain, which in turn influence mental health. We believe that certain starch variants may have a positive effect on this. There are a great many starch structures that are exceptionally healthy, but this remains a very poorly understood territory.’ UMCG is investigating whether the new products can genuinely have a positive effect on health. To predict this, UMCG is examining how the new starch structures interact with receptors in cell systems. De Vos notes that ‘if real health claims can be made at the end of the project, we will also conduct clinical trials.’
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