Enzymatically induced protein-AX networks in gf systems

The production of gluten-free doughs and breads is still a technological challenge. Despite the use of many additives, the quality of gluten-free baked goods is still lower than comparable products made from wheat, barley and rye. HPMC (hydroxypropylmethyl cellulose E 464) is often used as a binder to create more cohesion in the gluten-free dough. There is great potential for further optimization in gluten-free cereals such as corn and oats, in which structuring ingredients such as proteins and special dietary fibers, so-called arabinoxylans, can be used to stabilize doughs. By using enzymes, the proteins and arabinoxylans can be cross-linked to form a network, which stabilizes the dough. This leads to doughs with improved properties such as elasticity and gas holding capacity. In this project, a new approach will be realized by using a network of proteins and arabinoxylans for gluten-free baked goods. First, oat and maize varieties are examined for their protein and dietary fiber content, and their cross-linking quality is also assessed. The focus is on the amino acid tyrosine in the protein and the content of ferulic acid in the arabinoxylans. In addition, various enzymes are being examined to determine how well proteins and arabinoxylans are linked together. Modern analytical methods are used for this task. Selected varieties are then used to obtain enriched fractions of these structural components through grinding and extraction. These are then cross-linked in model dough systems by special enzymes, resulting in structures similar to the gluten network. These novel networks of protein and arabinoxylan have the potential to improve the dough properties of gluten-free baked goods and can therefore make a significant contribution to improving product quality.

Glutenfree cereal products are of increasing importance for people with coeliac disease as well as for consumers who choose glutenfree diets for lifestyle or health reasons. However, compared with wheatbased products, glutenfree foods often show inferior volume, texture, elasticity, and structural stability. The PROTAX project aimed to address these limitations by developing new, sciencebased strategies to improve the quality of glutenfree cereal systems using natural ingredients. The project focused on proteins and arabinoxylans, two naturally occurring biopolymers found in glutenfree cereals such as rice, maize, and oats. In a first step, suitable raw materials were identified and enriched using tailored dry and wet fractionation techniques. The results demonstrated that protein and fibrerich fractions can be produced while mainly preserving their functional properties, highlighting the importance of carefully designed processing strategies for glutenfree ingredients. A major achievement of PROTAX was the systematic investigation of enzymatic network formation between proteins and arabinoxylans. In particular, the combination of glucose oxidase and peroxidase proved highly effective, enabling controlled crosslinking reactions under mild conditions. These enzymeinduced networks significantly enhanced elasticity, structural stability, and gas retention in glutenfree model doughs. The effects were especially pronounced in ricebased systems, which are highly relevant for glutenfree baking. Beyond covalent crosslinking, the project revealed that noncovalent interactions also play a key role in stabilizing glutenfree batters and doughs. The balance between protein content, arabinoxylan concentration, and water availability was identified as a critical factor. Proteins primarily contributed to improved elasticity and interfacial stability, while arabinoxylans supported volume development. However, excessive arabinoxylan levels were shown to weaken the structure, underlining the need for carefully optimized formulations. To support these findings, PROTAX applied advanced analytical techniques, rheological testing, and mathematical modelling to describe structure-function relationships in increasing levels of complexity. These approaches provided a deeper understanding of how enzymatically induced protein-arabinoxylan networks form and how they influence the behavior of glutenfree systems. Overall, the PROTAX project delivers both fundamental scientific insights and practical concepts for improving glutenfree cereal products. The results offer a strong foundation for the development of more stable, higherquality, and more attractive glutenfree foods, using natural raw materials and biotechnology, and contribute to future innovation in cereal science and food processing.