Summary: Previous studies have shown that polyphenolic compounds have various bioactivities: from antioxidant activity to the modulation of enzymes, the action of polyphenol metabolites, interaction with the microflora, and interactions with macromolecules present in food. All of these bioactivities can together explain a potentially positive effect of polyphenols on health. Lately, attention is paid to interactions with macromolecules in food because they can affect the bioaccessibility of polyphenols. Bioaccessibility is defined as the amount of nutrients available for absorption in the gastrointestinal tract. If polyphenols through interaction with molecules from food are “captured” (linked), that can affect their availability for absorption and their effects in the body. Dietary fibers have the potential to bind polyphenols. Polyphenols can thus be protected from degradation and transferred to the lower parts of intestinal tract. This may affect the bioaccessibility, or have other potentially positive effects – polyphenols may in their original form show positive bioactivities in the lower digestive tract.

Project aim: In this project, the goal is to explore the bioaccessibility of polyphenols through two processes:

• The first will be to study the adsorption of polyphenols onto dietary fiber (ß-glucan), along with the impact of pH, temperature and time on this process. The interactions that can occur between polyphenols and dietary fibers will be interpreted through the interpretation of the adsorption process.
• Another process that will be studied is the simulated digestion process, in vitro. By studying this process, the amount of polyphenols (in fruit) in its original form upon digestion, and the effect of dietary fiber on this process will be explored.
• The results from the adsorption and simulated digestive processes will be used to interpret bioaccessibility of polyphenols and the impact of dietary fiber on bioaccessibility.