The influence of food matrix on the in vitro digestibility of wholegrain cereals and their antioxidant properties

Abstract

Wholegrain flours have drawn particular attention lately because of their potential to enhance life quality by preventing diseases linked to poor nutrition and by displaying numerous health benefits. The food matrix, which results in intricate relationships between specific chemical constituents and the food product's digestibility, is crucial to this subject. The objective of this study was to evaluate the nutritional potential of different oat and maize genotypes with varying grain colors as well as the antioxidant and digestive properties of microencapsulates obtained from blue maize. A modified in vitro multi-step digestion process comprising oral, gastric, duodenal, and colon phases was used to assess the digestibility of the investigated samples. The procedure developed by Hamzalıoğlu and Gökmen and proposed by Papillo et al. was carried out without any attempt to mimic the intricacies of gastrointestinal digestion. Oat hulls contained higher levels of total phenolic compounds and phenolic acids than flour. The majority of ferulic acid was found in the hulls and whole-grain flour. The oat hulls exhibited a greater antioxidant capacity. Conversely, the β- glucan level in the hulls was just 0.03–0.06%, whereas in the whole-grain oat flour samples it ranged from 4.07% to 5.33%. Brown whole-grain flour had the best in vitro digestibility (48.24%), followed by black (44.72%) and yellow oat flour (44.54%). Considering that the in vitro digestibility varied from 12.02% in the black genotype to 16.69% in the brown genotype, the powdered oat hulls' degradability was noticeably lower. Significant variations were found in the in vitro digestibility of all the studied maize flours. The highest digestibility was found in the flour of sweet maize hybrid (57.36%), while the lowest level was found in the flour of blue popping maize (19.67%). The pericarp was least affected by the digestive processes, while the germ showed the highest degree of degradation when it came to the digestibility of the various kernel sections. The microencapsulates had an average total free phenolic compound content of 31380 mg CE/kg. The initial raw material had an anthocyanin content of 1426 mg CGE/kg, whereas the average content in microencapsulates was 10677 mg CGE/kg. The microencapsulate digestion fluids containing 30% hydroxypropyl-β-cyclodextrin (HPCD) showed the highest anthocyanin residues (54-69%) after each in vitro phase. The microencapsulation system with 15% maltodextrin and 15% HPCD, on the other hand, demonstrated the least stability. As a result, these microencapsulates had the highest digestibility of 73.63%. The results indicate that the intricate processes of food degradation by digesting enzymes are significantly influenced by variations in chemical composition and inherent kernel structure. Nonetheless, more research on this specific topic is required in the near future.