## 3 Results and Discussion
In this form, starch becomes more accessible to digestive enzymes and rapidly undergoes the process of digestion and absorption [14]. At the same time, there is a part of starch that resists enzymatic hydrolysis, passes undigested through the small intestine, and reaches the colon, where it becomes a substrate for microbial fermentation forming short-chain fatty acids (SCFAs). This fraction is generally called resistant starch [20; 24]. From a nutritional point of view, this RS has a favorable, stabilizing effect on blood glucose levels and has potential to be a part of management and treatment programs to control type 2 diabetes [3; 20]. Among the different factors affecting starch digestibility, both internal (the amylose-to-amylopectin ratio, dietary fiber, fat, protein contents, starch-macromolecule interactions) and external ones can be specified (processing: cooking, parboiling, soaking,cooling or retrogradation) [20]. Special attention has been paid to polyphenols as secondary plants metabolites that are characterized by many bioactive properties, including, among others, the possible influence on the starch digestibility [9; 24; 25; 26]. On one hand, polyphenols may bind to starch granules, thus forming insoluble complexes that are resistant to the action of \(\alpha\)-amylase [5]. This might partly explain the increase in the amount of RS after the addition of different polyphenols to the wheat starch gels (Tables 1 and 2). However, little is known about the mechanisms by which polyphenols interact with starch, forming insoluble ligands. It has to be pointed out that the tested polyphenols were added to the starch after its pasting and gelatinization, which could limit the formation of hydrogen bonds between starch granules and polyphenols due to the fact that the starch has already been linked to the water molecules. On the other hand, it has been evidenced that polyphenols may directly act as inhibitors of \(\alpha\)-amylase and amyloglucosidase [25; 26; 27; 28]. However, their inhibitory properties strongly depend on their molecular structures (Table 3), and the differences between the resulting amounts of RS might be explained by the diverse chemical structures of the tested polyphenols. Generally, polyphenols can be classified as flavonoids and non-flavonoids [5; 29]. Within the group of flavonoids are the following sub-groups: flavones, flavonoids, isoflav, flavanones, and anthocyanins. The non-flavonoids are divided into phenolic acids, lignans, and stilbenes [5]. Flavonoids are composed of two aromatic benzene rings (A and B) and an oxygenated heterocyclic ring (C), attached to ring A. Subgroups of flavonoids differ from each other in terms of the type of ring C, the substitution pattern of hydroxyl (-OH) and methoxy (CH\({}_{3}\)) groups at positions R3, R5, R6, and R7 in the A-C ring system, as well as at positions R3\({}^{\prime}\)-R7\({}^{\prime}\) in ring B, and the position of ring B [30]. Phenolic acids differ from flavonoids in terms of their chemical structures as non-flavonoid compounds. They consist of a benzene ring connected with the carboxylic acid group and at least one hydroxyl group [27; 31]. Within the group of phenolic acids, there are two subgroups such as hydroxycinnamic acids and hydroxybenzoic acids [27].