## 4 Discussion  
Results of other studies that were conducted with the aim of creating protein/polyphenol enriched matrices proved that that type of protein matrix as well as the polyphenol source has a great impact on the adsorption of these valuable bioactives on the selected carrier. Additionally, the concentrations of the initial ingredients and the conditions during the formulation of such matrices was of great importance. Through the study on the formulation of delivery systems of raspberry phenolics based on brown rice protein matrix, it was concluded that, with a increase in the amount of protein matrix during the formulation of protein aggregates, a decrease in adsorption capacity occurred [16; 17; 18; 20]. Our results were in accordance with those results. However, in this case, a higher decrease in adsorption capacity with an increase in protein matrix was observed for total phenolic compounds and anthocyanins. The importance of the protein source and the amount of proteins in this source have been proven in the study of the binding of cranberry polyphenols on defatted soy flour (50% of proteins), soy protein isolate (70% of proteins), hempe protein isolate (70% of proteins), medium-roast peanut flour (50% of proteins) and pea protein isolate (85% of proteins) [16]. The highest adsorption of total phenolic of cranberries was determined for hempe protein isolate, and the lowest for soy protein isolate, while for anthocyanins the highest adsorption was observed on defatted soy flour and the lowest, again for soy protein isolate [16]. In the study of the adsorption of blueberry polyphenols on defatted soybean flour in combination with white whole wheat, brown rice or corn flours, it was concluded that proteins and other insoluble components of used plant flours were included in the overall adsorption of blueberry polyphenols. More precisely, it was concluded that the protein content of the utilized flours was not linearly related with the binding efficiency for blueberry anthocyanins [18], which is in accordance with the results of this study. Therefore, the authors conclude that, in their case, carbohydrates (the major components of flours) were also involved in the overall adsorption of phenolics. Additionally, when they individually tested the mentioned carriers, they determined that defatted soy flour, with the highest content of proteins, had the highest adsorption capacity of blueberry anthocyanins, followed by wheat, rice and corn flours [18]. For our protein aggregates, it can be concluded that, through the complexation of protein matrix and tart cherry juice, when a higher amount of protein matrix was used, additional interactions (hydrogen bonding and/or hydrophobic interactions) between protein chains occurred. In this way, the number of binding sites on proteins for polyphenols decreased. On the other hand, tart cherry juice contained flavor compounds that also bonded on protein  
Figure 3: IR spectra of protein matrix (Cas) and formulated aggregate (Cas\(\_\)TC). molecules, additionally diminishing the number of free binding sites on proteins. Generally, the reactivity of phenolics depends on the number of hydroxyl groups, but it also depends on their position, so this is also valid for interactions between phenolics and proteins and, additionally, the protein fraction--i.e., the free binding sites on them is very important [39; 40; 41]. Interactions of both a covalent and non-covalent nature are important between phenolics and proteins [42; 43]. Considering non-covalent binding between phenolics and protein hydrophobic association, hydrogen bonds, electrostatic attraction and van der Waals forces can be involved. However, hydrophobic interaction and the formation of hydrogen bonds were considered the most relevant non-covalent interactions for the complexation of phenolics with proteins [44]. In most cases, possible additional adsorption of flavor compounds next to phenolics is neglected.