**5. Conclusions**

In few previous studies, maltodextrin and whey protein have been used for the encapsulation of OMWW polyphenolic extracts [21–24]. However, in the present study, there was for the first time a direct comparison between the two materials for their e fficiency for the production of antioxidant powder. The results showed that both maltodextrin and whey protein were almost equally e ffective for the production of antioxidant powder, although in slightly di fferent encapsulation conditions. For example, the findings indicated that, in general, inlet/outlet temperature did not a ffect maltodextrin samples' antioxidant activity, but whey protein samples exhibited better antioxidant activity at lower temperatures (within the temperature range used; 100–160 ◦C). Gelatin was also first used in the mixture for OMWW extract's encapsulation, but the results showed that it decreased antioxidant activity, especially in whey protein samples. Furthermore, the present study is the first demonstrating that encapsulated OMWW extract protected from ROS-induced DNA damage. Finally, it is the first time, that an encapsulated OMWW extract (as well as in general an OMWW extract) has been shown to enhance antioxidant mechanisms (i.e., GSH) in endothelial cells. Of course, further studies are needed for the elucidation of mechanisms accounting for these possible beneficial e ffects.

**Author Contributions:** Conceptualization, D.S., K.P., and D.K.; methodology, D.S., K.P., and D.K.; supervision, D.S., K.P., and D.K.; carried out the experiments, K.K, Z.F., K.Z., E.K., C.M., P.G., and D.L.; writing, K.K., D.S., and A.S.V.; funding acquisition, D.S., K.P., and D.K.; resources, D.S., K.P., and D.K.

**Funding:** The work was funded in part by the "Biotechnology—Nutrition and Environment" and "Application of Molecular Biology—Genetics" MSc programs in the Department of Biochemistry and Biotechnology at the University of Thessaly.

**Conflicts of Interest:** The authors declare no conflict of interest.
