**4. Conclusions**

To improve food and environmental safety, it is important to properly manage agrifood waste so that it can be reintegrated into the existing bioeconomy [15]. The production of bio-waste, including apple pomace (AP), is expected to increase every year. Therefore, it is necessary to develop safe and effective methods for the processing and disposal of AP in accordance with the idea of sustainable development. The research results will allow for the acquisition of new knowledge as well as new bio-materials and technological solutions that could have a big economic impact in the future. Some of them are currently in use, e.g., green extraction techniques for the recovery of active substances from AP in an environmentally friendly manner, i.e., by lowering the energy consumption and reducing the amounts of harmful chemicals. Active compounds extracted from AP (including benzoic and cinnamic acid derivatives) can further replace the widespread synthetic chemicals and reduce the amounts of generated waste, e.g., they can be used as non-toxic, readily available and biodegradable anticorrosion agents or wood protectors in different industrial sectors. Through various processes (e.g., fermentation, anaerobic digestion and pyrolysis), AP can be transformed into fuels and/or fuel intermediates in solid (e.g., biochar-based hard carbon that can be used in Na-ion battery production), liquid (e.g., bioethanol, biodiesel, pyrolysis oil, etc.) and gaseous (e.g., biogas/biomethane, etc.) forms. Such transformations of apple waste into environmentally friendly energy and materials can not only reduce the consumption of conventional fossil feedstocks but also reduce the amount of GHGs emitted into the atmosphere. Finally, the AP can be considered as an environmentally safe biopolymer that can be applied as an innovative additive, e.g., in the production of structural or building elements or packaging materials in many other industries.

**Author Contributions:** Conceptualization M.K.; Visualization, E.G.; methodology, E.G., M.K. and G.Y.; Formal analysis E.G., M.K. and G.Y.; Writing—original draft preparation, E.G.; Writing—review and editing, M.K. and G.Y.; Funding acquisition, M.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** The source of funding for the study was the Polish Ministry of Higher Education and Science nr WZ/WB-IIS/5/2020. ´

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

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

#### **References**

