**4. Conclusions**

Consumers' interest in meat products formulated with natural preservatives has motivated researchers to evaluate the effectiveness and applicability of naturally occurring compounds with antioxidant and antimicrobial purposes. This study has proved that olive mill wastewater extracts are characterized by a phenolic profile and are able to significantly improve the oxidative and microbial stability of beef burger during cold storage.

Therefore, it was concluded that olive mill wastewater extracts could be successfully added to raw ground beef meat to act as natural antioxidants and antimicrobials with added health, environmental and economic benefits as well as increased consumer appeal. **Author Contributions:** Conceptualization, R.B., S.E. and R.R.; methodology, S.E. and R.B.; validation, S.E.; formal analysis, R.R., S.P. and A.T.; investigation, R.R., A.V. and B.S.; resources, A.V. and M.S.; data curation, R.R. and R.B.; writing—original draft preparation, R.R.; writing—review and editing, D.R., R.B. and S.P.; visualization, B.S.; supervision, R.B., S.E. and M.S.; project administration, M.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This paper is part of the research project (PSR GO-Nuovi alimenti—PSR "Dalla tradizione Umbra nuovi alimenti di origine animale ricchi in molecole bioattive per migliori caratteristiche di sicurezza e qualità salutistica" Programma di Sviluppo Rurale per l'Umbria 2014–2020—Misura 16—Sottomisura 16.1) funded by the European Commision, through the Umbrian Region (Italy), to develop rural agriculture and animal production in the member states.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The datasets generated for this study are available on request from the corresponding author.

**Acknowledgments:** The authors would like to thank Fattoria Luchetti and Clarita Cavallucci for their collaboration in the research activities. The study has been developed in the context of the project: Study of "green" strategies to ensure the hygiene and safety of prepared and processed foods of animal origin.

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