**4. Conclusions**

This study applied LCA to measure the circularity of a food waste system—in this case, refining oil from olive kernel. The damages of 1 kg of oil production from olive kernel to GWP, human health, ecosystem quality, and resource depletion were 1.37 kg CO2eq, 5.29 × <sup>10</sup>−<sup>7</sup> DALY, 1.21 × <sup>10</sup>−<sup>2</sup> PDF·m2·yr., and 24.40 MJ, respectively. The results highlighted that the studied system is relatively circular, resulting in low environmental impacts. Olive processing systems could be made more circular through food waste valorization. By managing the consumption of energy sources, such as natural gas, olive kernel oil production systems can become environmentally efficient. In this regard, further research is needed to determine the optimum temperature of olive kernel dough in the decanter, as well as the optimum temperature for warm water when added to the separator in the process of oil extraction from olive kernel. Further research is also required to explore the human health and microbiological risks of the oil produced from olive kernels, which were not considered in this study.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2304-815 8/10/3/590/s1, Supplementary 1.

**Author Contributions:** A.N. developed the initial concept of the research and contributed to the analysis and writing of the first draft of the manuscript. S.F. contributed to data collection and manuscript writing and editing. K.D. contributed to data collection and technical support. S.V.H. contributed to the concept, supervision, and editing of the article. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Ghent University Global Campus.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The inventory of the industrial-based olive kernel oil production system is provided in the paper. In addition, the inventory of emissions for refining one kilogram oil from olive kernel is also provided as Supplementary 1.

**Acknowledgments:** The authors would like to acknowledge the support provided by the Ghent University Global Campus.

**Conflicts of Interest:** The authors declare that they have no conflicts of interest.

#### **Appendix A**

**Table 1.** Datasets applied for calculation of emissions from off-site operations.


**Table 2.** Coefficients for calculation of emissions from natural gas combustion (gram).


#### **References**

