**4. Conclusions**

The results of this study have shown that, when conducted at an appropriate temperature, storage time of olive fruits can be prolonged to seven days without compromising the crucial aspects of olive oil quality. Although prolonged storage at room temperature increased the oil extractability index, this treatment exhibited many serious drawbacks, such as the elevated concentrations of fatty acid ethyl esters and waxes, loss of a certain proportion of valuable phenolic compounds and the occurrence of sensory defects in the obtained oil, most probably due to fermentative processes induced by accelerated post-harvest fruit ripening. Prolonged storage at the freezing temperature of −20 ◦C also resulted in significant alterations in the composition and quality of the obtained oil, including a decrease in the concentration of phenols and generation of the "frostbitten olives" sensory defect, presumably induced by freezing injuries and modified enzymatic activity in the fruits. The treatment that included prolonged refrigeration of fruits at +4 ◦C proved to be the most suitable for this purpose, since it preserved the composition and sensory quality most similar to that of the fresh oil of the control treatment, which corresponded to the highest quality category, extra virgin olive oil. The results obtained point to the need to improve olive fruit post-harvest storage technical capabilities and conditions, in order to prevent losses in olive and olive oil quality and value in situations when the harvested amount of fruit exceeds the processing capacity of available mills.

**Author Contributions:** Conceptualization, K.B.B.; methodology, K.B.B.; formal analysis, K.B.B., I.L., A.N., M.L., M.K.; resources, K.B.B. and I.L.; data curation, K.B.B., M.L., I.L.; writing—original draft preparation, K.B.B.; writing—review and editing, K.B.B., I.L., M.L.; visualization, K.B.B. and M.K.; supervision, K.B.B.; project administration, I.L. and K.B.B.; funding acquisition, I.L. and K.B.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Croatian Science Foundation (grant numbers: UIP-2014-09-1194 and DOK-2018-01-4693) and by the European Union from the European Social Fund (grant number: DOK-2018-01-4693).

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
