Phenolic and Fatty Acid Changes in ‘Leccino’ Olives ( Olea europaea L.) Under Different Postharvest Conditions

This study investigates the changes in mechanically harvested ‘Leccino’ olives stored under cold and room-temperature conditions from harvest up to 23 days of storage during two consecutive seasons. Variations in quality parameters, including maturity index, weight, firmness, and colour, were monitored throughout the storage period. In addition, the phenolic profile of the olives was analysed using HPLC, and the fatty acid composition was determined by GC–MS. These analyses enabled a comparison of changes across different storage durations, seasons, and storage conditions. Results show that fruit ripeness at harvest differed notably between the two seasons. In the second season, the olives displayed a higher maturity index, lower firmness, and lower content of certain individual phenolic compounds, indicating a more advanced stage of ripening compared to that of the previous year. These initial differences strongly influenced the subsequent development of fruit quality and biochemical characteristics during storage. Storage temperature had a significant effect on the quality parameters and metabolism. As expected, olives stored at room temperature lost their firmness and weight more quickly than those stored under cold conditions. The most abundant phenolic in olive fruit, oleuropein, degraded more rapidly at room temperature, resulting in a quicker accumulation of its derivatives. Fatty acids were more stable than phenolic compounds during storage, likely due to their lower susceptibility to enzymatic degradation and oxidative reactions under the tested conditions. While saturated fatty acids remained largely unchanged, a slight increase in unsaturated fatty acids was observed after 23 days of cold storage, possibly as a result of adaptations of the membrane to cold storage conditions.