Physicochemical Changes During Ripening of Moroccan Picholine Olives Under Irrigated Conditions: Guiding Optimal Harvest Timing for High-Quality Oil

Olive oil quality is highly influenced by cultivar type, agronomic practices, and harvest timing. This study investigates the evolution of key physicochemical parameters; fruit weight, pulp/pit ratio, moisture content, oil yield, and total polyphenol concentration, of the Moroccan Picholine cultivar throughout the 2018/2019 harvest season in the Meknès region under irrigated conditions. Nine sampling dates were assessed from early November to early February to monitor changes during ripening. Results showed a consistent increase in fruit and pulp weights, with the pulp/pit ratio peaking mid-December. The maturity index (MI) progressed from 1.4 to 4.9, showing strong positive correlations with fruit weight (r = 0.9313) and pulp weight (r = 0.9486). Moisture content decreased progressively with ripening (R2 = 0.9852), while oil content increased linearly, reaching 23.0% at full maturity (R2 = 0.9157). Total polyphenols displayed a curved progression, peaking at 2127 ppm in early January (MI = 4.3), and then gradually decreasing. These findings suggest that the semi-ripe stage (early January) represents the optimal harvest period for balancing oil yield and antioxidant quality. This work provides practical insights to guide harvesting strategies and improve the nutritional and sensory quality of Moroccan Picholine olive oil.