Effectiveness of post-harvest treatments for Manzanilla table olives and the suitability of Hojiblanca as a substitute for mechanical harvesting

Table olives are traditionally harvested manually, however, with the increasing labor cost, there is an urgent need to develop mechanical harvesting options for this product. The current study investigated the effectiveness of post-harvest field treatments (PHFT) in reducing bruising in Manzanilla olives, alongside evaluating additional cultivars as potential substitutes in commercial table olive production. Over three seasons, Manzanilla olives were treated immediately after harvest with a diluted NaOH solution or other chemicals, while bruising incidence and sensorial impact were assessed following Spanish-style fermentation. The results demonstrated that only the 1 % NaOH field treatment among compounds studied, effectively reduced bruising across multiple seasons without altering the sensorial characteristics of Manzanilla olives, as confirmed by a triangle testing method. No significant differences in bruising levels of fermented olives were observed between day (30 °C) and night (20 °C) harvesting (p < 0.05), suggesting that temperature variations did not significantly affect the olive quality. Hojiblanca and Picual olives were more robust during mechanical harvesting with a trunk shaker or electrical comb, however, using an overhead harvester severely damaged even the relatively resistant cultivars. Sensory evaluation through a paired-comparison test and ranking tests indicated no significant preference difference between Hojiblanca and Manzanilla (p < 0.05), supporting Hojiblanca's potential as a substitute for Manzanilla in table olive production. This study highlights the importance of PHFT and cultivar selection in optimizing quality and consumer satisfaction in mechanically harvested table olive production.