Olive oil industry is one of the most important industries in the world. Currently, the land devoted to olive-tree cultivation around the world is ca. 11 × 10⁶ ha, which produces more than 20 × 10⁶ t olives per year. Most of these olives are destined to the production of olive oils. The main by-products of the olive oil industry are olive-pruning debris, olive stones and different pomaces. In cultures with traditional and intensive typologies, one single ha of olive grove annually generates more than 5 t of these by-products. The disposal of these by-products in the field can led to environmental problems. Notwithstanding, these by-products (biomasses) have a huge potential as source of energy. The objective of this paper is to comprehensively review the latest advances focused on energy production from olive-pruning debris, olive stones and pomaces, including processes such as combustion, gasification and pyrolysis, and the production of biofuels such as bioethanol and biodiesel. Future research efforts required for biofuel production are also discussed. The future of the olive oil industry must move towards a greater interrelation between olive oil production, conservation of the environment and energy generation.

The leaves of the olive tree (Olea europaea L.) are one of the major solid wastes from the olive industry. Globally, the European Union is the largest producer of olive by-products, with Spain, Italy, Greece, and Portugal accounting for almost the entire production. Many questions remain to be solved concerning olive leaves (OL), including those related to possible differences in composition and/or biological activities depending on their geographical origin. In the present work, OL from Spain, Italy, Greece, and Portugal have been characterized according to their phytochemical profile, antioxidant capacity, neuroprotective activity, and anti-inflammatory effects. The Spanish and Italian OL samples presented the highest antioxidant and neuroprotective activities, while the Greek OL showed the lowest. These results were strongly associated with the content of oleoside methyl ester and p-hydroxybenzoic acid for the Spanish and Italian samples, respectively, whereas the content of decarboxymethyl elenolic acid dialdehyde form (hydrated) was negatively associated with the mentioned biological activities of the Greek samples. No country-related effect was observed in the anti-inflammatory activity of OL. Comprehensively, this work could provide a useful tool for manufacturers and R&D departments in making environmentally friendly decisions on how OL can be used to generate nutraceutical products based on the composition and origin of this by-product.

Olive pomace results from the production of olive oil. Even if olive pomace represents a potential environmental problem, it contains phenolic compounds, which are widely recognized for their beneficial properties for human health. In this study, an innovative and sustainable technological approach to extract phenolic compounds from fresh olive pomace, based on food-grade solvent instead of those usually adopted, is investigated. Characterization and shelf-life evaluation of the hydroalcoholic extracts obtained from the procedure developed for different industrial purposes were also carried out. The phenolic fractions of the different samples were studied with the Folin–Ciocâlteu method to quantify that the total reducing molecules and HPLC-MS/MS analysis was used to define the profile through the identification and quantification of 42 compounds, belonging to five chemical families. Regarding shelf-life, the hydroalcoholic extract showed no significant reduction in phenolic content, for both instrumental evaluations, retaining most of the phenolic compounds present in the raw material; negative attributes were not perceived by sensory evaluation. Thus, these lab-scale results can be the starting point to develop a procedure that is suitable for a real olive mill, representing a valorization strategy in a circular economy and the perspective of new business models.