Currently, the processes of obtaining and producing food as well as consumption habits give rise to new challenges for food safety. The presence of heavy metals in edible vegetable oils has harmful effects for humans. In this study, the scientific literature which reports the presence of heavy metals in different types of vegetable oils was analysed. More than 25 heavy metals are evaluated in 35 different oils from 24 countries. The widely studied metals are Cd, Pb, Cu, and Fe in olive oil, sunflower oil, rapeseed oil, and corn oils, mainly in Brazil, Turkey, China, Iran, and India. Likewise, the presence of Antimony (Sb) as a product of migration from PET containers to edible vegetable oils is a topic of great interest in recent years. Additionally, the different analytical techniques used for this purpose and the standards are analysed. This study highlights the main findings and challenges in this research field.

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.

Hemicellulosic biomass from olive-tree pruning (OTPB) was used as a raw material in order to produce a hemicellulosic hydrolysate to be fermented with the non-traditional yeast Candida guilliermondii FTI 20037 to obtain ethanol and xylitol. The main objectives of this research were to study the most relevant kinetic parameters involved in the bioconversion process and the correlation between stirred-tank bioreactor and agitated Erlenmeyer flask fermentation. In a first scale-up (using Erlenmeyer flasks) incubated on a rotary shaker at 200 rpm, fermentation assays were performed to determine the most convenient process conditions and the adaptation of the microorganism to the concentrated OTPB and added nutrients culture medium. The best conditions (2.5 kg m${}^{-3}$ of initial yeast cells, pH of 5.5 and 30 ${}^{°}$C) were set in a bench bioreactor. A comparative study on ethanol and xylitol production was conducted in two scale scenarios, obtaining different results. In the bioreactor, 100% of D-glucose and partially D-xylose were consumed to produce an ethanol yield of 0.28 kg kg${}^{-1}$ and an ethanol volumetric productivity of 0.84 kg dm${}^{-3}$ h${}^{-1}$ as well as a yield and volumetric productivity in xylitol of 0.37 kg kg${}^{-1}$ and 0.26 kg dm${}^{-3}$ h${}^{-1}$, respectively. The kinetic results allowed increasing the action scale and obtaining more real results than the previous steps to enable mini-plant and industrial scaling.