Maximizing Antioxidant Potential in Picual Virgin Olive Oil: Tailoring Agronomic and Technological Factors with Response Surface Methodology.

Over the past years, a prolonged drought has affected Spain, raising significant concerns across various sectors, especially agriculture. This extended period of dry weather is profoundly affecting the growth and development of olive trees, potentially impacting the quality and quantity of olive oil produced. This study aims to assess the impact of agronomic factors, i.e., olive maturation and irrigation management, as well as the technological factors involved in the production process, on the antioxidant content of Picual virgin olive oil. Mathematical models were developed to maximize the concentration of polyphenols, orthodiphenols, chlorophylls, carotenes, and tocopherols in olive oils. Findings indicate that increasing the malaxation temperature from 20 to 60 °C and reducing the mixing time from 60 to 20 min positively influenced the polyphenol and orthodiphenol content. Although irrigation did not significantly affect the polyphenols, pigments, and α-tocopherol contents, it may enhance the ß- and γ-tocopherol content. Optimal conditions for producing antioxidant-enriched virgin olive oils involved olives from rainfed crops, with a moisture index of 3-4, and a 60-min malaxation process at 60 °C. Under these conditions, the total phenol content doubled, pigment content increased fourfold, and α-tocopherol content rose by 15%. These findings provide relevant knowledge to interpret the year-to-year variation in both organoleptic and analytical profiles of virgin olive oils.

Fresh and Aromatic Virgin Olive Oil Obtained from Arbequina, Koroneiki, and Arbosana Cultivars.

Three factors for the extraction of extra virgin olive oil (EVOO) were evaluated: diameter of the grid holes of the hammer-crusher, malaxation temperature, and malaxation time. A Box-Behnken design was used to obtain a total of 289 olive oil samples. Twelve responses were analyzed and 204 mathematical models were obtained. Olives from super-intensive rainfed or irrigated crops of the Arbequina, Koroneiki, and Arbosana cultivars at different stages of ripening were used. Malaxation temperature was found to be the factor with the most influence on the total content of lipoxygenase pathway volatile compounds; as the temperature increased, the content of volatile compounds decreased. On the contrary, pigments increased when the malaxation temperature was increased. EVOO from irrigated crops and from the Arbequina cultivar had the highest content of volatile compounds. Olive samples with a lower ripening degree, from the Koroneiki cultivar and from rainfed crops, had the highest content of pigments.

Extraction of oleuropein and luteolin-7-O-glucoside from olive leaves: Optimization of technique and operating conditions.

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Valorisation of olive agro-industrial by-products as a source of bioactive compounds.

A large amount of olive-derived biomass is generated yearly in Spain, which could be used as a potential source of bioactive compounds. The present work evaluates the recovery of natural antioxidants from olive tree pruning (OTP) and olive mill leaves (OML). For this purpose, the effect of different solvents on the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity was evaluated. The solvent was found to have a significant effect (p < 0.05) on the TPC, TFC, and the DPPH, ABTS, and FRAP activity, affording similar results for the extracts from the two by-products. The extracts obtained using 50% ethanol showed high TPC (23.85 and 27.54 mg GAE/gdw for OTP and OML, respectively) and TFC (52.82 and 52.39 mg RE/gdw for OTP and OML, respectively). Also, the OTP and OML extracts exhibited notable antioxidant activity as measured by the ABTS method (45.96 and 42.71 mg TE/gdw, respectively). Using pyrolysis-gas chromatography/mass spectrometry, 30 bioactive compounds were detected in both extracts. Additionally, UPLC-DAD-ESI-MS allowed the identification of 15 compounds in the samples. Furthermore, the antioxidant extracts were found to inhibit the growth of several food pathogenic bacteria. This research demonstrates that these by-products from olive grove farming are a good source of antioxidant compounds with antibacterial properties, which have potential applications in the food and pharmaceutical industries.