Box–Behnken Design to Maximize Extraction and Minority Compound Content of Picual Variety Olive Oils

Abstract This work analysed the combined influence of fruit ripeness and key technological variables—malaxation time, talc dosage, and crusher grid size—on different responses of extra virgin olive oil (EVOO) obtained from Picual olives. Box-Behnken experimental designs were used for four maturity indices (MI 1.8 to 4.7), enabling the assessment of both main effects and interactions among factors. The results revealed consistent group-level trends: extraction efficiency increased with ripeness; phenolic content and antioxidant capacity peaked at intermediate ripening stages; and volatile compounds were most abundant at early maturity, optimising under short malaxation times for the last group. Significant interactions were observed between crusher grid size and malaxation time for the phenolic content, revealing that the optimal extraction strategy depends on a balance between mechanical rupture and enzymatic exposure. At higher MI, gentle crushing combined with short malaxation helps preserve them, whereas at early maturity, more intense crushing and longer malaxation favour maximal phenolic release. A key novelty of this work lies in the identification of compounds exhibiting behaviour that deviates from the general group trends. For instance, oleocanthal reached its maximum concentration at an early stage of maturity and under longer malaxation times. These compound-specific responses, together with statistically significant interactions among factors, underscore the utility of factorial experimental designs in uncovering complex response patterns. This approach offers valuable insights for optimizing EVOO production to enhance both nutritional and sensory quality attributes.