The slow, controlled mixing of the crushed olives during the milling process – the malaxation phase – might have a larger role in determining olive oil’s phenolic profile than previously thought.
New research published in Food Chemistry compiled years of studies on how malaxation temperature, time, oxygen exposure, and the addition of water impact the content and profile of polar phenolic compounds, especially secoiridoids, a subclass of phenols.
“These are the most representative phenolic class in olive oil, and they’re the ones most transformed during malaxation,” Ítala Marx, a postdoctoral researcher at the University of Córdoba and co-author of the research, told Olive Oil Times.
During malaxation, larger precursor molecules, such as oleuropein and ligstroside, naturally produced by the fruits, are converted – biotransformed – by enzymes.
Those convey smaller, highly bioactive compounds such as oleocanthal and oleacein, which are linked to olive oil’s pungency, bitterness and antioxidant power.
Decades of research have shown that daily consumption of olive oil rich in phenols produces significant health benefits.
Furthermore, the complete phenolic profile of extra virgin olive oil is deeply intertwined with its aromas and flavors.
“Phenolics are responsible for bitterness and pungency. So if you increase them, you naturally improve sensory complexity,” Marx said. “The consumer wants that ‘green’ flavor, that bitterness. These are linked to the phenolic profile.”
“That’s why we focused on secoiridoids,” she explained.“They’re at the core of both the sensory experience and the health-related value of extra virgin olive oil.”
“I started this work during my PhD,” Marx added. “My program was completely developed in industrial olive oil mills. All campaigns, from 2019 to 2022, were focused on how to optimize extraction to improve oil’s phenolic content, and malaxation was the core of my research.”
The review paper focused on how the enzymatic biotransformation happens during malaxation and how sensitive the process is to malaxation conditions.
“Everything depends on the olive cultivar. You can’t apply the same temperature and time and expect the same result from different olives,” Marx remarked.
The influence of cultivar, or genotype, is perhaps the strongest variable. “Genotype is the main factor that impacts olive oil’s phenolic composition,” Marx said. More