Olive Cultivar Remains Key to Fatty Acid Profile Despite Warming Climate

Over four decades of changing temperatures in Italy, researchers found only modest shifts in the fatty acid profile of olive oil.

A new study, published in the Journal of Food Composition and Analysis, suggests that amid climate change, the olive tree’s genotype remains a stronger determinant of that profile than temperature.

The first factor is genotype. Each cultivar starts from a certain fatty acid profile, which is then modified by climatic, agronomic and other variables.– Giovanni Spinelli, researcher and study co-author

For the study, researchers analyzed datasets and previous studies spanning 40 years, assembling information on 1,564 Italian monovarietal extra virgin olive oils produced between 1983 and 2023.

“When we first began studying the subject, we did not expect these results. Actually, we expected to find a much more significant impact on the fatty acid profile of olive oil,” Giovanni Spinelli, researcher and co-author of the study, told Olive Oil Times.

The researchers considered year of production, cultivar and geographic origin. They also linked fatty acid composition with climatic conditions during the production seasons, using Growing Degree Days (GDDs) as their main temperature indicator.

GDDs measure accumulated heat over time by adding, day by day, the amount by which average temperatures exceed a defined baseline needed for plant development. The measure estimates how much heat trees experience during a growing period.

The analysis confirmed a relationship previously observed in controlled experiments: Higher temperatures tend to be associated with lower oleic acid levels and relative increases in other fatty acids, including palmitic and linoleic acids.

Fatty acid composition develops through a series of biochemical reactions in the olive fruit, some regulated by enzymes known as desaturases. These enzymes introduce double bonds into fatty acids: One step converts stearic acid into oleic acid, while another converts oleic acid into linoleic acid.

Temperature can affect the activity and regulation of these enzymes, particularly during fruit development from pit hardening through ripening. Changes in their activity can therefore alter the balance of fatty acids eventually found in the oil.

Spinelli said these mechanisms have already been extensively investigated under controlled experimental conditions.

“Unlike most previous experiments conducted under controlled conditions, we intended to determine whether the same pattern could be detected across decades of real-world Italian production data,” Spinelli said.

However, the magnitude of the changes observed over the four decades was smaller than the researchers expected. According to the study, fatty acid proportions remained within relatively narrow ranges.

Based on the changes observed, climate-related shifts do not appear large enough to push the oils outside the parameters set by current International Olive Council standards, which include fatty acid composition among their purity criteria.

“The impact is there, and statistically it is significant, but its magnitude does not appear to be so high,” Spinelli said. “In practical terms, it is not disruptive.”

The finding was particularly relevant because one question behind the research was whether climate change could eventually push the fatty acid composition of some oils beyond existing commercial standards.

Spinelli said the researchers set out to determine whether the relationship between accumulated heat and oleic acid content was strong enough to pose a practical risk to those standards. The relationship was statistically detectable, but its magnitude was too small to threaten the thresholds during the period analyzed.

Part of the explanation may lie in the complexity of a dataset covering four decades, multiple regions and a large number of olive cultivars.

Temperature is only one of several factors acting on the tree. Water stress, the seasonal distribution of heat, temperature peaks and harvest timing may also contribute to changes in oil composition.

The year of production itself showed a stronger effect than Growing Degree Days. However, Spinelli cautioned against interpreting that “year effect” simply as climate change.

“Over forty years, many variables can change,” he said. “It is not possible to demonstrate that the effect of the year is explicitly the effect of climate change.”

That limitation reflects the trade-offs involved in analyzing such a broad dataset. Climate data were aggregated at the regional level despite substantial local variability.

Spinelli also noted that many of the monovarietal olive oils in the historical records had already undergone some selection, with samples often coming from olives harvested at an optimal stage of ripeness. Oils with unusually low oleic acid values may therefore be underrepresented.

According to the researchers, one result remains particularly clear: Cultivar is the main factor determining the fatty acid profile.

“The first factor is genotype,” Spinelli said. “Each cultivar starts from a certain fatty acid profile, which is then modified by climatic, agronomic and other variables.”

Previous controlled experiments have also shown that cultivars can respond differently to temperature changes. Spinelli cited Coratina as an example of a cultivar whose fatty acid composition can remain relatively stable across different environments, while Frantoio may show much larger changes when grown under climatic conditions very different from those of Tuscany.

The new study, however, does not rank climate-resilient cultivars.

Researchers separately examined cultivars previously identified in scientific literature as relatively stable, including Coratina, Sinopolese and Cerasuola, and compared their responses with those of other cultivars in the database.

Across the 40-year dataset, the two groups did not show a sufficiently clear difference to support such a classification.

Spinelli said the signal may have been diluted by the wide range of years, locations and environmental conditions included in the analysis.

The findings add another layer to recent research into climate change and olive oil composition.

A Slovenian study recently reported by Olive Oil Times, based on 1,643 oils, similarly associated higher temperatures with lower oleic acid levels but raised the possibility that climate-driven changes could eventually create problems for some protected designation specifications and regulatory thresholds.

Cultivar, geography, climatic conditions and the structure of the available data can all influence such results, Spinelli said.

He believes larger datasets, potentially extending beyond Italy and incorporating more countries and cultivars, could help clarify how robust the observed trends are and how much responses differ among growing regions.

Such research will require not only more data but longer time horizons.

“In olive growing research, if we want substantial results, we need both funding and time,” Spinelli concluded. “A comprehensive and broader research on such a subject would be significant.”