Is climate change messing with our olive oil?

When Cyclone Gabrielle swept across Aotearoa in early 2023, it had a devasting effect on crops around the country. Its arrival signalled a shift to an era where extreme weather events are becoming increasingly normal. Case in point: in March of this year, the government declared an official drought for the Greater Wellington, Manawatu-Wanganui, Taranaki and Northland regions. More recently, in June, residents of Wairoa, Hawke’s Bay, entered a State of Emergency after severe flooding struck their small coastal town.

Cyclone Gabrielle got Dr Danaé Larsen thinking. The food scientist and senior lecturer at the University of Auckland’s School of Chemical Sciences wondered: just how is the changing climate impacting the chemical and sensory qualities of certain foods? 

Danaé’s interest in science and food began as a child, experimenting in the kitchen. “It was scientific curiosity and a love of food,” she remembers. “I just put two and two together.” With a background that includes a PhD examining lipids in New Zealand king salmon, and co-founding Swiss-based start-up HPP Schweiz, which provides high-pressure processing for food preservation, she is now group leader of the University’s Larsen Lab.

Since 2022, she and a team of postgraduate students have been focused on sensory science, which she describes as “understanding how our brains perceive food in different ways and how we can manipulate properties in food to create new sensations for enjoyment and nutritional benefit”. They have studied the aroma compounds of food pairings, how smell impacts taste, the link between food texture and satiation, and now, the effect of climate change on the taste and chemical composition of olive oil.

“The olive harvest happens, depending on the region in New Zealand, from March, April, through to June, July,” Danaé explains. “In 2023, when the olives were already on the trees, we had a very wet summer in the North Island, including Cyclone Gabrielle, while the South Island was pretty dry. I wondered if there would be a noticeable difference between the olive oil produced in the South Island versus the North Island.” 

She is the inaugural recipient of the Edwards Olive Oil Research Fund, an endowed gift from international olive oil judge and former olive oil producer Margaret Edwards. The support has made the study possible, she says. “If I had not received this research fund, I would not have done this project. It’s as simple as that. Philanthropy is really crucial.” She hopes her research will result in findings that are meaningful to the olive oil industry and the wider scientific community.

To start, she and her team studied historical weather data. This helped them to build a picture of how rainfall, sunshine hours, air and soil temperature have behaved over time, which they can use to identify trends as the project progresses. They then analysed single-variety olive oil from the 2023 harvest taken from different areas around the country. Regions ranged from Northland, South Auckland, Waiheke Island and Wairarapa in the North Island to Nelson and Central Otago in the South Island. 

In the lab, they chemically mapped the olive oil’s lipid and polyphenol profiles. The latter is particularly important when it comes to flavours in olive oil, she says. “Polyphenols are compounds that can directly relate to taste. The characteristic bitter or pungent taste of some olives, the green, leafy taste of olive oil; these things are thought to be affected by rainfall. If there’s excessive rain, there are generally far fewer polyphenols in the fruit.” In theory, fewer polyphenols of particular types should equate to olive oil with a less bitter and green, or different, flavour altogether.

So, what do the project’s early results reveal? Although still in its infancy, preliminary findings show that the polyphenol profile of single-variety olive oil from the 2023 harvest does differ between regions, in particular, between those where rainfall and sunlight hours differed the most. 

The team has also identified differences in the olive oil’s fatty acid content and will next examine why this might be. In 2025, they will continue to investigate olive oil’s sensory properties to determine whether the changes they have detected translate into different flavour profiles. To do this, they will use sensory panels and, for the first time in New Zealand, an electronic tongue. 

It's an exciting start, says Danaé, who hopes their work will eventually help to future-proof the local olive oil industry. “This is really important because as climate change unfolds, there will probably be some areas of New Zealand that historically have grown olives that may not be as suitable anymore,” she explains. By establishing general trends in weather and the climate’s impact on olive oil quality, they aim to indicate what might happen to the chemical and sensory properties of olive oil as time goes on, so that growers can adapt.

There’s also potential to elevate New Zealand’s olive oil further on an international level. If scientific evidence can provide growers with information that enables them to enhance their product’s composition and sensory properties, they could garner recognition on the world stage, much like the wine industry. “We have so many growers now,” Danaé says. “We want to show them that, if you do each process the right way; if when you grow and mill the olives you really look after them, from the tree all the way through to the olive oil, you’re going to end up with a premium product. It can be up there with Sauvignon Blanc from Marlborough.”