Search "high polyphenol olive oil" in Australia and you'll get the same article roughly a dozen times over. Polyphenols are good for you, look for a number above 250mg/kg, buy early harvest, store it in a dark bottle. All true, and all fairly shallow.
Nobody's asking the more interesting questions: is every ppm number actually measured the same way, does a higher number always mean a better oil once it reaches your kitchen, and does the volcanic soil story actually hold up?
We make FORTE 659, a Reserve Champion and Victoria's Best EVOO at the 2025 Australian International Olive Awards, so we've got a fair bit of skin in this game. Here's the more honest version of the high polyphenol conversation.
What "High Polyphenol" Actually Means
Quick baseline, since it matters for everything after it. Polyphenols are the natural antioxidant compounds in olives, mainly hydroxytyrosol, tyrosol, oleocanthal and oleacein, that give a fresh EVOO its bitterness, its peppery throat catch, and most of the health claims attached to it.
The EU EFSA threshold for an oil to legally carry a polyphenol health claim sits at 250 mg/kg. Everyday supermarket olive oil usually sits well under that, often closer to 100-150 mg/kg. Anything meaningfully above 250 mg/kg is generally what the industry calls "high polyphenol."
For a full breakdown of where our range sits, our high polyphenol EVOO page has the lab numbers for FORTE 659 and the Mt Moriac Range. What follows here is the part most guides skip.
Not Every Polyphenol Number Is Measured the Same Way
This is the one almost nobody talks about, and it matters more than most of the marketing built around it. Polyphenol content can be tested through a few different methods, and they are not interchangeable:
- HPLC (High-Performance Liquid Chromatography) and LC-MS/MS are the two methods recognised by the International Olive Council as accredited for polyphenol quantification, under method COI/T.20/Doc No 29. LC-MS/MS is the more precise of the two, capable of identifying and measuring individual compounds like oleocanthal and hydroxytyrosol separately. A peer-reviewed HPLC method study developed specifically to support the EFSA health claim confirms this is the benchmark method producers rely on.
- NIR (Near-Infrared Spectrophotometry) is faster and cheaper, and plenty of Australian producers use it. It's a legitimate screening tool, but it isn't an IOC-accredited method for polyphenol claims, and it's more prone to producing inflated readings than HPLC or LC-MS/MS.
- qNMR and a few other methods circulate in the market too, and are also not IOC-accredited.
None of this means an oil tested via NIR is necessarily a bad oil. But it does mean two producers can both print a "high polyphenol" number on the label, using entirely different levels of analytical rigour, and the numbers still aren't telling you the same thing. FORTE 659's 659 mg/kg figure comes from HPLC testing at Modern Olives Laboratory, a NATA-accredited facility, which is closer to the gold standard end of that spectrum. When you're comparing polyphenol numbers between brands, it's worth asking which method produced them before assuming the bigger number wins.
Fresher Often Beats Higher
The Australian market has a growing corner of ultra-high-polyphenol imported oils, some genuinely reaching 900-1400 mg/kg, sourced from Italy, Spain and Greece and shipped to Australia, occasionally in temperature-controlled containers, but still over a journey of weeks to months before it reaches a warehouse, let alone a shelf.
Here's the part that gets left out of most of that marketing: polyphenols start declining the moment oil is milled. Light, heat and oxygen exposure all accelerate that decline, and a long freight timeline is exactly the kind of exposure that adds up. An oil that tested at 1100 mg/kg fresh off the mill in Puglia is not necessarily still at 1100 mg/kg by the time it's sitting in an Australian pantry three or four months later. Nobody's independently re-testing these oils at the point of sale in Australia to check, which means the number on the label may reflect a moment in the oil's life that's already well behind it.
This is where local production has a genuine, unglamorous advantage. Oil grown, milled and bottled in the Geelong region reaches Australian shelves in a fraction of the time. A locally-produced oil sitting at 400-650 mg/kg fresh may be delivering more usable polyphenol content at the point you actually pour it than an imported oil claiming double that number a season ago. Potency at the mill and potency in your kitchen are two different numbers, and only one of them is the one that matters to you.
The Volcanic Soil Claim Is More Complicated Than It Sounds
A lot of Australian producers, us included, lean on volcanic soil as shorthand for quality. It's not baseless, but it's also not as settled as the marketing suggests, and it's worth being straight about that.
The theory usually goes: volcanic soil creates mild stress on the tree (through mineral composition, drainage, or water availability), and that stress triggers the tree to produce more protective phenolic compounds as a natural defence response. There's real science behind part of that. Studies on olive trees under drought stress have shown measurable increases in specific phenolic compounds, and research on different water regimes has found total phenolic content in the resulting oil more than doubling under reduced irrigation compared to standard conditions.
But the research isn't uniformly in one direction. A systematic review of stressed olive trees and their fruit oil found that while stress generally triggers phenolic biosynthesis, specific compounds like hydroxytyrosol can actually decline the further that stress progresses, meaning too much stress can work against you, not for you.
And separately, most of the stress-response research has focused on leaves rather than fruit, where the effect doesn't always carry through the same way. In short: mild, well-managed stress from soil and water conditions can plausibly support higher phenolic content, but "volcanic soil" alone, without the actual stress physiology being right, isn't the guarantee it's often sold as.
What we'd say instead: our fruit grows in ancient basalt-derived soils around Mt Moriac, between the Otway Ranges and the Surf Coast, in a cool coastal climate that naturally moderates the growing season. That's a real, specific set of growing conditions. Whether "volcanic" is doing the heavy lifting, or whether it's the cooler climate, the drainage, the early harvest timing, or some combination, is genuinely harder to isolate than most olive oil marketing lets on, and we'd rather say that plainly than repeat a line that oversimplifies real, contested science.
What Actually Backs Up a High Polyphenol Claim
Given all that, here's a more useful checklist than "look for a big number":
- Ask what method produced the number. HPLC or LC-MS/MS from an accredited lab carries more weight than an unspecified test.
- Check how fresh the oil is, not just how high it tested. A recent harvest date matters as much as the ppm figure.
- Favour local or short-supply-chain oils where potency matters to you. Less time between mill and bottle means less time for the number on the label to have already moved.
- Treat terroir claims as a plausible factor, not a guarantee. Soil, climate and harvest timing all interact in ways that are still being studied.
Where Geelong Region Olives Sits in All This
FORTE 659 is tested via HPLC at a NATA-accredited lab, harvested early from Frantoio-forward fruit, and milled and bottled close to home rather than shipped across hemispheres. The Mt Moriac Range sits comfortably above the EFSA threshold at an accessible price point, tested the same rigorous way, and reaches you within a genuinely short window of harvest.
We're not going to tell you our oil is the highest-polyphenol oil available in Australia, because it isn't, and anyone claiming that without naming their test method should probably be asked more questions. What we can say is that the number on our label was tested properly, and it's a number that's still largely intact by the time it reaches your kitchen bench.
Shop the range tested via HPLC at a NATA-accredited lab, harvested early and bottled close to home, at geelongregionolives.com.au.