A certificate of analysis (COA) is a laboratory report that verifies the chemical composition of olive oil before purchase, ensuring quality, freshness, and authenticity.
A COA reports quality indicators such as free acidity, peroxide value, K232, and K270, which reveal the condition of the olives at harvest and how well the oil has been produced and stored to preserve its freshness. It also includes the fatty acid profile, FAEE, PPP, and DAGs, which help confirm the oil's authenticity and indicate whether it is fresh or made from older or poorly handled oils. Polyphenol content may also be reported, although not legally required, which is an indicator of an oil's health benefits and oxidative stability.
Meeting the extra-virgin limits is essential, but a high-quality oil sits well within the limits.
Here is what each figure on the COA means, what a good value looks like, and how to use it to make informed buying decisions.
What is a COA, and why do I need it?
A COA reports the results of laboratory tests on a specific lot of oil against the parameters set by the International Olive Council and reflected in other regulations. It is to prove that the oil is the grade the seller says it is, that it's fresh, and that it is of good quality.
For bulk and wholesale buyers especially, a recent COA tied to the exact lot you're buying is the best option, and you can make it a condition of the contract and of payment, so funds are released only against proof that the oil meets standards.
Freshness and quality
These four parameters describe the condition of the oil: how sound the olives were and how much the oil has degraded since.
|
Parameter |
Extra virgin limit |
What it means |
|
Free acidity (% as oleic acid) |
≤ 0.8% |
Breakdown of fats from poor, damaged, or overripe fruit or from milling delays. Lower means better fruit, handled fast. |
|
Peroxide value (meq O₂/kg) |
≤ 20 |
Primary, early oxidation. Rises with heat, light, air and age. Lower means fresher and better stored. |
|
K232 (UV absorbance) |
≤ 2.50 |
Early-stage oxidation, often from mishandled or over-ripe olives. |
|
K270 (UV absorbance) |
≤ 0.22 |
Later-stage oxidation linked to rancidity; also elevated by refined oil. |
|
Delta-K (ΔK) |
≤ 0.01 |
Flags blending with refined or lower-grade oils. |
The combination of factors reveals how the oil was made and stored: An oil with very low free acidity but a high peroxide value was probably made from good, sound fruit but then stored badly or allowed to age, so it has begun to oxidize. Low acidity and low peroxide together signal an oil that was both well-sourced and well-kept. Values that all sit right at the extra-virgin limit suggest the oil passes, but might be older.
Authenticity and age
These parameters are to ensure that the oil is fresh, pure olive oil.
Fatty acid profile: This indicates authenticity. Olive oil has a characteristic composition of 55–83% oleic acid, 7.5–20% linoleic acid, and less than 1% linolenic acid. A different composition suggests the oil has been mixed with cheaper seed oils, which are higher in linoleic or linolenic acid.
FAEE (fatty acid ethyl esters): The limit is ≤ 35 mg/kg for extra-virgin olive oil. They form when poor, over-ripe or fermenting olives are pressed, and they also appear in mildly deodorized (soft-refined) oils passed off as extra virgin.
PPP (pyropheophytin a): A chlorophyll breakdown product that rises steadily with time and heat. The California standard caps it at ≤ 17%. It shows both age and the presence of blended refined oil.
1,2-DAGs (diacylglycerols): In fresh oil, most diacylglycerols are in the 1,2 form; they convert to the 1,3 form as the oil ages and acidity rises. A high proportion of 1,2-DAGs (the California standard is ≥ 35%) indicates a fresh, well-made oil.
These are important because if a supplier blends old extra virgin oil into fresh EVOO, the usual quality tests like peroxide value, K232, and even the taste panel may not detect it, but FAEE, PPP, and DAGs will. That is why stricter regimes, such as the California and Australian standards, as well as many serious importers, rely on them, even though they are not yet part of the core IOC and Codex standards
Polyphenols
Polyphenols, also called biophenols or total phenols and reported in mg/kg, are a very useful figure to know because they indicate:
● Health benefits: Olive oil polyphenols protect blood lipids from oxidative stress at around 250 mg/kg.
● Shelf life: Polyphenols are natural antioxidants that protect the oil and resist oxidation, helping it stay fresh longer and indicating how long it will hold its grade.
● Flavour: They are responsible for the oil's bitter, peppery taste and smell.
If polyphenols aren't on your COA, ask for them separately.
What to watch out for
● No sensory (organoleptic) panel result: A taste panel is essential to prove EVOO grade; a COA without one is incomplete.
● An old test date: The numbers indicate the oil's condition at the time of testing, so an old one tells you little about the oil today.
● Missing authenticity markers on a premium oil: For high-value oil, the absence of a fatty acid profile or age markers is a risk worth investigating before purchase.
How to use a COA when purchasing
Ask for a recent, lot-specific COA and not a generic sample. Read it against both the legal limits and the premium benchmarks. For bulk purchases, write the required parameters into the contract and tie payment to them, so the grade is verified before money moves. Remember that a COA is relevant at the moment it is done, since oil oxidizes with age, heat, and light, so ensure the oil was harvested recently and is stored properly.
