Most olive oil purchase orders say "extra virgin" and stop there. That works when supplier and buyer already share an understanding of what the phrase commits to, and it fails the first time a lot arrives that one party considers extra virgin and the other does not. The phrase is not a description of taste or origin. In the European Union it is a legal category defined by four laboratory numbers and a sensory test, and a buyer who knows the four numbers can write a specification that ends the argument before it starts.
The four numbers, and the grade lines they draw
Commission Delegated Regulation (EU) 2022/2104 sets the marketing standards. For extra virgin olive oil: free acidity no higher than 0.8 %, peroxide value no higher than 20 mEq O₂/kg, K232 no higher than 2.50 and K270 no higher than 0.22. For virgin olive oil the acidity ceiling rises to 2.0 %, peroxide stays at 20, K232 rises to 2.60 and K270 to 0.25.
The structure matters more than the values. The limits are cumulative — an oil has to satisfy every one to hold the grade, and a single failure moves it down. There is no averaging, no allowance for a strong result on one parameter compensating for a weak one on another. That is what makes the numbers useful in a specification: each is a separate pass-or-fail line.
Free acidity: a record of the fruit, not the flavour
Free acidity measures free fatty acids released when the oil's triglycerides break down. Almost all of that breakdown happens before the oil exists — in the fruit, through bruising, through delay between harvest and milling, through olives left too long in bulk. Once the oil is pressed, acidity barely moves.
Two consequences follow for a buyer. Acidity is a reliable record of how the olives were handled, which is why it sits first in every grade definition. And it says almost nothing about how the oil tastes. A very low acidity is compatible with an oil that is flat, defective or simply unpleasant. Buyers who treat acidity as a quality score, rather than as a handling record, tend to be surprised by what arrives.
Peroxide, K232 and K270: three views of the same process
The other three numbers all track oxidation, at different stages of it.
Peroxide value captures the primary oxidation products that form first, as the oil is exposed to oxygen, light and heat. It is sensitive early and then, as those primary products break down into secondary ones, it can fall again — which is why a low peroxide value in an old oil is not reassuring on its own.
K232 and K270 are ultraviolet absorbance readings. K232 responds to conjugated compounds that form as oxidation advances. K270 responds to later-stage products and, importantly, is also raised by refined oil — which makes it a useful check against a virgin oil that has been extended with something that is not. Read together, the three give a picture of where an oil is in its ageing, which a single reading cannot.
The half of the definition that is not chemistry
An oil can pass all four numbers and still not be extra virgin. The grade also requires a sensory assessment by a trained panel, with a median of defects equal to zero and a median of fruitiness above zero. Fusty, musty, winey and rancid are defects with names because they occur, and none of them shows up as an acidity figure.
This is the part most often left out of a written specification. A buyer who lists the four chemical limits and nothing else has specified the easier half of the grade and left the half that determines whether the oil is actually enjoyable to the supplier's judgement. Where a buyer's product depends on flavour — as most retail olive oil does — the specification needs to say which panel method and which result it expects.
What belongs in a written brief
Four chemical limits, stated as maximums with the analytical method named. The sensory requirement, stated as a panel result rather than as an adjective. Then the things the grade does not cover but the buyer usually cares about: harvest year, origin at the level of country or region, and the storage and packaging conditions between mill and shipment, because an oil that met every limit at the mill can fail them after months in a warm tank.
TeraVella works in olive oil as a sourcing partner, not a producer — we do not claim to own a grove, a mill or a bottling line. What we do is verify a producer against your brief, put the target grade and its analytical limits in writing, collect batch analyses with the destination's required parameters, and manage documented shipment as a single point of contact. Bulk in tanker, IBC or tin, or bottled and labelled under your own brand. We hold ISO 9001, ISO 22000 and ISO 27001 and make no organic or other certification claim; where certified product is required, those documents come from the source. Volumes and prices are confirmed at quotation.
