I am an olive oil producer, in Portugal, and we're harvesting as I type.<p>I have made some remarks about olive oil production on HN in the past, but here are some remarks about olive oil quality, grading, and production:<p>Olive oils do degrade with time, which means triglycerols break into free fatty acids and glycerol (E → F + _ ). Of course aroma also changes with time, but this is more subjective, and decided by actually tasting samples.<p>So olive oil freshness comes in three gradings, defined by free fatty acid content: extra virgin (<0,5%), virgin (<2%), and lampante (>2%). These grades will generally decide the market value, but differentiation can change this (special varieties and a good aroma allow for a better price). Extra-virgin can, in principle, be sold as virgin (e.g. if aroma is not good enough for some reason) but not the other way around.<p>All my production is extra virgin. That is 100.00% extra virgin. I have never, nor my family has ever, produced anything but extra virgin olive oil. The worst I have seen around me was a producer getting 0,4% free acidity, which is still extra virgin.<p>Today, olive oil is industrially extracted by crushing the olives and separating water and fatty phases in a centrifuge, at cold temperatures.<p>Olives have around 20% w/w directly extractable oil, but the fatty content of the pomace contains around 40% fat. This oil can be further extracted in centrifuges, up to a point were some temperature will be needed. This fat won't be completely extracted, and that is up to the plant processing it, that usually keeps the pomace for itself. Heating does lower the quality of olive oil, and as such its price, but some data is good to put things into perspective.<p>Around 95% of Portugal's production was virgin/extra virgin, followed by the US (~90%), Greece (~75%), and Italy and Spain (both ~65%) the latter being the largest producer (~35% of world total). Portugal now ranks 7th in production volume, and is the first to put olive oil in the market, although the market is controlled by Spain. Future markets usually keep prices down for the starting weeks, and I hope this will change in the following years as Portuguese production increases.<p>Having this objective measure in mind, and without disregard for other characteristics that can improve olive oil general quality, one can say that Portuguese olive oil is the best, modesty aside.<p>But it does seem the US know what they're doing, although in smaller quantities!<p>Italy is one of the largest importers of Portuguese olive oil. I have no idea what they do with it.