Some oils are left unfiltered by preference Extra Virgin Olive Oil. Extra is the highest grade for the best, pure, unrefined and unprocessed oil of the fruit. To be graded as extra virgin, the oil must exhibit superior taste, aroma and color. And to meet the most exacting labeling standards, it must also have less than one percent free oleic acid. Olive oils that are judged deficient after the pressing are sent to a refinery for mechanical, chemical or heat processing.
Refined oil is colorless and tasteless.
Before the oil can be sold as ordinary olive oil, some virgin oil is blended back in to provide color and taste. Light or mild olive oils are also made this way, but less virgin oil is added back in. Olive groves are the most prominent feature of the Apulian landscape. In fact Apulia is the largest olive oil producing region of Italy, most of it still produced according to centuries old traditions. September and October are olive harvest months, while production takes place in November.