Van Gogh’s Olive Trees
Extra virgin cold pressed olive oil is one my essential foods. The extra virgin designation refers to the lack of refinery (chemical or heat) in preparation of the oil. This results in a lack of sensory defects and higher polyphenol content (antioxidants). The cold pressed designation refers to a one-time crushing without heating (the hotter the climate at time of harvest, the easier the job!).
Olive oil cultivation began at least 5000 years ago in the Mediterranean. In A History of Food Toussaint-Samat quotes Georges Duhamel as saying that the ‘Mediterranean ends where the olive ceases to grow.’ Apparently, so prominent was the olive in the ancient world market place, it was the symbol used to denote the fourth letter of early alphabets.
In an excellent review of olive oil volatile compounds, flavor development and quality, Kalua et al. (2005) indicate the key compounds to the scent of olive oil are aldehydes, alcohols, esters, hydrocarbons, ketones, and furans. They note the compound differences among various types of olive trees. Incidentally, Italian oils (my favorite) have a paucity of fruity esters, which probably explains my preference: I find most Spanish oils to be light and fruity, lacking the earthy peppery aromas I appreciate most. They also indicate the reason first cold-pressed is best: stored fruit (often bruised from harvesting) deteriorates as pathogenic micro-organisms and natural aging (including fermentation) take their toll. The result is a less stable oil with high acidity and anhedonic volatiles.
Next week, to continue with the Mediterranean theme: garlic!