I am a student with a keen interest in olive oil, especially the aroma and flavour compounds. I saw on the olive chemistry page of your site that there is a chemical test for rancidity, and I was wondering if you would be able to give me some details about it.
As lipids oxidize, they form hydroperoxides which may further decompose to aldahydes, ketones, acids and alcohols; Snyder et al (1985) reported that saturated carbonyl compounds such as pentanal, haxanal, octanal and nonanal are the major compounds formed in oxidized olive oil. John Harwood and Ramon Aparicio's "Handbook of Olive Oil" has an excellent chapter on olive oil oxidation.
Testing peroxide level and sensory analysis are the primary official ways to screen for rancid olive oils.
The rancimat test shows oxidative stability and is more often used for industrial frying oils, not olive oil.
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