Olive oil mixtures. Part two: Detection of soft deodorized oil in extra virgin olive oil through diacylglycerol determination. Relationship with free acidity

Abstract

The detection of soft deodorized olive oils in extra virgin olive oil (EVOO) has become a challenging task ever since it was demonstrated that: 1. The process does not form the typical refining markers, e.g. stigmastadienes, and 2. The determination of the fatty acid alkyl esters renders useful only when the deodorized matrix comes from oils with fermentative defects. Recently researchers have developed strategies to detect such kind of blends, being one of them based on the fact that both diacylglycerol (DAG) and free fatty acids are not interdependent after mild refining activities. Presently, we propose two factors to confirm the absence of soft deodorized oils in EVOO: R1 (10 × free acidity/DAG_exp) ≥ 0.23 and R2 (DAG_exp-DAG_theor) < 0, in genuine EVOO. We demonstrate that such approach is useful to detect the presence of soft deodorized olive oil when this is at least at 30% in the mixture.

Keywords: Diacylglycerols; Free acidity; OLEUM Project; Olive oil fraud; Olive oil illegal blends; Soft deodorization.