Blends of fresh olive oil and old olive oil: Characterization and quantification through chemical and sensory assessment

Abstract

AbstractThe present research work undertakes the investigation of the effect of storage on the quality of olive oil from Chemlali cultivar harvested from the Sfax region. The comparison of fresh and old olive oils was conducted through several physico‐chemical methods (free fatty acids, peroxide value, UV‐spectrophotometry [K232, K270, and ΔK], moisture content, total ethyl esters content, pyropheophytin, 1,2‐diacylglycerol content, and sensory analysis). A trivial rise in quality parameter along with a minor impact on the sensory scores was observed. Not only did the pyropheophytin and 1,2‐diacyglycerol criteria prove excellent performance as indicators of overall olive oil quality and freshness, but also underlined any problems during oil storage. Besides, pyropheophytin increment (17%) and the 1,2‐diacylglycerols decreased (35%) at normal storage conditions over time. On the other hand, when blending fresh extra‐virgin olive oil with old extra‐virgin olive oil, no detectable modifications of the chemical composition were observed. This is revealed by the trivial alteration of the parameters which are usually deemed as quality indicators, namely peroxide value, K232, and sensory evaluation. In fact, the most reliable technique appears to be the identification of ethyl esters, pyropheophytin and 1,2‐diacyglycerol.