Physicochemical and sensory characteristics of virgin olive oils in relation to cultivar, extraction system and storage conditions

This research was carried out to evaluate the effects of variety, extraction system and storage conditions such as packaging type and temperature variation on the quality of virgin olive oil. Several parameters were studied, namely, quality indices, polyphenols, tocopherols, volatile compounds and sensory properties. Thus, two olive varieties Chemlali (Tunisia) and Coratina (Italy) were selected. The olive oils were extracted by different industrial processes (super press, dual and triple phase decanter) then stored in the established conditions (ambient and refrigerator temperature) in the following packaging materials: clear and dark glass bottles and metal bottles. The oils were analyzed before and after being stored for 9 months. Principal Component Analysis and Graphical Modeling were applied to fully explore the influence of the studied factors. Results revealed that among samples, oils from Coratina cultivar were the richest in gamma-tocopherol while Chemlali oils contained the highest amount of Delta-tocopherol. Quality indices namely 1(232 and 1(270 values were mainly influenced by the storage date and packaging material. Meanwhile, free acidity and peroxide value were mainly influenced by the extraction system. Concerning tocopherols, alpha-tocopherol content was mainly influenced by the packaging material, beta-tocopherol was mainly affected by the storage date, for gamma-tocopherol content the main influencing factor was the cultivar whereas for Delta-tocopherol the main influencing factor was the extraction system. Regarding volatile compounds their amounts were influenced mainly by the storage date, that was influenced by the packaging material, where a considerable decrease was observed after storage which was reflected by the change of sensory characteristics of stored oils: loss of positive attributes fruitiness, bitterness and pungency and onset of defects which were mainly influenced by the storage date (fruity and bitter attributes), packaging material (pungent, rancid and fusty attributes) and extraction system (musty attribute). (C) 2013 Elsevier Ltd. All rights reserved.