# Flavor Chemistry of Virgin Olive Oil: An Overview
###### Abstract  
Virgin olive oil (VOO) has unique chemical characteristics among all other vegetable oils which are of paramount importance for human health. VOO constituents are also responsible of its peculiar flavor, a complex sensation due to a combination of aroma, taste, texture, and mouthfeel or trigeminal sensations. VOO flavor depends primarily on the concentration and nature of volatile and phenolic compounds present in olive oil which can change dramatically depending on agronomical and technological factors. Another aspect that can change the flavor perception is linked to the oral process during olive oil testing. In fact, in this case, some human physiological and matrix effects modulate the flavor release in the mouth. The present review aims to give an overview on VOO flavor, with particular emphasis on the mechanisms affecting its production and release during a tasting.  
extra virgin olive oil; phenolic compounds; volatile compounds; aroma release; virgin olive oil off-flavor; human saliva; oral process; panel test +
Footnote †: journal: Medical  
aroma, contributing to its typical \"green\" fruity odor [5]. Aldehydes such as hexanal, _trans_-2-hexenal, _cis_-3-hexenal, and _trans_-2-pentenal, both with alcohols (_cis_-3-hexen-1-ol, _trans_-2-hexen-1-ol, and 1-hexanol) and 1-penten-3-one contribute strongly to the typical green notes. The different nuances of VOO are related to the level and composition of the volatile fraction, which is affected by wide possible variations in olive oil production techniques and the starting raw material [4; 18; 19; 20]. In addition to the lipoxygenase pathway, various other reactions can lead to the formation of other volatile compounds which thus increase the olfactory complexity of the oil. However, when these reactions prevail, they can lead to the appearance of odor defects (off-flavor) [4].  
VOO is highly appreciated for its sensory properties, and sensory assessment is compulsory for every lot of VOO that is commercialized, in accordance with the national legislations of many countries and the standards of the International Olive Council (IOC) regulations on the trade standard of this product and its sensory assessment guide. In fact, olive oil that is to be classified as \"extra-virgin\" must not have any presence of unpleasant aroma defined as off-flavor, while lower categories can present a slight level of sensory defects which is categorized and quantified. The presence of off-flavors or absence of fruity aroma can therefore change the commercial category of a VOO, and when a defect is too strong, even if the chemical parameters are within acceptable ranges, it will result in a product that is not-marketable, unless refined [21]. VOO is therefore a highly regulated food both at national or supranational level, e.g., by the EU, and international level. In addition, its quality may be defined by a number of parameters assessed by analytical tests, but the sensory perception of odor is the ultimate determinant [22]. Sensory analysis is still the most effective tool to evaluate VOO quality. The method established by the current EU legislation to assess the organoleptic characteristics of VOO is through sensory analysis, specifically the so-called \"panel test\" conducted according to the IOC method [8].  
Tasting virgin olive oils is a multisensory experience that involves the visual, olfactory, gustatory and tactile senses, whereas the latter is less relevant in VOO testing. Smell, taste and mouth-feel sensations are defined with only word \"flavor\". Investigating the factors that influence VOO flavor is of importance for the production and appreciation of a successful product.