Virgin Olive Oil: process parameters affecting the oxidative stability and sensory quality during domestic storage

The oil produced from the fruits of Olea europaea by the use of physical means such as pressure or centrifugation and without any chemical treatment is defined as virgin olive oil (VOO). Over the past decade, the consumption of olive oil has decreased in three world main producing countries (Italy, Spain and Greece), whereas it is increasing in most of Central and Northern Europe, particularly in Poland . Malaxation (the slow mixing of the olive paste after milling) is a crucial step in the production of a high quality VOO. The malaxation time and especially temperature significantly affect the overall quality of VOO, because they can influence the total amount and profile of selected micro constituents, such as the hydrophilic antioxidants present in the olive paste which diffuse into the VOO. These minor polar compounds are strictly related both to the sensory properties and to the oxidative stability of VOO upon thermal treatment and during the domestic storage. In the EU, the sensory properties of VOO (intensity of the defects perceived, their fruitiness and other positive attributes) are used to grade the quality of a VOO on the basis of an official organoleptic assessment by a trained panel . Moreover, the sensory quality is particularly important in VOO for marketing reasons, especially in countries where virgin olive oil has become more and more popular in recent times. In fact, extra-VOO is judged to have a superior taste compared to other olive and seed oils. ‘Bitter’ and ‘pungent’ are positive attributes in the specific vocabulary of the organoleptic assessment of VOO and are always positively correlated with the oxidative stability and thus with the nutritive quality of VOO . However, consumers (not only) in Central and Northern Europe always prefer VOOs with a ‘ripe fruity’ or ‘sweet’ taste, according to recent surveys. The modulation of time and temperature in the processing technology before and during malaxation can be an interesting strategy on an industrial scale. It allows obtaining a VOO with a tailor-made bitter/pungent attribute from olive varieties which are naturally rich of phenolic compounds. Therefore, the resulting VOO can better meet the taste and preference of targeted groups of consumers. The use of different operating conditions (equipment, time and temperature) during VOO processing are presented and discussed in relationship with the effects on the VOO quality in the fresh oil and during the domestic storage (shelf life) of the product.