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A. BENDINI* - L. CERRETANI - M.D. SALVADOR1 G. FREGAPANE1 - G. LERCKER2

OLIVE OIL

Dipartimento di Scienze degli Alimenti - Università di Bologna P.zza Goidanich 60 - 47023 Cesena - FC - Italy Departamento de Tecnología de Alimentos - Universidad de Castilla-La Mancha Avda Camilo José Cela 10 - 13071 Ciudad Real - Spain 2 Dipartimento di Scienze degli Alimenti - Università di Bologna V.le Fanin 40 - 40127 Bologna - Italy *e-mail: alessandra.bendini@unibo.it

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STABILITY OF THE SENSORY QUALITY OF VIRGIN OLIVE OIL DURING STORAGE AN OVERVIEW Key words: minor compounds, oil storage, phenols, sensory stability, virgin olive oil, volatiles

INTRODUCTION The assurance of the stability and quality of food products is a matter of great concern for producers and sellers. In the case of fats and oils, oxidation (one of the most fundamental reactions in lipid chemistry) is the main cause of quality deterioration and its reaction rate determines the shelf life of this type of food product. To maintain the phenol and volatile molecule content responsible for the highly appreciated organoleptic and nutritional properties in newly produced virgin olive oil during storage, it is absolutely essential to control all the factors that promote lipid oxidation. The high oxidative stability of virgin olive oil with respect to other vegetable oils is mainly due to its fatty acid composition, in particular, to the high monounsaturated-to-polyunsaturated ratio, and to the presence of minor

compounds that play a major role in preventing oxidation. In spite of its high stability, virgin olive oil is also susceptible to oxidative processes, such as enzymatic oxidation, which occurs when the oil is in the fruit and during the extraction process, photo-oxidation, when the oil is exposed to light, and autoxidation which mainly occurs during processing and storage when the oil is in contact with oxygen (Frankel, 1985). This review is mainly concerned with the autoxidation process, the main cause of deterioration of virgin olive oil during its shelf life. Lipid oxidation occurs through the interaction of the triacylglycerol fatty acids with molecular oxygen which yields hydroperoxides by a free radical mechanism. The activation energy of this reaction is high and the initiation of lipid oxidation requires traces of transition metals or exposure to light; the reaction is accelerat-

ABSTRACT The storage conditions of bottled or tank-stored virgin olive oil, as well as all the agronomical and technological variables of the processing stages, are particularly relevant for preserving the highly valued organoleptic quality of this product. All the efforts made in the olive grove and in the oil mill to produce virgin olive oil with good sensory characteristics can be undermined if improper storage conditions are used. In particular, it is necessary to protect the oil against lipid oxidation which can have many deleterious effects on the quality of virgin olive oil, including the formation of unpleasant organoleptic characteristics, the drastic reduction of the bouquet and taste notes as well as the reduction of naturallyoccurring antioxidant compounds and therefore shortening of its the shelf life. The oxidation process during storage is known and involves changes to both the major and minor components of virgin olive oil. To slow down the oxidation rate during storage, certain factors such as the presence of oxygen and traces of metals, exposure to light and the binomial storage time/temperature, must be kept under control. This overview will present the importance of reducing these pro-oxidizing effects, as well as the main changes which may occur during the storage of virgin olive oil at the expense of the minor constituents that are more relevant for the olfactive and gustative characteristics and its impact on the aroma and taste of the oil, particularly the phenolic and volatile compounds.

Italian Food & Beverage Technology - LX (2010) march -

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ITALIAN BEVERAGE TECHNOLOGY 60/2010  

Rivista esclusivamente in inglese, sviluppata a supporto di tutte quelle aziende italiane che vogliono puntare sull’export di macchine, prod...

ITALIAN BEVERAGE TECHNOLOGY 60/2010  

Rivista esclusivamente in inglese, sviluppata a supporto di tutte quelle aziende italiane che vogliono puntare sull’export di macchine, prod...