Influence of olive fruit fly attack on quality and composition of ‘Rosinjola’ virgin olive oil

Abstract

In this work, the influence of olive fruit fly (Bactrocera oleae Rossi) attack on the quality of 'Rosinjola' virgin olive oil (free fatty acids, peroxide value, specific extinction at 232 and 270 nm, and sensory evaluation) as well as on the fatty acid and volatile composition was investigated. Olive fruits were collected and divided into two groups according to the presence (100% infested) or absence (healthy, 0% infested) of infestation by olive fruit fly, and a third group was made by mixing the two previously described groups in equal proportions (50% infested). Each group of olive fruits was separately processed under the same conditions to produce corresponding virgin olive oils. The results of oil acidity, a sign of hydrolytic degradation of olive oils, showed that olive fruit fly infestation at the 50 and 100% levels significantly reduced the quality of oil. Sensory score and intensity of positive sensory characteristics of the investigated oils decreased with increasing fruit fly infestation, but defects in oils as a consequence of fruit fly attack were not detected. Considering the fatty acid composition, olive fly attack caused only a slight reduction of palmitic acid. The volatile profile of investigated olive oils showed that olive fly attack led to a decrease in total C6 volatiles (a decrease in C6 aldehydes, but an increase in C6 alcohols) and an increase in total C5 volatiles. The results confirmed the importance of healthy fruit in obtaining high-quality virgin olive oil, but, despite the olive fruit fly attack, 'Rosinjola' oil still maintained extra virgin olive oil category according to market quality parameters.