engleski

Effect of olive friut fly attack on quality and volatile composition of olive oil: formation of grubby defect

The aim of this work was to evaluate the effect of olive fruit fly (Bactrocera oleae (Rossi)) attack on quality (free fatty acids, peroxide value, specific extinction on 232 and 270 nm, sensory evaluation and fatty acid composition) and volatile composition of olive oil. Therefore, olive fruits, obtained from cultivar Leccino grown in Istria (Croatia), were collected and divided into three groups according to the presence (infested - 100% and 50%) or absence of infestation (healthy – 0%) by the olive fruit fly. Each group was separately processed under the same conditions to produce olive oils. The results of oil acidity and peroxide value, signs of hydrolytic and oxidative degradation of olive oils, showed that olive fruit fly infestation at the 100% level significantly reduced the quality of olive oil. Olive oil fatty acid profiles were unaffected by olive fly attack. Sensory score and intensity of positive sensory characteristics of the investigated oils decreased by the increase of fruit fly infestation level. Occurrence of grubby defect was detected in oil as a consequence of fruit fly attack and its intensity increased by the increase of a fruit damage degree. In the oil obtained from fruits at the 100% level of infestation formation of rancid defect, sight of oxidative degradation, was also detected. Volatile profile of the investigated oils was evaluated using headspace solid-phase microextraction – gas chromatography/mass spectrometry. Olive oils from fly infected olives, especially at the 100% infestation level, had higher values of some volatile compounds (octane, methyl acetate, heptanal, isoamyl alcohol, E-ocimene, Z-2-penten-1-ol, 1-hexanol, octanol, 3-buten-1-ol, butanoic acid, pentanoic acid, α-farnesene and E-2-hexenoic acid). A significant degree of correlation between individual volatiles and determined negative sensory attributes (grubby and rancid defects) of oils obtained from infested fruits were established.

Bactrocera oleae; Olive oil; Quality; Sensory characteristics; Volatile compounds

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