Chemical Composition and Biological Activities Assess-Ment of Olive Fruit Volatiles From Different Varieties Grown in Tunisia

Abstract

Volatile compounds, present in olives, are responsible for the olive fruit flavor and oil aroma, influencing the consumer’s preference. These compounds have a biological activity to fight off pathogens. The aim of this work is to characterize volatiles in pulps and cores of Chemlali, Arbequina and Koroneiki olives, collected from Menzel Mhiri-Kairouan, and to test both the efficiency of these compounds against two bacteria and six phytopathogenic fungal species, by diffusion and dilution methods, and their antioxidants activities. The analyzis of volatiles were determined by GC-FID and GC-MS in three cultivars at the full ripening stage. Thirty five compounds were identified, such us an assortment of phenol, alcohol, hydrocarbon, aldehyde and terpenes derivatives. A high changes in volatiles was noted between cultivars and fruit organs. In fact, the major compounds in the pulps and the cores, of different cultivars, are (E)-2-decenal (46.9%), nonanal (19.6%), 1-hexadecene (16.3%), 7-Methyl-1,3,5-cycloheptatriene 7-Methyl-1,3,5-Cycloheptatriene (15.47%), (E,E)-2,4-decadienal (14.5%) and 1-tetradecene (14.6%). Also, the cores volatiles illustrated more richness in aldehydes than the pulps for all cultivars. Volatile fractions exhibited a moderate to important antibacterial activities against bacteria. However, Arbequina cores volatiles and both Chemlali and Koroneiki pulps volatiles established a moderate to higher activities against tested fungi. The DPPH and ABTS•+ tests demonstrated that the highest antioxidant capacity of volatiles were assigned to Arbequina cores and Koroneiki pulps. The Principal Components Analysis showed a significant relationship between antioxidants and/or antimicrobial properties and the levels of the main volatile compounds (limonene, methyldecane, nonanal, E-2-decenal, camphor, geranic acid, tetradecene, hexadecane, tetradecane) in different fruit organs.