Dynamic Accumulation of Volatile Compounds Between Olive Pulps and Stones and Its Relation with the Fatty Acids Content During the Oil Extraction Process of Ouslati and Chemlali Olive Fruits

Abstract

AbstractThe characterization of both volatiles and fatty acids of Tunisian olive varieties (Ouslati and Chemlali) is achieved in order to understand their correlation with the aroma accumulation via the lipoxygenase (LOX) pathway. The main identified volatiles in both crushed pulps and crushed stones are hexanal, E‐(2)‐hexenal, (Z)‐3‐hexen‐1‐ol, 1‐hexanol, and hexyl acetate. With regard to their fatty acid composition, results show that both de‐stoned (DOO) and conventional (COO) olive oils contain mainly unsaturated fatty acids. The results also show that oleic acid (C18:1) is the main fatty acid in both DOO and COO. Meanwhile, linoleic acid (C18:2) is present in a relatively higher percentage (5.2% and 19.8%, respectively, for Ouslati and Chemlali DOI) than linolenic fatty acid (C18:3) (<2%). The analysis of volatiles shows that more than 80% of total LOX‐compounds from both crushed pulps and crushed stones have linolenic acid as synthesis precursor despite its lower level (2%). Moreover, the contribution of olive parts in generating aroma is much higher in crushed pulps (more than 80%) than in crushed stones, which explains the fact that DOO, extracted from crushed pulps, contains the dominant amount of volatiles. Therefore, the obtained results promote both the consumption and the marketing of DOO.Practical Applications: The aroma and the organoleptic properties of olive oil are strictly correlated with both the olives quality and the extraction techniques used. Many technologies are developed to extract olive oil with highest quality. De‐stoned olive oil extraction process is one of these technical procedures. In the present work, the characterization of volatiles in pulp and stone separately provides important information about the contribution of olive constitutive parts on the accumulation of olive oil aroma during the oil extraction process.