Differences in n‐alkane profiles between olives and olive leaves as potential indicators for the assessment of olive leaf presence in virgin olive oils

Abstract

The olive (Olea europaea) is one of the most important crops in the Mediterranean region for economic and culinary reasons. Cuticular waxes coat olives and olive leaves and play a significant role in plant physiology and resistance against environmental stresses. The present study describes n-alkane profiles in cuticular waxes of olives and leaves of three Italian varieties (Frantoio, Leccino and Maraiolo) during different stages of olive development. Additionally, the study investigates the differences between n-alkane profiles of extra virgin olive oils with low and high leaf content. Olive leaves are characterised by the predominance of n-alkanes with longer carbon chains (n-C 29 -C 33 ) compared with olives (n-C 25 -C 29 ). During all stages of olive ripening period, n-alkane average chain length (ACL) values of olive leaves are significantly higher compared with those of olives. Extra virgin olive oils with admixture of leaves have significantly different n-alkane profiles than those free from leaf material. Practical applications:The results of this study will contribute significantly to the currently very limited information on n-alkane data from olive tree varieties used for oil production. The presence of leaves increases the concentrations of long chain n-alkanes (n-C 31 -C 35 ) in extra virgin olive oils, therefore studying the differences between n-alkane profiles of olives and olive leaves could help establishing the presence of leaf material in produced extra virgin olive oils. Information about the relative and absolute concentrations of n-alkanes in olives, olive leaves and olive oil will also be useful for biochemical and metabolic studies of the olive tree.

Cuticular Waxes of Arabidopsis thaliana Shoots: Cell-Type-Specific Composition and Biosynthesis

“…The occurrence of very low amounts of compounds at the high end of the homolog distribution suggested that they are formed merely as by-products of the normal wax biosynthesis machinery rather than through dedicated processes specific to their chain lengths. Characterization of enzymes involved in wax precursor elongation in respective species may reveal whether, in these cases, single FAEs indeed form both the ubiquitous chain lengths and the C 35+ homologs [ 2 , 6 , 23 , 39 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ].…”

Evidence to Support the Anti-Cancer Effect of Olive Leaf Extract and Future Directions

“…Consequently, olive leaf extract (OLE) may hold an even greater potential than EVOO for improving health outcomes. During EVOO processing leaves can unintentionally be left in the mixture if the separation methods are inadequate, alternately leaves can also be added to EVOO mixtures to provide health benefits and improve flavor [ 23 ]. The addition of leaves increase the phenolic and chlorophyll content of the oil but also the organoleptic traits as measured in volunteer taste tests [ 24 ].…”

n-Alkanes and n-Alkenes in Virgin Olive Oil from Calabria (South Italy): The Effects of Cultivar and Harvest Date

“…There was a depleting trend, even if the content of the last sampling of six out nine cultivars was higher than the last but one ( Table S14 ). In a study conducted in Tuscany (central Italy) on Frantoio, Moraiolo and Leccino cultivars, C31 was found to be the highest n -alkane in olive leaves, and was present in higher quantities in olive leaves than in olive fruits; this condition was repeated each month in samplings from July to November [ 19 ].…”

“…Mihailova et al found C34 in higher quantities in olive leaves than in olive fruits throughout the whole ripening season; this happened also for C30, C32, C33 and C35. In brief, this condition was found for all the high-chain n -alkanes and, consequently, the oil extracted from batches of olive fruits containing a high leaf content showed a high n -alkane content [ 19 ].…”

“…n -Alkane content was found to be affected by the geographic origin of the oil [ 18 ] and can be used to detect enhanced concentrations of leaf material in olive oil, because n -alkane profiles of olive leaves were found not to exhibit significant variations during the harvest season in contrast to n -alkanes in olive oil [ 19 ].…”