Biochemical, mineral and anatomical characteristics of the olive tree cv. Chetoui growing in several Tunisian areas

To tolerate harsh climatic conditions, olive tree Chetoui has developed some anatomic, physiologic and biochemical mechanisms. The aim of this study was to determine the indicators of stress in leaves, stems and roots growing under various climatic conditions. To protect against stress conditions this cultivar increased cuticle thickness, protective structures and building parenchyma tissues of leaves, woods and roots from the North to the South. The volatile compounds, extracted from northern and southern Chetoui leaves and roots, were analyzed by GC-FID and GC-MS. Great changes in volatiles were illustrated in the studied organs, by enrichment in phenolics and fatty acids for leaves and in hydrocarbons for roots of southern Chetoui. Also, a reduction in terpenes, alcohols and carbonylic compounds was noted in both southern samples. Moreover, minerals of all organs of Chetoui, varied in content and allocation, but their levels are the highest in leaves. The changes in volatiles might be affected by changes in the mineral elements uptake or accumulation under environment stress. A significant correlation was noted between phenolic compounds and sodium, nitrogen, and calcium contents. However, terpenoids was highly correlated with phosphorus content for all organs and studied areas. The detection of new volatiles, anatomical and mineral changes seem to be efficient indicators of adaptation of Chetoui to environment stress conditions

Assessment of the climatic condition’s impact on volatiles, polyphenols and mineral contents in tunisian olive tree (Olea europaea L.)

The severity of climate causes biochemical and nutritional changes in plants. Our study focuses on the adaptation of the olive tree to the climatic conditions by the improvement of essential oils, polyphenols and macro-elements synthesis in leaves, stems and roots of Meski, growing under various bioclimatic zones of Tunisia (North, Centre and South). The mineral content was determined using a flame photometer and the volatile components were analyzed by GC-FID and GC-MS. Meski cultivar resists to severe climatic conditions, in maintaining its nitrogen content almost constant in leaf and wood for all studied areas. Moreover, leaves showed richness in calcium and sodium than roots for all areas. The GC-MS analysis of Meski leaves allowed the identification of fifty seven components. The main constituents were (E)-β-damascenone, nepetalactone, geranic acid, (E)-β-damascone, (E)-nerolidol, (E)-2-decenal whose levels varied significantly with climate conditions. In fact, to adapt to the severity of climate, southern Meski leaves produced more essential oils and polyphenols than the northern ones. Therefore, the increase of essential oils and polyphenols can be considered as a response of the tree to surround aggressions and to oppose the oxidative stress that results from the severity of climatic conditions, characteristic of the southern area

Chemical composition and biological activities assessment of olive fruit volatiles from different varieties grown in Tunisia

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

How different amounts of leaves added during the extraction process affect the biochemical composition of Chemlali olive oil cultivar?

Olive leaves are rich in antioxidant compounds. During harvest, they reached about 10% of the total weight which can affect the olive oil quality. So, this work aimed to study the effect of adding different amounts of leaves (1, 2, 5, 10 and 20%) during the olive oil extraction of cv. Chemlali. Changes in physico-chemical indices, oil stability, fatty acid composition, antioxidant contents and volatile composition were evaluated. The obtained olive oils with the addition of less than 10% leaves were classified as Extra Virgin Olive Oil (EVOO). Polyphenols and bitterness index were the highest for treatments with addition of less than 10% leaves. Twenty-nine volatile compounds were identified. Total aldehydes and C6 compounds, responsible of the positive attributes, were the most abundant and were strongly affected by the addition of leaves. Olive oils with 2 and 5% added leaves were rich with aldehydes responsible of green and fruity flavor and in polyphenols