Abstract The unique and delicate flavor of olive oil is attributed to a number of volatile components. Aldehydes, alcohols, esters, hydrocarbons, ketones, furans, and other compounds have been quantitated and identified by gas chromatography‐mass spectrometry in good‐quality olive oil. The presence of flavor compounds in olive oil is closely related to its sensory quality. Hexanal, trans ‐2‐hexenal, 1‐hexanol, and 3‐methylbutan‐1‐ol are the major volatile compounds of olive oil. Volatile flavor compounds are formed in the olive fruit through an enzymatic process. Olive cultivar, origin, maturity stage of fruit, storage conditions of fruit, and olive fruit processing influence the flavor components of olive oil and therefore its taste and aroma. The components octanal, nonala, and 2‐hexenal, as well as the volatile alcohols propanol, amyl alcohols, 2‐hexenol, 2‐hexanol, and heptanol, characterize the olive cultivar. There are some slight changes in the flavor components in olive oil obtained from the same oil cultivar grown in different areas. The highest concentration of volatile components appears at the optimal maturity stage of fruit. During storage of olive fruit, volatile flavor components, such as aldehydes and esters, decrease. Phenolic compounds also have a significant effect on olive oil flavor. There is a good correlation between aroma and flavor of olive oil and its polyphenol content. Hydroxytyrosol, tyrosol, caffeic acid, coumaric acid, and p ‐hydroxybenzoic acid influence mostly the sensory characteristics of olive oil. Hydroxytyrosol is present in good‐quality olive oil, while tyrosol and some phenolic acids are found in olive oil of poor quality. Various off‐flavor compounds are formed by oxidation, which may be initiated in the olive fruit. Pentanal, hexanal, octanal, and nonanal are the major compounds formed in oxidized olive oil, but 2‐pentenal and 2‐heptenal are mainly responsible for the off‐flavor.
Abstract For 4 consecutive years population studies were made on the olive fruit fly in the Sebronas valley which is located at ca 600 m altitude in Western Crete. Olive flies were trapped in olive trees at highest numbers in April‐May and August—October. Fruit infestation was very intense in spring and fall on old fruits left unharvested and new fruits, respectively. Relatively high numbers of flies were also trapped in walnut, cherry, apple and plane trees, in order of preference, and very few in chestnut, arbutus and vine. Very few flies were trapped in the above plants after September, that is in the period olive flies oviposit intensively in the olive fruits. At the beginning of summer, most females had no developed eggs in the ovaries and no sperm was detected in their spermathecae. In the few females that had eggs, the number of eggs per female was much smaller than in spring or fall. During this period the weather is warm‐dry and no olive fruits, old unharvested or new ones, suitable for oviposition exist in the trees. In the 4th year of this study, when no insecticides were applied against the olive fly in the valley due to small crop production, extensive larval mortality was observed in fall due to parasitization. Zusammenfassung Populationsstudien bei der Olivenfliege, Dacus oleae (Gmel.) (Dipt., Tephritidae) in West‐Kreta Vier Jahre hindurch wurden bei D. oleae im Sebronas‐Tal, 600 müber NN, im westlichen Kreta, Populationsstudien durchgeführt. Die meisten Fliegen wurden in den Olivenbäumen von April bis Mai sowie August bis Oktober gefangen. Der Fruchtbefall war im Frühjahr und Herbst entsprechend sehr stark und betraf alte sowie neue Früchte. Relativ viele Fliegen wurden auch in Walnuß‐, Kirschen‐, Apfel‐ und Platanenbäumen (in der Reihenfolge des Befalls) sowie in sehr geringem Maß in Erdbeerbäumen und Wein gefangen. In all diesen Wirtspflanzen wurden nur sehr wenige Fliegen nach dem September gefangen, also zur Zeit der Eiablage der Fliegen in die Olivenfrucht. Zu Beginn des Sommers hatten die meisten Weibchen noch nicht ihre Eier entwickelt, auch waren ihre Samenblasen noch ohne Spermien. Bei den wenigen Weibchen mit bereits ausgebildeten Eiern war die Eizahl pro Weibchen viel geringer als im Frühjahr oder Herbst. Zu Sommerbeginn ist das Wetter trocken‐warm, und die Olivenfrüchte — alte wie junge — sind zur Eiablage nicht geeignet. Im 4. Jahr der Untersuchungen, in welchem im Tal keine Insektizide gegen die Olivenfliege ausgebracht wurden, konnte im Herbst eine erhebliche Parasitierung des Schädlings beobachtet werden.
Abstract Olive oil is a natural juice obtained by mechanical or physical means from the fruit of the tree Olea europaea L. Many historians believe that the olive cultivation began during the Palaeolithic and Neolithic periods (5000–3500 bce ). Most of the world's olive trees grow in the Mediterranean Basin. Olive oil has always been an important component in the diet of Mediterranean people, but in the past years this oil has become more popular among consumers in Northern Europe, the United States, Canada, and Australia. Olive oil quality depends mainly on the cultivar, microclimate, soil conditions, fruit health, and processing conditions. Several studies have confirmed that extra virgin olive oil (EVOO) helps to reduce oxidative stress, high blood pressure, obesity, fatty liver, and insulin resistance, diseases that are closely related to diabetes and coronary heart disease. This chapter focuses on the origin and history of olive tree, statistics of world production, and consumption of olive oil. It also deals with olive fruit processing, olive oil classification and categories, quality and purity criteria, olive oil components, olive oil analysis, deterioration, and adulteration. Phenolics and other minor functional compounds of olive oil are discussed in detail.
Abstract The present study comprises the second part of an ongoing study focusing on olive oil from five less well‐known Greek cultivars for three of which there are no data available in the literature regarding their chemical composition. A total of 74 olive oil samples were collected during the harvesting periods 2012–2013 and 2013–2014. Headspace‐solid phase microextraction was applied to determine the olive oil volatile profile. Fifty‐six compounds were identified and semi‐quantified by CG–MS. Furthermore, fatty acid composition, conventional quality parameters and color parameters were determined in an effort to characterize and differentiate olive oils according to cultivar. All samples were characterized as extra virgin olive oils. Data obtained showed significant differences between the cultivars. Multi‐element analysis in combination with chemometrics resulted in a high classification rate of 86.5 % for the combination of volatiles plus color, 89.2 % for the combination of VC plus FA, and 91.9 % for the combination of FA composition plus color plus CQP.
Olive fruit of cv ‘Mastoides’ grown on two locations at altitudes of 100 and 800 m were harvested at three dates and used for determination of average weight, fruit oil and moisture contents and the following oil quality characteristics: titratable acidity, peroxide value, K232,270 coefficients, total phenol, tocopherol and chlorophyll content as well as fatty acid and phenol composition. Towards maturation, fruit moisture content decreased but oil content increased. Titratable acidity of oil of both altitudes was low, with higher the oil obtained from fruits from 100 m. Oil peroxide value was higher in the oil of fruits from 800 m at all harvest times and it showed an increase towards maturation in both locations. Total phenol content was higher in oil from 100 m elevation and showed a gradual decrease towards maturation at both altitudes. The ratio unsaturated saturated fatty acids was higher in oil of fruits from 800 m at the first two harvest dates but did not differ significantly at the third harvest. Only α-tocopherol was found in the oil from both elevations. Some phenolic compounds were detected in the first harvest but disappeared with fruit maturation, while other compounds not detected in the first harvest appeared later. Elevation influenced not only the phenol content but also its composition.
Abstract To elucidate the influence of the cultivation area and climatic conditions on volatiles of virgin olive oil from Gemlik cultivar, an investigation was carried out. Five Turkish geographical zones (Balıkesir, Aydın, Manisa, Antalya and Hatay) were chosen. From these areas, fruits were collected at the same maturity stage and processed using a small experimental olive oil mill, applying identical processing conditions for all olive samples. Headspace solid‐phase microextraction (HS‐SPME) technique coupled to GC/MS was used for volatile analysis. Twenty‐seven compounds were identified and characterised, representing 96.40–98.74% of the total GC area. The major volatile representing about 50% was the (E)‐2‐hexenal. This compound was found in higher concentrations on olive oils from Antalya than from Hatay area. Hexanal was the second most abundant volatile compound and varied between 13.89 and 28.96%. Comparing the olive growing areas Hatay and Antalya, the hexanal concentration was about 29 and 14%, respectively. Generally, a significant difference in the composition of volatile compounds between the oils from the same olive cultivar and from different geographic regions was recorded. The results suggest that climatic factors, latitude and longitude affect the formation of volatiles.
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