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Author
Fernández Nobau, Jordi
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Abstract
Citrus essential oils are natural chemical compounds of fundamental importance in the global market. They are known for their multiple applications; from ancient medicine to food, cosmetics, and perfumery. Today, citrus fruits are considered the most famous natural essential oils in the world.
Citrus fruits have many compounds in common, but each citrus has its own aroma that contributes to the characteristic olfactory note of the oil. In this work, essential oils obtained industrially by cold expression of four different citrus fruits have been studied: Mandarin Clementina (Citrus Clementina Vegetable Patch. Ex Tanaka) and lemon (Citrus limon L.) grown in Sicily and Valencia. Green tangerine (Citrus deliciosa Tenore) grown in Calabria, Sicily and Valencia. Orange (Citrus sinensis L.) cultivated in Sicily, Valencia, Brazil, and Catalonia (extracted by hydrodistillation).
In this final master's work, two methods have been developed and optimized that allow the analysis of citrus essential oils using HRGC-FID and HRGC-MS. In the first one, a medium polarity column (6% cyanopropylphenyl 94% dimethyl silicone) was used and in the second, a polar column (polyethylene glycol). On the other hand, limonene has been quantified in the different samples by applying the developed method and using the medium polarity column. Finally, the volatile fraction has been investigated by identifying and quantifying the compounds present in essential oils of citrus fruits by means of HRGC-FID and HRGC-MS using a column of medium polarity and another polarity.
The compounds present in citrus essential oils with a concentration of not less than 0.025% have been quantified by HRGC-FID. The polar column offers better resolution, allowing the quantification of between 37 and 48 compounds depending on the citrus fruit analyzed, while the medium polarity column only allows quantifying between 25 and 32 compounds. However, with the polar column and the more selective and sensitive MS detector, up to 66 compounds have been identified, some of them overlapping or at the trace level.
Comparison of the chromatographic profiles of essential oils has made it possible to determine that their components present qualitative and quantitative differences depending on the origin of the fruit. Likewise, the characteristic compounds of essential oils that contribute to the olfactory note of each fruit have been determined.
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