Fruit Sensations: Aromatic And Flavorful Oils Unveiled

The aroma and flavour of fruits are determined by a combination of volatile compounds, which are mainly comprised of esters, alcohols, aldehydes, ketones, lactones, terpenoids and apocarotenoids. These compounds are derived from the breakdown of lipids, amino acids, terpenoids and carotenoids.

The most important aroma compounds include amino acid-derived compounds, lipid-derived compounds, phenolic derivatives, and mono- and sesquiterpenes.

The specific aroma and flavour of a fruit is dependent on the combination of volatiles, the concentration and the perception threshold of individual volatile compounds.

For example, volatile esters often represent the major contribution to the aroma and flavour of apples and peaches.

Citrus fruits, on the other hand, have a rind which contains a lot of essential oil. The citrus fruit peel can be steam-distilled or cold-pressed to make essential oils.

Citrus fruits such as oranges, lemons, and grapefruits have a rind which contains a lot of essential oil

Citrus fruits are renowned for their highly fragrant aromas and complex flavors. They are native to South Asia, East Asia, Southeast Asia, Melanesia, and Australia. The large citrus fruit of today evolved originally from small, edible berries over millions of years.

The essential oils from citrus fruits can be obtained through steam distillation or cold-pressing the fruit peel. Citrus fruits have a unique aroma that depends on the combination of volatiles, the concentration, and the perception threshold of individual volatile compounds.

The most important aroma compounds in citrus fruits include amino acid-derived compounds, lipid-derived compounds, phenolic derivatives, and mono- and sesquiterpenes.

The essential oils from citrus fruits have various therapeutic properties and are used in aromatherapy. They are also used as flavoring agents and in cleaning products.

The health benefits of citrus essential oils include improved mood, reduced stress, enhanced focus, improved skin health, and a boosted immune system.

In addition to the essential oils, citrus fruits are also a good source of vitamin C and citric acid.

Fruit volatile compounds are mainly comprised of esters, alcohols, aldehydes, ketones, lactones, terpenoids and apocarotenoids

The volatile compounds in fruit that give them their aroma and flavour are comprised of esters, alcohols, aldehydes, ketones, lactones, terpenoids and apocarotenoids.

Esters are the most abundant volatile compounds emitted by apples and, together with α-farnesene, have been proposed for cultivar classification.

Aldehydes and alcohols are produced by the enzymatic breakdown of unsaturated fatty acids.

Terpenoids are derived from the universal C5 precursor isopentenyl diphosphate (IPP) and its allylic isomer dimethylallyl diphosphate (DMAPP).

Apocarotenoids are synthesised from carotenoids.

The most important aroma compounds include amino acid-derived compounds, lipid-derived compounds, phenolic derivatives, and mono- and sesquiterpenes

Amino acid-derived compounds are a diverse group of molecules that contribute to the overall sensory experience of fruits. These compounds are formed through various biochemical pathways, including the shikimate pathway and the degradation of amino acids such as phenylalanine, tyrosine, and tryptophan.

Lipid-derived compounds are another important group of aroma compounds found in fruits. Lipids are essential components of cell membranes and are involved in energy storage. During the maturation and disruption of plant tissues, lipid oxidation occurs, resulting in the formation of volatile compounds that contribute to the characteristic flavour of many fruits.

Phenolic derivatives are a diverse class of compounds that include flavonoids, phenolic acids, and anthocyanins. They are derived from the shikimate pathway and play a vital role in plant defence mechanisms. In fruits, phenolic derivatives contribute to colour, astringency, and bitterness, as well as providing health benefits due to their antioxidant properties.

Monoterpenes and sesquiterpenes are types of terpenes, which are aromatic compounds derived from the mevalonic acid pathway or the methylerythritol phosphate pathway. They are responsible for the aroma and flavour of many fruits, including strawberries, raspberries, and grapes. Terpenes also have important biological activities, such as antioxidant and anti-inflammatory properties.

Overall, these four groups of aroma compounds play a crucial role in determining the unique sensory characteristics of fruits and contribute to their overall appeal and nutritional value.

The most common methods of extracting essential oils from fruit are cold-pressing and steam-distilling

Cold-pressing

Cold-pressing is a traditional method used for extracting oils from fruits that degrade when exposed to heat, such as lemons, oranges, and grapefruits. This technique involves scraping or pricking the fruit, usually the peels, and pressing, rinsing, and then separating the extracted oil from the fruit using water. Cold-pressed oils retain natural flavours, colours, sterols, and vitamins. However, not all fruits are suitable for cold-pressing, and the process is not efficient for high-volume extraction.

Steam-distilling

Steam-distilling is the most common extraction technique for essential oils. In a still, pressurized steam is passed through the fruit, rupturing the plant structures that hold the essential oils and releasing constituent volatile and non-volatile compounds. The resulting liquid is condensed and naturally separates into two layers: essential oil and hydrosol. Examples of hydrosols include rosewater and orange flower water.

The shelf life of cold-pressed fruit oils is about 6 months

Cold-pressed oils have a limited shelf life because they are prone to rapid rancidification, oxidation, and spoilage if not used within this time frame. To maximise shelf life, cold-pressed oils should be stored in the cold (refrigeration) and dark (non-transparent bottles) places.

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