ARTIKEL KIMIA ORGANIK I

Essential Oil ( Minyak Atsiri)

Oleh:

AWILDA MIKE PERTIWI

1120006

I A

KIMIA ANALISIS

AKADEMI TEKNOLOGI INDUSTRI PADANG

PADANG

2012Essential oil

An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants.

Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the

plant from which they were extracted, such as oil of clove. An oil is "essential" in the sense that it

carries a distinctive scent, or essence, of the plant. Essential oils do not form a distinctive category for

any medical, pharmacological, or culinary purpose.

Essential oils are generally extracted by distillation. Other processes include expression, or solvent

extraction. They are used in perfumes, cosmetics, soaps and other products, for flavoring food and

drink, and for adding scents to incense and household cleaning products.

Various essential oils have been used medicinally at different periods in history. Medical applications

proposed by those who sell medicinal oils range from skin treatments to remedies for cancer, and often

are based solely on historical accounts of use of essential oils for these purposes. Claims for the

efficacy of medical treatments and treatment of cancers in particular, are now subject to regulation in

most countries.

As the use of essential oils has declined in evidence-based medicine, one must consult older textbooks

for much information on their use. Modern works are less inclined to generalize; rather than refer to

"essential oils" as a class at all, they prefer to discuss specific compounds, such as methyl salicylate,

rather than "oil of wintergreen".

Interest in essential oils has revived in recent decades with the popularity of aromatherapy, a branch of

alternative medicine that claims that essential oils and other aromatic compounds have curative effects.

Oils are volatilized or diluted in a carrier oil and used in massage, diffused in the air by a nebulizer,

heated over a candle flame, or burned as incense.

Characteristic of essential oil

Essential oils are volatile due to low vapor point. In addition, the arrangement of its component

compounds strongly affects the human nervous (especially in the nose) so it is often a certain

psychological effect (strong smell). Each constituent has the effect of individual compounds, and

mixtures can produce different flavors.

Chemically, essential oils are composed of a complex mixture of various compounds, but a particular

compound is usually responsible for a particular scent. Most of the Essential Oils in a class of organic

compounds including terpenes and terpenoids which are soluble in oil / lipophilic.

Production

Distillation

Today, most common essential oils, such as lavender, peppermint, and eucalyptus, are distilled. Raw

plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, or peel, is put into an alembic

(distillation apparatus) over water. As the water is heated, the steam passes through the plant material,

vaporizing the volatile compounds. The vapors flow through a coil, where they condense back to liquid,

which is then collected in the receiving vessel.

Most oils are distilled in a single process. One exception is ylang-ylang (Cananga odorata), which takes

22 hours to complete through a fractional distillation.

The recondensed water is referred to as a hydrosol, hydrolat, herbal distillate or plant water essence,

which may be sold as another fragrant product. Popular hydrosols include rose water, lavender water,

lemon balm, clary sage and orange blossom water. The use of herbal distillates in cosmetics is

increasing. Some plant hydrosols have unpleasant smells and are therefore not sold.

Expression

Most citrus peel oils are expressed mechanically, or cold pressed (similar to olive oil extraction). Due to

the relatively large quantities of oil in citrus peel and low cost to grow and harvest the raw materials,

citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils that are obtained

as byproducts of the citrus industry are even cheaper.

Prior to the discovery of distillation, all essential oils were extracted by pressing.

Solvent extraction

Most flowers contain too little volatile oil to undergo expression and their chemical components are too

delicate and easily denatured by the high heat used in steam distillation. Instead, a solvent such as

hexane or supercritical carbon dioxide is used to extract the oils. Extracts from hexane and other

hydrophobic solvent are called concretes, which are a mixture of essential oil, waxes, resins, and other

lipophilic (oil soluble) plant material.

Although highly fragrant, concretes contain large quantities of nonfragrant waxes and resins. Often,

another solvent, such as ethyl alcohol, which is more polar in nature, is used to extract the fragrant oil

from the concrete. The alcohol is removed by evaporation, leaving behind the absolute.

Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. This method has many

benefits including avoiding petrochemical residues in the product and the loss of some "top notes"

when steam distillation is used. It does not yield an absolute directly. The supercritical carbon dioxide

will extract both the waxes and the essential oils that make up the concrete. Subsequent processing

with liquid carbon dioxide, achieved in the same extractor by merely lowering the extraction

temperature, will separate the waxes from the essential oils. This lower temperature process prevents

the decomposition and denaturing of compounds. When the extraction is complete, the pressure is

reduced to ambient and the carbon dioxide reverts to a gas, leaving no residue. An animated

presentation describing the process is available for viewing.

Supercritical carbon dioxide is also used for making decaffeinated coffee. Although it uses the same

basic principles, it is a different process because of the difference in scale.

Usefulness of essential oils in the industry

Essential oil obtained from distillation or can be extracted by distillation. So that the extract can be used

for cosmetics, soaps, perfumes, food flavorings, add flavor to the household products and other

products. In the medical science of essential oils are used as medicine.

The main components of essential oils

Terpenes are a large and diverse class of organic compounds, produced by a variety of plants,

particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit

terpenes from their osmeteria. They are often strong smelling and thus may have had a protective

function.

They are the major components of resin, and of turpentine produced from resin. The name "terpene" is

derived from the word "turpentine". In addition to their roles as end-products in many organisms,

terpenes are major biosynthetic building blocks within nearly every living creature. Steroids, for

example, are derivatives of the triterpene squalene.

When terpenes are modified chemically, such as by oxidation or rearrangement of the carbon skeleton,

the resulting compounds are generally referred to as terpenoids. Some authors will use the term

terpene to include all terpenoids. Terpenoids are also known as isoprenoids.

Terpenes and terpenoids are the primary constituents of the essential oils of many types of plants and

flowers. Essential oils are used widely as natural flavor additives for food, as fragrances in perfumery,

and in traditional and alternative medicines such as aromatherapy. Synthetic variations and derivatives

of natural terpenes and terpenoids also greatly expand the variety of aromas used in perfumery and

flavors used in food additives. Vitamin A is an example of a terpene.

Terpenes are released by trees more actively in warmer weather, acting as a natural form of cloud

seeding. The clouds reflect sunlight, allowing the forest to regulate its temperature.

The aroma and flavor of hops, highly desirable in some beers, comes from terpenes. Of the terpenes in

hops myrcene, b-pinene, b-caryophyllene, and a-humulene are found in the largest quantities.

Types

Terpenes may be classified by the number of terpene units in the molecule; a prefix in the name

indicates the number of terpene units needed to assemble the molecule.

Hemiterpenes consist of a single isoprene unit. Isoprene itself is considered the only

hemiterpene, but oxygen-containing derivatives such as prenol and isovaleric acid are

hemiterpenoids.

Monoterpenes consist of two isoprene units and are derived from the molecular formula

C10H16. Examples of monoterpenes are: geraniol, limonene and terpineol.

Sesquiterpenes consist of three isoprene units and are derived from the molecular formula

C15H24. Examples of sesquiterpenes are: farnesenes, farnesol. (The sesqui- prefix means one

and a half.)

Diterpenes are composed of four isoprene units and have the molecular formula C20H32. They

derive from geranylgeranyl pyrophosphate. Examples of diterpenes are cafestol, kahweol,

cembrene and taxadiene (precursor of taxol). Diterpenes also form the basis for biologically

important compounds such as retinol, retinal, and phytol. They are known to be antimicrobial

and antiinflammatory.

Sesterterpenes, terpenes having 25 carbons and five isoprene units, are rare relative to the

other sizes. (The sester- prefix means half to three, i.e. two and a half.) An example of a

sesterterpene is geranylfarnesol.

Triterpenes consist of six isoprene units and are derived from the molecular formula C30H48.

The linear triterpene squalene, the major constituent of shark liver oil, is derived from the

reductive coupling of two molecules of farnesyl pyrophosphate. Squalene is then processed

biosynthetically to generate either lanosterol or cycloartenol, the structural precursors to all the

steroids.

Sesquarterpenes are composed of seven isoprene units and are derived from the molecular

formula C35H56. Sesquartepenes are typically microbial in their origin. Examples of

sesquarterpenes are ferrugicadiol and tetraprenylcurcumene.

Tetraterpenes contain eight isoprene units and are derived from the molecular formula C40H64.

Biologically important tetraterpenes include the acyclic lycopene, the monocyclic gamma-

carotene, and the bicyclic alpha- and beta-carotenes.

Polyterpenes consist of long chains of many isoprene units. Natural rubber consists of

polyisoprene in which the double bonds are cis. Some plants produce a polyisoprene with trans

double bonds, known as gutta-percha.

Kesimpulan :

Minyak Atsiri, atau dikenal juga sebagai Minyak Eteris (Aetheric Oil), Minyak Esensial, Minyak

Terbang, serta Minyak Aromatik, adalah kelompok besar minyak nabati yang berwujud cairan kental

pada suhu ruang namun mudah menguap sehingga memberikan aroma yang khas. Minyak Atsiri

merupakan bahan dasar dari wangi-wangian atau minyak gosok (untuk pengobatan) alami. Di dalam

perdagangan, sulingan Minyak Atsiri dikenal sebagai bibit minyak wangi.

Minyak Atsiri merupakan metabolit sekunder yang biasanya berperan sebagai alat pertahanan diri agar

tidak dimakan oleh hewan (hama) ataupun sebagai agen untuk bersaing dengan tumbuhan lain (lihat

alelopati) dalam mempertahankan ruang hidup. Walaupun hewan kadang-kadang juga mengeluarkan

bau-bauan (seperti kesturi dari beberapa musang atau cairan yang berbau menyengat dari beberapa

kepik), zat-zat itu tidak digolongkan sebagai Minyak Atsiri.

Minyak Atsiri merupakan suatu minyak yang mudah menguap (volatile oil) biasanya terdiri dari

senyawa organik yang bergugus alkohol, aldehid, keton dan berantai pendek. Minyak atsiri dapat

diperoleh dari penyulingan akar, batang, daun, bunga, maupun biji tumbuhan, selain itu diperoleh juga

terpen yang merupakan senyawaan hidrokarbon yang bersifat tidak larut dalam air dan tidak dapat

disabunkan. Beberapa contoh minyak atsiri yaitu minyak cengkeh, minyak sereh, minyak kayu putih,

minyak lawang dan lain-lain.

Ciri-ciri :

Minyak Atsiri bersifat mudah menguap karena titik uapnya rendah. Selain itu, susunan senyawa

komponennya kuat mempengaruhi saraf manusia (terutama di hidung) sehingga seringkali memberikan

efek psikologis tertentu (baunya yang kuat). Setiap senyawa penyusun memiliki efek tersendiri, dan

campurannya dapat menghasilkan rasa yang berbeda.

Secara kimiawi, minyak atsiri tersusun dari campuran yang rumit berbagai senyawa, namun suatu

senyawa tertentu biasanya bertanggung jawab atas suatu aroma tertentu. Sebagian besar Minyak

Atsiri termasuk dalam golongan senyawa organik terpena dan terpenoid yang bersifat larut dalam

minyak / lipofil.

Produksi Minyak Atsiri

1. Destilasi

Minyak atsiri yang berasal dari tumbuhan yang diambil bunga, biji, kulit kayu, akar dan daun yang

dimasukkan kedalam labu didih dari alat destilasi (satu set alat destilasi), kemudian ditambahkan

dengan pelarut dan dipanaskan. Setelah itu uap akan melewati bahan tanaman dan kemudian uap

menuju kondensor dan didinginkan hingga diperoleh destilat yang murni.

Destilat ini disebut juga dengan esensi tanaman yang memiliki bau yang harum, namun juga ada

yang tidak berbau enak atau busuk sehingga tidak bisa dijual.

2. Ekspresi

Sebelum adanya teknik destilasi maka untuk mendapatkan minyak atsiri dari tanaman dapat

digunakan dengan cara merendam dan menekan bahan sehingga didapatkan hasil pres-an. Namun

cara ini sepertinya tidak efektif karena akan memerlukan bahan yang banyak dan tenaga yang lebih

serta waktu yang lama. Cara ini juga tidak efektif karena hasil pres-an tidak terlalu murni.

Kedua cara inilah yang umum digunakan untuk mendapatkan minyak atsiri dari bahan-bahan yang

mengandung minyak tersebut.

Kegunaan minyak atsiri dalam industri

Minyak atsiri diperoleh dari penyulingan atau dapat diekstrak dengan cara destilasi. Sehingga hasil

ekstrak tersebut dapat digunakan untuk kosmetik, sabun, parfum, penyedap makanan, menambahkan

aroma pada produk-produk rumah tangga serta produk lainnya. Didalam ilmu medis minyak atsiri

digunakan sebagai obat

Komponen Utama Minyak atsiri

Terpena merupakan suatu golongan hidrokarbon yang banyak dihasilkan oleh tumbuhan dan terutama

terkandung pada getah dan vakuola selnya. Pada tumbuhan, senyawa-senyawa golongan terpena dan

modifikasinya, terpenoid, merupakan metabolit sekunder. Terpena dan terpenoid dihasilkan pula oleh

sejumlah hewan, terutama serangga dan beberapa hewan laut. Di samping sebagai metabolit

sekunder, terpena merupakan kerangka penyusun sejumlah senyawa penting bagi makhluk hidup.

Sebagai contoh, senyawa-senyawa steroid adalah turunan skualena, suatu triterpena; juga karoten dan

retinol. Nama "terpena" (terpene) diambil dari produk getah tusam, terpentin (turpentine).

Terpena dan terpenoid menyusun banyak minyak atsiri yang dihasilkan oleh tumbuhan. Kandungan

minyak atsiri memengaruhi penggunaan produk rempah-rempah, baik sebagai bumbu, sebagai

wewangian, serta sebagai bahan pengobatan dan kesehatan.

Tipe-tipe Terpena

Terpen-terpen adalah suatu golongan senyawa yang sebagian besar terjadi dalam dunia tumbuh-

tumbuhan. Hanya sedikit sekali terpen-terpen yang diperoleh dari sumber-sumber lain.

Monoterpen-monoterpen dan seskuiterpen adalah komponen utama dari minyak menguap atau minyak

atsiri. Minyak menguap ini diperoleh dari daun atau jaringan-jaringan tertentu dari tumbuh-tumbuhan

atau pohon-pohonan. Minyak atsiri adalah bahan yang mudah menguap, sehingga ia mudah

dipisahkan dari bahan-bahan lain yang terdapat dalam tumbuh-tumbuhan. Salah satu cara yang paling

popular untuk memisahkan minyak atsiri dari jaringan tumbuh-tumbuhan ialah penyulingan. Senyawa-

senyawa di dan triterpen tidak dapat diperoleh dengan jalan destilasi uap, tapi diperoleh dari tumbuh-

tumbuhan dan tanaman karet atau resin dengan jalan isolasi serta metoda pemisahan tertentu.

Beberapa contoh terpenoid :

Monoterpen :

Seskuiterpen :

Politerpen :

Terpenoid Tak Teratur :

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