Volatile oils are generally mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons. The odor and taste of volatile oils is mainly determined by these oxygenated constituents, which are to some extent soluble in water but more soluble in alcohol. NOTE Rose water & tinctures of lemon
1.They possess characteristic odors. 2.They are characterized by high refractive indices. 3.Most of them are optically active. 4.Their density is generally lower than that of water (except for sassafras, clove & cinnamon oils). 5.May darken in color when exposed to light. 6.They are immiscible with water, but they are sufficiently soluble to impart their odor to water. The aromaticity of water depend on this slight solubility.
Essential oils are prepared by: A.Distillation. B.Scarification and expression. C.Extraction. D.Enzymatic hydrolysis. E.Enfleurage.
There are three basic types of essential oil distillation: 1.water or "hydro-distillation" 2.water and steam or "wet steam" 3.steam or "dry steam 1- Hydro-distillation in this method the plant material is immersed totally in boiling water. The disadvantages are that the heat is difficult to control and hence the rate of distillation is variable. Also there is a possibility for overheating and "burning" which lead to a poorer quality oil.
2- Water/steam distillation the plant material is placed on a grid which keeps the plant material above the water level. The water is boiled below the grid and "wet" steam passes through the plant material. Over packing of the still can cause the steam to leave parts of the plant un-extracted. 3- Steam Distillation by direct steam provided from a separate boiler. The still contains a grid plate under which an open steam pipe is fitted. The advantages of "dry" steam distillation are that it is rapid, therefore it is less likely to damage those oils. Most advanced type of distillation
These are mechanical techniques carried at room temperature. Used in preparation of heat sensitive oils. Process: Squeezing of the plant material under water stream which yield a mixture of essential oil, water, cellulose, wax and other substance. Removal of water an cellulose by centrifugation. Removal of wax by chilling followed by feltration.
For preparation of delicate flowers oils which contain either small amounts of oils or heat sensitive oils Classified into: I.Non-volatile solvent extraction. II.Volatile solvent extraction. III.Extraction with supercritical gases.
For glycosidic volatile oils e.g. mustard oil. Principle: 1.Subjecting the plant material to enzymatic hydrolysis to liberate the volatile constituents. 2.Separation of the volatile constituents by distillation or extraction. 3.Purification of the products.
Used to extract oils utilized in perfumery. Process: A glass plate is covered with a thin coating of especially prepared and odourless fat. The freshly cut flowers are individually laid on to the fat which in time becomes saturated with their essential oils. The flowers are renewed with fresh material.
Carrier oils AKA fixed or base oils; are the oily non volatile part of the plant, typically obtained from the seed or nut. They are called fixed as they have large molecules that do not evaporate like the essential oils. Several points differ between volatile oils and fixed oils: 1.Volatile oils can be distilled from their natural sources. 2.Volatile oils do not consist of glyceryl esters of fatty acids. Hence, they do not leave a permanent grease spot on paper and cannot be saponified with alkalis. 3.Volatile oils do not become rancid as do the fixed oils, but instead, on exposure to light and air, they oxidize and resinify.
Origin: Clove consists of the whole flower buds of Syzygium aromaticum. F. Myrtaceae.dried until they become reddish-brown. Morphology The flower bud is reddish-brown and consists of a quadrangular stalked portion, the hypanthium, 10 mm to 17.5 mm long, surmounted by four divergent lobes of sepals which surround a globular head.The head is globular and dome-shaped, composed of four imbricated petals
The powder is dark brown and has strong aromatic spicy agreeable odour and warm spicy agreeable taste Examine under a microscope The powder shows epidermis and underlying parenchyma Large oil glands short fibers occurring singly or in small groups with thickened, lignified walls. abundant of parenchyma containing cluster crystals of calcium oxalate numerous triangular pollen grains Xylem vessels and fibres. Note : prisms of calcium and Starch granules are absent.
Uses relieve pain and to promote healing flavouring industries (spice) anaesthetic properties (for toothache) Antispasmodic and carminative In manufacture of vanillin. Active constituents volatile oil (15 -20%),which contain eugenol (85%). Pyrogallol tannin. Chemical test sudan III red colour. FeCl3 blue colour. KOH: needle crystals of K eugenate.
Clove Stalks Externally, they are brownish and rough.internally presence of prisms of calcium oxalate and pseudo crystal sheath. Mother Cloves This can be detected by the presence of much starch in the seeds. Brown Cloves ( Expanded flowers) Exhausted Cloves lighter than water
Origin: German chamomile is the dried flower heads of Matricaria chamomilla, family Compositae Morphology The flower head is almost hemispherical, with hollow receptacle carrying two types of small sessile flowers called florets: ray florets and central or disc florets.
Active constituents: flavonoid glycosides. volatile oil contains matricarin which converted to chamazulene by heating. Uses calm frayed nerves (tranquilizer). carminative, antispasmodic. local anti-inflammatory for sun burns Chemical test: sudan III : red colour
Origin : Is dried ripe fruits of Pimpinella anisum F. Umbelliferae Morphology Anise fruits are greyish brown, about 2-12mm. long, ovoid,They are broad near the base, and taper gradually towards the apex, which is crowned with a stylopod. Cremocarp separated into its meri-carps which usually remain united and attached to a pedicel longer than the fruit. Each mericap possesses five ridges, rough to touch due to presence of short, stout hairs
The powder is greenish-yellow or brownish-green. The powder have strong aromatic agreeable characteristic taste and sweet strongly aromatic taste shows the following characters: fragments of branched vitta usually crossed by the cells of the endocarp aleurone grains micro-rosettes of calcium oxalate non-glandular, unicellular warty hairs Few fibres and pitted parenchyma
Active constituents 1. Volatile oil (2 to 6%) contain anethole 2. fixed oil and protein. Uses: Carminative flavoring agent Stimulant Chemical test: Sudan III
Origin: Cinnamon is the dried bark of cinnamomum zeylanicum, Family Lauraceae, deprived of most of its cortex known as Ceylon Cinnamon. Morphology Cinnamon occurs as quills (single or double compound quills ).1 meter in length.
powder: a reddish brown powder with a characteristic pleasant and aromatic odour and taste, showing fragments of: fibres, they are thick-walled and lignified with lumen and few slit-shaped pits. thin-walled oil cells Sclereids, isodiametric, thick wall, lignified, the outer wall is less thickened than the others. Starch granules and needle crystals of calcium oxalate. Cork cells are rare
Constituents: 1) volatile oil (0.5 -1 % ) (contains cinnamicaldehyde, eugenol) 2) tannin and mucilage Uses: - Carminative - Antispasmodic - Mild astingent - Flavoring agent. The oil is also a powerful germicide Chemical test: Sudan III, Rhuthenium red, FeCl3 and KOH for eugenol
Origin: It is the dried bark of Cinnamomum cassia,Family Lauraceae. Morphology: Chanelled pieces or Single quill up to 40 cm long, earthy brown colour with patches of the thin grayish cork.
Powder : differs than cinnamon in: 1.Odour is less delicate, taste as cinnamon but slightly mucilaginous. 2.Numerous fragments of cork cells, polygonal with slightly thick wall, contains reddish brown content. 3.Fibres are shorter and thicker.
Active constituents: Volatile oil consisting of Cinnamicaldehyde,no eugenol is found Use The same uses as cinnamon bark Chemical test all as cinnamon but negative test for eugenol
Origin: they dried from the leaves and flowering tops of Mentha piperita F. Labiatae
Powder the powder is brownish-green. with an aromatic characteristic odour and an aromatic taste followed by a sensation of cold in the mouth. It is characterized microscopically by the presence of fragments of: cells of the epidermis having wavy walls and diacytic stomata Glandular labiaceous hair, unicellular base with multicellular head composed of 8-16 radiating cells Non-glandular hairs. Different types of xylem vessels, fibres and wood parenchyma. Calcium oxalate crystals are absent
Active constituents 1. Volatile oil : chief components are menthol 2. Tannin Uses: 1. carminative and flavoring agent. 2. inflammation of the mouth and pharynx (oral preparations) 3. Menthol is used in pharmaceutical preparations as local antipruritic, counter irritant and antiseptic. 4. Recently the oil is used for treatment of colitis. 1. Chemical test: Sudan III