Essential oil extraction methods of aromatic crops

Essential oil extraction methods of aromatic crops

• 1.
  Essential oil extractionmethods of Aromatic crops COURSE CODE: AGRN-725
• 2.
  What are Essentialoil Essential oils may be defined as volatile odoriferous oils of vegetables origin.  Essential oils are aromatic substances widely used in the Perfume industry, Food and Flavoring, Cosmetics, and Pharmaceutical Products. They have high value in economic since they enter a wide range of industry.
• 3.
  Extraction Methods 1. Distillationincludes :  Steam distillation.  Water distillation. 2. Expression of rasping process 3. Solvent extraction. 4. Maceration. 5. Enfluerage. 6. Pneumatic method
• 4.
  a. Steam distillation The steam was operated at low flow to minimize the amount of water produced; the treated plant was cut for small parts to allow the steam to open the pockets which contain oil. Three condensers were used; the first one is installed on the apparatus, the second one is coil in cold path of water and the third one is flask in cold path of water to get the largest possible quantity of oil and to halt any escape of essential oil from the system. The temperature and pressure were carefully controlled to avoid burning the oil and it was about 100 C and 1 bar. Steam distillation apparatus was modified by adding a valve in the bottom of the apparatus .  Each type of treated plants was collected before doing its experiment, and then the bad parts were removed, after that the plant was cleaned perfectly and cut for small pieces.
• 5.
   The steamgenerator was switched on to produce steam for the experiment, the treated plant was put in the apparatus after it was prepared, cooling water valve was switched on for condensing vapor and the steam was introduced from the bottom of the retort at low flow . The liquid produced was filled in bottle as shown in figure below:
• 6.
  b. Water distillation Itis applied to plant material that is dried and not subject to injury by boiling. Turpentine oil is obtained in this manner. The crude turpentine oleoresin is introduced into the distilling chamber and subjected to heat until all volatile mater (both oil and water) is condensed in the condensing chamber, Before distillation the plant material must be disintegrated to some extent i.e comminuted. Flowers, leaves and other thin nonfiberous parts of the plant can be distilled without comminution, seeds and fruit must be crushed, roots and stalks and all woody materials should be cut into short length in order to expose a great number of oil glands. The comminuted material should be distilled at once to avoid loss of oil by evaporation.
• 8.
  The outer regionof the peel, which contains the oil glands is removed by means of a grater. The rasping are placed in a horsehair bags and strongly pressed. The liquid obtained is turbid, but on standing the oil separates and can be decanted and filtered. 2. Expression on rasping process
• 9.
  3. Solvent extraction Thismethod was used to extract oil from different seeds (lemon seed etc.) at room temperature and using ethanol and n-hexane as a solvents. The next figure shows the main steps for extraction essential oil. Amount of 150 g lemon seeds were grinded in house grinder and put in 1000 ml beaker, then amount of 450 ml ethanol was poured to them, so the solid liquid ratio is roughly 1:3. A mixture of grinded seed and ethanol were mixed in the beaker by using mixer for three hours . Suction filtration was used in order to separate the liquid from other solid material. Rotary evaporator device was used to separate the oil from the ethanol.
• 10.
  10 ml ofpure lemon seeds oil was obtained from this experiment. In addition of lemon seed oil, pure oil was extracted from different seeds such as ( pumpkin seed , aniseed and grape seed) by using different quantities and two different solvents (ethanol and n-hexane). The next figure shows the main steps for extraction essential oil.
• 11.
  Solvent extraction steps-
• 12.
  4. Maceration method Theflowers are gently heated in melted fat (lard or fixed oil) being incorporated and rotated in the fluid until exhausted, then they are strained out, squeezed and the exuded fluid is returned to the fat and so on until a special concentration is reached. The volatile oil containing fat is allowed to cool and the volatile oil is obtained by 3 successive extractions with alcohol. The volatile oil can be obtained in pure form by recovery of alcohol.
• 13.
  The principles ofenfleurage are simple. As certain flowers e.g. jasmine continue their physiological activities of developing and giving off volatile oil even after picking Fats possesses the ability of absorption and if brought in contact with fragrant flowers, readily absorb the volatile oil emitted. In this process, quantities of fresh flowers are lightly layered over a specially prepared fat base, as refined lard, tallow or fatty acids of high molecular weight. The fat is spread in a thin layer on both sides of glass plate supported on a rectangular wooden frame or chassis. Process- Several chassis are placed one above the other so that the flowers get sandwiched between the two layers which absorbs the oil as it is given off. Exhausted glowers are removed and replaced by the fresh flowers until the fat is saturated with flower oil. The perfumed fat must then be removed from the glass plates; the final product is called pomade. 5. Enfluerage
• 14.
  The pomade isextracted three times with alcohol 95% ( Triple extraction), the clear solution known as extracts. The extract contains a small quantity of alcohol soluble fat. The extract is concentrated in a vacuum still at low temperature till free from alcohol; the concentrated flower oil is called absolute of enfluerage., absolute of pomade or liquid concretes.
• 15.
  6. Pneumatic method Thisprocess is similar in principle to the enfluerage method and involves the passage of a current of warm air through the flowers. The air laden with suspended volatile oil is then passed through melted fat in which the volatile is dissolved and absorbed.