Anise Oil Production Process by leaves

Anise leaves are used to produce anise oil, also known as fennel oil, which can produce 0.8-1.0 kg of anise oil per 100 kg of fresh leaves.

The cultivation of star anise is divided into fruit forests for the purpose of fruit picking and leaf forests for the purpose of oil steaming. Due to the different management purposes, the management methods also differ. For those who manage leaf forests, they can interplant crops within two or three years of planting to promote growth and reduce the labor required for care and management.

When the trees grow up and cannot be interplanted, they need to carry out soil and fertilizer management, such as cultivation and fertilization, to ensure that the trees grow vigorously and sprout a large number of branches and leaves. In order to dwarf the canopy and encourage the sprouting of more side branches and the formation of a clump-like canopy, the tree is usually truncated at 1.3 meters.

The oil content varies depending on the age of the tree. Generally, the oil content of old leaves is higher than that of young leaves, so it is best to collect old branches and leaves that are more than a year old. The season for oil collection and steaming generally begins in October, after autumn, and ends in February of the following year. However, if the resources are abundant and the cultivated area is large, branches and leaves can be harvested all year round for oil steaming. Branches and leaves are cut from the base of the branches with a sickle or a woodshedder, 50-70 cm in length, tied with straw and brought back for oil steaming.

In general, there are more than ten branches on each tree in the leaf forest, but only seven or eight branches or half of the branches should be harvested. The cut should be neat and smooth to facilitate the healing of the incision and the sprouting of new branches. Pick branches and leaves to maintain the height of the tree about 1.5-2 meters, octagonal generally three to five years after planting branches and leaves yield less, each plant can receive about 2 kg, between the sixth and twenty years for the prime of life, branches and leaves, the most, each plant can receive about 3 kg, after which production decreases year by year, five to six decades will be senile and withered.

There are currently two production processes for steamed anise oil.

Direct fire heating single pot distillation process

The direct fire heating single pot distillation process is the traditional production process of star anise oil, which is still widely used by individual operators due to its simple equipment, easy mobility and low investment. The process and equipment has been gradually perfected after several reforms, but there are still shortcomings such as low oil yield, long production time, and large fuel consumption. Its production process is as follows.

The anise leaf into the distillation pot, filled with water, the water level 5-10 cm from the flower plate, heated by direct fire and the evaporation of water vapor through the flower plate on the anise leaf layer, so that the anise oil and water vapor distilled out together, condensed by the condenser, cooler, after cooling, into the oil-water separator for oil-water separation, due to the anise oil is lighter than water, suspended in the water, oil-water separation The water containing anise oil is returned to the distillation pot for double distillation to improve the oil yield. The technical and economic indicators of the anise branch oil distillation are as follows.

  • Oil yield 0.8-1.0%
  • Distillation time 8-10 hours
  • Firewood consumption 100-120 kg firewood/kg oil
  • Freezing point ≥15 degrees Celsius

Direct steam heating double boiler tandem distillation process

The tandem distillation process has a more complete process and equipment than the single pot distillation process, which uses high efficiency steam boilers instead of direct fire stoves. The use of coal instead of firewood is of great significance for the protection of forest resources and the maintenance of ecological balance. The process is as follows.

Direct steam heating double boiler tandem distillation equipment consists of two distillation kettles, a condenser, a cooler, and two oil-water separators. The heating method is direct steam. Let’s assume that pot 1 is a refill pot and pot 2 is a pot that has reached the required distillation time. At this time, the oil-water steam mixture produced by the No. 2 distillation kettle does not enter the condenser and separation system, but strung into the No. 1 distillation kettle. 1 distillation kettle produces oil-water steam mixture, introduced by the gooseneck into the condenser, cooler, condensing cooling, and finally into the 1, 2 oil-water separator for oil-water separation.

The distillate is separated from the oil and water, with the oil layer at the top and the water layer at the bottom, and the oil layer is released as a product and the water layer is discharged to the outside. When the distillation reaches the end of the distillation, the No. 2 distillation pot is discharged and new material is put in. At this time, the No. 1 distillation kettle produced by the oil and water mixture of steam cascade into the No. 2 distillation kettle cycle production. The technical and economic indicators are as follows.

  • Oil yield ≥1%
  • Distillation time 6 hours
  • Coal consumption 35-40 kg coal/kg oil
  • Freezing point ≥15 degrees Celsius

Properties and Uses of Anise Oil

Anise oil, also known as anise oil, is a colorless transparent or light yellow liquid when it is above 20 degrees Celsius, and flaky crystals will precipitate when the temperature drops. It is slightly soluble in water and easily soluble in ethanol, ether and chloroform.

Anise oil is a complex composition of aromatic oils, its main component is the trans-anise brain, content of more than 80%. It also contains α-pinene, limonene, linalool, 4-terpineol, artemisinin, anise aldehyde and other components. Its quality indicators are as follows.

  • Relative density 0.987-0.988
  • Freezing point ≥15 degrees Celsius
  • Rotation -2 degree to +1 degree
  • Refractive index 1.533-1.560
  • Dissolve 1 ml of insoluble matter in ethanol and clarify with 3 ml of 90% ethanol.

Negative test for heavy metals (in terms of lead)

Aniseed oil is commonly used as a flavoring agent for food flavors such as alcohol, beverages, candy, baked goods, chewing gum and cigarettes. It is also a good masking agent for those unpleasant odors and is used in soaps and fragrances, mouthwashes and toothpastes. A more important use of aniseed oil is to isolate the aniseed brain, as a preparation of anisaldehyde, anisyl alcohol, anisic acid and its esters.

In the pharmaceutical industry, aniseed oil is the main raw material for the synthesis of the cathartic hormone estrogen.