Distillation, pressing and extraction, adsorption. The steam distillation method is simple in operation and easy to operate. Most of the aromatic oils produced at home and abroad are produced by steam distillation, and it is still one of the main methods for producing aromatic oils in the future. . However, some aromatic plants cannot be processed by steam distillation. What kind of products should be used to produce which products, due to the many factors involved, should be considered comprehensively. When aromatic plants are in contact with hot water and water vapor Most of the components in aromatic plants are heat sensitive substances, and should be considered first when selecting a processing method.

Subcritical (butane, etc.) low temperature extraction

The whole production process of the method is carried out at a low temperature, the nutrient content of the material is not damaged, and the yield is high, and the product has a good appearance. The quality is comparable to that of carbon dioxide supercritical extraction. Large-scale production can be formed, and one-time equipment investment is small. Production costs are low.

1. The citrus oil obtained by steam distillation of citrus oil is more distant from the pressed oil than the pressed oil. This is because the ingredients in the citrus oil are easily damaged by contact with hot water and steam, so the mandarin is distilled. The quality of orange oil is poor. Similarly, when jasmine is steam distilled, some components are destroyed by heat, and therefore, steam distillation cannot be used.

2. Volatilization of the aroma components contained in aromatic plants Some aromatic plants cannot distill their fragrance components by distillation. Vanilla, black peas, benzoin, etc. cannot be distilled by steam distillation. The method can only distill a very small amount of essential oil, but the extraction method not only has a high yield, but also extracts valuable components of the fragrance. This is because the fragrance components of this spice plant are less volatile and can only be extracted.

3. The parts and structures of essential oils in plant tissues contain citrus peels of essential oil sacs, which have larger oil sacs and are located in the superficial parts of the outer cortex, and the citrus peel has a softer structure, so it is suitable for pressing. Raise the oil.

4. After picking the fragrant flowers, the fragrant flowers such as fragrant night jasmine and jasmine can be continuously released under suitable conditions. If the appropriate temperature and humidity can be given after harvesting, there is still vitality in a certain period of time. In the petals, combined with the fragrant ingredients of the cockroaches, the free fragrant ingredients can continue to be released under the action of the enzyme. If the adsorption method is employed, the oil yield can be increased. What should be paid attention to when processing aromatic plants? Aromatic plants, as natural flavors, are often expensive and seasonal and regional. At the same time, it must be noted that all kinds of natural essential oils have their own characteristic aromas, and they are beautiful and soft, which is not enough for synthetic spices. In the middle and the middle of May, it is the blooming period of the rose. It is best to use the fresh roses picked on the day. Rinse the petals with water, remove any impurities such as dust from the top, and drain the water. Due to the chemical nature of rose essential oils, extracting rose essential oil from roses can be done by distillation in water. The specific steps of this experiment are as follows:

1. Weigh 50 g of rose petals into a 500 mL round bottom flask and add 200 mL of distilled water. Install the distillation unit as shown in Figure 6-2 of the textbook. The distillation apparatus includes two iron racks, an alcohol lamp, an asbestos net, a distillation bottle, a rubber stopper, a distillation head, a thermometer, a straight condenser, a liquid pipe, a conical flask, and a rubber hose connecting the water inlet and the water outlet. All instruments must be dried beforehand to ensure no water. The whole distillation unit can be divided into three parts: left, middle and right. The left part is distilled by heating, the middle part distills the distillate, and the right part is used for receiving. The instruments are generally installed in a bottom-up, left-to-right order. The order in which the instruments are removed is the reverse of the installation. The specific installation sequence and method are as follows.

(1) Fixed heat source - alcohol lamp.

(2) Fix the retort so that it is away from the heat source as shown in Figure 6-2 of the textbook, and keep the axis of the retort perpendicular to the horizontal plane of the iron frame.

(3) Install a distillation head so that the cross section of the distillation head is parallel to the iron stand.

(4) Connect the condenser. Ensure that the upper outlet is upwards and connected to the pool through the rubber hose; the lower inlet is downward and connected to the faucet through the rubber hose.

(5) Connect the liquid pipe (or tail pipe).

(6) Align the receiving bottle mouth with the outlet of the tail pipe. Atmospheric distillation generally uses a conical flask instead of a beaker as a receiver. The receiving bottle should be weighed before the experiment and recorded.

(7) Fix the thermometer on the distillation head so that the upper limit of the thermometer mercury ball is on the same horizontal line as the lower limit of the side tube of the distillation head.

2. After the distillation unit is installed, a few zeolites can be added to the distillation flask to prevent the liquid from boiling excessively. Turn on the faucet, slowly let in cold water, and then start heating. It can be observed during heating that the liquid in the retort gradually boils, the vapor gradually rises, and the thermometer reading also rises slightly. When the top of the vapor reaches the thermometer mercury ball, the thermometer reading rises sharply. During the entire distillation process, it should be ensured that the mercury ball of the thermometer often has droplets formed by condensation. The time and speed of distillation are controlled, usually from 1 to 2 drops per second. After the distillation is completed, the heat source should be withdrawn first, then the water is stopped, and finally the distillation unit is disassembled, and the order of disassembly is opposite to that during installation. 3. Collect the milky white emulsion in the Erlenmeyer flask, and add a sodium chloride solution with a mass concentration of 0.1 g/mL to the Erlenmeyer flask to separate the emulsion. It was then poured into a separatory funnel and the oil and water layers were completely separated by a separatory funnel. Open the top plug, then slowly unscrew the piston, release the lower layer of rose essential oil, and collect it with the receiving bottle. Anhydrous sodium sulfate was added to the receiving flask, and the water contained in the oil layer was removed and allowed to stand overnight.

In order to better separate the two layers of oil and water, attention should be paid to the correct use of the separatory funnel. The use of the separatory funnel is as follows.

(1) First dry the piston and apply a layer of grease to the piston. Be careful not to apply the grease too thick or allow the grease to enter the piston hole to avoid contaminating the extract.

(2) After plugging the piston, rotate the piston a few times to make the grease evenly distributed. Check the top plug and the piston of the separatory funnel for water leakage with water, and confirm that it is not leaking before use.

    (3) Place the separatory funnel in an iron ring of appropriate size and fixed on the iron frame, and close the piston. Pour the liquid to be separated into the funnel from the upper opening and plug the top plug. Note that the top plug cannot be greased.

(4) Remove the separatory funnel, use the palm of the right hand to hold the top plug of the funnel and hold the funnel neck, hold the funnel piston with your left hand, press the piston with the thumb, tilt the separatory funnel slightly, and oscillate back and forth (when starting to oscillate) slow).

(5) After shaking, the funnel mouth remains in the original tilt state, the left hand is still held at the funnel piston, the lower nozzle points to the unmanned place, and the piston is opened with the thumb and forefinger to release the steam in the funnel or the resulting Gas, in order to balance the internal and external pressure, this operation is also called "deflation."

(6) Repeat the above operation until only a small amount of gas is released from the separatory funnel. The separatory funnel was shaken vigorously for 2 to 3 minutes, and then the funnel was placed back into the iron ring until the liquid was allowed to stand for stratification.