Introduction to lemon citronella, the efficacy and function of lemon citronella

Lemon citronella was widely cultivated in Taiwan in the 1940s and 1950s to extract citronella oil for export. At that time, mint oil and camphor oil were one of the most important agricultural products for Taiwan to earn foreign exchange. After 1957, due to the development of chemical synthesis technology, natural citronella oil was inferior to chemical synthesis, and citronella was forgotten to survive in the mountains. At present, only sporadic production, commonly seen in tourist attractions vendors, to dispel mosquitoes as a function of selling. In fact, citronella is widely used, not only in the extraction of citronella oil as mosquito repellent, but also in the international market, citronella oil is widely used in perfume, cosmetics, soft drinks, soap, detergent and other essential materials, and has a long history. As a result, when many people touch this plant that looks like mango and smell it at first, they can't help but evoke the familiar smell of childhood, suddenly remembering that it is the soap or soap smell of ancient life. Fresh or dried lemongrass has a pleasant lemon flavor and can be used as lemonade instead of lemon. Brewing with hot water as herbal tea or herbal tea is also very delicious. The tender stem at the base is suitable for adding flavor to fish and broth dishes. In India and Southeast Asian countries, citronella is a necessary raw material for home diet, and it is even used as a cold and wind-dispelling herb.

Lemon citronella, also known as citronella, is a perennial evergreen herb of Poaceae (Gramineae), Cymbopogon. It is widely cultivated in tropical and subtropical regions. Lemongrass in English mainly refers to Cymbopogon citratus (DC.) cultivated in West Indies and Ceylon. Ex Nees) Stapf. The species of citronella. In addition, citronella cultivated in East India, scientific name: Cymbopogon flexuosus (DC.) Stapf., is a variety known as cochin or malabar grass in its producing area, also known as lemongrass. At present, the world's main producing countries include Guatemala, India, Chinese mainland, Paraguay, the United Kingdom, Ceylon and other countries, as well as Indonesia, Africa, Central and South America and parts of South America. The cultivated area is roughly estimated to be about 50,000 hectares. the products of citronella in the international market include fresh grass, hay, essential oil and potted plants. statistical analysis shows that the market price is stable and the demand is increasing.

Plant classification

There are about 50 to 60 species of citronella (Cymbopogon), which is the only species of Gramineae with special aroma of ​​ in its leaves. The classification of citronella is mainly divided into five species: 1. Lemon citronella, essential oil market known as West Indian citronella (west indian lemongrass), scientific name: Cymbopogon citratus (DC. Ex Nees) Stapf. two。 C. flexuosus (Nees es steud.) W, the essential oil market is called East India citronella (east indian lemongrass); 3. Ceylon citronella (Ceylon citronella), scientific name: C. nardus. 4. Java citronella (Java citronella), scientific name: C. winterianus. 5. Martin citronella (palmarosa and gingergrass), scientific name: C. martinii), etc. The first two main components are citral (citral), while Ceylon citronella and Java citronella mainly contain citronellal (citronella). Martin citronella contains a large amount of geraniol (geraniol) in addition to citronellal and citronellol, and the extracted essential oil is called palmarosa. The other varieties are the varieties bred by the main cultivated countries according to the composition and content of essential oil or agronomic characters. Lemon citronella and Ceylon citronella were widely cultivated in Taiwan in the past. The former has lemon aroma and pleasant taste, fresh or dry stems and leaves can make tea, bath, dim sum and meat, fish soup dishes, or extract essential oils for aromatherapy, flavors, perfumes and cosmetics. The latter has a strong smell, sensitive people will have the feeling of dizziness, it is suitable to extract essential oils to dispel bad smells or worms, and is often used to make primary processing soaps, candles and other products. In addition, there are species of citronella steppe in Taiwan, whose scientific name is C. tortilis, which is scattered in the hills and fields of Taiwan. There is another genus in the family Gramineae, that is, the grass grass, its fragrance exists in the roots, in addition to essential oils can be extracted, but also can be used as medicinal and soil and water conservation plants.

Agronomic characteristics

Lemon citronella is a perennial herb with lemon aroma. The plant has a large number of tillers and clumps, with a maximum diameter of about 2 meters. The leaves are wide and strip-shaped, clasping stems, up to 1 meter in length and 1.5 to 3.0 centimeters in width. The color of leaves is mostly green, and the depth varies according to the cultivation environment, so it is not easy to be used as a basis for classification. Both sides of the leaf blade are rough and grayish white; the leaf sheath is smooth; the ligule is thick and scaly. The edges are serrated, so you should be careful when you touch them. They are easy to be cut. Lemon citronella (C. citrates) stem color is mostly light green to medium green. Citronella (C. flexuosus) has two types (types), one with apple green to white stem and the other with red stem. The color of the stem is mostly light green to medium green. Wax powder is common in stem internodes.

Lemon citronella seldom heads and blossoms, so it is propagated by root plant or stem tiller. Occasionally flowering in summer and autumn, the inflorescence is a loose panicle, composed of multi-node pairs of racemes, branched, base interrupted, branches slender and downward arched, the first branch has 1-5 nodes, the second and third branches have about 2-3 nodes and simple. Racemes have 4 nodes, spike rachis internodes villous, each pair of racemes supported by boat-shaped, sheath-shaped involucre; spikelets awnless, sessile spikelets bisexual, stalked spikelets lead-purple. Because citronella rarely blossoms, it is difficult to identify the differences between varieties by the structure of floral apparatus. The appearance of the plant is difficult to identify because of the different cultivation environment and management methods. In the initial cultivation, you can directly look for reliable seedling merchants to buy, supplemented by the identification of aroma. Generally, citral is the main aroma component of lemon citronella and meandering citronella. On the other hand, the leaf sheath of citronella is dark red, with dense fine bristles, and a long loose and drooping inflorescence can be seen at flowering. Citronellal and citronellol are the main aroma components of essential oil.

Cultivation environment and key points

Cultivation environment: citronella prefers warm, wet all-sunshine environment and sandy soil with good drainage. The main cultivated areas in India are distributed in the areas where the average temperature is between 18 and 29 ℃, the average annual rainfall is 70 to 410mm, and the soil pH is between 5.0 and 5.8 (East India) and the soil pH is between 4.3 and 8.4 (West India). However, the climatic environment for the maximum oil yield per metric ton of fresh grass is that the suitable temperature for growth is between 25 and 30 ℃ and the average annual rainfall is between 2500 and 3000mm. At the same time, the annual amount of nitrogen fertilizer is about 186 kg per hectare, phosphate fertilizer 26 kg / ha, potash fertilizer 384 kg / ha and so on. Nitrogen fertilizer had a great effect on the fresh grass yield of aboveground parts of the plant, while potassium fertilizer had a great effect on the yield of citronella oil.

Propagation methods: citronella citronella rarely blossoms and bears fruit, so the propagation methods are mainly root plants or tillers. Mature lemon citronella, each with about 50-200 ramets, cut off the upper leaves, leaving about 10-15 cm with roots, and can be planted directly in the field. On the other hand, sinuous citronella can reproduce seeds with a sowing rate of about 5-10 kg / ha.

Main points of cultivation: the distance between cultivated rows and plants is generally 100X45 cm. The first harvest is feasible about 6 to 8 months after planting, and then once every 3 to 4 months on average. The report points out that the yield of fresh grass and essential oil harvested 20 cm from the ground is higher. The hay yield is about 4-6 metric tons per hectare, and citronella oil production is 30-40 kg per hectare (4 to 5 harvests per year), which can be harvested mechanically or manually.

Chemical composition

Citronella grass contains volatile oil (essential oil). Citronella oil is extracted by steam distillation, and the extraction rate of essential oil is about 0.2 to 0.5%. Citronella should be withered and then extracted after harvest. Citronella oil is generally yellow to dark yellow. The essential oil can detect more than 100 kinds of chemical constituents, and the main chemical composition is citral 70% 80% (citral) and geraniene (myrcene) about 20%, and contains citronellal (citronellal), geraniol (geraniol geraniol), levorneol (l-borneol), 1mer 8-p-menthadiene-5-ol (1min 8-menthadienyl 5-ol) and so on. These ingredients are mainly used in perfumes and cosmetics. It is generally believed that the citral content of lemon citronella is lower than that of meandering citronella, but there is no final conclusion.

Application of citronella citronella

Application of fresh grass and hay: lemon citronella can be used throughout the grass, fresh grass or dried plant leaves and stems have a strong lemon flavor, which is widely used in soups and meat seasonings in India, Vietnam, Thailand and other countries in Asia, such as adding leaves to curry. In India, crush citronella and put it in clean water, which is used as shampoo and toilet water. It can also be used to add flavor to non-alcoholic beverages, baked goods and pastries. Lemon citronella tea brewing method: take about 3 grams of hay or cut an appropriate amount of fresh grass (5-10 grams), brew in 250 grams of hot water, sit for 5-10 minutes to drink, can also be mixed with other herbs. At present, farmers in central Taiwan also sell dried citronella pillows.

Application of citronella oil: citronella oil can be directly used as perfume, cosmetics, soap, cream and other processing products. Lemon citronella essential oil is a semi-dry essential oil, which is thought to be helpful to oily skin in aromatherapy. Because citral can be used as the raw material for the synthesis of ionone (ionones; perfume and cosmetic flavor raw material). Therefore, citral can be fractionated from citronella oil as an essential ingredient in soft drinks, soaps, perfumes, cosmetics and detergents, as well as to cover up the bad smell of many industrial products.

Medicinal uses: in traditional or folk medical applications, citronella is considered to have the effect of dampness and deworming. In the classification of Chinese herbal medicine, its nature and taste function is classified as pungent and warm. The function is to dispel wind and dehumidification, reduce swelling and relieve pain. In addition, related research reports have pointed out that lemon citronella essential oil has sedative and antimicrobial effects. Sinuous citronella essential oil has antifungal effect. Volatile oil has insecticide and mutagenic effect. The report points out that citronella is toxic to fungi. At present, in the cultivation and management of some organic cultivation, diluted citronella oil is used as an organic insecticide or planting citronella grass as a repellent plant, but the actual effect remains to be confirmed by experimental data.

Safety and side effects: at present, extracts or essential oils from lemon citronella plants have been evaluated as safe and can be used for edible or external use, and no side effects have been reported. However, citronella essential oil is irritant, excessive use will cause redness and swelling, need appropriate use.

Over the years, people like to grow some fruits themselves, and consumers are increasingly interested in the cultivation and application of vanilla. The harvested plants can be used for tea, cooking, bathing and soaking. The Summer Solstice has passed in recent days, and Lesser Heat and Greater Heat will follow one after another. hot weather, coupled with mosquitoes flying, try to use lemon citronella essential oil products or cook a pot of lemon citronella chicken soup and fish soup when going out for an outing or staying at home. it may eliminate some annoying mosquitoes and summer citronella, citronella has a pleasant lemon aroma, but also has the advantages of high-temperature, humid climate, soil environment and rapid growth. Cultivation and management is extremely easy. Operators can be cultivated on the edge of the farm or around the vanilla field. When swaying in the wind, the stems and leaves rub and naturally emit the natural aroma of citronella!