Lemongrass (Cymbopogon flexuosus) is a perennial herbaceous plant belonging to the botanical family Poaceae. It forms dense clumps with long, narrow, ribbon-like leaves of an intense green color, with a fresh, citrusy and slightly pungent scent that is noticeable as soon as the leaves are rubbed. It is cultivated in various tropical and subtropical regions mainly for the production of essential oil.
As a food ingredient, citronella is used mainly in fresh or dried form (leaves and sometimes tender stalks) and, in very small amounts, as food-grade citronella essential oil. It is a typical component of many Asian cuisines (soups, curries, marinades, fish and chicken dishes), to which it imparts citrus notes reminiscent of lemon but more herbaceous. It can also be used in herbal teas and infusions with a refreshing, slightly citrusy taste. Because its aroma is intense, it is used sparingly so as not to overpower the other flavors in the dish.
Cymbopogon flexuosus, commonly known as Lemongrass or East Indian Lemongrass, is a perennial grass native to tropical regions of Asia. It is widely used for its aromatic properties and is a key ingredient in many culinary and medicinal applications. The plant is recognized for its tall, slender stems and citrusy fragrance.
Botanical Classification:
- Kingdom: Plantae
- Order: Poales
- Family: Poaceae
- Genus: Cymbopogon
- Species: Cymbopogon flexuosus
Plant Characteristics: Cymbopogon flexuosus is characterized by:
- Leaves: The plant has long, narrow leaves that are green and can grow up to 1.5 meters (5 feet) in length. The leaves are known for their lemon-like aroma, which is released when they are crushed or cut.
- Stems: The stems are tall and slender, growing in clumps. They are typically 1-2 meters (3-6 feet) tall.
- Flowers: Cymbopogon flexuosus produces inconspicuous flower spikes that are not prominently displayed. The primary value of the plant lies in its leaves rather than its flowers.
- Soil and Light: Prefers well-drained, sandy loam soils and full sun. It thrives in warm climates and can tolerate periods of drought once established.
Chemical Composition and Structure: The chemical composition of Cymbopogon flexuosus includes:
- Essential Oils: The leaves contain essential oils that are rich in citral, a compound responsible for the lemon-like scent. Citral is composed of two isomers: neral and geranial.
- Flavonoids: The plant also contains flavonoids, such as luteolin and quercetin, which have antioxidant and anti-inflammatory properties.
- Saponins: These compounds may have mild diuretic and expectorant effects.
Uses and Benefits:
- Culinary Uses: Lemongrass is widely used in cooking for its citrus flavor. It is a common ingredient in Thai, Vietnamese, and other Southeast Asian cuisines, adding a fresh, lemony taste to soups, curries, and teas.
- Medicinal Uses: In traditional medicine, lemongrass is used for its purported benefits in digestion, detoxification, and as a mild sedative. It is also believed to have antimicrobial and anti-inflammatory properties.
- Aromatherapy: The essential oil extracted from lemongrass is used in aromatherapy for its refreshing and uplifting scent. It is used in diffusers, massage oils, and skin care products.
- Cosmetic Uses: Lemongrass oil is included in skincare products for its astringent and toning properties. It is also used in shampoos and conditioners for its ability to add shine and reduce dandruff.
Applications:
- Culinary: Used fresh or dried in cooking to impart a lemony flavor to various dishes. Essential in recipes such as Thai curry, soups, and marinades.
- Medicinal: Used in herbal remedies and teas for its digestive and detoxifying effects.
- Aromatherapy: Included in essential oil blends for its invigorating and mood-enhancing properties.
- Cosmetics: Incorporated into skincare and haircare products for its toning, astringent, and fragrance benefits.
INCI Functions:
Cosmetic astringent. This ingredient exerts a direct effect on the skin by tightening dilated pores by contracting stratum corneum cells and removing superfluous oil.
Fragrance. It plays a very important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability. It is able to create a perceptible pleasant odour, masking a bad smell. The consumer always expects to find a pleasant or distinctive scent in a cosmetic product.
Environmental and Safety Considerations:
- Environmental Impact: Cymbopogon flexuosus is a hardy plant that can be grown with minimal impact on the environment. It can be cultivated in various soil types and is beneficial for erosion control due to its dense growth.
- Safety: Lemongrass is generally safe for culinary and topical use. However, essential oils should be used with caution in high concentrations as they may cause skin irritation in some individuals. Perform a patch test before widespread application and consult a healthcare provider if using for medicinal purposes.
Studies
Lemongrass oil has antibacterial activity due to its components including Geraniol, Citral and Neral (1), has antioxidant, antidepressant, sedative, nervine properties (2) and bactericidal activity (3) acting against many species of bacteria such as :
- Acinetobacter baumanii
- Aeromonas veronii
- Enterococcus faecalis
- Escherichia coli
- Klebsiella pneumonia
- Salmonella enterica
- Serratia marcesens
- Proteus vulgaris
- Enterobacter aerogenes
- Corynebacterium equii
- Staphylococcus aureus
Lemongrass essential oil is used as:
• insect repellent
• aromatherapy
• astringent
• base for chemical perfumes such as geraniol and citronellol
Studies have also shown antifungal properties of Lemongrass oil (4).
Other studies
References_____________________________________________________________________
(1) Teuscher E. Medicinal Spices-A Handbook of Culinary Herbs, Spices, Spice Mixtures and Their Essential Oils. Stuttgart, Germany: Medpharm Scientific Publishers; 2006.
(2) Gardner ZE, McGuffin M. American Herbal Products Association's botanical safety handbook. 2nd ed. Boca Raton: CRC Press, American Herbal Products Association; 2013.
(3) Friedman M, Henika PR, Mandrell RE. Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica. J Food Prot. 2002;65(10):1545–1560
Abstract. An improved method of sample preparation was used in a microplate assay to evaluate the bactericidal activity levels of 96 essential oils and 23 oil compounds against Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica obtained from food and clinical sources. Bactericidal activity (BA50) was defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in CFU relative to a buffer control. Twenty-seven oils and 12 compounds were active against all four species of bacteria. The oils that were most active against C. jejuni (with BA50 values ranging from 0.003 to 0.009) were marigold, ginger root, jasmine, patchouli, gardenia, cedarwood, carrot seed, celery seed, mugwort, spikenard, and orange bitter oils; those that were most active against E. coli (with BA50 values ranging from 0.046 to 0.14) were oregano, thyme, cinnamon, palmarosa, bay leaf, clove bud, lemon grass, and allspice oils; those that were most active against L. monocytogenes (with BA50 values ranging from 0.057 to 0.092) were gardenia, cedarwood, bay leaf, clove bud, oregano, cinnamon, allspice, thyme, and patchouli oils; and those that were most active against S. enterica (with BA50 values ranging from 0.045 to 0.14) were thyme, oregano, cinnamon, clove bud, allspice, bay leaf, palmarosa, and marjoram oils. The oil compounds that were most active against C. jejuni (with BA50 values ranging from 0.003 to 0.034) were cinnamaldehyde, estragole, carvacrol, benzaldehyde, citral, thymol, eugenol, perillaldehyde, carvone R, and geranyl acetate; those that were most active against E. coli (with BA50 values ranging from 0.057 to 0.28) were carvacrol, cinnamaldehyde, thymol, eugenol, salicylaldehyde, geraniol, isoeugenol, citral, perillaldehyde, and estragole; those that were most active against L. monocytogenes (with BA50 values ranging from 0.019 to 0.43) were cinnamaldehyde, eugenol, thymol, carvacrol, citral, geraniol, perillaldehyde, carvone S, estragole, and salicylaldehyde; and those that were most active against S. enterica (with BA50 values ranging from 0.034 to 0.21) were thymol, cinnamaldehyde, carvacrol, eugenol, salicylaldehyde, geraniol, isoeugenol, terpineol, perillaldehyde, and estragole. The possible significance of these results with regard to food microbiology is discussed.
Hammer KA, Carson CF, Riley TV. Antimicrobial activity of essential oils and other plant extracts. J Appl Microbiol. 1999;86(6):985–990
Abstract. The antimicrobial activity of plant oils and extracts has been recognized for many years. However, few investigations have compared large numbers of oils and extracts using methods that are directly comparable. In the present study, 52 plant oils and extracts were investigated for activity against Acinetobacter baumanii, Aeromonas veronii biogroup sobria, Candida albicans, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serotype typhimurium, Serratia marcescens and Staphylococcus aureus, using an agar dilution method. Lemongrass, oregano and bay inhibited all organisms at concentrations of ≤2·0% (v/v). Six oils did not inhibit any organisms at the highest concentration, which was 2·0% (v/v) oil for apricot kernel, evening primrose, macadamia, pumpkin, sage and sweet almond. Variable activity was recorded for the remaining oils. Twenty of the plant oils and extracts were investigated, using a broth microdilution method, for activity against C. albicans, Staph. aureus and E. coli. The lowest minimum inhibitory concentrations were 0·03% (v/v) thyme oil against C. albicans and E. coli and 0·008% (v/v) vetiver oil against Staph. aureus. These results support the notion that plant essential oils and extracts may have a role as pharmaceuticals and preservatives.
(4) Li WR, Shi QS, Ouyang YS, Chen YB, Duan SS. Antifungal effects of citronella oil against Aspergillus niger ATCC 16404. Appl Microbiol Biotechnol. 2012 Oct 19.
Abstract. Essential oils are aromatic oily liquids obtained from some aromatic plant materials. Certain essential oils such as citronella oil contain antifungal activity, but the antifungal effect is still unknown. In this study, we explored the antifungal effect of citronella oil with Aspergillus niger ATCC 16404. The antifungal activity of citronella oil on conidia of A. niger was determined by poisoned food technique, broth dilution method, and disc volatility method. Experimental results indicated that the citronella oil has strong antifungal activity: 0.125 (v/v) and 0.25 % (v/v) citronella oil inhibited the growth of 5 × 10⁵ spore/ml conidia separately for 7 and 28 days while 0.5 % (v/v) citronella oil could completely kill the conidia of 5 × 10⁵ spore/ml. Moreover, the fungicidal kinetic curves revealed that more than 90 % conidia (initial concentration is 5 × 10⁵ spore/ml) were killed in all the treatments with 0.125 to 2 % citronella oil after 24 h. Furthermore, with increase of citronella oil concentration and treatment time, the antifungal activity was increased correspondingly. The 0.5 % (v/v) concentration of citronella oil was a threshold to kill the conidia thoroughly. The surviving conidia treated with 0.5 to 2 % citronella oil decreased by an order of magnitude every day, and no fungus survived after 10 days. With light microscope, scanning electron microscope, and transmission electron microscope, we found that citronella oil could lead to irreversible alteration of the hyphae and conidia. Based on our observation, we hypothesized that the citronella oil destroyed the cell wall of the A. niger hyphae, passed through the cell membrane, penetrated into the cytoplasm, and acted on the main organelles. Subsequently, the hyphae was collapsed and squashed due to large cytoplasm loss, and the organelles were severely destroyed. Similarly, citronella oil could lead to the rupture of hard cell wall and then act on the sporoplasm to kill the conidia. Nevertheless, the citronella oil provides a potential of being a safe and environmentally friendly fungicide in the future.
Lemongrass 
Neral
