Lemongrass as a Natural Flavoring: A Comprehensive Technical Guide
Here is a comprehensive technical guide for Lemongrass, structured in the same format as the previous guides. All key information for flavorists has been incorporated.
Lemongrass as a Natural Flavoring: A Comprehensive Technical Guide
The Society of Flavor Chemists requires certified flavorists to be able to identify the plant part used, derivatives, organoleptic characteristics, and major chemical component(s) characterizing the aroma and flavor of the 80 natural flavorings listed on its syllabus for the qualification test and interview. Lemongrass is included among these essential items.
Introduction
Lemongrass is a fragrant, tropical grass in the genus Cymbopogon, a member of the Poaceae (grass) family. Two species are of primary commercial importance: West Indian Lemongrass (Cymbopogon citratus) , which is the primary species used in culinary and flavor applications, and East Indian Lemongrass (Cymbopogon flexuosus) , which is used more in perfumery and as a source of citral. Native to Southeast Asia, lemongrass has been used for centuries in the cuisines of Thailand, Vietnam, Indonesia, Malaysia, and other tropical regions, and has become increasingly popular worldwide.
For flavorists, lemongrass oil offers a bright, fresh, intensely citrusy, and herbaceous aroma dominated by citral (neral and geranial), which provides the characteristic lemon-like note. It is one of the richest natural sources of citral, making it invaluable for adding a fresh, green, and sharp citrus character to a wide range of applications—from Southeast Asian cuisine and herbal teas to beverages and confectionery. Unlike lemon oil, lemongrass oil has a distinctly green, grassy, and tea-like undertone that gives it a unique profile.
A critical distinction for flavorists is the difference between West Indian Lemongrass (Cymbopogon citratus) , which has a sweeter, more delicate, and slightly more floral profile with higher citral content (70–85%), and East Indian Lemongrass (Cymbopogon flexuosus) , which has a more pungent, camphoraceous, and herbaceous profile with lower citral content (65–80%). For culinary and flavor applications, West Indian Lemongrass is generally preferred.
Plant Parts Used
The leaves (and the lower, tender portion of the stalk) are the plant parts used for flavoring purposes. The following characteristics are notable:
- Source Plants:
- West Indian Lemongrass (Cymbopogon citratus (DC.) Stapf): Native to Southeast Asia; the primary species for culinary use. Has a sweeter, more delicate, and higher citral content.
- East Indian Lemongrass (Cymbopogon flexuosus (Nees ex Steud.) W. Watson): Native to India and Sri Lanka; used more in perfumery and for citral isolation. Has a more pungent, camphoraceous profile.
- Plant Description: Tall, perennial grass, growing 1–2 meters in height, with long, narrow, gray-green leaves that have a strong lemon-like aroma when crushed. The base of the stalk is bulbous and tender.
- Harvesting: The leaves are harvested 3–4 times per year when the plant is mature (typically 4–6 months after planting). The leaves are cut, partially dried, and then steam-distilled.
- Essential Oil Content: Fresh leaves yield 0.3–0.8% essential oil; dried leaves yield 0.5–1.5%.
The essential oil is obtained by steam distillation of the fresh or partially dried leaves. The oil is rich in citral (neral and geranial), which together constitute 65–85% of the oil.
Lemongrass Species: West Indian vs. East Indian
Flavorists must distinguish between the two main species, as they have different chemical compositions and flavor profiles.
| Characteristic | West Indian Lemongrass (Cymbopogon citratus) | East Indian Lemongrass (Cymbopogon flexuosus) |
|---|---|---|
| Common Names | West Indian Lemongrass, Madagascar Lemongrass | East Indian Lemongrass, Cochin Lemongrass |
| Origin | Southeast Asia (cultivated worldwide) | India, Sri Lanka, Southeast Asia |
| Primary Components | Citral (neral + geranial) 70–85%, myrcene, limonene | Citral 65–80%, myrcene, limonene, camphene, methyl heptenone |
| Camphoraceous Notes | Low | Moderate (camphene) |
| Aroma Profile | Sweet, delicate, citrusy, lemony, slightly floral | Sharp, pungent, lemony, grassy, camphoraceous |
| Flavor Character | Clean, fresh, sweet lemon | Harsher, more herbaceous, less sweet |
| Typical Use | Culinary, flavoring, teas, beverages | Perfumery, citral isolation, lower-cost applications |
| FEMA No. | 2625 | 2626 |
Derivatives
Lemongrass is commercially available in several forms. The following details include technical specifications important for procurement and formulation.
Lemongrass Essential Oil (West Indian)
Production Method: Steam distillation of fresh or partially dried leaves of Cymbopogon citratus.
Description: Pale yellow to amber-yellow mobile liquid with a characteristic fresh, bright, intensely citrusy, lemony, and slightly sweet, grassy, floral aroma. The oil is dominated by citral.
Technical Notes: Yield is typically 0.5–1.5% from fresh leaves. The oil is composed primarily of citral (neral + geranial) (70–85%), with significant amounts of myrcene, limonene, and other terpenes. Storage in a cool, dry place away from light is critical to prevent oxidation.
Lemongrass Essential Oil (East Indian)
Production Method: Steam distillation of Cymbopogon flexuosus leaves.
Description: Pale yellow to amber-yellow mobile liquid with a sharp, pungent, lemony, grassy, and slightly camphoraceous aroma.
Technical Notes: Lower citral content than West Indian; contains more camphene and methyl heptenone. Used more in perfumery.
Citral (Isolated)
Production Method: Fractional distillation of lemongrass oil or other citral-rich oils to isolate citral (neral and geranial).
Description: Pale yellow to amber mobile liquid with an intensely fresh, lemon-like, sharp, and aldehydic aroma. Citral is a mixture of the isomers geranial (citral a) and neral (citral b).
Technical Notes: Citral (CAS No. 5392-40-5) is the primary character-impact compound of lemongrass and other citrus oils. It is highly reactive and prone to oxidation and polymerization.
Dried Lemongrass Leaves
Production Method: Harvesting and drying of lemongrass leaves.
Description: Dried, gray-green to pale yellow grass blades with a characteristic fresh, lemony aroma.
Technical Notes: Used for teas, infusion, and sachets.
Lemongrass CO₂ Extract
Production Method: Supercritical carbon dioxide extraction of lemongrass leaves.
Description: Yields a product with a more complete profile than the essential oil, capturing heavier, less volatile components. Often greener in color and richer in character.
Organoleptic Characteristics
Aroma Profile (West Indian Lemongrass Oil)
When evaluated, West Indian lemongrass oil reveals a bright, fresh, and intensely citrusy aromatic profile:
- Primary Note: Fresh, bright, intensely lemony, citrusy
- Citral Character: Sharp, bright, lemon-like, aldehydic, slightly green—the signature note
- Grassy: Fresh, hay-like, green, tea-like
- Sweet: Slightly sweet, floral undertones
- Herbaceous: Subtle, reminiscent of verbena or lemon balm
- Floral: Light, delicate floral notes
- Green: Fresh, leafy
The overall aroma is often described as "bright, fresh, and intensely lemony with distinct grassy, tea-like undertones."
Aroma Profile (East Indian Lemongrass Oil)
When evaluated, East Indian lemongrass oil reveals a sharper, more pungent aromatic profile:
- Primary Note: Sharp, pungent, lemony, grassy
- Citral: Present but with more pungent, camphoraceous undertones
- Camphoraceous: Fresh, medicinal, slightly harsh
- Grassy: Stronger, more hay-like
- Less Sweet: Less floral sweetness than West Indian
Taste Characteristics
At typical usage levels, West Indian lemongrass provides:
- Lemon: Fresh, bright, intense lemon character
- Grassy: Clean, green, tea-like notes
- Herbal: Fresh, herbaceous, slightly floral
- Sweet: Subtle, pleasant sweetness
- Bitter: Slight, pleasant bitterness in higher concentrations
- Cooling: Slight, fresh sensation
The Key to Lemongrass's Unique Flavor
Lemongrass's characteristic bright, fresh, lemony flavor comes from its exceptionally high citral content:
Primary Components:
- Citral (70–85%): A mixture of the isomers geranial (citral a) and neral (citral b). Citral provides the sharp, bright, lemon-like, aldehydic, and slightly green notes—the signature character of lemongrass. The ratio of geranial to neral is typically 2:1 to 3:1.
Supporting Components:
- Myrcene (5–15%): A monoterpene hydrocarbon that contributes fruity, balsamic notes
- Limonene (1–5%): A monoterpene hydrocarbon that contributes fresh, citrus notes
- Geraniol (trace–1%): A monoterpene alcohol that contributes sweet, rose-like notes
- Nerol (trace–1%): A monoterpene alcohol that contributes sweet, rose-like notes
- Camphene (trace–1%): Contributes fresh, camphoraceous notes (higher in East Indian)
- Methyl Heptenone (trace–1%): Contributes fruity, slightly fatty notes (higher in East Indian)
The combination of extremely high citral content with myrcene and other supporting terpenes gives lemongrass its distinctive fresh, lemony, and grassy character—more intense and green than lemon oil, and without the terpenic complexity of lemon.
Major Chemical Components
Key Aroma Compounds (West Indian Lemongrass Oil)
| Component | Typical Percentage | Organoleptic Contribution | CAS No. |
|---|---|---|---|
| Citral (geranial + neral) | 70–85% | Sharp, bright, lemon-like, aldehydic, green; characteristic lemongrass note | 5392-40-5 (geranial), 106-26-3 (neral) |
| Myrcene | 5–15% | Fruity, balsamic | 123-35-3 |
| Limonene | 1–5% | Fresh, citrus | 138-86-3 |
| Geraniol | trace–1% | Sweet, rose-like, floral | 106-24-1 |
| Nerol | trace–1% | Sweet, rose-like, floral | 106-25-2 |
| Camphene | trace–1% | Fresh, camphoraceous (higher in East Indian) | 79-92-5 |
| Methyl Heptenone | trace–1% | Fruity, slightly fatty (higher in East Indian) | 110-93-0 |
Comparison: West Indian vs. East Indian Lemongrass Oil
| Component | West Indian (C. citratus) | East Indian (C. flexuosus) |
|---|---|---|
| Citral | 70–85% | 65–80% |
| Myrcene | 5–15% | 5–15% |
| Limonene | 1–5% | 1–5% |
| Camphene | trace–1% | 1–5% |
| Methyl Heptenone | trace–1% | 1–5% |
| Aroma | Sweet, delicate, citrusy | Sharp, pungent, camphoraceous |
Comparison: Lemongrass vs. Lemon vs. Citronella
| Characteristic | Lemongrass (C. citratus) | Lemon (Citrus × limon) | Citronella (C. winterianus) |
|---|---|---|---|
| Primary Component | Citral (70–85%) | Limonene (60–80%) | Citronellal (30–45%) |
| Character-Impact | Citral | Citral | Citronellal, geraniol |
| Aroma Profile | Fresh, lemony, grassy, sweet | Fresh, bright, citrusy, sharp | Sharp, lemony, rosy, floral, soapy |
| Flavor Character | Intense lemon, green, tea-like | Clean lemon, tart | Lemony, floral, peppery |
Applications in Flavoring
Regulatory Status
Lemongrass oil is approved as a natural flavoring substance:
- United States: Lemongrass oil is generally recognized as safe (GRAS). It is listed under 21 CFR §182.20 as a natural flavoring substance (FEMA No. 2625 for West Indian lemongrass oil, 2626 for East Indian lemongrass oil).
- European Union: Permitted for use in food flavorings under Regulation (EC) No 1334/2008.
- China: Approved food flavor under GB 2760.
Typical Usage Levels (mg/kg)
The following usage levels are based on FEMA GRAS determinations and industry standards:
| Application | West Indian Lemongrass Oil (mg/kg) | East Indian Lemongrass Oil (mg/kg) |
|---|---|---|
| Non-alcoholic beverages | 10–80 | 5–50 |
| Alcoholic beverages | 20–150 | 10–80 |
| Baked goods | 10–80 | 5–50 |
| Hard candy | 20–150 | 10–100 |
| Frozen dairy | 5–50 | 5–30 |
| Gelatins and puddings | 5–50 | 5–30 |
| Soft candy | 10–80 | 5–50 |
| Chewing gum | 20–150 | 10–100 |
| Sauces and marinades | 10–100 | 5–80 |
| Soups and broths | 10–80 | 5–50 |
Note: These ranges represent typical industry usage. West Indian lemongrass oil is used at higher levels than East Indian due to its sweeter, more pleasant character.
Usage & Dosage Best Practices
Flavorists should observe the following guidelines when working with lemongrass:
Select the Correct Species:
- West Indian Lemongrass (C. citratus): Use for sweet, delicate, authentic lemongrass character. Preferred for culinary and premium flavor applications.
- East Indian Lemongrass (C. flexuosus): Use only where a sharper, more pungent, camphoraceous character is desired, or for cost-sensitive applications.
Start Moderate, Titrate: Lemongrass oil is potent and can become overpowering if overused. Begin at the lower end of typical usage ranges (e.g., 10–20 mg/kg in beverages) and adjust upward.
Pre-Dilution: Pre-dilute in ethanol or propylene glycol for easier handling and more even dispersion.
Citral Stability: Citral is highly reactive and prone to oxidation and polymerization. Use fresh oil and store properly. For long-shelf-life products, consider using encapsulated citral or antioxidants.
Flavor Synergies: Lemongrass pairs exceptionally well with:
- Southeast Asian cuisine: Coconut milk, galangal, kaffir lime, ginger, chili, fish sauce
- Citrus: Lemon, lime, orange, yuzu
- Herbs: Mint, basil, cilantro, coriander, parsley
- Spices: Ginger, turmeric, cardamom, black pepper
- Fruits: Coconut, mango, pineapple, papaya, berry
- Tea: Green tea, herbal teas, jasmine tea
- Savory: Seafood, poultry, pork, beef
- Beverages: Lemonade, cocktails (mojitos, gin and tonic), sodas
Flavor Applications: Lemongrass serves as a primary flavor or modifier in:
- Southeast Asian cuisine: Tom yum soup, green curry, larb, satay, stir-fries, marinades
- Beverages: Lemongrass tea, lemongrass lemonade, cocktails (lemongrass mojito, lemongrass gin and tonic), sodas, flavored waters
- Confectionery: Lemongrass candies, chocolates, ice cream, sorbet
- Baked goods: Lemongrass cakes, cookies, shortbread
- Savory: Soups, broths, marinades, sauces, dressings
- Herbal teas: Lemongrass tea, blends with chamomile, mint, ginger
Fragrance Applications
Lemongrass oil is used in perfumery and functional fragrance for:
- Citrus colognes: Adds a fresh, green, lemony top note
- Masculine fragrances: Adds freshness and brightness
- Aromatherapy: Used for its uplifting, energizing properties
- Household products: Cleaners, detergents, soaps
- Insect repellents: Lemongrass is a natural insect repellent
Blends well with: Bergamot, lemon, lime, ginger, mint, rosemary, jasmine, ylang-ylang.
Example Formula: Tom Yum Soup Flavor Base
The following formula demonstrates the use of West Indian lemongrass oil in a classic Thai tom yum soup flavor system.
Tom Yum Soup Flavor Concentrate
| Component | Percentage (%) | Function | Technical Note |
|---|---|---|---|
| West Indian lemongrass oil | 25.0 | Primary herb | Fresh, lemony, grassy character |
| Kaffir lime oil | 15.0 | Citrus, floral | Adds authentic Thai note |
| Galangal oil | 15.0 | Spicy, ginger-like | Adds warmth |
| Chili oil (capsicum) | 10.0 | Heat | Adds pungency |
| Lime oil | 10.0 | Citrus brightness | Adds freshness |
| Fish sauce flavor | 10.0 | Umami, savory | Adds depth |
| Garlic oil | 5.0 | Savory note | Adds depth |
| Shallot oil | 5.0 | Savory note | Adds depth |
| Coconut flavor | 5.0 | Creamy note | Optional, for coconut milk version |
| Total | 100.0 |
Usage Instructions: Use at 0.05–0.2% in finished soups, broths, or marinades.
Alternative: Lemongrass-Ginger Tea Flavor
| Component | Percentage (%) | Function |
|---|---|---|
| West Indian lemongrass oil | 50.0 | Primary lemony, grassy note |
| Ginger oil | 20.0 | Warm, spicy note |
| Lemon oil | 10.0 | Citrus brightness |
| Honey flavor | 10.0 | Sweetness |
| Chamomile oil | 5.0 | Floral, apple-like |
| Ethanol | 5.0 | Solvent |
| Total | 100.0 |
Usage Instructions: Use at 0.05–0.2% in finished herbal teas or beverages.
Alternative: Lemongrass Oil Pre-Dilution for Lab Use
| Component | Percentage (%) | Function |
|---|---|---|
| Ethanol (190 proof) | 90.0 | Solvent |
| West Indian lemongrass oil | 10.0 | Active ingredient |
Method: Mix thoroughly. Store in amber glass bottles in a cool, dark place. Use 0.1–1.0% in flavor formulations for easy handling.
Shelf Stability & Storage
Understanding the stability of lemongrass oil is critical for maintaining flavor quality.
Lemongrass Essential Oil
Storage Recommendation: Store in a full, airtight container (preferably under nitrogen blanketing) in a cool, dry place away from light. Refrigeration is strongly recommended for long-term storage.
Stability Notes: Lemongrass oil is highly unstable due to its high citral content (70–85%). Citral is prone to oxidation, polymerization, and acid-catalyzed rearrangement. Oxidized citral develops off-notes (musty, plastic-like, metallic). The oil can darken and thicken over time. Shelf life is typically 6–12 months when properly stored; terpeneless citral (isolated) is also unstable.
Dried Lemongrass Leaves
Storage Recommendation: Store in airtight containers in a cool, dry, dark place.
Stability Notes: Dried leaves maintain potency for 12–24 months.
Stability in Finished Products
- Heat stability: Citral is heat-sensitive; may degrade during high-temperature processing.
- pH stability: Citral is susceptible to acid-catalyzed rearrangements and oxidation at low pH. Use antioxidants and consider encapsulation for low-pH products.
- Oxidation: Highly susceptible to oxidation; use antioxidants (e.g., mixed tocopherols, rosemary extract) for long-shelf-life products.
- Light sensitivity: Protect from light.
Safety Considerations
General Safety
Lemongrass oil is generally recognized as safe (GRAS) for use as a flavoring at approved levels (FEMA 2625, 2626). However, it has significant safety considerations due to its high citral content.
Important Considerations
- Skin Sensitization: Citral is a known skin sensitizer. Oxidized citral is more likely to cause sensitization. Lemongrass oil is subject to IFRA restrictions for fragrance use.
- Mucous Membrane Irritation: Can cause irritation to eyes and mucous membranes.
- Allergies: May cause allergic reactions in sensitive individuals.
- Pregnancy: Safe in food amounts; concentrated essential oil should be used with caution during pregnancy.
- Citral Stability: Due to its instability, fresh oil should be used; avoid using oxidized oil.
Maximum Usage Levels (IFRA)
For fragrance applications, lemongrass oil is subject to IFRA restrictions due to its citral content. Flavorists developing products for topical applications should consult current IFRA standards.
Skin Safety
- Essential oil: May cause sensitization; dilute properly for topical applications.
- Protective measures: Wear suitable gloves when handling concentrated essential oil.
Quality Control & Sourcing
Flavorists should implement the following quality checks when sourcing lemongrass oil.
Essential Requirements for Certificates of Analysis (COA)
For West Indian Lemongrass Oil:
- Botanical identity: Cymbopogon citratus (DC.) Stapf
- Origin: Guatemala, Costa Rica, Brazil, India, etc.
- Citral content (geranial + neral): 70–85% (GC analysis)
- Myrcene content: 5–15%
- Physical properties: Specific gravity (0.870–0.905), refractive index (1.480–1.490), optical rotation (-5° to -15°)
For East Indian Lemongrass Oil:
- Botanical identity: Cymbopogon flexuosus (Nees ex Steud.) W. Watson
- Origin: India, Sri Lanka
- Citral content: 65–80%
Common Adulteration Risks
- Dilution with synthetic citral
- Extension with less expensive oils (e.g., citronella, lemon)
- Substitution of West Indian with East Indian oil (different profile)
- Mislabeling of origin or species
Sourcing Considerations
| Type | Origin | Characteristics |
|---|---|---|
| West Indian | Guatemala, Costa Rica, Brazil | Highest quality; sweet, delicate, high citral |
| West Indian | India | Good quality; slightly less sweet |
| East Indian | India | Pungent, camphoraceous; used in perfumery |
Traditional and Culinary Applications
Traditional Uses
- Thai: Essential in tom yum soup, green curry, larb, marinades, stir-fries, and beverages
- Vietnamese: Used in pho, spring rolls, marinades
- Indonesian: Used in soto, marinades, and traditional medicines
- Malaysian: Used in curries, laksa, and marinades
- Cambodian: Used in amok, soups, and marinades
- Philippine: Used in soups, marinades, and traditional medicines
- Latin American: Used in some Caribbean and Central American cuisines
Culinary Pairings
Lemongrass pairs well with:
- Proteins: Seafood (shrimp, fish, crab), poultry (chicken, duck), pork, beef
- Vegetables: Coconut, eggplant, bamboo shoots, mushrooms, bell peppers
- Herbs: Cilantro, mint, basil, kaffir lime leaves, Thai basil
- Spices: Ginger, galangal, turmeric, chili, black pepper, coriander, cardamom
- Citrus: Lemon, lime, kaffir lime, yuzu
- Sweet: Coconut milk, palm sugar, honey
- Savory: Fish sauce, soy sauce, garlic, shallots
Sustainability and Sourcing
Cultivation Practices
Lemongrass is cultivated in tropical regions worldwide:
- Guatemala, Costa Rica: Major producers of high-quality West Indian lemongrass oil.
- India: Large-scale producer of both West Indian and East Indian lemongrass.
- Brazil: Significant producer.
- Thailand, Vietnam, Indonesia: Traditional origins; used primarily for culinary applications.
Quality Considerations
When sourcing lemongrass oil, consider:
- Species verification: West Indian (C. citratus) is preferred for culinary applications.
- Citral content: Higher citral (75–85%) indicates higher quality.
- Origin: Central American West Indian lemongrass is traditionally considered high quality.
- Certifications: Organic, non-GMO, fair trade.
Summary
Lemongrass is a bright, fresh, and intensely citrusy natural flavoring prized for its high citral content (70–85%) . The two main species—West Indian Lemongrass (Cymbopogon citratus) and East Indian Lemongrass (Cymbopogon flexuosus) —have distinct profiles, with West Indian being sweeter, more delicate, and preferred for culinary applications, and East Indian being more pungent and camphoraceous.
Key characteristics:
- Primary component: Citral (70–85%)
- Aroma profile: Fresh, bright, intensely lemony, grassy, tea-like
- Typical usage: Oil 5–150 mg/kg; dried leaves 0.5–2%
- Primary applications: Southeast Asian cuisine, herbal teas, beverages, marinades, soups
Critical considerations for flavorists:
- Distinguish West Indian from East Indian: West Indian is sweeter, more delicate; East Indian is more pungent, camphoraceous.
- Citral stability: Highly unstable; store properly (refrigeration, nitrogen blanketing) and use within 6–12 months.
- Flavor synergies: Pairs with coconut, galangal, ginger, chili, lime, and seafood.
- Potency: Use at moderate levels (10–50 mg/kg); overuse can result in a harsh, medicinal character.
- Sourcing: Central American West Indian lemongrass is traditionally considered the highest quality.
References and Further Reading
The information presented in this guide is synthesized from:
- Regulatory documents from FDA, FEMA (Nos. 2625, 2626), and international food safety authorities.
- Published scientific literature on Cymbopogon citratus and Cymbopogon flexuosus.
- Standard textbooks on natural flavoring materials.
- Industry technical data from major suppliers.
- Traditional culinary knowledge documented in public domain sources.
Key References:
- FEMA Flavor Ingredient Library: Lemongrass Oil (West Indian) (FEMA 2625), Lemongrass Oil (East Indian) (FEMA 2626)
- Journal of Essential Oil Research: Lemongrass oil composition studies
- TGSC Information System: Lemongrass Oil
Disclaimer: This article is for educational and training purposes only. When using lemongrass in commercial products, always verify current regulatory status in your jurisdiction, conduct appropriate safety assessments, and source ingredients from reputable suppliers who can provide documentation of botanical identity, origin, and quality. West Indian and East Indian lemongrass have different profiles and are not interchangeable for culinary applications. Lemongrass oil is highly unstable; store properly and use within recommended timeframes. The formulas and usage levels provided are illustrative examples and may require adjustment based on specific product requirements and regulatory compliance.
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