Understanding the pH of Lemongrass
The most prominent fact about lemongrass's acidity is that its pH is far less acidic than that of a lemon, despite its name and fragrance. While lemon juice has a pH of approximately 2.0, scientific studies on lemongrass essential oil and tea have consistently shown a pH level much closer to neutral. For instance, one study found lemongrass tea to have a pH ranging from 5.8 to 6.3, while another on the essential oil indicated a pH of 6.57. This positions lemongrass as a mildly acidic or near-neutral food item, which is a significant distinction for those managing health conditions sensitive to acidity, such as acid reflux.
The mild acidity comes from the presence of various phenolic acids and free fatty acids, rather than the concentrated citric acid that gives lemons their sourness. This chemical profile is why lemongrass can impart its refreshing, lemony scent without the intense, puckering tartness characteristic of citrus fruits.
The Role of Citral in Lemongrass
The aromatic profile of lemongrass is primarily due to a compound called citral, which is a mixture of the two isomeric aldehydes, geranial and neral. Citral is a volatile monoterpene that provides the distinct, fresh, and citrusy aroma. It is not a carboxylic acid like citric acid, but rather an aldehyde, which is responsible for the pleasant smell but not the sour taste. This is the key difference that explains why lemongrass smells like a lemon but doesn't taste intensely sour.
In addition to citral, lemongrass also contains other phenolic compounds, including chlorogenic acid, caffeic acid, and p-coumaric acid. These are potent antioxidants and contribute to the plant's known health benefits, but they are present in much lower concentrations than the citric acid in a lemon, thus contributing only mildly to the overall acidity.
Comparing Lemongrass vs. Lemon: A Chemical Breakdown
To better illustrate the difference in their acidic nature, the following table compares the chemical properties of lemongrass and lemon.
| Feature | Lemongrass | Lemon |
|---|---|---|
| Primary Aromatic Compound | Citral (an aldehyde) | Citral, Limonene, other terpenes |
| Primary Acid | Phenolic acids (e.g., chlorogenic) | Citric acid (high concentration) |
| Typical pH Level | Mildly acidic to neutral (approx. 5.8–6.6) | Highly acidic (approx. 2.0) |
| Flavor Profile | Lemony, grassy, earthy | Sharp, sour, tart |
| Astringency | Minimal | Significant |
Culinary and Medicinal Applications
Lemongrass is a versatile herb used widely in Southeast Asian cuisine, adding a light, citrusy, and slightly gingery flavor to dishes without overwhelming them with sourness. The edible part of the stalk is typically bruised, minced, or pounded to release its aromatic oils into broths, marinades, curries, and teas. For example, in Thai cooking, lemongrass is a fundamental ingredient in dishes like Tom Yum and Tom Kha Gai.
It is also a popular ingredient in herbal teas for both its flavor and potential health benefits. Among the many potential benefits noted by researchers are antimicrobial, antioxidant, and anti-inflammatory properties. A 2024 review highlights the potential of lemongrass essential oil in treating oral health problems like gingivitis and periodontitis. The antioxidant-rich profile comes from its phenolic and flavonoid compounds, which are beneficial for overall health.
Beyond food, lemongrass oil is used in aromatherapy and personal care products for its pleasant scent. Its low acidity also makes it suitable for use in cosmetics and skin care, where higher acid content could cause irritation.
How to Prepare Lemongrass
To get the most out of your fresh lemongrass stalks, you can prepare them in several ways depending on your culinary goals:
- For Infusion: Bruise the woody stalk by bashing it with the flat side of a knife or a rolling pin. This releases the aromatic oils, making it perfect for flavoring soups, teas, and curries. Remember to remove the stalks before serving.
- For Mincing: To incorporate the herb directly into marinades or curry pastes, use only the bottom, more tender part of the stalk. Peel off any dry outer layers and chop finely with a sharp knife.
- For Freezing: For long-term storage, chop the tender part of the lemongrass and freeze it in an airtight container or ice cube tray.
Conclusion
Ultimately, the question of whether does lemongrass have acid is a matter of nuance. While it does contain mildly acidic compounds like phenolic acids and free fatty acids, it does not possess the high concentration of citric acid that defines the sour taste of a lemon. Its signature citrusy aroma is a product of aldehydes, particularly citral, a compound very different from the strong organic acids found in citrus fruits. This makes lemongrass a favorable choice for adding a bright, refreshing flavor to foods and drinks without contributing significant acidity, offering a palatable and beneficial option for a wide range of consumers. The evidence from various studies clearly indicates that its pH is far closer to neutral, confirming its mild-mannered nature in both flavor and chemistry.
Conclusion
While lemongrass possesses some mildly acidic compounds and has a slightly acidic to neutral pH, the popular perception that its lemony scent equates to high acidity is a misconception. Its characteristic flavor and aroma come from citral, a non-acidic aldehyde. The actual acids present are in low concentrations, making it a gentle ingredient suitable for those concerned about acidity in their diet. When used in cooking or as a tea, lemongrass offers a unique flavor profile and a host of potential health benefits, all without the intense sourness of true citrus.
Summary
Lemongrass contains mildly acidic phenolic and free fatty acids, but its pH is far closer to neutral than that of a lemon. The citrusy aroma is primarily from the aldehyde citral, not a high concentration of citric acid. This makes it a great choice for flavoring foods and drinks without adding a sour or highly acidic element, which is beneficial for those with acid sensitivity or dietary restrictions.
