The Botanical Connection: A Tale of Two Varieties
At the core of the flavor mystery is a simple biological fact: celeriac and celery are different cultivars of the same species, Apium graveolens. This botanical relationship is a direct explanation for their similar taste. The same way that a red apple and a green apple from the same tree species will have similar apple-y flavor notes despite differences, these two vegetables share a fundamental flavor profile because they share the same genetic code.
Over centuries of cultivation, farmers bred varieties of Apium graveolens to emphasize different plant parts. The variety Apium graveolens var. dulce was bred for its crunchy, long stalks, which we know as common celery. Conversely, the variety Apium graveolens var. rapaceum was cultivated for its large, bulbous root, which is celeriac, or celery root. This selective breeding focused on developing specific physical attributes, but it did not alter the core chemical makeup responsible for the characteristic taste.
The Flavor Compounds: Phthalides and Terpenes
To understand the flavor on a chemical level, we must look at the compounds present in both plants. The unmistakable celery aroma and taste are primarily attributed to a class of chemical compounds known as phthalides. These organic compounds, including sedanolide and sedanenolide, are synthesized by the plant and are present in varying concentrations in both celery and celeriac.
Another group of compounds, terpenes, also plays a role in the overall aroma and flavor. Limonene, a prominent terpene, is found in both and contributes to their citrusy, herbaceous notes. Because both varieties come from the same species, they both produce these same key flavor-producing chemicals. It is the concentration and overall balance of these compounds that creates the subtle differences in their taste.
Celeriac's Earthier, Nuttier Flavor Profile
While the chemical building blocks are the same, celeriac's taste is often described as earthier, nuttier, and more intense than the watery, crisp taste of celery stalks. Several factors contribute to this differentiation:
- Concentrated Compounds: The flavor compounds in celeriac's bulbous root are more concentrated than in the stalks of celery, giving it a more pronounced and robust taste.
- Cooking vs. Raw: Cooking celeriac, for example, by roasting, brings out a mellow sweetness that is not present in raw celery. Raw celeriac is firm and crunchy, with a pungent celery-like flavor with notes of parsley.
- Terroir and Growing Conditions: The flavor of any vegetable is influenced by its growing environment (terroir), including soil composition and climate. Since celery stalks and celeriac roots are harvested at different stages and are cultivated differently, their growing conditions will impart slightly different nuances to the finished product.
Comparison Table: Celery vs. Celeriac
| Feature | Common Celery (Apium graveolens var. dulce) | Celeriac (Apium graveolens var. rapaceum) |
|---|---|---|
| Cultivated Part | Stalks (petioles) | Bulbous root (hypocotyl) |
| Appearance | Long, crisp, green stalks with leaves | Knobby, rough, brown exterior with a creamy white interior |
| Texture | Crunchy, high water content, and fibrous | Dense, firm, and starchy, similar to a potato or turnip |
| Key Flavor Notes | Crisp, fresh, herbaceous, and watery | Earthy, nutty, with a concentrated celery and parsley flavor |
| Best Culinary Uses | Raw in salads, as a snack, or in stocks and soups | Roasted, mashed, pureed, or grated raw for salads and slaws |
Culinary Applications and Interchanges
While celery and celeriac share flavor components, their different textures and flavor concentrations mean they are not always interchangeable in recipes. For example, the crisp, watery crunch of celery is essential for a classic mirepoix, while the creamy density of celeriac is perfect for a rich winter soup or mash. In slow-cooked applications like stews or stocks, however, their similar flavor profiles allow for some substitution. Celeriac can provide a deeper, earthier celery base to a stock, adding richness, while celery stalks will contribute a fresher, more delicate flavor.
What are Phthalides?
Phthalides are the main class of organic compounds responsible for the characteristic celery flavor and aroma. These compounds, such as 3-n-butylphthalide (NBP), are found in varying concentrations in both celery and celeriac. NBP has also been the subject of research for its potential medicinal properties. Phthalides are also involved in the distinct taste of other vegetables in the Apiaceae family, including parsley.
Conclusion: A Family Resemblance
The reason why celeriac tastes like celery is a clear-cut case of shared botanical ancestry. As different varieties of the same plant species, Apium graveolens, both vegetables produce the characteristic flavor compounds, primarily phthalides. While common celery is bred for its crisp stalks and fresh flavor, celeriac is bred for its dense root, resulting in a more concentrated, earthy, and nutty flavor profile. Their distinct textures and flavor concentrations mean they are not simply identical versions of each other but offer different culinary strengths. Understanding this family connection not only demystifies their shared taste but also empowers cooks to use each vegetable to its full potential.
Celeriac's Flavor in Different Preparations
- Raw: When grated raw for a rémoulade or salad, celeriac offers a crisp texture and a powerful, slightly peppery celery flavor with notes of parsley.
- Roasted: Roasting celeriac caramelizes its natural sugars, mellowing its intensity and developing a pleasant sweetness.
- Mashed or Puréed: When boiled and puréed, celeriac becomes silky and creamy, offering a refined, smooth base for dishes, much like mashed potatoes.
Culinary Tips
- Preparation: Celeriac has a thick, knobby skin that is not edible and must be peeled with a sharp knife before use. The peeled flesh oxidizes and browns quickly, so it's best to soak it in acidulated water (water with lemon juice or vinegar) if not using immediately.
- Pairings: The earthy and nutty flavor of celeriac pairs well with rich proteins like pork and duck, as well as fruits like apples and various nuts.
- Substitutions: In soups and stews, celeriac can be used in place of celery, providing a more robust flavor and a heartier texture.
Botanical Insight
The term 'celery root' is a bit of a misnomer, as the edible part of celeriac is actually a swollen stem base, or hypocotyl, not a true root. This botanical detail helps explain its unique texture and dense, starchy character compared to other root vegetables.
