Celeriac (Apium graveolens var. rapaceum) commonly known as celery root, is a variety of celery cultivated for its large, edible tuber. Unlike stalk celery, which is grown for its stems, celeriac produces a knobby root with a mild, nutty flavor and an earthy aroma. It is widely used in European cuisine, particularly in France and Germany, and is gaining popularity worldwide due to its versatility and nutritional benefits. It is a biennial plant but is typically harvested as an annual before flowering.

Botanical Classification

• Kingdom: Plantae
• Clade: Angiosperms
• Class: Eudicots
• Order: Apiales
• Family: Apiaceae
• Genus: Apium
• Species: Apium graveolens
• Variety: rapaceum

Plant Characteristics

• Root: The edible portion is a rough, round, and knobby tuber with a firm white interior.
• Leaves & Stems: Green, celery-like leaves emerge from the root but are not as commonly consumed.
• Flowers: Small, white flowers appear in the second year of growth if the plant is left unharvested.
• Flavor: Earthy, slightly sweet, and similar to celery with a mild nutty undertone.
• Growth Cycle: Slow-growing, requiring 120–150 days to mature.

Nutritional Facts (Per 100g, Raw)

Celeriac is low in calories but rich in fiber, essential vitamins, and minerals, making it a great addition to a balanced diet.

Chemical Composition

Celeriac contains several bioactive compounds that contribute to its health benefits:

• Flavonoids & Polyphenols: Act as antioxidants with anti-inflammatory properties.
• Phthalides: Volatile compounds contributing to its characteristic aroma.
• Essential Oils: Includes limonene, which has potential antimicrobial effects.
• Dietary Fiber: Supports gut health and digestion.

How to Cultivate Apium graveolens var. rapaceum

1. Climate:
   • Thrives in cool temperatures (15°C to 20°C).
   • Requires a long growing season (4 to 5 months).
2. Soil Requirements:
   • Prefers deep, rich, well-drained soil with high organic content.
   • pH between 6.0 and 7.0 is ideal.
3. Planting:
   • Best grown from seeds started indoors 10–12 weeks before the last frost.
   • Seedlings should be hardened off before transplanting.
4. Watering:
   • Requires consistent moisture but cannot tolerate waterlogging.
5. Fertilization:
   • Benefits from nitrogen-rich organic fertilizers to support steady growth.
6. Harvesting:
   • Ready for harvest when the root reaches 10–15 cm in diameter, usually in late autumn.
7. Storage:
   • Stores well in cool, humid conditions and can last several months.

Uses and Benefits

Culinary Uses

• Can be eaten raw (e.g., in celeriac remoulade, a French salad).
• Cooked in soups, stews, gratins, and purees.
• Roasted, boiled, mashed, or turned into fries as a low-carb alternative to potatoes.
• Used in vegetable juices and smoothies.

Health Benefits

• Heart Health: High potassium content helps regulate blood pressure.
• Digestive Health: High fiber promotes gut health and regularity.
• Anti-Inflammatory: Antioxidants contribute to reducing inflammation.
• Bone Health: Vitamin K supports calcium absorption and bone strength.
• Low-Calorie & Nutrient-Dense: Supports weight management and overall well-being.

Agricultural & Environmental Benefits

• Can be used in crop rotation to improve soil health.
• Requires less water than traditional root vegetables like potatoes.

Applications

• Food Industry:

  • Used in processed vegetable blends, soups, and dehydrated vegetable powders.
  • Incorporated into plant-based diets.

• Medical & Nutritional:

  • Studied for its potential role in reducing inflammation and oxidative stress.
  • Used in functional foods due to its fiber and antioxidant content.

• Agriculture:

  • Suitable for organic farming due to its pest-resistant nature.
  • Helps improve soil structure in mixed cropping systems.

Environmental and Safety Considerations

Environmental Benefits

• Requires minimal chemical inputs compared to some other crops.
• Can be grown in cooler climates, reducing the need for excessive irrigation.

Safety

• Generally safe for consumption, but individuals allergic to celery should avoid celeriac.
• Some people may experience mild skin irritation when handling raw celeriac due to its natural compounds.

Research and Future Potential

With increasing interest in low-carb, nutrient-rich vegetables, Apium graveolens var. rapaceum is gaining popularity in health-conscious diets. Researchers are exploring its potential benefits for heart health, digestion, and inflammation reduction. The food industry is also investigating new ways to incorporate celeriac into plant-based products and functional foods. In agriculture, efforts are focused on developing more resilient and high-yielding celeriac varieties to promote sustainable cultivation.

References__________________________________________________________________________

Godlewska K, Pacyga P, Michalak I, Biesiada A, Szumny A, Pachura N, Piszcz U. Field-Scale Evaluation of Botanical Extracts Effect on the Yield, Chemical Composition and Antioxidant Activity of Celeriac (Apium graveolens L. Var. rapaceum). Molecules. 2020 Sep 14;25(18):4212. doi: 10.3390/molecules25184212. 

Abstract. The use of higher plants for the production of plant growth biostimulants is receiving increased attention among scientists, farmers, investors, consumers and regulators. The aim of the present study was to examine the possibility of converting plants commonly occurring in Europe (St. John's wort, giant goldenrod, common dandelion, red clover, nettle, valerian) into valuable and easy to use bio-products. The biostimulating activity of botanical extracts and their effect on the chemical composition of celeriac were identified. Plant-based extracts, obtained by ultrasound-assisted extraction and mechanical homogenisation, were tested in field trials. It was found that the obtained formulations increased the total yield of leaves rosettes and roots, the dry weight of leaves rosettes and roots, the content of chlorophyll a + b and carotenoids, the greenness index of leaves, the content of vitamin C in leaves and roots. They mostly decreased the content of polyphenols and antioxidant activities in leaves but increased them in roots and conversely affected the nitrates content. Extracts showed a varied impact on the content of micro and macroelements, as well as the composition of volatile compounds and fatty acids in the celeriac biomass. Due to the modulatory properties of the tested products, they may be used successfully in sustainable horticulture.

Bauermeister K, Ballmer-Weber BK, Bublin M, Fritsche P, Hanschmann KM, Hoffmann-Sommergruber K, Lidholm J, Oberhuber C, Randow S, Holzhauser T, Vieths S. Assessment of component-resolved in vitro diagnosis of celeriac allergy. J Allergy Clin Immunol. 2009 Dec;124(6):1273-1281.e2. doi: 10.1016/j.jaci.2009.07.033. 

Abstract. Background: Previous studies have demonstrated insufficient sensitivity of commercially available celeriac extract reagents in the diagnosis of celeriac allergy. Objective: We sought to assess the diagnostic performance of specific IgE determination based on recombinant and purified natural celeriac allergens in comparison with an extract-based assay and to investigate interference by IgE to cross-reactive carbohydrate determinants and its biologic activity.....Conclusion: Component-resolved diagnosis allowed an increase in diagnostic sensitivity from 67% to 88% compared with extract-based diagnosis. Sensitization to Api g 5 was attributable to its glycan moieties but did not interfere with diagnostic specificity.

Nurkhoeriyati T, Kulig B, Sturm B, Hensel O. The Effect of Pre-Drying Treatment and Drying Conditions on Quality and Energy Consumption of Hot Air-Dried Celeriac Slices: Optimisation. Foods. 2021 Jul 29;10(8):1758. doi: 10.3390/foods10081758. 

Abstract. Celeriac is a good source of fibre, trace minerals, and phenolic compounds; it has a pleasant aroma but is a perishable material, prone to discolouration. This research investigated the optimisation of the quality and energy demand in hot-air dried celeriac slices. The experiment utilised the I-optimal design of response surface methodology with 30 experiment runs. Pre-drying treatments (blanching at 85 °C, three minutes; dipping in 1% citric acid solution, three minutes; no pre-drying treatment), drying temperatures (50, 60, and 70 °C), air velocities (1.5, 2.2, and 2.9 m/s), and thickness (three-, five, and seven-mm) were applied. The drying conditions affected drying time significantly (p < 0.0001). The model by Midilli and others and the logarithmic model fitted best with celeriac slices drying kinetics. Blanched samples had a higher ΔE*ab (total colour difference) and BI (browning index) but lower WI (whiteness index) than samples with other pre-drying treatments. The rehydration ratio decreased with the increase of sample thickness and blanching (p < 0.0001). A quadratic model described the specific energy consumption (Es) best. The dried samples compared with fresh samples had increased antioxidant activity but decreased total phenolic compound value. The optimisation solution chosen was 58 °C drying temperature, 2.9 m/s air velocity, and 4.6 mm sample thickness with acid pre-drying treatment.

EFSA (European Food Safety Authority); Anastassiadou M, Bellisai G, Bernasconi G, Brancato A, Carrasco Cabrera L, Ferreira L, Greco L, Jarrah S, Kazocina A, Leuschner R, Magrans JO, Miron I, Nave S, Pedersen R, Reich H, Santos M, Scarlato AP, Theobald A, Vagenende B, Verani A. Modification of the existing maximum residue level for phenmedipham in celeriac. EFSA J. 2021 Mar 22;19(3):e06482. doi: 10.2903/j.efsa.2021.6482.