Cloves (Syzygium aromaticum, syn. Eugenia caryophyllata)

Description

• Spice made from the unopened flower buds of the clove tree, harvested pre-bloom, then dried to a reddish-brown and sold whole (cloves), ground, as oleoresin, or essential oil.

• Sensory profile: warm, sweet-balsamic, slightly peppery aroma with a hallmark eugenol note and mild oral numbing; high intensity and long persistence.

Caloric value (per 100 g)

• Ground spice: about 270–290 kcal/100 g; mostly carbohydrates and fiber, with modest fat and protein.

• Per teaspoon (~2 g ground): ~5–6 kcal (typical spice-level use).

Key constituents

• Volatile oil in buds ~10–20%: mainly eugenol (~70–90% of the volatile fraction), eugenyl acetate, β-caryophyllene, and minor terpenes.

• Polyphenols (tannins), phenolic acids, flavonoids with notable antioxidant capacity; manganese is the standout mineral.

• Oleoresin: lipophilic extract concentrating non-volatile aromatics that fix and round the flavour.

Production process

• Harvest immature buds → withering/drying (sun or warm air) to target moisture → cleaning, grading (whole buds, heads, stems).

• Low-temperature milling for ground spice; steam distillation for essential oil; food-grade solvent extraction for oleoresin → standardisation.

• Decontamination options: steam or irradiation (where permitted); avoid non-compliant ETO residues.

Sensory and technological properties

• Very high flavouring power: easily dominates blends → use low dosages and control infusion time.

• Stability: essential oil is sensitive to light/oxygen/heat; whole cloves protect volatiles better than ground.

• Functionality: antioxidant and antimicrobial effects (linked to eugenol) aid marinades and pickles; brown hue may darken pale foods.

Food applications

• Spice blends: garam masala, baharat, Chinese five spice, pumpkin spice.

• Sweet/bakery: gingerbread, cookies, spice breads, compotes and jams.

• Beverages: mulled wine, chai, infusions, syrups.

• Savory: stews, curries, pilaf rice, marinades, pickles/condiments.

• Extracts: oleoresin for sauces/condiments; essential oil only in micro-doses with proper dilution.

Nutrition and health

• Culinary amounts are small; contribute antioxidants and manganese.

• Eugenol: sensory/antimicrobial actions; excess may cause oral irritation or nausea.

• Interactions: caution with anticoagulant/antiplatelet therapies and during pregnancy/lactation for essential oil use; follow good practice.

Fat profile

• Not nutritionally relevant for whole/ground spice; oleoresin/essential oil contain lipophilic and volatile fractions used for aroma, not lipid intake.

Quality and specifications (typical topics)

• Moisture ≤ ~12% (whole buds).

• Volatile oil (steam distillation): buds often ≥ ~15 mL/100 g; eugenol used as marker.

• Low defects/foreign matter; microbial specs appropriate for spices (apply post-harvest treatment as needed).

• Pesticides/heavy metals within limits; granulation uniform for ground spice; low aw.

Storage and shelf life

• Store dark, airtight, cool/dry; avoid light, heat, and oxygen.

• Shelf life: whole 24–36 months; ground 12–18 months; oils/oleoresins typically shorter (follow supplier specs).

Allergens and safety

• Naturally gluten-free; not among major allergens; rare idiosyncratic sensitivities possible.

• Essential oil is concentrated: always dilute, not for direct ingestion; avoid pediatric use without professional guidance.

INCI functions in cosmetics

• INCI: Syzygium Aromaticum (Clove) Bud Oil, Leaf Oil, Flower Oil, Clove Extract, Eugenol.

• Roles: fragrance, masking, antimicrobial/soothing in oral-care and topical products; observe fragrance allergen and usage limits.

Troubleshooting

• Bitter/metallic or astringent notes: overdose or over-extraction → reduce dose/time; add fat or sugar to round edges.

• Aroma loss: aged ground spice → prefer whole buds and grind fresh.

• Undesired darkening: use brief infusion or spice sachets for early removal.

• Medicinal/pungent profile too strong: replace part with allspice or cinnamon for a softer blend.

Sustainability and supply chain

• Grown in the tropics (e.g., Indonesia, Madagascar, Tanzania, Sri Lanka, India); monitor social standards and residues.

• Prefer traceability and responsible schemes; operate under GMP/HACCP; manage effluents toward BOD/COD targets; use opaque/recyclable packaging.

Labelling

• Common names: “cloves”, “ground cloves”; extracts: “clove oleoresin”, “clove essential oil”.

• In ingredient lists, can appear as “spices” or “natural flavours” where permitted by regulation and recipe.

Conclusion

Clove is a high-impact, complex spice that structures both sweet and savoury dishes at very low doses. Careful control of form (whole vs. ground), extraction time, and storage maximises freshness, safety, and sensory consistency.

Mini-glossary

• Eugenol — Key phenylpropanoid behind clove’s character; contributes pungency and antimicrobial action.

• Oleoresin — Lipophilic extract concentrating volatile and non-volatile spice components for full and persistent flavour.

• GMP/HACCP — Good manufacturing practice / hazard analysis and critical control points: preventive hygiene systems with validated CCPs.

• BOD/COD — Biochemical/chemical oxygen demand: indicators of wastewater impact during processing.

Studies

In traditional medicine, they have traditionally been used to treat various disorders such as diabetes, diarrhea, reproductive problems and respiratory disorders (1).

Recent studies have shown its antibacterial efficacy (2).

The essential oil of cloves showed genoprotective effects (3).

Other plants of the Syzygium species that have shown healing properties:

• Syzygium cumini L.
• Syzygium polyanthum (Wight.) 
• Syzygium malaccense 
• Syzygium brazzavillense
• Syzygium formosum (Wall.)
• Syzygium polyanthum 
• Syzygium paniculatum Gaertn.
• Syzygium guineense 

Cloves studies

References________________________________________________

(1) .  Kasetti RB, Rajasekhar MD, Kondeti VK, Fatima SS, Kumar EG, Swapna S, Ramesh B, Rao CA. Antihyperglycemic and antihyperlipidemic activities of methanol:water (4:1) fraction isolated from aqueous extract of Syzygium alternifolium seeds in streptozotocin induced diabetic rats  Food Chem Toxicol. 2010 Apr;48(4):1078-84. doi: 10.1016/j.fct.2010.01.029

(2)   Famuyide IM, Aro AO, Fasina FO, Eloff JN, McGaw LJ. Antibacterial and antibiofilm activity of acetone leaf extracts of nine under-investigated south African Eugenia and Syzygium (Myrtaceae) species and their selectivity indices.  BMC Complement Altern Med. 2019 Jun 20;19(1):141. doi: 10.1186/s12906-019-2547-z.

Abstract. Background: Antimicrobial resistance (AMR) remains an important global health issue but the gap between AMR and development of new antimicrobials is increasing. Plant extracts may have good activity per se or may be sources of effective antimicrobial compounds which can act against planktonic and/or biofilms of pathogens. We determined the antimicrobial efficacy and cytotoxicity of some under-investigated plants from the Myrtaceae family endemic to South Africa. The ability of the plant extracts to inhibit or destroy pre-formed bacterial biofilms was also determined. Methods: Based on previous preliminary in vitro screening and on chemotaxonomy, nine species from the Myrtaceae family were selected. The antimicrobial activity of the crude acetone leaf extracts was determined against six common nosocomial pathogens, namely: Gram-positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium) using a two-fold serial microdilution assay with p-iodonitrotetrazolium violet as growth indicator. The number of antimicrobial compounds present in extracts was determined by bioautography. Cytotoxicity of extracts was determined against Vero kidney cells using a colorimetric tetrazolium-based assay. The total antibacterial activity (TAA) in ml/g and selectivity index (LC50/MIC) of the plant extracts were calculated. A modified crystal violet assay was used to determine the antibiofilm activity of the extracts. Results: Syzygium legatii, Syzygium masukuense, and Syzygium species A had the best activities against Gram-negative and Gram-positive bacteria (MIC) values ranging from 0.04-0.08 mg/ml. Eugenia erythrophylla had the best MIC (0.02 mg/ml) against Bacillus cereus. Many extracts had relatively low cytotoxicity (LC50 > 20 μg/ml) leading to reasonable selectivity indices. Three leaf extracts (Syzygium masukuense, Syzygium species A, and Eugenia natalitia) were moderately cytotoxic (20 μg/ml < LC50 < 100 μg/ml). The plant extracts had a good capacity to reduce biofilm formation and good to poor potential to destroy pre-formed biofilms. Conclusions: The plant species examined in this study had varying degrees of antibacterial activity against bacterial planktonic and biofilm forms with some having good activity against both forms. Several of these selected species may be potential candidates for further investigation to isolate antimicrobial compounds and to determine the mechanism of activity.

(3)   Horky P, Skalickova S, Smerkova K, Skladanka J. Essential Oils as a Feed Additives: Pharmacokinetics and Potential Toxicity in Monogastric Animals. Animals (Basel). 2019 Jun 13;9(6). pii: E352. doi: 10.3390/ani9060352. Review.

Abstract. Essential oils (EOs) are now a hot topic in finding modern substitutes for antibiotics. Many studies have shown positive results and confirmed their high antibacterial activity both in vitro and in vivo. Deservedly, there is an attempt to use EOs as a substitute for antibiotics, which are currently limited by legislation in animal breeding. Given the potential of EOs, studies on their fate in the body need to be summarized. The content of EO's active substances varies depending on growing conditions and consequently on processing and storage. Their content also changes dynamically during the passage through the gastrointestinal tract and their effective concentration can be noticeably diluted at their place of action (small intestine and colon). Based on the solubility of the individual EO's active substances, they are eliminated from the body at different rates. Despite a strong antimicrobial effect, some oils can be toxic to the body and cause damage to the liver, kidneys, or gastrointestinal tissues. Reproductive toxicity has been reported for Origanum vulgare and Mentha arvensis. Several publications also address the effect on the genome. It has been observed that EOs can show both genoprotective effects (Syzygium aromaticum) and genotoxicity, as is the case of Cinnamomum camphor. This review shows that although oils are mainly studied as promising antimicrobials, it is also important to assess animal safety.