Green onion
(aerial parts of Allium fistulosum L., and sometimes young plants of Allium cepa ; family Amaryllidaceae)
Description
• Fresh, mildly sulfurous aromatic vegetable; crisp white pseudostem and tender hollow green leaves.
• Used raw (garnish, salads, sauces) and cooked (stir-fries, soups, broths, omelettes, Korean pajeon).
• Sold whole or trimmed/sliced; also available frozen, dehydrated (flakes/powder), and as purées.

Indicative nutrition values (per 100 g edible fresh portion; typical)
• Energy: 25–35 kcal; water 89–92%
• Carbohydrate: 5–7 g (sugars 2–3 g) • Fibre: 1.5–2.5 g • Protein: 1.5–2.0 g
• Fat: 0.1–0.3 g — of which SFA (saturated fatty acids; advisable to keep low for LDL control) are minimal; MUFA and PUFA are negligible
• Key minerals: potassium 200–300 mg; calcium 45–70 mg; magnesium 12–20 mg
• Vitamins: vitamin C 8–15 mg; vitamin K notably present; folates present
• Note: fructans higher in the white portion than in the greens
Key constituents
• Sulfur precursors (ACSOs): methiin, isoalliin; in presence of alliinase they form the typical volatiles.
• Thiosulfinates and disulfides: drive the onion-like character; decline with heat/storage.
• Polyphenols/flavonoids: quercetin/kaempferol derivatives (richer in leaves); chlorophylls and carotenoids.
• Fructans (short-chain FOS) with potential prebiotic activity (level varies by plant part).
• Minerals (K, Ca) and water-soluble vitamins (C, folate); vitamin K concentrated in green blades.
Production process
• Cultivation & harvest at young stages; grading by diameter/length; trimming of roots/damaged ends.
• Washing and trimming; for fresh-cut (RTE): gentle drying and modified-atmosphere packing.
• Processing options: quick-freeze slicing; dehydration (air-dry or freeze-dry); purées/pastes (optional blanch to soften pungency).
• Packaging: light/oxygen-barrier packs with low headspace; cold chain for untreated fresh product.
Sensory and technological properties
• Aroma/flavour: fresh, herbal, lightly sweet; cooking develops caramelised and rounded notes.
• Functionality: contributes savoury top-notes and mild sulfur cues; participates in Maillard during cooking; green leaves add faint colour.
• Stability: sulfur volatiles are oxygen/heat-labile; very fine chopping accelerates aroma loss.
Food applications
• Raw: salads, tartares, poke bowls, green sauces, toppings.
• Cooked: light sautés, ramen/soups, omelettes, pajeon, fillings, grain/noodle dressings.
• Ingredients: infused oils, aqueous extracts, snack seasonings (flakes/powders), purées for culinary bases.
Nutrition & health
Green onion is low-calorie, with negligible fat and a modest contribution of fibre and vitamin C; the green blades provide meaningful vitamin K. Fructans in the white portion can have prebiotic effects for many, yet may provoke symptoms in FODMAP-sensitive individuals—using smaller amounts or favouring the green tops often improves tolerance.
The sulfur compounds (ACSOs → thiosulfinates) underpin flavour and show antioxidant/antimicrobial potential in research; in ready-to-eat foods their levels fall with cutting, heat, and time.
From a cardiometabolic viewpoint, saturates are very low and sodium is naturally modest, making green onion suitable in lower-salt cooking and lipid-friendly patterns—overall impact depends on the recipe context. For people on vitamin-K-managed therapies, consistent intake of the green portion is advisable per clinician guidance.
Portion note: As a fresh aromatic, 20–30 g (about 2–3 tablespoons chopped). As a vegetable in sautés/soups, 60–100 g per serving.
Quality and specifications (typical topics)
• Fresh: high turgor, bright green leaves without yellowing, white crisp pseudostem, no off-odours or slime; minimal soil residues.
• Sizing: total length, pseudostem diameter, white/green ratio; tolerance for defects per spec.
• Residues/contaminants: pesticides ≤ MRL; metals within limits; nitrates monitored where required.
• Microbiology: controlled loads for fresh-cut; absence of Listeria/Salmonella.
• Processed: moisture for flakes/powders in spec (e.g., ≤8%); water activity controlled; standardised colour/aroma.
Storage and shelf-life
• Whole fresh: 0–4 °C, high RH (85–95%), away from ethylene; 7–14 days depending on initial freshness.
• Fresh-cut/RTE: 0–4 °C, 3–5 days; avoid free moisture in pack.
• Frozen: ≤ −18 °C; thaw cold; do not refreeze.
• Dehydrated: cool/dry place, barrier pack; 12–24 months.
• Key risks: leaf yellowing, slime, loss of crunch, aroma fade.
Safety and regulatory
• Designations: “green onion”, “spring onion”, or “scallion” (local usage applies); for ingredients: “dehydrated green onion”, “green onion purée”, “green onion extract”.
• Allergens: none among priority allergens; rare Allium sensitivities occur.
• Production and packing under GMP/HACCP; thorough washing/sanitation for fresh-cut lines.
• Nutrition/health claims only if thresholds are met (e.g., “source of vitamin C” when compliant).
Labeling
• Name of the food, grade/size (fresh), origin, lot, date mark; storage instructions.
• For processed forms: ingredients list, any antioxidants/acids used, directions for use and yield in recipes.
Troubleshooting
• Over-pungent/metallic notes: excess sulfur compounds or Cu/Fe contact → use sharp stainless knives, avoid prolonged fine mincing, minimise air exposure.
• Slime/decay: cold-chain breaks or excess pack moisture → dry well, use absorbers, improve airflow.
• Leaf yellowing: ethylene, light, or high temperature → separate from climacteric fruit, shade from light, lower storage temp.
• Aroma loss in cooking: high heat/long times → add some green onion at the end or use infused oil.
Sustainability and supply chain
• Field: crop rotations, targeted nitrogen and irrigation for lower impacts.
• By-products: trimmings to compost, feed, or bioenergy.
• Plant: heat/air recovery, CIP water reuse, wastewater management toward BOD/COD targets; recyclable, lightweight packs.
• Systems: traceability, supplier audits, residue (MRL) programs under GMP/HACCP.
Conclusion
Green onion is a versatile flavour-builder that delivers freshness and savoury complexity with minimal calories. Final quality hinges on freshness, oxygen management after cutting, cooking profile, and proper storage—and it can help reduce salt while keeping dishes interesting.
INCI functions (cosmetics)
• Allium Fistulosum (Green Onion) Extract/Water: skin-conditioning; antioxidant potential linked to phenolics; characteristic odour must be managed in formula; uses/claims subject to cosmetic regulations.
Mini-glossary
• SFA: Saturated fatty acids — high intakes can raise LDL; keep low overall.
• MUFA: Monounsaturated fatty acids — helpful when replacing saturates.
• PUFA: Polyunsaturated fatty acids — include n-6/n-3 families; beneficial when balanced and protected from oxidation.
• ACSOs: S-alk(en)yl-L-cysteine sulfoxides, the key non-volatile sulfur precursors in Allium.
• FODMAP: Fermentable carbs that can trigger GI symptoms in sensitive people (onion fructans are FODMAPs).
• PPO: Polyphenol oxidase, enzyme behind enzymatic browning.
• Maillard: Heat-driven reactions of reducing sugars with amino groups producing colour and roasted aromas.
• MRL: Maximum residue limits for pesticides on foods.
• GMP/HACCP: Good manufacturing practice / hazard analysis and critical control points — preventive hygiene/process-control systems.
• BOD/COD: Biochemical/chemical oxygen demand — wastewater impact metrics guiding treatment.