"A practical supplier guide to citral (CAS 5392-40-5): the lemon-note monoterpene aldehyde used in food flavor, fine fragrance, personal care, and as a key intermediate for geraniol, ionone, and menthol. Covers specs, applications, and sourcing notes."
-Deshangchemical-chemechemi
What citral actually is
Citral is the molecule most people recognize by smell before they ever learn the name. Carrying the CAS number 5392-40-5, it is the volatile monoterpene aldehyde behind the sharp, bright lemon character in everything from lemongrass oil to household cleaners. On paper it is C10H16O, molecular weight 152.23, and it never arrives alone: it is a pair of geometric isomers, geranial (citral A) and neral (citral B), working together to give that recognizable citrus punch. For formulators and purchasing teams, citral earns attention because it sits at the crossroads of three different industries — food flavor, fine fragrance, and industrial synthesis.
Identity and how it is made
In its pure form citral is a pale yellow liquid. The physical constants buyers check most often are a boiling point near 229 °C, a density around 0.888 g/mL at 25 °C, and a melting point below −10 °C. It is practically insoluble in water but dissolves readily in the usual organic solvents, which is why it behaves well in both aqueous and oil-based systems. In nature it concentrates in plant oils — lemongrass and lemon leaf are the classic sources — but commercial supply leans on synthesis. Two routes dominate: the isoprene-based chemical route and newer biological fermentation routes that appeal to brands chasing bio-based or “natural” claims. In the United States it carries FEMA number 2303 for flavor use, and it is listed under EINECS 226-394-6.
Food and beverage flavoring
Citral’s first job is flavor. In beverages it builds the lemon, lime, and generic citrus top note in carbonated drinks, iced teas, and functional beverages without the cost and batch variation of cold-pressed lemon oil. Confectioners use it in hard candies, gum, and bakery to recreate the sweet-sour lift of fresh lemon, and a small dose in yogurt or ice cream reads as “refreshing” rather than “chemical.” Beyond adding aroma, citral earns its place in processing: it masks the stale oxidized-oil note that appears in fried and baked goods, and when compounded with antioxidants it helps slow the off-notes that lead to spoilage. In cost-sensitive SKUs it is a practical stand-in for natural lemon oil — instant lemon tea powders are the obvious example. Flavor houses often round out a citrus profile by pairing citral with ethyl vanillin (CAS 121-32-4), which deepens and sweetens the impression. Anyone formulating for the Chinese market should keep GB 2760 maximum-use limits in view; citral is permitted, but the dosage ceiling is not optional.
Fragrance and personal care
In perfumery citral is a top-note staple. It gives summer colognes and sport fragrances their instant citrus snap, and it turns up in cleansing products from lemon hand soap to shampoo and body wash. Household cleaners use it for the same reason: it deodorizes while it cleans, so a floor or dish product smells “fresh” instead of “chemical.” Citral also carries mild functional benefits. It shows measurable antibacterial activity against strains such as Staphylococcus aureus, which helps extend the shelf life of leave-on skin care, and it has a documented insect-repellent effect. That last property is why citral is so often compounded with citronella-type materials — for example our citronellol (CAS 106-22-9), another terpene alcohol — in mosquito sprays and outdoor products.
Citral as a synthesis intermediate
Citral’s biggest long-term value is not as a finished ingredient but as a starting point. Hydrogenate it and you get geraniol and nerol, the rose-type terpene alcohols that anchor a large share of fine fragrance. Push the chemistry further and citral becomes ionone, the violet and nutty note that also serves as an intermediate on the route to vitamin A. Menthol, the cooling agent in everything from toothpaste to topical analgesics, can also be traced back through citral-based routes. This is why citral demand tracks not just consumer flavor trends but also vitamin and fragrance production cycles. For teams that also use other terpenes, citral pairs naturally on the bench with materials such as linalool (CAS 78-70-6), a floral terpene alcohol we supply for the same fragrance and personal-care applications, and with d-limonene (CAS 5989-27-5), the citrus terpene that doubles as a green solvent in cleaners and degreasers. Citral even feeds into UV-absorber chemistry through cinnamate derivatives, tying it loosely to the photostability work formulators do in sun care.
Handling, storage, and buying notes
Citral is stable enough for routine use, but it is sensitive to light, heat, and air — which is why storage at 2–8 °C in a sealed, amber container is the standard recommendation, and why it should be kept away from strong oxidizers and alkalis. On specifications, most buyers ask for the isomer ratio (geranial/neral balance), the assay (often 95% min or higher for fragrance grade), and a low residue profile for food and cosmetic grades. Sample evaluation matters more than a datasheet here: a lemon note that smells “cooked” or “plastic” usually points to oxidation or overheating during production, and that is hard to see on paper. For flavor and cosmetic work, insist on the right grade and the relevant regulatory backing; for industrial synthesis, assay and isomer profile drive the yield of whatever you are making downstream. When building complex accords, citral is frequently combined with trans-anethole (CAS 4180-23-8), whose sweet anise character balances a sharp citrus front.
Bottom line
Citral is one of those quiet building blocks that shows up across the label — in the drink, in the detergent, and in the molecule you synthesize from it. For teams sourcing it at scale, the differentiators are grade consistency, documented regulatory status, and a supplier who can hold the lemon note batch after batch.
