Fatty Acid Composition of Oils

Fatty Acid Composition of Oils — reference table

What fatty acids are and why composition matters

An oil or fat is chemically a mixture of triglycerides — a glycerol backbone carrying three fatty acids — and it is those fatty acids that determine almost everything about how the oil behaves. A fatty acid is a chain of carbon atoms with an acid group at one end, and oils differ in two main ways: the length of the chains and the number of carbon–carbon double bonds (the degree of unsaturation). Together these set an oil's melting point, stability, viscosity and use. Because each oil has a characteristic mix of fatty acids, the fatty-acid composition is an oil's fingerprint — the single most informative thing you can know about it — which is why this table underlies so much of oil chemistry, from refining choices to iodine and saponification values to how an oil performs in a pan or a paint.

How fatty acids are named: the C:D notation

Fatty acids are written in a compact C:D notation — the number of carbon atoms, a colon, then the number of double bonds. So C16:0 is palmitic acid (sixteen carbons, no double bonds, saturated); C18:1 is oleic acid (eighteen carbons, one double bond, monounsaturated); C18:2 is linoleic acid (two double bonds, polyunsaturated); and C18:3 is alpha-linolenic acid (three double bonds). The 'omega' number (as in omega-3, omega-6) says where the first double bond sits counting from the far end of the chain. This notation makes the table readable at a glance: a low first number means a short chain (high saponification value), and a high second number means more unsaturation (high iodine value and lower stability). Almost every oil is built from a handful of these acids in different proportions.

The three families: saturated, mono- and polyunsaturated

The summary columns group fatty acids into three families by their number of double bonds. Saturated fatty acids (no double bonds — lauric, myristic, palmitic, stearic) are straight, pack together well, and so make fats harder and more stable; oils rich in them (coconut, palm) are solid or semi-solid and resist oxidation. Monounsaturated fatty acids (one double bond — chiefly oleic) sit in the middle: liquid but reasonably stable, as in olive and high-oleic oils. Polyunsaturated fatty acids (two or more double bonds — linoleic, alpha-linolenic) have multiple reactive sites, so oils rich in them (sunflower, safflower, flax) are liquid and oxidation-prone, going rancid faster. This three-way split is the quickest way to read the table: the saturated-to-polyunsaturated balance predicts an oil's texture, stability and shelf life, which is why the summary columns are given alongside the detailed acids.

Lauric acid (C12:0)

Lauric acid is a short, twelve-carbon saturated fatty acid that defines the 'lauric oils' — coconut and palm kernel — where it can make up roughly 45–53% of the fatty acids. Its short chain and full saturation give these oils several distinctive properties: they are hard or semi-solid at cool room temperature yet melt sharply near body temperature, they are very stable against oxidation (no double bonds to attack), and they have a high saponification value because a gram of oil packs in many of these light molecules. In soap-making, lauric acid is prized for producing a hard bar that lathers quickly, and in oleochemistry it is a key raw material for foaming surfactants. So an oil high in lauric acid is instantly recognisable by its hard-but-sharp-melting, stable, high-saponification character — the compositional opposite of a polyunsaturated seed oil.

Myristic acid (C14:0)

Myristic acid is a fourteen-carbon saturated fatty acid, the next up the chain from lauric, and it travels with it: the lauric oils (coconut ~16–21%, palm kernel a little less) are the main sources, and it also appears in smaller amounts in many fats. Like all saturated acids it firms up a fat and adds stability, and being short-chain it contributes to the high saponification value of the lauric oils. On its own it is rarely the dominant acid of a food oil, but it is a reliable marker of the lauric oils and part of what makes coconut and palm kernel oil behave as they do. In the fatty-acid table, a meaningful myristic figure is a strong hint that you are looking at a tropical lauric oil rather than a temperate seed oil, where myristic is usually only a trace.

Palmitic acid (C16:0)

Palmitic acid is a sixteen-carbon saturated fatty acid and the most abundant saturated fatty acid in nature, present in almost every oil and fat to some degree. It is the dominant saturated acid in palm oil (~40–46%, hence the name) and a major component of cottonseed and cocoa butter, while forming the modest saturated fraction (~8–17%) of most seed oils. Being saturated, palmitic acid raises melting point and stability, so oils rich in it tend toward the semi-solid and keep well. Because it is so widespread, palmitic acid is often the 'baseline' saturated acid against which an oil's character is read: a high palmitic figure points to palm, cottonseed or a tropical fat, while a low one is typical of the light liquid oils like canola and safflower. It is a workhorse of both food fats and oleochemistry.

Stearic acid (C18:0)

Stearic acid is an eighteen-carbon saturated fatty acid, longer than palmitic, and it is most prominent in cocoa butter (~33–37%) and in animal fats, appearing only modestly in most seed oils. Its length and full saturation make it solid and stable, and in cocoa butter its particular pairing with palmitic and oleic acids produces the famous sharp melt-in-the-mouth behaviour. Stearic acid is also the target of full hydrogenation, which saturates unsaturated acids up to stearic to make a hard, trans-fat-free base fat that can then be blended and interesterified. So among the saturated acids, stearic is the one most associated with premium confectionery fats and with the hard fully-saturated fats used in modern fat modification, distinct from the more ubiquitous palmitic acid.

Oleic acid (C18:1)

Oleic acid is the principal monounsaturated fatty acid — eighteen carbons with a single double bond (an omega-9) — and it is the dominant acid of olive, high-oleic sunflower and safflower, canola and avocado oils, where it can reach 60–90%. Its single double bond is the reason oleic oils occupy the sweet spot of the table: liquid at room temperature yet much more oxidation-stable than the polyunsaturated oils, because there is only one reactive site per molecule rather than several. This combination of fluidity and stability makes high-oleic oils excellent frying and all-round cooking oils, which is precisely why plant breeders created high-oleic sunflower and safflower and why canola's oleic-rich, low-saturated profile is so valued. An oil dominated by oleic acid is, in short, a stable liquid oil — the workhorse profile of the modern kitchen and the target of a great deal of oilseed breeding.

Linoleic acid (C18:2)

Linoleic acid is the main polyunsaturated fatty acid of the plant world — eighteen carbons with two double bonds, an omega-6 — and it dominates standard sunflower, safflower, corn, grapeseed and soybean oils, where it commonly reaches 50–80%. Its two double bonds make it liquid and reactive: oils rich in linoleic acid have a high iodine value and oxidise relatively quickly, so they are lighter, less heat-stable oils better not overheated or stored too long. Linoleic acid is an essential fatty acid in the chemical sense that the body cannot synthesise it, which is a factual point about the acid rather than any dietary recommendation. In the table, a high linoleic figure marks the classic polyunsaturated seed oils — the light, liquid, oxidation-prone oils that sit at the opposite end from the stable lauric and oleic oils.

Alpha-linolenic acid (C18:3, omega-3)

Alpha-linolenic acid is the triple-unsaturated omega-3 fatty acid — eighteen carbons with three double bonds — and it is what sets a handful of oils apart. Flaxseed is dominated by it (~50–58%, the highest of the common oils), and it is notable in walnut, hemp, canola and soybean. Three double bonds make it the most reactive of the common fatty acids: oils rich in it have the highest iodine values, oxidise fastest (developing off flavours quickly), and at the extreme become drying oils that polymerise in air — which is why flaxseed oil is both a delicate food oil and a traditional paint and wood-finish oil. Its presence is the reason omega-3-rich oils must be kept cold and used fresh and cannot be used for high-heat frying. In the table, a meaningful alpha-linolenic figure flags the most perishable, most reactive oils, with flax at the extreme.

Erucic acid (C22:1) and the very-long-chain acids

Erucic acid is a very long-chain monounsaturated fatty acid — twenty-two carbons with one double bond — and it defines mustard oil and traditional high-erucic rapeseed, where it can make up 20–50% of the oil. Its great length gives these oils the lowest saponification values in the table (heavy, few molecules per gram). The desire to remove erucic acid drove the breeding of canola from rapeseed — the single most important compositional change in the history of the crop — so the presence or absence of erucic acid is exactly what separates traditional rapeseed and mustard from modern food-grade canola. Other very-long-chain acids such as arachidic (C20:0) and behenic (C22:0) appear as minor but characteristic components of groundnut oil, where they help confirm its identity. These long-chain acids sit at the low-saponification end of the spectrum, opposite the short-chain lauric acids.

Ricinoleic acid — the castor outlier

Ricinoleic acid is the great oddity of the table: an eighteen-carbon monounsaturated fatty acid carrying an unusual hydroxyl (–OH) group on its chain, found in almost no other common oil but making up about 87–90% of castor oil. That hydroxyl group changes everything: it gives castor oil its very high viscosity, its unusual solubility, and its reactivity as a chemical raw material — which is why castor is an industrial (non-edible) oil for lubricants, coatings, plastics and a wide range of chemical derivatives rather than a food oil. It also explains why castor sits apart on both the iodine and saponification charts, since neither ordinary unsaturation nor ordinary chain length fully captures a hydroxy acid. Ricinoleic acid is the clearest example in the table of how a single unusual fatty acid can define an oil's entire character and industrial role.

How fatty-acid composition is measured

Fatty-acid composition is measured by gas chromatography (GC), and understanding the method helps explain why the figures are ranges. The oil's triglycerides are first converted into fatty-acid methyl esters (FAME) — a step called transesterification or methylation that makes the individual fatty acids volatile enough to analyse. The FAME mixture is then injected into a gas chromatograph, where the different fatty acids separate as they travel through a column according to their chain length and unsaturation, each emerging at a characteristic time and registering as a peak. The area under each peak gives that fatty acid's proportion of the total, so the output is a full profile — palmitic, stearic, oleic, linoleic, linolenic and the rest — as percentages. Standardised procedures are published by AOCS and ISO. Because real oils vary with variety, origin and season, and because methods differ slightly, published composition figures are given as indicative ranges rather than fixed values — which is exactly how this table presents them.

The omega classification: omega-3, -6 and -9

The 'omega' labels that appear on oils are simply another way of describing where a fatty acid's first double bond sits, counting from the methyl (far) end of the chain. An omega-9 acid has its first double bond at the ninth carbon from that end — oleic acid is the main one. An omega-6 has it at the sixth carbon — linoleic acid is the dominant example. An omega-3 has it at the third carbon — alpha-linolenic acid. So the omega number is a structural descriptor, not a quality grade: it tells a chemist about the position of unsaturation, which affects how the acid behaves. Reading the table through this lens, the oleic (omega-9) oils are the stable monounsaturated ones, the linoleic (omega-6) oils are the common polyunsaturated ones, and the alpha-linolenic (omega-3) oils are the most reactive. The much-discussed omega-6-to-omega-3 balance of an oil is a compositional observation about its linoleic and alpha-linolenic content; here it is described chemically and is not a dietary claim.

Minor and unusual fatty acids

Beyond the handful of major acids, oils carry minor and unusual fatty acids that, though small in quantity, are often characteristic enough to help identify an oil. Palmitoleic acid (C16:1) appears in macadamia and some fish and animal fats. Gamma-linolenic acid (GLA), a different omega-6 triple-unsaturated acid, is notable in evening primrose, borage and hemp oils. The very-long-chain saturated acids — arachidic, behenic, lignoceric — are minor markers of groundnut oil. Some oils carry small amounts of trans fatty acids naturally, and others acquire them through partial hydrogenation (the reason that process fell out of favour) — though interesterification and full hydrogenation do not create them. These minor components rarely change an oil's bulk behaviour, but they matter for authenticity testing, since an unexpected minor acid, or the wrong ratio of minor acids, can reveal a blend or adulteration that the major acids alone might miss. So a full composition profile looks beyond the headline acids to this long tail of minor ones.

Composition and fat modification

The fatty-acid composition of an oil is not necessarily used as-is; the industry has several tools to modify it or its behaviour, and the table helps show what each does. Hydrogenation adds hydrogen across double bonds, reducing unsaturation — it moves an oil up the saturation scale (lowering its iodine value) to harden it, and if partial, creates trans fats. Interesterification, by contrast, rearranges fatty acids between triglycerides to change melting behaviour without changing the fatty acids themselves, so it leaves the composition figures in this table unchanged while altering the fat's physical performance. Fractionation physically separates an oil into higher- and lower-melting fractions of different composition, as with palm olein and stearin. And blending simply averages the compositions of two oils. So when reading a composition figure, it is worth knowing whether the oil is a natural one or has been modified — hydrogenation and fractionation change the numbers, while interesterification and blending change the behaviour or the mixture without altering the underlying acids of each component.

Why the same oil varies

A crucial caveat in reading any composition table is that the figures are ranges, not constants, because a single oil's composition varies with variety, growing conditions and season. The clearest driver is variety and breeding — standard versus high-oleic sunflower, or high-erucic rapeseed versus canola, are dramatic examples where the same crop yields chemically different oils. But even within one variety, climate and temperature shift the balance: oilseeds grown in cooler conditions tend to produce more unsaturated oil (a plant response that keeps the oil fluid at lower temperatures), so the same sunflower variety can differ between a hot and a cool growing region. Maturity at harvest, soil and agronomy add further variation. This is why product standards define composition as acceptance ranges rather than exact values, and why this table does the same. A single quoted percentage for an oil should be read as the centre of a real range, not a fixed property.

Matching oil composition to use

Pulling the table together, composition is ultimately a guide to what an oil is good for. For high-heat frying, the stable oils win — the saturated lauric and palm oils and the monounsaturated oleic oils (olive, high-oleic sunflower, canola, rice bran), which resist oxidation and hold up to repeated heat. For light cooking and dressings, the linoleic oils (sunflower, corn, grapeseed) are fine used gently. For flavour finishing, the delicate omega-3-rich oils (flax, walnut, hemp) shine but must stay cold and unheated. For confectionery and structured fats, the sharp-melting saturated fats (cocoa butter, palm and palm kernel fractions) are chosen and often fractionated or interesterified to a target. And for industrial uses, the reactive extremes serve — drying linseed for coatings, hydroxy-acid castor for lubricants and chemicals. So a glance at an oil's dominant fatty acid and its saturated-to-polyunsaturated balance points directly to its ideal role, which is the practical payoff of the whole table.

Reading an oil by its dominant acid

The fastest way to use this table is to note each oil's dominant fatty acid, because that single fact predicts much of its behaviour. Oils dominated by lauric acid (coconut, palm kernel) are hard, stable and high-saponification. Oils dominated by palmitic acid (palm) are semi-solid. Oils dominated by oleic acid (olive, high-oleic sunflower, canola, avocado) are liquid but stable — good all-round and frying oils. Oils dominated by linoleic acid (sunflower, safflower, corn, grapeseed, soybean) are liquid and less stable — light cooking oils better not overheated. Oils high in alpha-linolenic acid (flax, and notably walnut and hemp) are the most oxidation-prone, better used cold, and at the extreme become drying oils. And the outliers — erucic (mustard) and ricinoleic (castor) — sit apart. Learning these few groupings turns the table from a wall of numbers into a quick, practical guide.

Composition, stability and shelf life

The most immediate practical consequence of composition is oxidative stability. Every double bond is a site where oxygen can attack, so the more polyunsaturated an oil, the faster it oxidises and turns rancid — which is exactly what the iodine value summarises. This is why the highly saturated lauric oils keep almost indefinitely, the oleic oils keep well, and the polyunsaturated and omega-3-rich oils (sunflower, safflower, flax, walnut) must be kept cool, dark and airtight and used sooner, as set out in how to store edible oil. Composition also sets the smoke point behaviour and how an oil holds up to repeated frying. So the fatty-acid table is not an abstract chemistry reference: it directly predicts how long an oil lasts, how it should be stored, and what it is fit to cook.

Why breeding creates high-oleic oils

One pattern in the table deserves special note: several crops appear in two very different forms. Standard sunflower and safflower are high in polyunsaturated linoleic acid and so oxidation-prone; their high-oleic versions, bred to shift the profile toward monounsaturated oleic acid, are far more stable and behave like olive oil. Likewise, canola was bred from rapeseed specifically to remove the erucic acid of the traditional crop. These examples make a crucial point about reading any composition figure: the crop name alone does not fix the oil's composition — the variety matters, sometimes enormously. A 'sunflower oil' figure is meaningless without knowing whether it is the standard (linoleic) or high-oleic type, which is why the table lists them separately and why a real specification names the type, not just the crop.

Composition, identity and adulteration

Because each oil has a characteristic fatty-acid fingerprint, composition is the most powerful tool for identity and authenticity. Gas chromatography measures the full fatty-acid profile, and a sample whose profile falls outside the expected ranges for its declared oil is flagged as blended, substituted or adulterated — for example, a cheap high-linoleic oil added to a premium high-oleic one shifts the measured profile detectably. This is why product standards for named oils specify fatty-acid composition ranges, and why composition testing, backed by iodine and saponification values, is central to trade and regulatory checking. The ranges in this table are the kind of reference such checks are read against, though the authoritative limits live in the official standards for each named, graded oil.

Tropical oils versus temperate seed oils

One of the deepest patterns in the table is the divide between tropical fats and temperate seed oils. The tropical oils — coconut, palm kernel, palm and cocoa butter — are rich in saturated fatty acids (lauric, myristic, palmitic, stearic) and so tend to be solid or semi-solid at room temperature and very stable. The temperate seed oils — sunflower, soybean, rapeseed, corn, safflower — are rich in unsaturated acids (oleic, linoleic, alpha-linolenic) and so are liquid and, at the polyunsaturated end, oxidation-prone. This is not a coincidence: it reflects the biology of where each plant evolved, since a fat that stays solid suits a hot climate while a more unsaturated oil stays fluid in the cold. The practical upshot is that the two groups fill different roles — tropical fats provide the hard, stable structure for baking, confectionery and long shelf life, while temperate liquid oils provide everyday cooking and finishing oils. Recognising which side of this divide an oil sits on is the first, fastest read of any composition figure.

Fatty acids and melting point

The most visible consequence of composition is whether an oil is solid or liquid, and this follows directly from its fatty acids. Saturated fatty acids have straight chains that pack together tightly, so they need more energy to melt — the more saturated a fat, the higher its melting point and the more solid it is at room temperature. Unsaturated acids have a kink at each double bond that stops them packing neatly, lowering the melting point and keeping the oil liquid; the more double bonds, the lower the melting point. This is why coconut and palm are semi-solid, olive and canola are liquid, and highly polyunsaturated flax stays liquid even when chilled. Chain length adds a second dimension — longer chains melt higher — so the very-long-chain erucic and behenic acids raise melting point too. The winterizing and fractionation processes exploit exactly these differences, cooling an oil so its higher-melting (more saturated or longer-chain) fractions crystallise out. So melting behaviour, texture and the whole solid-versus-liquid character of an oil are written directly in its fatty-acid table.

Fatty acids and smoke point

Composition also shapes how an oil behaves under heat, though less directly than melting point. An oil's smoke point — the temperature at which it starts to visibly smoke and break down — is governed less by the fatty acids themselves than by the free fatty acids and impurities present, which is why refining (removing those) raises the smoke point far more than composition alone. That said, composition matters for how well an oil survives repeated heating: highly polyunsaturated oils degrade and polymerise faster under prolonged heat than stable monounsaturated or saturated oils, so a high-oleic oil holds up to repeated frying better than a high-linoleic one even at a similar initial smoke point. This is a key reason the stable oleic oils are preferred for commercial frying, and why the high-oleic versions of sunflower and safflower were bred. So while the smoke point on a label is mostly about refining, the fatty-acid profile is what decides whether an oil stays good through many frying cycles — a distinction worth keeping clear.

Essential fatty acids in the chemical sense

Two of the fatty acids in this table are described as essential fatty acids: linoleic acid (omega-6) and alpha-linolenic acid (omega-3). In the strict chemical and biological sense, 'essential' means simply that the human body cannot synthesise these acids itself and so must obtain them from the diet — it is a statement about biochemistry, not a ranking of oils or a dietary recommendation. Because linoleic acid is abundant in the common seed oils (sunflower, safflower, corn, soybean) and alpha-linolenic acid is concentrated in a few oils (flax especially, and canola, walnut and soybean), the composition table is often consulted for which oils supply which essential acid. It is worth stating plainly, though, that this platform describes these acids chemically — where they occur and how they behave — and does not offer nutritional advice, which is the province of qualified dietary authorities. The 'essential' label here is a fact about the molecules, included because it is part of understanding why these particular fatty acids are so often discussed.

Composition, the meal and the by-products

An oil's fatty-acid composition is the headline, but the same seed also yields a meal or cake and, in refining, various by-product streams, and composition ripples through all of them. The meal left after oil removal is valued mainly for its protein, but its residual oil carries the seed's fatty-acid signature, which matters for feed. In refining, the fatty acids removed as free fatty acids end up in the soapstock or deodorizer distillate, so an oil's composition shapes the character of those recovered streams too — a lauric crude yields lauric-rich by-products, a linoleic crude yields linoleic-rich ones. Even the gums removed in degumming carry fatty acids as part of their phospholipids. So the composition table is not just about the finished oil: it describes the fatty acids that flow through the whole process, into the oil, the meal, the soapstock and the distillate. Reading an oilseed operation as a whole means tracking that single fatty-acid signature as it distributes across every product and co-product.

Reading a composition specification

In trade and quality work, fatty-acid composition appears as a specification — a set of acceptance ranges an oil must meet to be sold as a named, graded product — and reading one correctly matters. A Codex or national standard for, say, sunflower oil lists a permitted range for each major fatty acid (palmitic, stearic, oleic, linoleic and so on), and a real oil must fall within all of them to qualify. This is how the high-oleic and standard types are distinguished in trade: they meet different composition specifications despite sharing a crop name. When an independent lab tests an oil by gas chromatography, the measured profile is checked against the applicable specification, and a value outside any range signals a non-conforming, mislabelled or adulterated oil. So a composition specification is both an identity definition and a quality gate. The ranges in this table are the kind of reference such a check draws on, while the authoritative, legally-binding limits live in the official standard for each specific oil and grade.

How oilseed breeding reshaped these numbers

It is worth appreciating that several rows in this table look the way they do because of decades of plant breeding, not just nature. Canola is the landmark case: traditional rapeseed was high in erucic acid, and breeders in the twentieth century developed the low-erucic, low-glucosinolate 'canola' type, fundamentally changing the oil's composition and creating one of the world's major food oils. High-oleic sunflower and safflower were bred to shift those crops from oxidation-prone linoleic profiles toward stable oleic ones, giving the food industry trans-fat-free frying oils. Soybean varieties have been developed with lower alpha-linolenic acid to improve stability, and high-oleic soybean now exists too. These programmes mean that a composition figure is a snapshot of available varieties, not a fixed law of nature — and that the same crop name can span very different oils depending on the type grown. It also means the table will keep evolving as breeding continues, which is one more reason its figures are given as indicative ranges rather than fixed constants.

The specialty and industrial oils

A cluster of oils sit apart from the food mainstream because of an unusual dominant fatty acid, and the table is the quickest way to spot them. Castor is the clearest case, dominated by hydroxy ricinoleic acid and used almost entirely for industrial chemistry rather than food. High-erucic rapeseed and mustard, dominated by very-long-chain erucic acid, are used both as regional food oils and as industrial feedstocks. Tung oil (not in the food table) is an extreme drying oil dominated by a conjugated triple-unsaturated acid, used purely for coatings. And flaxseed, though a food oil, doubles as an industrial drying oil because of its high alpha-linolenic content. What these share is that a single unusual acid — hydroxy, very-long-chain, or highly conjugated — pushes the oil out of the ordinary food range and into a specialty or industrial role. Reading the table, an oil whose dominant acid is none of the familiar palmitic, oleic or linoleic is a signal to look closer, because it is likely a specialty oil with distinctive uses and handling.

Composition, viscosity and physical properties

Beyond melting point and stability, fatty-acid composition shapes an oil's other physical properties, viscosity among them. In general, longer chains and more saturation raise viscosity, while the hydroxy group of ricinoleic acid makes castor oil far more viscous than any ordinary oil — the property behind its use as a lubricant. Composition also affects density (the subject of a separate density table), refractive index and solubility, all of which are used alongside the fatty-acid profile to characterise and identify oils. These physical properties are not independent of the composition table but downstream of it: the same features that set an oil's melting point — chain length, unsaturation, any unusual groups — also set how thick it flows, how it bends light and how it dissolves. So while this table lists fatty acids as percentages, those percentages quietly determine a whole family of measurable physical properties that engineers and analysts rely on, which is part of why the composition profile is regarded as the most fundamental description of an oil.

Why oils overlap and the profile must be read as a whole

A practical subtlety in using this table is that the ranges for different oils overlap, so no single fatty-acid figure identifies an oil on its own. Many temperate seed oils share a similar modest palmitic content; several are high in linoleic acid; oleic acid is common to olive, canola, high-oleic sunflower and avocado. Because of this overlap, identity is established not by one number but by the whole profile read together — the particular combination of all the major and minor acids, cross-checked against iodine and saponification values. Two oils might match on oleic acid yet differ clearly on their linoleic, linolenic or minor-acid content, and it is that fuller pattern that distinguishes them. This is why laboratories report the complete gas-chromatography profile rather than a single figure, and why authenticity testing weighs the entire fingerprint. The lesson for reading the table is to treat each oil's row as a pattern, not a list of independent numbers — the shape of the whole profile is what carries the identity.

Using this table with the iodine and saponification charts

This composition table is the most detailed of three related references, and the trio is designed to be read together. The iodine value chart collapses an oil's unsaturation into a single number — essentially a summary of the oleic, linoleic and linolenic content shown here. The saponification value chart collapses its average chain length into a single number — a summary of whether the oil is short-chain (lauric) or long-chain (erucic). So the two derived charts are, in effect, condensed readings of this composition table: a high iodine value corresponds to the polyunsaturated rows here, a high saponification value to the lauric rows. For a quick comparison, the single-number charts are convenient; for the full picture — including which specific acids and any unusual ones an oil contains — this composition table is the reference. Used together, they let you move between a fast summary and the underlying detail, and cross-checking an oil across all three is a strong way to confirm an oil's identity, as the quality-testing guide describes.

A note on nutrition and scope

This table describes the chemical composition of oils — which fatty acids they contain and in what indicative proportions — and its purpose is to explain how composition governs an oil's physical behaviour, stability, processing and use. It is not nutritional or health advice, and the terms here (saturated, monounsaturated, omega-3 and so on) are used in their chemical sense to describe the oils, not to rank them for any dietary purpose. Dietary guidance is a separate matter set by qualified authorities and is outside the scope of this engineering-and-processing reference. For how these compositional facts feed into oil testing and quality, see the quality-testing guide; for the two derived characterisation numbers, see the iodine value and saponification value charts.

Oil-by-oil fatty-acid signatures

Each oil below is summarised by its characteristic fatty-acid signature. Figures are indicative ranges as a percentage of total fatty acids, and vary by variety, origin and season — treat them as a map of each oil's character, not a specification. Oils are grouped loosely from the most saturated (lauric) through the oleic and linoleic oils to the omega-3-rich and specialty oils.

Coconut. Coconut oil is the archetypal lauric oil: overwhelmingly saturated (indicatively ~86–92% of its fatty acids), with lauric acid (C12:0) alone making up roughly 45–53%, plus substantial myristic (C14:0, ~16–21%) and palmitic (C16:0, ~8–10%). Only a small fraction is unsaturated — a little oleic and very little linoleic. This short-chain, highly-saturated profile makes coconut oil solid at cool room temperature, extremely stable against oxidation, and high in saponification value while very low in iodine value. It is the compositional opposite of the polyunsaturated seed oils.

Palm kernel. Palm kernel oil — pressed from the seed inside the palm fruit, not the flesh — is the other major lauric oil, close cousin to coconut. It is roughly 80–85% saturated, dominated by lauric acid (~45–52%) and myristic acid, with more oleic (~12–16%) than coconut. Because of this lauric character it resembles coconut oil far more than it resembles palm oil from the same fruit, a distinction that trips up many readers. Its hard, stable, high-saponification profile suits confectionery fats, soaps and surfactants.

Palm. Palm oil, from the fruit mesocarp, is almost evenly split between saturated and unsaturated fat. Its saturated portion (~49–52%) is dominated by palmitic acid (C16:0, ~40–46%) — palm oil is the classic palmitic-rich oil — while oleic acid (~37–40%) and some linoleic (~9–11%) make up the unsaturated side. This balance leaves it semi-solid at room temperature, which is why it is so widely fractionated into a liquid olein and a solid stearin. It is compositionally quite different from the lauric palm kernel oil.

Cocoa butter. Cocoa butter has an unusual and prized composition: high in saturated fat (~57–64%) but with an even split between stearic acid (C18:0, ~33–37%) and palmitic acid (~24–30%), plus a large slug of oleic acid (~30–36%). This particular arrangement gives it a sharp melting profile just below body temperature — hard and brittle at room temperature, melting cleanly in the mouth — the property that makes it the benchmark confectionery fat. Its stearic-rich saturation sets it apart from the palmitic-rich palm and the lauric coconut oils.

Olive. Olive oil is the benchmark monounsaturated (oleic) oil: around 70–80% oleic acid (C18:1), with a modest saturated fraction (~13–17%, mostly palmitic) and relatively little polyunsaturated linoleic (~5–12%). This high-oleic profile gives it good oxidative stability for a liquid oil and a moderate iodine value. Because so much of its value lies in flavour and minor components, olive oil is often sold unrefined (virgin), unlike the commodity seed oils that are fully refined to neutrality.

High-oleic sunflower. High-oleic sunflower is a bred variant whose composition is deliberately shifted toward oleic acid (~80–90%), far from the standard sunflower profile. Its saturated fraction is small (~8–10%) and its polyunsaturated linoleic is low (~5–9%). The result is an oil that behaves much like olive oil compositionally — stable, high in oleic acid, low in iodine value — and is prized as a stable frying oil. It is the clearest illustration that the crop name alone does not fix an oil's composition: standard and high-oleic sunflower are chemically very different oils.

Groundnut (peanut). Groundnut (peanut) oil sits in a balanced middle: oleic (~40–60%) and linoleic (~20–38%) between them dominate, over a moderate saturated fraction (~15–20%, palmitic and stearic). A distinctive feature is its content of long-chain saturated acids — arachidic (C20:0), behenic (C22:0) and lignoceric (C24:0) — which are minor but characteristic and are part of how groundnut oil is identified. Its balance of oleic and linoleic gives a good all-round frying and cooking oil with reasonable stability.

Cottonseed. Cottonseed oil is notable for a comparatively high saturated fraction (~26–30%, mostly palmitic) sitting alongside a high linoleic content (~48–58%) and modest oleic (~15–22%). This palmitic-plus-linoleic signature gives it more body than the lighter seed oils and made it a traditional frying and shortening oil. Crude cottonseed oil also naturally contains gossypol, a pigment that must be removed in refining — one reason cottonseed is sold refined.

Sesame. Sesame oil is well-balanced between oleic (~37–43%) and linoleic (~40–48%) acids, over a modest saturated fraction (~14–17%). This near-even split of the two main unsaturated acids gives it a moderate stability and a versatile character. Sesame is also unusual for its natural antioxidants (sesamol and related lignans), which help it keep better than its polyunsaturated content alone would suggest — a reminder that the fatty-acid table does not capture everything about an oil's behaviour.

Rice bran. Rice bran oil has a balanced profile — oleic (~38–45%) and linoleic (~30–38%) over a moderate saturated fraction (~20–25%, mostly palmitic). What makes rice bran distinctive is not its fatty acids so much as its high content of unsaponifiable matter — including oryzanol and tocols — which sits outside the fatty-acid table (and is not counted by saponification value). Its balanced acids give it good frying stability, and it is valued as a high-smoke-point cooking oil.

Corn (maize). Corn (maize) oil is a linoleic-dominant oil: polyunsaturated linoleic acid makes up roughly 45–60%, with variable oleic (~24–42%) and a modest saturated fraction (~12–15%, mostly palmitic). This puts it among the polyunsaturated seed oils, with a fairly high iodine value and correspondingly moderate oxidative stability. Like other linoleic-rich oils it is fully refined to a neutral commodity oil and used widely for frying and food manufacture.

Soybean. Soybean oil, the world's highest-volume seed oil, is linoleic-dominant (~50–57%) with a notable slug of alpha-linolenic acid (C18:3, omega-3, ~5–8%) — unusual among the common seed oils — over moderate oleic (~20–30%) and a saturated fraction of ~14–16% (mostly palmitic). Its linolenic content makes it more prone to a particular kind of oxidative flavour reversion, historically managed by light hydrogenation or, now, by interesterification and breeding. It carries valuable phosphatides removed in degumming as lecithin.

Sunflower (standard). Standard (linoleic) sunflower oil is one of the most polyunsaturated common oils: linoleic acid around 60–70%, with modest oleic (~15–25%) and a small saturated fraction (~10–12%). This gives it a high iodine value and lower oxidative stability, which is precisely why the high-oleic version was bred. The two sunflower types are compositionally very different oils sharing a crop name — a key caveat when reading any 'sunflower oil' figure.

Safflower (standard). Standard safflower oil is the most linoleic-rich of the common oils — polyunsaturated linoleic acid can reach 70–80% — with very little oleic (~10–15%) and a small saturated fraction (~8–10%). This makes it the highest-iodine-value ordinary food oil and among the least oxidatively stable, better used unheated. As with sunflower, a high-oleic safflower exists with an almost inverted profile, again showing how breeding reshapes a crop's oil.

Grapeseed. Grapeseed oil is another strongly linoleic oil (~68–73% linoleic), with modest oleic (~15–20%) and a small saturated fraction (~10–12%). A by-product of winemaking, it is a light, neutral, polyunsaturated oil with a fairly high iodine value and moderate stability. Its high linoleic content places it firmly among the polyunsaturated seed oils rather than the more stable oleic oils.

Rapeseed / canola. Canola (low-erucic rapeseed) has one of the lowest saturated fractions of any common oil (~6–8%) and is oleic-dominant (~58–64%), with linoleic (~18–22%) and a useful amount of alpha-linolenic acid (omega-3, ~8–11%). This oleic-with-omega-3 profile and low saturation define modern canola. Crucially, food-grade canola is bred to remove the erucic acid that dominates traditional high-erucic rapeseed — the compositional change that created 'canola' from rapeseed.

Mustard / high-erucic rape. Mustard oil and traditional high-erucic rapeseed are defined by erucic acid (C22:1), a very long-chain monounsaturated acid that can make up 20–50% of the oil — the feature that distinguishes them from modern canola and gives them the lowest saponification values (long chains, heavy molecules). The rest is oleic, linoleic and alpha-linolenic. It was the desire to remove erucic acid that led to the breeding of canola from rapeseed.

Flaxseed (linseed). Flaxseed (linseed) oil is dominated by alpha-linolenic acid (C18:3, omega-3) at roughly 50–58% — the highest of the common oils — plus linoleic (~14–17%) and oleic (~18–22%) over a small saturated fraction (~9–11%). This triple-unsaturated dominance gives it the highest iodine value of any food oil and makes it a drying oil that polymerises in air — which is why, beyond food, it is a traditional paint, varnish and wood-finish oil. It is highly oxidation-prone and must be kept cold and used quickly.

Walnut. Walnut oil is highly polyunsaturated, dominated by linoleic acid (~53–60%) with a notable amount of alpha-linolenic acid (omega-3, ~10–14%) and modest oleic, over a small saturated fraction (~9–11%). This high, doubly-unsaturated content gives it a rich flavour but low oxidative stability, so it is a premium finishing oil, kept cold and used fresh rather than a cooking oil.

Hemp. Hemp seed oil is among the most polyunsaturated oils, with linoleic (~50–60%) and a high alpha-linolenic (omega-3, ~15–25%) content, plus some gamma-linolenic, over a small saturated fraction (~9–11%). This very high polyunsaturation gives it a high iodine value and poor heat stability, so like flax and walnut it is a cold-use specialty oil. Its notably balanced omega-6 to omega-3 ratio is often highlighted, though that is a compositional observation, not a health claim.

Avocado. Avocado oil, pressed from the fruit flesh rather than a seed, is oleic-dominant (~60–70%), much like olive oil, with a moderate saturated fraction (~15–20%, mostly palmitic) and modest linoleic (~10–15%). This monounsaturated-rich profile gives it good stability and a relatively high smoke point when refined, and it is used both as a premium culinary oil and, refined, as a stable cooking oil.

Castor. Castor oil is the great outlier: about 87–90% ricinoleic acid, an unusual hydroxy monounsaturated fatty acid found in almost no other common oil. This single dominant acid, with its extra hydroxyl group, gives castor oil its uniquely high viscosity, its solubility behaviour and its value as an industrial (non-edible) oil for lubricants, coatings and chemical derivatives. Its composition is why castor sits apart on both the iodine and saponification charts and is treated as a specialty rather than a food oil.

Related pages

Iodine value chartSaponification value chartOil smoke pointsQuality testing guideCodex oil standardsOilseeds

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