What is a fatty acid and why does the shape of fat determine everything?

By Rosan van der Glas, Application scientist, NoPalm Ingredients  ·  August 2026  ·  5 min read

The science behind why palm oil is solid, why olive oil is liquid, and why getting yeast to produce the right fat is one of the hardest problems in food biotechnology, explained without a chemistry degree.

Fats and oils sound simple. We eat them, cook with them, apply them to our skin. We have strong intuitions about them: butter is solid, sunflower oil is liquid, cocoa butter makes chocolate snap cleanly when you break it. But almost nobody knows why.

The answer is molecular geometry. The shape of fat, at a scale a billion times smaller than anything you can see, determines everything: whether it is solid or liquid at room temperature, whether it melts cleanly in your mouth, whether it holds its structure in a cream cheese or a chocolate coating. And that shape is exactly what NoPalm Ingredients has spent four years learning to influence.

This is the explainer I wish existed when I started working on fermentation-derived fats. No jargon where plain language will do. No shortcuts where the detail actually matters.

Start here: what is a fatty acid?

A fatty acid is a long chain of carbon atoms. Each carbon in the chain is bonded to hydrogen atoms, and at one end of the chain there is a carboxylic acid group, the part that makes it an acid.

Think of it as a string of beads. Each bead is a carbon atom. The string has a specific length, typically between 8 and 24 beads for the fatty acids that matter in food and cosmetics. And the string can be either straight or kinked, depending on the bonds between the beads.

That distinction, straight or kinked, is the most important thing to understand about fat.

Straight chains: saturated fatty acids

When every carbon in the chain is bonded to the maximum number of hydrogen atoms, the chain is straight. These are called saturated fatty acids, saturated because there is no room for more hydrogen.

Straight chains pack together tightly, like pencils in a box. When many of them pack together, they form a solid structure. This is why palm oil, coconut oil, and butter, all rich in saturated fatty acids, are solid or semi-solid at room temperature.

Kinked chains: unsaturated fatty acids

When two adjacent carbons in the chain form a double bond instead of a single bond, the chain develops a kink. These are called unsaturated fatty acids, there is a gap in the hydrogen saturation at the double bond.

Kinked chains cannot pack as tightly as straight ones. They push apart, leaving space between them. This is why oils rich in unsaturated fatty acids, olive oil, sunflower oil, rapeseed oil, are liquid at room temperature. Their chains cannot organise into a solid structure.

Fatty acids with one double bond are called monounsaturated (oleic acid, the main fatty acid in olive oil, is the most familiar example). Fatty acids with multiple double bonds are called polyunsaturated. The more double bonds, the more liquid and unstable the fat, which is why highly unsaturated oils go rancid quickly.

From fatty acids to triglycerides: how fat is actually structured

In food, cosmetics, and the human body, fatty acids almost never exist on their own. They are attached in groups of three to a glycerol molecule: a short, three-carbon backbone that acts as an anchor.

This three-fatty-acid structure is called a triglyceride. Almost all of the fat in the foods you eat, the oils you cook with, and the skincare products you use is triglycerides. The specific combination of fatty acids attached to the glycerol backbone determines the properties of the fat: its melting point, its texture, its stability on the shelf, its behaviour in a food formulation or a cosmetic product.

Palm oil is not a single molecule. It is a mixture of thousands of different triglycerides, each with a slightly different combination of fatty acids. What makes palm oil so remarkably functional is that this particular mixture has a fatty acid profile, dominated by palmitic acid, that produces specific melting and crystallisation behaviour almost perfectly suited to food and cosmetics applications.

Why this matters for replacing palm oil

When a food manufacturer asks us whether REVÓLEO™ can replace palm oil in their product, they are really asking: does REVÓLEO™ have the same triglyceride composition and fatty acid profile as the palm oil fraction they currently use? And does that composition behave the same way in their specific formulation?

This is why palm oil replacement is genuinely hard. It is not enough to produce a fat that is generally similar. The fatty acid profile, the specific proportions of C16:0, C18:0, C18:1, and other fatty acids, and the triglyceride structure need to match with precision. A small deviation in the ratio of palmitic acid to stearic acid changes the melting curve. A different triglyceride structure changes the crystallisation behaviour. Either of those differences affects the final product in ways that a formulator will detect immediately.

What makes REVÓLEO™ different is that we can influence the fatty acid composition of our yeast-derived oils through fermentation. The yeast accumulates fat inside its cells through a natural metabolic pathway, and by controlling key fermentation parameters we can steer the resulting fat towards specific functional properties. While the exact fatty acid profile and triglyceride composition may differ from those of conventional oil fractions, REVÓLEO™ can be designed to exhibit melting and crystallisation behaviour that closely resembles the fats used in a given application. 

Ultimately, successful semi-solid fat replacement is not about creating an identical molecule-for-molecule copy. It is about delivering the functional performance that manufacturers need in their products, from processing through to consumer experience. 

One thing worth understanding about crystallisation

There is one more level of complexity worth understanding, because it is relevant to some of the most demanding applications like chocolate, cream cheese, margarine, and cosmetic butters.

Triglycerides can crystallise in multiple different forms, called polymorphs. The same fatty acid composition can produce a fat that is grainy and waxy (the wrong polymorph) or smooth and glossy (the right one). The correct polymorph depends on how the fat is cooled and processed, which is why chocolate tempering is an art form, and why margarine manufacturing requires precise temperature control.

The science of fat is four hundred years old. The science of getting yeast to produce precisely the right fat, at food-grade quality, at industrial scale, is something NoPalm Ingredients is building in real time.

If you want to understand how that process works, from sugar to REVÓLEO™, the next article in this series will walk through the full fermentation process step by step.

Rosan van der Glas
Application scientist, NoPalm Ingredients. Food technologist. Has been working on making the food we love more sustainable.

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