Leapin Lipids

by Miranda Kohout

Fats are complicated. Different types of fats are chains of various types of molecules and chains of molecules, some long, some short, all with unique properties. While it would be educational to take a deep dive into fat on a molecular level, this is the sort of greasy rabbit hole that is too easy to slide down, and with little immediately useful practical knowledge to show for it once we’ve reached the bottom. Instead, let’s skim the surface, focusing on where fat comes from and how it works in day-to-day applications.

Sources of Fat

Fat comes from two sources: plants and animals. Synthetic fats do exist and are used in food, but largely not outside of industrial kitchens.

Dairy

Butter

Dairy butter’s rich, golden flavor is unparalleled, but it has another stand-out quality that endears it to bakers and pastry chefs: its specific mixture of solid and liquid fat molecules means it is the only fat that is plastic at room temperature, making it nearly ideal for many applications.

When we add butter to a recipe, we’re not just adding fat, but an emulsion of fat and water, along with some proteins, sugars and minerals found in milk solids. A garden-variety, major-label butter is around 80% fat and nearly 20% water. European-style or “dry” butters have fat contents as high as 84%.

Removing the water and solids from butter creates clarified butter. It is solid at room temperature, rather than plastic and has a lower melting point than butter – 76°F (24°C) as opposed to 90°F (32°C) for butter. It has a much higher smoke point than butter, making it ideal for high-heat cooking.

Cream

Cream is a component of milk enriched with fat. There are different types of cream, each with a different proportion of fat. The percentage of fat in the cream determines its viscosity and its versatility. Light cream, for example, contains around 20% fat. It will whip, but it is better suited for applications in which the chef does not need to introduce air to a product. Heavy cream (heavy whipping cream), by contrast, is between 35 and 40% fat. This higher fat content is what allows heavy cream to whip quickly and produce good volume. More fat equals more stability for the final whipped product.

Like butter, cream contains a certain percentage of water. In the case of cream, it is mostly water. Cream with a fat content of 40% is nearly 60% water. When you balance a ganache formula or analyzing a crémeux, it is vital to calculate cream’s contributions to fat and water content separately, as we would with butter.

Note that while cream can be heated without breaking its emulsion and allowing the fat and water to separate, it cannot be frozen. Jagged ice crystals will tear through the fat’s protective membrane, and once the frozen cream is heated, its butterfat will melt out into greasy pools.

To whip cream easily and have it remain whipped without breaking down, you must chill the fats in the cream. The butterfat in well-chilled cream develops a crystalline structure that quickly destabilizes the fat molecules, allowing them to trap air quickly and effectively. Heating butterfat (the main fat in heavy cream), even the slightest amount, softens it. Soft fat will not trap or hold air. Whipped cream that is left out to become warm quickly loses its structure.

Milk

Milk contains far less fat than cream, with whole milk containing a mere 3-5% fat. The fattiest portion of the milk has been separated to use as cream.

Not, in fact, Butter: Margarine and Vegan Butters

A shortage of butter in late-19th-century France led to the invention of margarine. While that early French innovator made his margarine using beef tallow, today margarine is made from a variety of vegetable fats. Depending on the qualities of the different fats used, margarine will work for baking and pastry applications. Many bakers and chefs wrinkle their noses in disgust at the thought of using margarine in their creations. Those same chefs and bakers may have an entirely more positive reaction to the idea of vegan butter. While margarine may contain some milk solids to give it flavor, vegan butter is made exclusively from non-animal sources. The two ingredients are otherwise the same. In the U.S., both margarine and butter must contain at least 80% fat. Less than that, and it must be labeled a “spread.”

Egg Yolks

Not only are egg yolks a source of fat, but the yolks’ fats act as emulsifiers. This is because, as is true with many of our favorite pastry fats, egg yolks, themselves, are an emulsion, containing both high- and low-density lipoproteins as well as an emulsifying protein. Yolks lend their emulsifying properties to our batters and sauces, though it should be noted that their emulsifying power is strongest when the egg yolks are raw and warm. Cold yolks have cold, stiff fats, and the proteins in cooked yolks have coagulated, trapping most of the emulsifying lipoproteins.

Vegetable shortening

Perhaps even more maligned than margarine, “shortening” is an unspeakable word in some bakeries and kitchens. Its key selling point is that it remains solid at warmer temperatures such as those found in most bakeries. By contrast, butter’s ideal working temperature is around 20°C, and it softens quickly as a kitchen heats up. This ability to remain solid makes shortening ideal for creaming and adding air, working into tart doughs, and especially for laminating. Shortening often contains nitrogen gas, too, further enhancing its leaving properties.

Shortening, in short, does everything we wish butter could do, and we love it for these properties. Shortening falls short in two significant ways: it lacks the rich, nuanced flavor of butter, and it remains solid above body temperature. Because it stays solid when eaten, it leaves a greasy, waxy coating in the mouth. These two qualities are enough to deter many traditional bakers and pastry chefs from using it. However, you may find a secret stash for use (in combination with butter) in pie dough and biscuits in the refrigerators or pantries of some chefs.

Oils: coconut oil, nut oils, olive oil

The primary appeal of coconut oil is its ability to serve as a butter substitute in plant-based baking and cooking. It has a relatively high melting point, which allows us to whip it and work with it much like butter. However, the window in which coconut oil is workable is much narrower than for butter. It is also very brittle at cooler temperatures, making rolled or laminated doughs a challenge. Liquid oils such as those from nuts or olives are not used very often in the pastry kitchen. While they can add wonderful flavors, they are liquid at room temperature. This means doughs made with them will never get firm, and they are of no use at all for leavening.

Cocoa Butter

Though using cocoa butter in cookies and cakes can produce fantastic results, this fat generally rules the chocolatier’s realm. There is no fat quite like it, and its unique properties are what make high-quality artisan bonbons, tablets and spreads possible.

Cocoa butter’s structure is primarily composed of saturated fat. It is uniquely regular in structure, allowing it to form a dense network of compact and stable crystals that leaves no loose oil to seep out. When properly crystallized, the cocoa butter in chocolate is responsible for chocolate’s gloss, hardness and ability to retract. It has an enhanced aroma, a smooth mouthfeel and a longer shelf life compared to chocolate that has not been crystallized. In fillings, cocoa butter can create a firmer filling without adding any sweetness.

Fat’s Functions:

Transmitting Flavor

As fat melts in the mouth, it coats the tongue, prolonging contact between our taste buds and flavor compounds. Chefs and bakers can take advantage of this property by combining the flavoring elements in their recipe with the recipe’s fat. Citrus zests should be creamed with butter and sugar. Vanilla should be mixed into egg yolks. Flavoring elements can be infused in or added to heavy cream.

Leavening

One of the wonders of fat, specifically butter, is its ability to add air to baked goods such as cakes and cookies. To maximize butter’s ability to trap air, remember that temperature is crucial. If the butter is too hot or too cold, it won’t trap air effectively. Warm, soft butter won’t have the structure to trap air and warming butter too much will break its emulsion, leading to baked goods with a greasy texture. Cold butter will careen around the mixer bowl in large lumps, avoiding any air incorporation.

It is also important, if perhaps less obvious, to whip butter slowly. Aerating butter slowly forms many consistent tiny bubbles. Networks of small bubbles are much more stable than the large bubbles created when we crank the mixer up to “high” and leave the butter to whip. Furthermore, the high speed will create friction, softening the butter and limiting its ability to trap and hold air. For maximum aeration and good stability, use butter at a temperature of 65°F, and keep the mixer at medium speed.

Emulsifying

Most emulsions seen in the pastry kitchen are a combination of water and fat. We create emulsions such as ganache, and we employ emulsions such as butter and cream. Some fats, such as those found in egg yolks, are both emulsions and emulsifiers, themselves, strengthening and stabilizing our batters, mousses, and ice creams.

Affecting Texture and Creating Structure

Creating tender, crumbly, or friable doughs or incredible flaky layers is where fat really shines.

In cakes, shortbreads and tart doughs, fat coats flour proteins, preventing them from joining together and forming gluten. It also keeps them from absorbing water, another key component in gluten formation. This waterproofing quality also helps create a dough that resists sogginess, thereby extending the shelf life of our tarts, sandwich cookies and other products. For doughs such as this, it is beneficial to ensure that the fat is thoroughly incorporated into the flour. For this reason, the butter used to create tart doughs and sablés can be warmer than that meant for whipping or creaming. These are also applications in which soft and creamy shortening can be a good choice. Oils will certainly coat flour proteins well, but doughs made with oil will be harder to handle, as the fat will remain liquid, making for a very soft dough.

In cakes, butter creates a dense and lush texture, while oil results in a cake that is moist and tender. In both cases, the fat coats the flour proteins, preventing gluten formation and blocking water absorption, leaving more moisture for the cake. Cakes made with oil will remain soft even when cold. Remember, also, that while oil is 100% fat, butter is around 80% fat and will contribute extra moisture to the cake in the form of water.

In products such as biscuits or pie doughs, where a flaky texture is the goal, smaller particles of butter help prevent gluten formation, as in tart doughs, and large pieces of butter form pockets in the dough, creating a flaky texture. Some bakers and chefs will reach for a combination of shortening and butter here, with shortening excelling at coating the flour proteins, and butter creating large pockets, as well as generating steam from the water it contains.

These tiny pockets are writ large in laminated products, where many continuous layers of butter create the flaky structure typical of a croissant or Danish. In the lamination process, perhaps more than for any other application, it is imperative to keep butter cool. Cold butter will crack, resulting in interrupted layers or torn dough, and warm butter will ooze out of the dough. Here, once again, shortening can make the job easier, as it maintains a soft, yet solid, texture at warmer temperatures. However, the flavor of shortening and the unpleasant mouthfeel keep most artisans from using it in their viennoiserie.

Trivia

In 1927, an insurance agent and baker to the stars invented the Chiffon Cake. He jealously guarded the cake’s secret, baking it only for celebrities at Los Angeles’s famous club, The Brown Derby. In 1947, he sold the recipe to General Mills. The recipe was published a year later, revealing the revolutionary ingredient that gave the cake its signature tenderness and light texture: vegetable oil.

(This article appeared in the Fall 2025 issue of Pastry Arts Magazine)