19.2 The fats a kitchen uses: butter, lard, shortening, oils

Butter

Butter starts as cream, which may be sweet, neutralized or ripened, pasteurized and brought to 30 to 40% fat. Churning, or whipping too far, makes the fat clump away from the watery part, which is buttermilk. The fat is washed and kneaded until it is smooth and plastic. Color is often added to make it look richer, and salt helps it keep.

Butter must be at least 80% milk fat by weight. The only other ingredients allowed are milk solids, salt, air or an inert gas, permitted color and permitted bacterial culture. Its grade name is Grade 1. The rules also name two kinds: whipped butter, with air or inert gas beaten evenly through it and up to 1% added edible casein or caseinates, and cultured butter, made from cream with a permitted bacterial culture added.

Sweet butter, also called unsalted, is made from cream with very little acid, and has no salt. It is used where butter must be the only fat, as in French buttercream. Keep it in the refrigerator.

For flavor, butter is the best baking fat. Its drawbacks are cost and its handling. It creams moderately well, so allow up to five extra minutes of creaming in a cake for full volume. Its plastic range is narrow, only 18 to 20°C (64 to 68°F): at 10°C (50°F) it is nearly too hard to work, and by 27°C (80°F) it is too soft, and it is hard to work in hot weather. Adding an emulsifier, about 2% of the flour weight, helps a butter cake.

Butter is a dairy product. Dairy products are kept refrigerated, between 2 and 4°C (36 and 39°F), covered and in their own area, because the fat in them picks up strong smells nearby. The signs of spoiling are plain: butter turns darker and smells sour.

For why whole butter is a poor fat at high heat, and for clarified butter and its smoke point, see chapter 7: Dry heat with fat

Lard

Lard comes from the fatty tissue of pigs and holds 12 to 18% water. Worry about diet has made it less popular than it was, but bakers still use it in yeast doughs, in pie pastry and for greasing pans.

Its wide plastic range is its strength: you can work lard into a pie dough at fairly low temperatures, which butter will not allow. Its weaknesses keep it out of cakes. It is fibrous and does not cream well, and some grades have a strong flavor of their own.

Margarine

Margarine is made mostly from vegetable oils, partly hydrogenated, with a little milk powder and bacterial culture for a buttery taste. It holds 80 to 85% fat, and the rest is much like butter. It can be bought white but is usually colored. Bakers use several kinds:

• General purpose margarine melts at a low temperature and blends into dough for everyday baking.
• Cake margarine creams very well.
• Roll-in margarine is plastic enough to be rolled into Danish pastry.
• Puff pastry roll-in is the waxiest kind, with the highest melting point.

Margarine once came only in solid blocks heavy in saturated and trans fat. Most margarine now comes in tubs: soft, spreadable and not hydrogenated, so low in both. Take great care before swapping a soft tub margarine for a solid one in a recipe.

Shortening

Since hydrogenated vegetable oil was invented early in the 20th century, shortening has come to mean almost only that. Shortening and lard have much in common:

• Both are semi-solid fats.
• Both are close to 100% fat, where butter and margarine are about 80%.
• Both have a higher smoke point than butter or margarine.
• Because they hold less water, both spatter less, which makes them safer for frying.

Shortening was long made from partially hydrogenated oils, so it carried trans fat. One leading brand brought out a low-trans version in 2004, and in January 2007 reformulated all its products to under one gram of trans fat a serving. Many other brands have changed since 2006. Shortening without hydrogenation can be made from palm oil.

Hydrogenated shortenings are the main fat of commercial baking. What they share:

• Their oils are largely those used for margarine.
• They cream well.
• They contain no water.
• They keep for six to nine months.
• Each is hydrogenated to suit its job.

There are three main kinds:

• Emulsified shortening, also called high-ratio fat. Its added mono- and diglycerides spread the fat finely, so a cake can carry a lot of sugar and liquid. The cake comes out fine-textured, light, high, moist for longer and tender. It is also the usual fat in many white icings. High-ratio fats blend well with ingredients that attract water, such as sugar and starch.
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• Roll-in pastry shortening, or special pastry shortening (SPS). It is semi-waxy, with a large plastic range, and it stretches and lifts well, so it is used in puff and Danish pastry, where layers of fat and dough are rolled together. The choice is always a trade between cost, taste and lift. A roll-in that does not cling to the palate may melt too low to give a puff pastry its full rise.
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• Deep-frying fat. Its smoke point reaches as high as 250°C (480°F). It resists heat and breakdown, leaves no off taste, is not greasy once the food is cold, and contains an agent to stop foaming.
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Oils and coconut fat

Oil labels follow set rules:

• "Vegetable oil" may name a blend of more than one plant oil used in another food.
• In a cooking, salad or table oil, each oil must be named, such as canola or corn.
• Coconut, palm, palm kernel and peanut oil, and cocoa butter, must always be named.
• If any oil in a blend has been hydrogenated or modified, the label must say so, as in "hydrogenated vegetable oil".

In baking, oil goes into:

• chemically leavened batters such as muffins;
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• doughs, in place of solid fat;
• short sponges, in place of butter.

Coconut fat has a very small plastic range and a fairly low melting point, yet it is hard. Bakers use it to firm up buttercream. It can be made to melt at different points, usually 32 to 36°C (90 to 96°F).

Melting point and blends

A fat that melts low, like butter, is hard to handle in the heat. A fat that melts very high is unpleasant to eat because it clings to the roof of the mouth. A melting range of 40 to 44°C (104 to 112°F) is a fair middle way, though newer fats can melt higher without clinging.

Most fats you buy are blends. Some are all plant oils; others mix plant and animal fat, often about nine parts plant to one part animal, though that is not a rule. Such mixtures used to be called compound fats.

What fat does in baking

• Tenderizes. Enough fat "shortens" the strands of gluten in flour, which is where shortening gets its name. Lard was the classic example.
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• Holds air. Beaten with a paddle, a fat that creams well traps many tiny air pockets, and the better it creams, the lighter the cake.
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• Lubricates. Fat lets the gluten network stretch, and makes dough easier to mix and handle.
• Keeps it moist. Fat slows drying in both dough and batter. A shortening that is all fat does this better than butter or margarine.
• Feeds. Fat is a dense source of energy and carries fatty acids the body needs.
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