A food scientist describes the subtle chemical differences between butter and margarine, and how they can affect your baked goods. Butter and margarine are emulsions, which are mixtures of tiny water droplets spread throughout a continuous fat matrix.
Chemical Structures
Fatty acids are long chains of carbon surrounded by hydrogen atoms. In a triglyceride, there are three fatty acids, each one connected to the same three-carbon glycerol molecule, which acts as the backbone of the molecule. While the backbone is always the same, the number of carbons in the fatty acids can vary.
Butter’s fatty acids are mainly saturated, which makes them fit together and stack compactly to form a nice straight chain, because they have no double bonds between the carbons. Margarine’s fatty acids are mainly unsaturated, from blended plant oils. The unsaturated fats give them an irregular shape on a molecular level.
Making Butter and Margarine
Butter is made by shaking or churning cream, which causes fat globules to rupture. The fat leaks out and forms semi-solid grains of butter. Margarine, on the other hand, is made by chemically rearranging fatty acids on the glycerol molecule in a modification process called interesterification, which makes the oil solid and the fats more uniformly distributed.
Butter has an official standard of identity set forth by the U.S. government, which means manufacturers must meet specific guidelines for their product to be considered butter. This food standard is one of the oldest in the U.S.
Flavor and Color
Butter gets its golden color from beta-carotene, an orange pigment present in grass. Cows eat the grass but do not metabolize beta-carotene efficiently, so it is expressed in their milk. Margarine is naturally colorless, but producers add synthetic beta-carotene to it to mimic the color of butter.
Margarine producers also add flavors such as diacetyl, a distinctive butter-flavor molecule, and blends of whey components and preservatives to replicate the flavor of butter. They may add emulsifiers such as lecithin or monoglycerides to keep the water and fat from separating.
Baking Differences
When you heat butter, the proteins and lactose in it combine, creating that signature brown color and a delicious nutty, toasty, caramelized flavor. Because margarine doesn’t contain lactose, it won’t brown as well as butter, nor will it impart the same level of aromatics.
When baked in a very hot oven, butter contains enough water to form steam, which separates doughs into layers of flaky pastry. Water content varies in margarine, and while it forms some steam, it will not perform as well as butter.
Original reporting: KTBS 3 (Shreveport) — read the source article.
