What is ‘browning’ food?

April 22, 2008

From my recent forays into cooking, I frequently have come across recipes asking me to brown a food. I also remember Alton Brown mentioning it on his show, Good Eats, when discussing stews. He made sure to brown the outside of his short ribs in a skillet before braising them in the oven. In search of answers as to what browning is and why we do it, I turned to Harold McGee’s On Food and Cooking.

There are two primary browning reactions you’ll be attempting in the kitchen: carmelization and Maillard reactions. Carmelization occurs in a reaction of sugars, which are made up of carbon, oxygen, and hydrogen. Heating table sugar to around 330 degrees Fahrenheit will produce carmelization, such as when you carmelize onions. Carmelization, while the simplest of browning reactions, can produce hundreds of products, including “sour organic acids, sweet and bitter derivatives, many fragrant volatile molecules, and brown colored polymers.”

You may have noticed that your carmelized onions have a distinctly sweet flavor - that’s the sucrose in the onion reacting. I find it interesting that carmelization produces such a wide range of flavors across different foods. I would expect a specific cooking method to produce predictable results, but apparently that is not the case here - so don’t go carmelizing whatever you find and expect to end up with something sweet and delicious every time.

Maillard reactions, named for the Louis Camille Maillard, the discoverer and a French physician, are more complex than carmelization. In Maillard reactions, a carbohydrate reacts with an amino acid and ends up producing a wide array of products, like carmelization. Maillard reactions, however, produce meatier, earthier flavors because nitrogen and sulfur are added to the products from the amino acids. Also, Maillard reactions can begin at lower temperatures than carmelization - around 230 degrees Fahrenheit.

There is a third type of browning possible, one you will probably use less often, at temperatures below boiling. Egg whites will brown when simmered for 12 hours, the base for beer is darkened through browning by boiling, and meat or chicken stock will brown when reduced. I probably will never simmer an egg white for 12 hours, but the reduction of stock is a possibility in the future. These are less frequent, but potentially useful.

From my understanding, the browning of regular fruit over time occurs from the reaction of phenolic compounds with oxygen and does not produce any new flavors. This browning, sometimes called enzymatic browning, is different than the methods described above. To make it more confusing, dried fruits do slowly undergo a browning reaction like those above between carbohydrates and amino acids.

You normally achieve browning through dry cooking methods because besides for the special cases (egg whites, beer, stock, etc.), browning occurs at temperatures above boiling. This means that techniques like braising, boiling and steaming don’t produce browned foods and as a result these water-cooked foods will hold their true flavor better. Browned foods, on the other hand, become richer and more complex with the browning reactions. Roasting, baking, frying, and grilling are all good ways to brown food. The outside quickly becomes dry, heats up and browns, while the inside can stay moist and cook through more slowly. Bread crust is a good example of browning on the dry outside of a food.

Oddly enough, there are potential health side effects for browning food. First, the destruction of amino acids in the reaction destroys healthy nutrients. Second, one study from Sweden proposed that it can alter DNA and make one more susceptible to cancer. Although I can’t read the whole thing, here is another article that discusses side effects of browning. Of course this would be too simple if it were the only side to the story. Another study has linked browning to the protection of DNA.

Browned food adds flavor and complexity to foods, so remember that the next time you bite into the crust on a loaf of bread. Taste those delicious carbohydrate reaction products. Regarding the side effects, in my opinion, just eat a varied diet and don’t worry about it.

photo credit: Tanya Dropbear

Posted in Food Science, Techniques |