The Chemistry of BBQ

One of the best joys of a sunny summer day is the gathering of friends and family to enjoy the enticing aroma and deliciousness of a smoked flamed barbeque. The art of preparing meat and the technique of grilling has become somewhat of a science in its own. The “World Series of Barbeque”, The  American Royal Barbecue Contest is held annually in Kansas City, Missouri. In Memphis, Tennessee, The World Championship Barbecue Contest is held during the Memphis in May, and according the Guinness Book of World Records it is said to be the largest pork barbecue contest in the world!

But what is responsible for that taste we all crave? Where does it come from? And how can we make it taste even better and avoid the unhealthy stuff?

Enthusiasts would say that secret spices or special types of chipped wood influence the flavor of the meat. Maybe true; but according to chemistry, the fundamental ingredient that produces flavor in meat is heat! Commonly observed in a barbecue is a “browning” of the surface of the meat in a phenomenon called the Maillard reaction.

Louis Camille Maillard
http://commons.wikimedia.org
/wiki/File:Louis_Camille_Maillard.jpg

This reaction is also responsible for:

  • Toasted bread
  • Biscuits
  • French Fries
  • The distinctive color of beer
  • Fried onions
  • Dried or condensed milk
  • Roasted coffee
  • Dulce de leche
  • Roasted meat
  • The burnished surface (crust) of brioche, cakes, yeast, and quick breads
  •  And maple syrup

The Maillard – “browning” -reaction.
http://www.meninaprons.net/archives
/2007/05/food_dictionary_the_maillard_r.html

The reaction was named after Louis Camille Maillard who first observed it in 1912 while attempting to replicate biological protein synthesis. Maillard observed that when he heated amino acids and sugars, the reaction mixture began turning brown. Meat contains roughly 20% protein. The reaction begins when meat is heated in a process which begins to denature the proteins contained in meat. Heat disrupts the configuration of these proteins which results in a slight color change on the surface. At around 300 – 500 F the Maillard reaction begins to take place.

You observe this reaction while grilling meat.  It has also been given attention in Venezuela where scientists have purportedly developed a novel method of keeping beer fresh. By adding the drug aminoguanidine and a chemical called 1,2-diaminobenzene (1,2-DAB) to the beer, the Maillard reaction is manipulated (although scientists don’t know how)!

It was not until the 1940s that a connection was made between “browning” and flavor. According to legend, scientists were attempting to prevent an unappetizing taste when soldiers began complaining of their eggs (a dehydrated powdered mix) turning brown and tasting just awful. Although the powdered egg mix was stored at room temperature, the amount of amino acids and sugars was high enough to stimulate the Maillard reaction. Soon enough scientists discovered the importance of the Maillard reaction and its central role in producing flavors and aromas. In fact, after an analysis of beef, over 600 different aroma producing molecules were identified!

Like all chemical reactions, experimental conditions contribute to the final product. Likewise, the Maillard reaction is affected or can be manipulated by the following conditions:

  1. Temperature
  2. pH
  3. Water
  4. & marinades (composed mainly of acid, oil, and herbs).

Marinades

The acid in marinades helps to play a key role in adding flavor to meat. Acid, like heat, also denatures proteins and creates “channels” for artificial flavor and moisture to seep in, giving the meat a “juicier” taste. However, keeping meat in an acidic environment for an extended time will result in advance degradation of proteins, making the outer surface layer “mushier”. In addition, acids tend to “brown” less readily, according to Sara J. Risch, a Baltimore flavor chemist with Science By Design. This is because the Maillard reaction reacts more readily at high pH values:

Mechanism is Initiated in a Basic pH Environment
http://blog.khymos.org/2008/09/26/speeding-up-the-maillard-reaction/

There is a down side to using an acidic solution: the Maillard reaction is inhibited to some degree, causing a reduction in flavor. Thus, the use of a weak base (such as sodium bicarbonate –baking soda) can speed up the reaction and enhance the flavor of food.  You can see the results of increasing the pH in the video below:

The oil found in marinades is also important. Since cell membranes are mainly composed of a phospholipid bilayer, oils can easily cross this barrier and further penetrate into the meat, carrying additional flavors with it.

Chemistry 101: Like dissolves like!

          “Most flavors tend to be fat-soluble,” says Risch.

           “It really is the fat that carries the flavor. A really

            lean piece of meat just doesn’t carry as much flavor.”

According to the American Cancer Institute, an added bonus of marinating meat is the protective effect against harmful carcinogens– cancer causes compounds- that are produced during grilling.

At high temperatures, amino acids + sugar + creatine (substance found in muscle), react to produce cancer-causing compounds collectively called heterocyclic amines, according to the cancer institute. Another class of carcinogens, Polycyclic aromatic hydrocarbons (PAHs), are formed when fat drips onto hot coals or stones. During flare-ups or via smoke, these toxic chemicals travel and adhere to the surface of the meat.

One way to circumvent and avoid these harmful compounds is by marinating. Nutrition adviser with the cancer institute, Karen Collins, says that marinating meat can reduce the amount of heterocyclic amines produced by as much as 99 percent .

“A marinade may act as a “barrier,” keeping flames from directly touching the meat. Or the protective powers may be due to typical marinade ingredients, such as vinegar,

citrus juice, herbs, spices and olive oil.  So think of it as sunscreen for your meat.” Cancer-causing compounds can be further avoided by cutting off any charred meat before serving says Risch.

So with the right ingredients, a “dash” of chemistry, we can turn up the heat (Not too high now!), pop open a cold one (I like lemonade, but that’s just me), and kick it with some friends at the grill! Maybe talk about chemistry?  Or grilling?  After all, they are one and the same!

Here are my healthy grilling tips:

  • Avoid “fatty” pieces of meat – or pre-boil to reduce the amount of fat.
  • Always marinate meat – significantly reduces HCAs formed.
  • A moderate browning of the meat is okay – avoid excess browning or charring as carcinogens are produced.
  • Sugar containing sauces are tasty, but burn easily and contributes to the the production of HCAs – use those type of sauces close to the end.
  • Lastly, eating barbeque frequently is not healthy as harmful chemicals may tend to build up if not given time to be metabolized and excreted.

And for your viewing pleasure, here’s a video on the Chemistry of Barbeque from Bytesize Science.  Enjoy!

8 thoughts on “The Chemistry of BBQ

  1. Wow! Really cool. Exactly what I was looking for. Do you know if the reaction would have an effect on the methyl mercaptans in asparagus? People are always saying asparagus is hard to pair with wine, but when it is grilled it seems to go along just fine. Thank you!

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