For thousands of years people have known that the smoke from burning wood can enhance the flavour of food and help to preserve meat. When food is exposed to smoke in an enclosed area, dark brown drops will form as the smoke cools to become a liquid. Controlled methods of cooling smoke make it possible to gather it as a liquid, which can then be used as a seasoning to flavour food without needing a smoke house, smoking box, or a 'buccan', as Native Americans call such a device.

What is Smoke?

Smoke from burning wood is the result of pyrolysis, the transformation of a substance by heat. The wood's two primary components, lignin and cellulose, contribute to the resulting blend of compounds that make up smoke. This smoke contains some ingredients that provide an anti-bacterial effect and others that provide flavour. It also contains some substances that are considered unhealthy. (It is smoke after all - don't say you weren't warned.)

A typical liquid smoke's nutritional information label shows a zero in every category. The exception of sodium and/or calories found in small amounts seem to be the result of ingredients added to the final product.

Obtaining Liquid Smoke

One liquid smoke making process was patented by SE Colgin in the early part of the 20th Century. The Colgin company still produces liquid smoke today using modern, computer-controlled and state-of-the-art equipment.

The process begins with wood chips that are subjected to high temperature. A high moisture level allows the wood to smoulder rather than burn, thus producing smoke. The hot smoke is captured and transferred to a series of condensers that cool the vapors of smoke into a liquid. This liquid is usually refined and filtered, and may be aged in Oak barrels for a more mellow product.

Flavour

The primary smoke flavour comes from the pyrolysis of the lignin in the wood, while the pyrolysis of cellulose adds a hint of a 'burnt sugar'. Many types of wood can be used, as well as other combustible materials. In Europe the traditional smoking wood was Alderwood, though now Oak or sometimes Beech is used, while in North America Hickory, Mesquite, Oak, Pecan, Alder, Maple, Apple, Cherry or Plum may be used for smoking. Different types of wood will yield different flavours, and combinations are often used. Corn cobs are used by some in North America to smoke bacon or ham, while peat is used to dry and smoke barley malt for Scotch whiskey and some beers. Uncooked rice, sugar, and tea, heated at the base of a wok are used for Chinese tea-smoking.

Smoke as a Preservative

Long before referigeration was invented, meat was smoked to increase its shelf life. This is due to the fact that the chemicals and organic acids found in smoke lower pH, and this increase in acidity destroys the walls of bacteria cells. The phenolics that are present in smoke also have a bacteriacidal action which helps to preserve the meat.

In university studies, researchers have added liquid smoke to pathogenic bacteria in petri dishes, showing that it inhibited microbial growth. Liquid smoke also works well against salmonella, listeria and other spoilage organisms. Beef tissues, trimmings and ground beef were found to have reduced amounts of bacteria on the surface after having liquid smoke added. This seems to show that washing large meat trimmings with liquid smoke may have a sterilizing effect.

Uses for Liquid Smoke

Liquid smoke is used in many different ways. It can be applied to meat before cooking for both its anti-biotic effect or to give the food a smoky flavour. It can also flavour almost any other food but since it is very potent, moderation is key. Before heating a gas grill, liquid smoke can be sprayed onto the cool lava rocks to give a wood fire flavour.

Recipes

• Steak with papaya marinade is a Guide Entry recipe that refers to liquid smoke. It has been changed to use barbeque sauce because the author had trouble finding liquid smoke in local stores. Liquid smoke should probably not be directly substituted into the recipe because it is far more potent than BBQ!
• Epicurious.com is a website that provides free recipes. A search for 'liquid smoke' takes you to several including Chinese Smoked Chicken, Smoky Clam Chowder, sauces including Red Wine Barbecue Sauce, and more.
• Allrecipes.com is another free website with several liquid smoke recipes, including the Drunk Chicken which involves inserting a can of beer into the chicken before cooking.
• It is unlikely that a cocktail recipe exists that makes use of liquid smoke, although it is probably possible to make one up with a bit of thought. However, it's doubtful whether the result of such persuit would taste any good and drinking it would be about as healthy as falling off a log.