Lambert & Ewers Smoked Meats

When natural smoke is generated from wood, hundreds of chemical compounds are produced. The most important part of smoke for food products are the gases in which close to 100 different chemical compounds have been identified. Smoke also includes many particulate components that make smoke visible in the air when the smoke is formed, but which are not needed, or may even be undesirable, for application to meat products.

The gaseous compounds in smoke are the source of the color, flavor and preservative effects of smoke. These compounds include several carbonyls, phenols, organic acids and alcohols. It’s important to understand that the generation of these compounds from wood sources is dependent on the temperature at which the smoke is being formed. Smoldering sawdust or wood chips can vary from about 300 degrees F to over 800 degrees F, depending on moisture content and air flow. The most desirable mix of gaseous compounds is produced in the lower temperature range of about 300 degrees F to 450 degrees F.

Determining the best smoke-gas mixture is important because different compounds in the gas mix each produce a characteristic effect on the smoked product. Color, for example, is the result of carbonyls, while flavor is the result of both carbonyls and phenols. The phenols are also particularly effective as antioxidants and help to preserve flavor, another advantage of smoke application. Organic acids in wood smoke are good antimicrobial agents and will reduce bacterial numbers. The acidity of the acids from smoke will also denature the surface proteins on the product to form a surface “skin,” a process important to products such as frankfurters. Alcohols in wood smoke are also potential antimicrobial agents and contribute to the preservative effect of smoke.

When the best smoke generation conditions for natural smoke have been determined, the next consideration is how to achieve the best deposition of the smoke gases on the product surface. Here, several factors come into play. It almost goes without saying that the density of the smoke generated will affect the amount of smoke contact with the product, so a heavy smoke, highly concentrated with the desirable gas components, will be more effective. However, air flow within the smoke chamber will also be a factor. Moderate air flow increases the smoke-to-product contact by pushing the gases onto the product, but increased air flow will reduce smoke density and may reduce smoke deposition. The best combination of smoke density and simultaneous air flow within the application chamber will need to be determined.

The major determinant of natural smoke deposition on product surfaces, however, is the product surface moisture content at the time of smoke application. Of course, the casing used must be a type that is highly permeable to smoke, but given that, a wet surface will absorb more smoke than a dry surface and will result in darker surface color. Excessive surface moisture is likely to result in dull brown or even black color tones.

Virtually all smokehouse processing sequences use a drying step prior to smoke application to prepare and equilibrate the product surface for smoke. Smoke color can be adjusted by the pre-smoking step, with a dryer surface resulting in lighter smoke color. A general rule of thumb is that the product surface should be somewhat sticky just prior to smoking. Likewise, the relative humidity in the chamber during application of smoke will affect product surface moisture and, consequently, smoke deposition.

The primary advantage to traditional natural smoke is the authentic flavor. Disadvantages of natural smoke include air-emission issues from smoke exhaust and the presence of polycyclic hydrocarbons. Some of the polycyclic hydrocarbons, particularly benzopyrene and dibenzanthracene, are mutagens and/or carcinogens. These compounds can be reduced in natural smoke by restricting smoke generator temperature to the lower end of the smoke generation temperature range, about 500 degrees F or less.