Published September 1, 2007. From Cook's Illustrated.
Liquid smoke can be just fine—as long as you know what to avoid when selecting a brand.
We were among the many people who assume that there must be some kind of synthetic chemical chicanery going on in the making of "liquid smoke" flavoring. But according to the Colgin Company (which has been bottling liquid smoke since the 19th century), that's not the case. Liquid smoke is made by channeling smoke from smoldering wood chips through a condenser, which quickly cools the vapors, causing them to liquefy (just like the drops that form when you breathe on a piece of cold glass). The water-soluble flavor compounds in the smoke are trapped within this liquid, while the nonsoluble, carcinogenic tars and resins are removed by a series of filters, resulting in a clean, smoke-flavored liquid.
Curious about the manufacturing process for this product, we wondered if we could bottle up some smoke for ourselves. To do this, we created a small-scale mock-up of the commercial method, involving a kettle grill, a duct fan, a siphon, and an ice-chilled glass coil condenser.
In a comparison of homemade and store-bought liquid smoke, homemade was praised for its clean, intense, smoky flavor. But we spent an entire day and $50 on materials to produce 3 tablespoons of homemade liquid smoke. Commercial liquid smoke is just fine, especially if you avoid brands with additives such as salt, vinegar, and molasses. Our top-rated brand and contains nothing but smoke and water.