By Christopher Warsow, Contributing Editor
Although there is no legal definition in the food industry for an infusion, many informal ones are out there. It just depends on whom you ask. From the culinary sense, an infusion is adding a desired flavoring agent, usually plant-derived, to a steeping liquid. From a flavor manufacturer’s standpoint, an infusion is the method of extracting a flavoring material from any solid―what we commonly think of as an “extract.”
Avenues to flavor
From my perspective, infusion is a passive form of extraction. For instance, adding rosemary and garlic to olive oil and leaving it on the counter under ambient conditions creates an infusion. Expediting this process with heat or mechanical methods forms an extract.
According to the Flavor and Extract Manufacturers Association (FEMA), Washington, the several methods of making an extract should be based on the solubility of the substance that needs to be extracted. Most solvents can be classified as polar (alcohol) or non-polar (oil). If you remember your high school chemistry, like dissolves like. That means paprika oleoresin―an oil-soluble material― will readily dissolve in oil, but will not dissolve in water.
A typical commercial extraction of a spice volatile would be to grind the spice and dissolve and extract it into hexane. The hexane is distilled off and recovered to be used again. The resinous material that remains is the oleoresin, which can be used to flavor food products.
One of the first examples of infusion that I learned in culinary school was the first step in making a béarnaise sauce. According to “The Professional Chef,” the Culinary Institute of America’s textbook, the first step is to make an infusion of peppercorns, dried tarragon and tarragon leaves into tarragon vinegar. I found this recipe unique because it calls for making an infusion with an infusion (the tarragon vinegar), thereby adding a powerful burst of flavor to the sauce. The tarragon vinegar is made by simply placing fresh tarragon into 30-grain distilled white vinegar brought to just below the boiling point, sealing it in a sterilized glass bottle, then allowing it to cool to ambient temperature. The mixture is heated to kill any bacteria that may be present on the tarragon. It is allowed to sit in a cool, dark place for at least three weeks. Then, for this béarnaise preparation, the tarragon vinegar is further infused with tarragon and peppercorns. The resulting “double infusion” is then added to the egg and clarified-butter emulsion at the end of cooking to flavor the sauce.