infusion is the process of extracting flavor compounds from materials such as herbs and spices using a solvent such as water, ethanol, or glycerin. See ethanol and glycerin. Infusion is typically a quick technique used to prepare a drink or tincture for immediate use, as opposed to maceration, which is a longer and sometimes more complex process. A simple example of an infusion is the preparation of coffee or tea.
The most basic infusion is soaking a spice in water for a few minutes to extract some of the flavor compounds. Increasing the temperature of the water during the process is an excellent way to shorten the infusion time and extract more flavor compounds. Using a combination of water and ethanol, like vodka, can extract different flavors as some compounds may only be soluble in alcohol but not water.
Many liqueurs and spirits start as infusions that are then distilled to capture the aromatic flavors. A common example is gin, where the botanicals are infused into high-proof alcohol and then distilled to extract the aromatics. An innovative rapid infusion method used by many modern mixologists combines botanicals and a solvent—water or a spirit—in a soda siphon, which is then pressurized with capsules of nitrous oxide, an inert gas. This forces the liquid into the plant materials’ cell walls and extracts the flavor compounds. What previously took a few hours or longer can be accomplished in a few minutes. One of the unique benefits of this method is that infused cocktails can be prepared fresh.
Natural colors for cocktails can be created using infusion techniques. See hue/color. Absinthe gets its green color from an infusion process that extracts chlorophyll from herbs like hyssop and melissa. A brilliant yellow color can be made by infusing turmeric or saffron in alcohol. Red colors can be made using cherries, elderberries, or cochineal.
With all methods of infusion, there are a few caveats that need to be mentioned. Increased temperature or pressure can speed up the process, but these methods can also extract undesirable compounds. For example, preparing infusions using hot water may extract more flavor compounds in a short period of time, but as the liquid cools, a haziness may form in the final products because some compounds are only soluble at the higher temperature. Also, higher infusion temperatures can create “cooked” flavors or cause aromatics to vaporize, causing a loss of flavor. Performing a taste test and standardizing methods is the best way to get consistent results with infusions.
Malle, Bettina, and Helge Schmickl. The Artisan’s Guide to Crafting Distilled Spirits. Southport, NC: Spikehorn, 2015.
Morgenthaler, Jeffrey. “Infusions, Tinctures, and Bitters.” In The Bar Book: Elements of Cocktail Technique, 119–130. San Francisco: Chronicle Books, 2014.
By: Darcy O’Neil