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From tea and French press coffee to flavored vinegars and oils and even many traditional soda pops, infusions have always been a part of our daily lives. Now they are becoming more and more prevalent as many talented chefs and bartenders are creating custom infusions for use in both food and cocktails.
These infusions can be used in unique and novel ways but they all stem from the same process, transferring flavor from herbs, spices, and other flavoring agents into a liquid. Exploring this process allows you to create many wonderful dishes, from custom cocktails and personalized sodas to flavorful vinaigrettes and sauces.
An infusion is both the process of, and the result of, extracting flavors from food into a liquid. This is usually done by soaking the food in the liquid for a long period of time. The liquid is typically water, alcohol, oil, or vinegar and can be hot or cold. The infusion process also works both ways, with the food taking on some of the flavors of the liquid.
Infusions originally were used for several purposes including preserving food over the winter. Fruits and berries could be placed in alcohol or vinegar and they would go much longer without spoiling. People noticed that in addition to preserving the food, the liquid the food was stored in took on the flavors of the items being preserved and tasted much better. Eventually infusions began to be a way to flavor liquids instead of just preserving foods.
There are two main components to infusions, the liquid or food to be infused, and the flavoring agent. The two components are combined together and the flavors from the two meld into each other, leaving an infused liquid or food behind.
A simple example is infusing mint into vodka. The mint is the flavoring agent and the vodka is the liquid to be infused. If you take a handful of mint leaves and cover them in vodka you have started the infusion process. As the mint sits in the vodka, the alcohol slowly leeches out the flavors, aromatics, and essential oils from the mint, resulting in a mint-flavored vodka.
The flavor of the liquid also penetrates the food being preserved in it. In the mint example, this isn't helpful due to the mild flavor of vodka, but some infusions result in both a flavored liquid and a flavored solid at the end, like rum-infused raisins or Luxardo maraschino cherries.
Infusions can be made with either hot or cold liquids. The higher the temperature, the faster the infusion is made, though typically the bitter components are pulled out faster as well. In an open system such as a pot on the stove, many of the aromatics can be released into the air due to the heat, where they are lost, resulting in a less flavorful infusion. Using a closed system such as a Ziploc bag or Mason jar prevents this from happening.
Temperature also greatly affects how quickly the various flavor compounds are pulled out of the flavoring agents. Different flavors are extracted at different temperatures so varying the temperature will have an impact on the final flavor profile. The longer the liquid is infused for, and the hotter it is, the stronger and more bitter the resulting infusion will be.
The speed of the infusion also depends on the type of liquid being infused. For example, high proof alcohol pulls flavor out much more quickly than oil does. In general, alcohol is the best infusion liquid because ethanol is a natural solvent and quickly pulls essential oils out of flavoring agents.
Another determining factor in infusions that is normally ignored is pressure. The higher the pressure used, and the faster it is released, the more quickly the infusion takes place and the more flavor is extracted. The whipping siphon is the main piece of equipment used to control the pressure, though there are other ways of controlling the pressure including a vacuum chamber, a chambered vacuum sealer, and instant marinating containers.
Infusing results in a more even distribution than muddling or mixing does. It also pulls out more nuanced flavors over time.
There are many methods used to create infusions. I generally focus on traditional infusions and infusions created using a sous vide machine or whipping siphon. I also touch on fat washing and dishwasher infusions, as well as vacuum infusions.
In general, traditional infusions are more well rounded, take longer to make, and are more nuanced. Whipping siphon infusions take the shortest amount of time and tend to create less bitter, more aromatic and delicate infusions. Sous vide infusions fall in between and there is more control over the end flavor profile because of the variability in the temperature used during the infusion process.
I go into much more detail about the different infusion methods but in general they all produce great results. If you are comfortable with a certain method, feel free to use it for all your infusions. For each method I offer a "Converting Other Infusion Methods" section that discusses, for example, how to tweak a sous vide recipe for use in a whipping siphon.
Don't feel restricted in the types of recipes you can make because of the equipment you have on hand. Almost every recipe can be lightly tweaked to work in a Mason jar on your counter, in a whipping siphon, or with a sous vide machine, the choice is yours!
There are several methods used in traditional infusions. One is a cold, time based infusion, and the other two are quicker, hot infusions.
Making a traditional cold infusion is a very easy process. Just fill a Mason jar or bottle with flavorful herbs, spices, food, or other flavoring agents. Then add enough alcohol, vinegar, or oil to cover it. Seal the container and place it in a dark location to sit for anywhere from overnight to several weeks, shaking it every few days. Once the liquid has infused, just strain out the solids and the infusion is ready to be used.
Infusions can also be made more quickly by heating them. This is very common for infused oils, vinegars, or water-based infusions.
For infusions using hot liquids, there are two main methods. The first method entails bringing the liquid to a boil by itself and then pouring the hot liquid over the flavoring agents. The flavoring agents are allowed to steep anywhere from a few minutes to about an hour before being strained and used. Most teas fall into this category, as well as vinegar -based "quick pickles" and many other vinegar infusions.
The second hot infusion method is to combine the liquid and flavoring agents in a pot and bring them to a simmer. They are simmered for anywhere from a few minutes up to an hour. I'll often do this in an oven for convenience. The liquid is then cooled and strained before being used. Many syrups and some vinegar infusions are done this way, as are most oil infusions.
Using a whipping siphon to create infusions is the fastest and most time efficient method. To infuse liquids it usually takes only 1 to 5 minutes, with certain intense infusions sometimes taking up to an hour. That is several days or even weeks faster than most traditional infusions.
This technique was popularized by Dave Arnold from the French Culinary Institute and is often referred to as "Rapid Nitrous Infusion". It uses the high pressures inside a whipping siphon to force the liquid into the solids, enabling it to extract the flavors. When the pressure is released, the liquid is removed from the solids, extracting more flavor, as well as leaving some of its flavor behind.
Most infusions use N2O, also known as laughing gas. It's a semi-sweet gas that quickly dissipates once the pressure is released, leaving no off-flavor behind.
Place the flavoring agents into the whipping siphon with the liquid you want to infuse. Make sure the infusing liquid is at least at room temperature. If it is too cold the infusion will not be as strong.
Seal the siphon and add a N2O charge to it. Swirl the siphon for 15-30 seconds then fully charge it. Swirl it for a few more seconds then let it sit for 1 to 5 minutes, depending on the type of infusion you are making.
I've found that 1.5 to 2 minutes is a pretty good time range for most infusions. The time can be extended to 30 to 60 minutes for infusions where you want a lot of bitterness to be extracted.
With the siphon upright, place a towel over the nozzle and quickly vent the siphon. Open the siphon, wait for the fizzing to stop, then strain the liquid. Let the infusion sit for a few minutes for the flavors to even out then it's ready to use.
Sous vide, or low temperature precision cooking, is the process of cooking a food at a precise temperature. This usually occurs while the food is sealed in plastic and is submerged in a container of heated water. This same technique can be easily applied to speed up the process of making infusions.
The higher temperatures used in sous vide infusions means the flavors are extracted much faster than in traditional infusions. The infusion is also in a sealed container which prevents evaporation and flavor loss. Because of the high precision of sous vide machines the temperature used can also be tightly controlled, determining how much the liquid is cooked from the heat and affecting the flavors of the infusion.
Using sous vide for infusions is much more forgiving than when cooking food. With a steak, a few degrees of variability can be the difference between a medium-rare steak or a medium one. Or on the other end, a medium-rare steak and one that is unsafe to eat.
Unless you are aiming for a very, very specific flavor profile, infusions are not hurt much by small variations in temperature. This helps open the door for low-cost methods of sous vide such as when done in a beer cooler or on a stove top. I've seen recipes using a crock pot or even a dishwasher. You can even just use a pot of water on the stove, heated to around 140&def;F to 170°F (60°C to 176°C) and monitored with a thermometer.
The general process of making a sous vide infusion is very easy. First, preheat the water bath to the temperature you want to infuse at. This is typically 131°F to 160°F (55°C to 71.1°C) for vinegar, water or alcohol and 149°F to 176°F (65°C to 80°C) for oils. The temperature used affects the flavor profile of the infusion as different flavors are extracted more quickly at different temperatures.
Place all of the flavoring agents into the liquid you are infusing and seal them in a sous vide bag, Mason jar, or heat-proof glass bottle.
Heat the infusion in the water bath until the flavor profile you are seeking is achieved. This is usually 1 to 4 hours for vinegar or alcohol and 3 to 12 hours for oil. The amount of time the infusion is heated affects both the strength of the infusion as well as the flavor profile.
Once the infusion has been completed it should be chilled in an ice bath so the volatile aromatics will return to the liquid. Once it is chilled, strain the liquid and then it is ready to be used.
Fat washing is the process of infusing the flavors of tasty fats into alcohol. It was pioneered by the crew at PDT, wd-50, and Tailor restaurants and bars, and it is a relatively easy process. First combine a flavorful liquid fat with the alcohol you want to infuse. Shake them together and let them sit for about an hour then freeze the mixture until the fat separates. Strain it out and you are all set.
This process works with oil, butter, bacon fat, and most any other fat. To strain the mixture, freeze it until the fat solidifies then strain it using cheesecloth or a coffee filter. Some fats like olive oil won't freeze well and are best removed using a separatory funnel.