"Infusion" is a general term used to describe the method of soaking plant material in a liquid to impart its flavor to the medium. Infusions can be made from a wide range of ingredients: leaves, stems, seeds, barks and berries are common. Fruits and vegetables work well, too.
My favorite thing about creating these concoctions is that you can sometimes use otherwise inedible ingredients to create something truly fabulous. Spent vanilla pods and fruit peels, a handful of berries or herbs, and other fragrant and/or flavorful items that might find their way to the compost bin can be used to create delicious infusions.
The recipes don't take much effort and are a great way to use up the little ends of this and that you may have in the kitchen. You can use the husks of the vanilla bean after you have scraped out the seeds or you can make your extract and then use the seeds from those pods in recipes. Spent pods can also be dried and added to your sugar bowl to scent your sweetener with warm, tropical notes. Citrus extract is made using the zest from the fruit (leave the pith behind). It's a super way to use up the rinds from spent fruit.
The liquid in your infusion, also called the "menstruum" will vary with your intended use. Water can be used to make an infusion. So can alcohol of any type, oil and sweet solutions made from sugar, honey and glycerin. Different methods for making infusions can be used to create beverages, medicines, and flavorings. Here's how.
Cold infusions are made by steeping the material in liquid for a long while and letting time slowly and gently do its work. The process releases less tannins than hot infusions, so they lack the bitter flavors that hot infusions can sometimes have. Cold infusions retain more of the flavor of the material being infused, so you won't lose the bright, fresh flavor of delicate herbs and fruits. Cold brewed coffee and tea, known for their smooth flavor, are examples of cold infusions.
Infused vodka is a fun party trick. Clean out a glass jar or bottle, add some flavoring agents, such as a handful of berries or the husk of a vanilla bean, and cover them with vodka. Put the container in a cool, dark place for a few days, up to a few weeks to allow the flavor to develop, shaking or turning the container every so often to distribute the liquid. Strain out the solids and decant the flavored hooch back into the container or into a decorative, food grade decanter. Infused vodkas made with berries of any sort, a vanilla bean, grated ginger root or chili peppers are always a hit. You can also sub out the vodka for any liquor that is at least 80 proof, which ensures that you are infusing, not fermenting or rotting, your flavoring ingredients. And don't throw out those solids! You can blend those vodka drenched fruits into adult beverages and desserts or use them to flavor cooked foods, where the heat of the process will burn off the alcohol.
Infused vinegar uses the same method as infused vodka. You can use them to great effect in vinaigrettes. Think strawberry vinegar in a spinach salad. Infused vinegars are terrific diluted with water or seltzer (at a 1:8 ratio) to create a traditional beverage called a "shrub." Refreshing and delicious, shrubs were popular in Colonial times and are now seeing a comeback. So called "drinking vinegars" that are popping up in gourmet shops are a type of shrub, sometimes with additional sugar or fruit purees added. But when you make them at home you can see just how economical they are. From a few berries infused in eight ounces of vinegar, you will get sixty-four ounces of delicious shrub.
Infused water has become all the rage in health clubs and spas and is de rigueur at tony picnics. Specialized bottles that partition the flavoring ingredients away from the water have been designed to allow eaters to make their own infused waters without the pesky bother of cucumber slices or oranges sections from bumping against their lips and teeth. But you don't need a membership or specialized equipment to enjoy infused water. Just slice up anything you think would be flavorful to sip on and add it to your water jug, glass or bottle. Cucumbers, citrus segments (or just their peels), chunks of melon or pineapple are all really tasty.
Extracts are just highly concentrated cold infusions. They are easy to make and can be created for a fraction of the cost of store bought. Alcohol is the typical menstruum used to make extracts. Use the same method described above for making flavored vodka, using a high concentration of flavoring material to alcohol. For herbs, you'll want about a 1:1 ratio. For non-vegetal items such as nuts and spices, you can use less but still more than the straight infusion described above. For instance, instead of one vanilla bean in a 750 ml bottle of vodka for a flavored liquor, you will need to use two or three beans in a cup of vodka. Citrus is another great extract option. Pack a pint jar half full of zest strips, cover with a cup of vodka and let it go. Allow your extracts to diffuse for much longer than flavored vodka or vinegar. Two to three months should do it. Strained and bottled, preferably in a dark bottle or kept in a dark place, they keep for a year or more.
Tinctures are the strongest infusions and are often used for medicinal purposes. Dried or fresh herbs and flowers such as mint, calendula or rosemary are infused to extract their oils and leave the plant material behind. Alcohol is also the most popular menstruum to make tinctures. The ratio of plant material to alcohol is the highest of all infusions: about 3:1 for most recipes, but higher for some. Tinctures keep for up to five years.
Those sensitive to alcohol often turn to vegetable glycerin as their menstruum when making tinctures. Be sure to use culinary grade glycerin and dilute it 75/25 with water. Then use 1:2 dried plant matter to the glycerin mixture. Crush the herbs first to encourage infusion. Remove to a cool dark place for four to six weeks and then strain. You can store the infused glycerin in a cool dark place for six to twelve months.
Hot infusions are made by heating your infusing medium before introducing your flavoring agents to it. Hot infusions release more of the plants' volatile oils, sometimes with a pleasingly bitter note from the tannins that have been unlocked as well. This is a great method to use when you want faster results - hot infusions do their work in minutes rather than the hours or days that cold infusions can take. They are also good at releasing flavors that cold water is too gentle to unleash. Tea and coffee are common hot infusions.
Flavored oils are often made by hot infusion. Mild flavored or neutral oil, such as organic canola or safflower oil, is gently heated until it is warm. Garlic or herbs are then added to the oil and allowed to steep to impart their flavors. The plant material is then strained out and the oil decanted for future use. Scented oils made from fragrant plants such as lavender, rosemary, thyme and citrus peel can be made from hot infusion.
The oil should be refrigerated and used within several weeks. Although the oil has been strained, small particles of food material can remain suspended in the liquid and act as a vector for contamination. Never heat alcohol. The flame can easily leap into the pot and catch on fire.
Decoctions are like hot infusions, except that you don't just pour hot water over the plant material, you simmer it for an extended time. This method is helpful for barks, such as cinnamon, dried hard herbs and berries such as elderberry, and roots and rhizomes.
Fruit peel "tea" can be made by simmering apple or pear peels in hot water until fragrant; sweeten and sip on a cold winter's night. Homemade cold remedies and other home cures, such as this elderberry syrup, which often call for woody herbs, barks and dried items are often created by decoction.
Hot herbal infusions and decoctions are sometimes referred to as "tisanes." The term is used, in part, to differentiate such beverages from teas, which technically can only be made with leaves from the Camellia sinensis plant. Herbal "teas," therefore, are really tisanes, not teas, unless they contain the leaves of the tea plant.