A flavored oil is, as its name implies, an oil that has been infused with flavoring elements, such as herbs or spices. They have three primary uses in the kitchen. First and foremost they obviously add flavor. But they also provide a visual appeal as well as a means of enriching a dish without the use of saturated fat.
Fats in general have been maligned for their caloric content and in certain cases, for their adverse relationship to cardiovascular health. But our fat-phobia has overshadowed their culinary benefits, namely the transmission of flavor. Fats carry a one-two punch of flavor: They are tasty in and of themselves but even more importantly, fats transmit the flavors of other components. Many aromatic agents, e.g., herbs and spices, are fat soluble. This means their chemical constituents are dispersed and released best in a lipid medium. In the case of flavored oils, the oil provides the backdrop by which other sapid compounds can be enhanced and rendered more available to our eagerly awaiting taste buds.
Flavored oils also add a pleasing aesthetic dimension to a dish. Because the oil adopts the color of its flavoring agent, a panoply of hues is possible. The oil can simply be drizzled over a dish or artistically disbursed on the plate much like paint on a canvas.
Finally, while all fats possess the exact same calorie load, (9 calories per gram to be exact), polyunsaturated fats such as vegetable oil and monosaturated fats such as olive oil, are reputed to lower cholesterol levels. So while there’s no way around the caloric equation, at least non-saturated fats provide some possible health benefits. Thus, oils are a great way to enrich a dish without the cardiac willies some people experience with butter or cream.
Oils can be flavored via many different items: herbs, (such as basil, rosemary or thyme), spices, (curry powder), roots, (ginger or horseradish), citrus zest, (such as lemon rind), and vegetables, (shallots, hot peppers, and garlic). There are basically two approaches two making flavored oils, the cold infusion and the hot infusion method. The difference between the two is whether the oil is heated.
The simplest and most straightforward cold infusion method is to place the flavoring elements in a jar or container, add the oil, seal it, and let it sit at room temperature for a number of hours. For example, add a number of sprigs of rosemary and a few whole garlic cloves to a container of olive oil and the next day you’ll have a delicious rosemary-garlic oil.
In the cold infusion method the flavoring ingredients are sometimes fabricated prior to being submerged in the oil by blanching, puréeing, or grating. Basil is often blanched prior to making basil oil. Blanching the basil softens it but more importantly preserves the bright green color which accentuates the final appearance of the oil. Bell peppers may be pureed and/or simmered prior to introducing the oil. Pureeing the ingredients renders them more dissolvable while simmering them concentrates their flavor and evaporates excess water. Items such as ginger or horseradish may be grated first to boost their flavor dissemination.
In the hot infusion method, the oil and flavoring elements are brought to a simmer, (typically between 180-200 degrees). The oil is then removed from the heat, allowed to steep until cool, and then placed in an air tight container. It is vital not to overheat the oil or it can develop an unpleasant, cooked taste. Using a thermometer to ensure the proper temperature range is a prudent course of action. The hot infusion method works best with woody herbs and dried spices. Analogous to toasting dried spices in a pan, heating them with the oil releases more of their flavor compounds. Since the hot infusion method is quicker it is the procedure of choice for impromptu cooking.
In both the cold and hot infusion methods, after the ingredients have fully flavored he oil, the oil may or may not be strained. The decision is often based on aesthetic and textural considerations. Should you desire your oil to appear more translucent or be devoid of any matter that could alter its mouth feel, straining is in order.
A very important consideration when making flavored oils is sanitation. Even non-flavored oil will eventually go rancid via the process of oxidation. Flavored oils however, are also susceptible to bacterial growth due to the addition of moisture from the flavoring ingredients. Returning to the aforementioned basil oil, after blanching the basil, it should be wrung as dry as possible in a kitchen towel.
The surefire means of avoiding all spoilage issues is to use the oil in a timely manner, routinely less than a week. Make sure the container is clean and dry before adding the oil and as stated, the lid should be air tight. Moreover, endeavor to use a container whose size barely holds the oil so there is minimal leftover air. Flavored oils that are not going to be used promptly should also be refrigerated. Flavored oils made from dried ingredients or ingredients that have been simmered, (either in the oil or not), are less prone to bacterial infestation due to their depleted moisture content. For example, I love hot chile oil. I simply grind pre-dried hot peppers and add oil. Chances are slim of any sanitary blunders with dried chiles so I usually leave this oil at room temperature. However, if making a large batch for use over an extended period of time, I will refrigerate it. Conversely, if using fresh hot peppers, I would make a small batch for prompt use and definitely refrigerate it from the onset.
There are innumerable ways of enlivening your food with flavored oils. Drizzle them over your finished dish for a burst of flavor and color. Drizzle basil oil over a tomato and mozzarella salad, rosemary-garlic oil over sautéed pork chops, or some ginger oil over your stir-fry. There are countless other combos. Substitute flavored oils for regular oil in salad dressings. Lemon oil can add a zingy citrus highlight to a salad. Employ them in marinades, bread crumb toppings, stuffings, sauces, homemade mayonnaise, and more. Or simply pour herbed oil on a plate, sprinkle it with salt and pepper and dip your Italian bread in it! Yum!
As for the ratios of flavoring ingredients to oil, it is not an exact science. Indeed, I never measure but rather just eyeball what looks to be sufficient. A little bit less or more is not going to make a dramatic difference. Nevertheless, a general rule of thumb is about four to six tablespoons of herbs/spices per pint of oil. As for the oil itself, I always use olive oil. While you certainly can employ plain vegetable oils, olive oil has a richer taste.
Finally, you can cook with some flavored oils depending on the nature of its flavoring elements. A flavored oil made from a delicate ingredient such as basil could have its nuances decimated by the heat needed to sauté. On the other hand, oils composed of sturdier base ingredients that are amenable to higher heat, (such as dried chiles or curry powder), can be utilized for cooking. Generally speaking though, flavored oils are more likely to excel as the grand finale.