Cookbook:Citrus

| Fruit

The citrus fruits are a group of semi-tropical acidic fruits.

Characteristics
All citrus varieties have same basic characteristics. These include a thick, bitter peel with an aromatic outer skin (the zest) and an inner flesh that is divided into very juicy segments. They are all sour, but the flavor of each variety differs in overall sweetness, acidity, bitterness, and specific aromatic compounds. The color of the skin varies from green to yellow to orange, depending both on variety and the growing climate.

After juicing, the flavor of the juice gradually becomes more bitter due to enzymatic activity. In some cases this is desirable in order to develop the flavor of the juice. However, it may be especially undesirable in some applications, such as with orange juice.

Selection and storage
As citrus ripen only on the tree, make sure to only procure ripe fruits—they will not ripen later on. Make sure your fruits feel dense and generally firm all over, with no browning or bruising. The skin should feel slightly waxy.

Citruses will keep for a couple days at room temperature, but refrigeration is best, and refrigerated whole citrus can often last for up to a couple weeks. Once cut, peeled, or zested, the fruits will dry out within a day or so. Citrus fruits themselves do not freeze well, but the juice can be frozen—do note, however, that the juice can become less aromatic the longer it is frozen.

Preparation
You can prepare citrus fruits in a couple ways, depending on the use. One common method is to peel the fruit, removing the pith to expose the segments but leave them contained—this prevents juice from getting everywhere. Alternatively, you can just use a knife to slice the fruit into segments, but this will create juicy surfaces that may or may not be desirable. To juice citruses, they are typically cut in half and squeezed, sometimes with the help of a juicer or reamer. Note that cold fruits are much harder to juice, so it's good to bring them to room temperature first. When zesting citrus, you'll want to make sure to only remove the aromatic outer skin and leave behind the thick, bitter white pith itself.

It's a good idea to wash the fruits just before use to remove any residual wax and/or pesticides.

Use
Citrus and their juices are consumed in a variety of ways, from raw to cooked. Sweeter varieties may simply be peeled and eaten straight. Citrus juice can be used as a flavoring agent for various beverages, dessert applications, dressings, marinades, and more, where it adds significant acidity. The flavorful zest is also used, and its oils contribute a more aromatic character than the juice does. Both the fruit and zest may be used to various extents as garnishes.