Spice of the Week - Onion

Onions are the indispensable vegetable, the strong (yet sweet) cornerstone of modern cooking, not just in our culture but around the world. Whether it's a soup, stew, stir-fry, salad or sauce, chances are the recipe includes onions or garlic (very likely both) or one of their relatives. These members of the Allium genus (part of the lily family) don't just add flavor, they add richness and complexity.

Spice Description

The onion is an edible bulb. While it is a vegetable at heart, it also acts as a spice inasmuch as it can provide an aromatic undertone to various meat and vegetable dishes, without being a major ingredient. The characteristic appearance of the onion is well known, but there are many variations of color, shape and size. The color varies from white to red to purple, the shape from spherical to almost conical, and the diameter at the largest point from 10mm (1/2in) to 8cm (3in) or 'more. Onions should be firm, though not rock hard. The papery skin should be tight over the surface of the bulb. Spring onions, or scallions, are immature plants where the bulb has not completely formed. They may be cylindrical, the green stem shading into the white bulblet, which may be almost spherical. Onions are also available in processed form, as dried flakes and powder, or liquid.

Plant Description and Cultivation

A hardy biennial but cultivated as an annual. Although the bulbous plant with its long-bladed leaves has many varieties of shape and color, it is so familiar that it is not necessary to add to what has already been said under Spice Description.

Preparation and Storage

Onions may be used whole, sliced, chopped, diced or liquidised. It is important to observe the cooking instructions carefully, as the flavour of onions is greatly influenced by their treatment. A recipe where onions are to be 'fried till golden' will suffer if the onions are browned. Small onions and picklers are easier to peel if they are first immersed in boiling water for ten seconds and then rinsed in cold water before removing the skins. To prevent the eyes from watering, peel onions under cold water or put them in the freezer for ten minutes before chopping. Should onions be excessively strong, boil them whole for five minutes before proceeding with the recipe. Firm unblemished onions should keep for several weeks if stored in a cool airy place. Too much warmth will encourage sprouting. Home-grown onions must be quite dry before stringing. Dried onion flakes and powder should be stored in airtight containers.

Culinary uses

Onion is a basic flavoring in the kitchen. It is used as a vegetable, or as a spice to bring out the flavor of other dishes without overpowering them. It often accompanies meat - especially mince and meat dishes such as shepherds pie and meat loaf which would be insipid without it. Onion is also widely used in soups, pickles and cooked vegetable dishes, sauces, hearty casseroles, and bean and lentil dishes. It is a common ingredient in marinades, and an onion studded with cloves is often a main flavoring in stocks and courts-bouillons. There are many classic recipes featuring onion including such familiar dishes as tripe and onions, steak and onions, French onion soup, coq au yin, sauce soubise, to name but a few. Equally famous in India is do pvaza, a dish of meat cooked with a, much as double its weight of onions. The shallot is frequently used in Mediterranean and American cookery, the rocambole in country recipes. Spring onions are common in fresh summer salads and in Chinese and Japanese cookery.

Chemical Composition

Onion contains protein, sugars, cellulose, minerals, a fixed oil, an essential oil and over 80 per cent water. The amount of essential oil is very small but it contains the aromatic and tear-producing properties associated with onion. These are caused by sulphides which are produced by the reaction of the enzyme alliinase on an amino acid. These substances are normally in separate cells in the tissues, but when the onion is cut and bruised, rupturing the cells, the reaction takes place. Cooking has the opposite effect, preventing the enzymatic action and thus milder and less pungent flavors are produced. The chemistry of the Alliaceae family, including garlic, shallots etc, is very similar. The calorific value of raw onion is 38 calories per 100g, or roughly 20 calories for a 3oz onion.

Attributed Medicinal Properties

Antiseptic, diuretic, expectorant and rubefacient. Onion's antiseptic properties as a juice or paste have been used for wound healing, skin complaints (acne), insect bites, hemorrhoids, boils, toothache, earache and respiratory complaints. The raw juice is diuretic and the whole onion is an appetite stimulant and digestant. It has been used as a vermifuge. It is believed to stimulate the liver and is beneficial to the heart and nervous system.