Onions, garlic and leeks; here are the differences

Onions, garlic and leeks are crops that can be locally grown by farmers, stored and sold at good profit. Onions are a good dietary source of vitamin C, B6, biotin, chromium, calcium and fibre. Garlic contains manganese, vitamin C, vitamin B6, calcium and selenium.

Leeks are a good source of manganese, vitamin B6, copper, iron, folate, vitamin C, dietary fibre, magnesium, calcium and vitamin A in the form of carotenoids. Onions and garlic are both basic cooking ingredients.

These together with shallots, chives and leeks, belong to the allium or onion family. The typical onion or garlic flavour results from an enzyme that acts with sulphur in the soil. Alliums generally have shallow fibrous roots that grow at the base of the plant.

Their leaves are thick and fleshy. They grow as bulbs. Onions are mostly round, slightly flat or cone-shaped.

Their skin can be white, yellow, red or purple. White onions have a sharper, pungent flavour as compared to the yellow ones.

They are also more tender and have thinner skin. Red onions are sweet and mild enough to be eaten raw.

Both the flesh and the outer skin of the red onions have a deep reddish-purplish colour. Green onions are immature onions that are harvested before the bulb forms.

Multiplier onions are one variation of the common onions that grow and form four to five bulbs inside each leaf sheath.

Garlic is a plant made up of many cloves. Each clove has about two papery leaves and a thick storage leaves that forms the clove.

Garlic is categorised as hard-neck and soft-neck. Hard-neck has a milder flavour than soft-neck.

It develops from a flowering stalk (scape) that dries to form the stiff “neck” of this garlic. The soft-neck garlic do not develop from the scape, so their stems stay soft and flexible making them good for garlic braiding.

A garlic braid is an orderly way used to store the produce making it convenient to pick up a clove or more when needed.

Shallots are similar in appearance with onions but they form a cluster of small bulbs instead of a single one. They have a brown skin with flesh that is purple. Just like garlic bulbs, they are divided into individual cloves.

Leeks are plants that grow long, with thick white stems. The leaves are solid, flat and folded. Leeks do not grow into bulbs. Leaves grow from the base of the plant. They sprout opposite each other on the stem. New leaves grow above the old. Leeks are sweeter than onions.

Chives grow in a stack as a herb. They have mild flavour. The chive plants do not form large bulbs. They have long green stems that are hollow and usually used fresh.

Culinary uses

White onions are cooked just like yellow onions but can be chopped into smaller pieces and used as an ingredient in chutney making.

Besides their use for basic cooking, yellow onions commonly characterised by their strong flavour and aroma, are good for making onion soup.

The deep colour in red onions makes them suitable additions to salads as well as filling for sandwiches and burgers, enhancing their appearance.

For the green onions, the entire plant is usually used including the shoots. They are used to garnish soups and in dishes like omelettes where crunchiness and colour are important characteristics. Leeks are good for soups and sauces. Cooked leeks have creamy texture hence used to flavour soups, sauces and stews.

Chives are used in various dishes including soups and salads. Shallots have a more intense flavour and due to their small size and thin layers, they can be diced and added to salad dressing as well as sauces.

Sweet onions are the best for making onion rings. The sweet onions are usually larger and slightly flatter than the yellow onions.

They are lighter in colour and have a less opaque skin; they contain extra sugars that give them the sweeter flavour.

Alliums grow well in drained soil with high organic matter as well as sandy soils if they are watered. They cannot grow well on heavy clay soils and soil that stays wet.

They have shallow roots and plants dry out quickly.

Ms Ndungi is based at the Department of Human Nutrition, Egerton University.