Ingredient

Flaxseed

Flaxseed — linseed, the same thing under two names — is a small hard seed with a tough hull. Whole, it largely passes through undigested; ground, it becomes one of the most useful binders in a kitchen. The grinding is not a refinement, it is the whole point.

Whole against ground

A flaxseed hull is hard and slippery and is not readily broken down in digestion, so whole seeds go through more or less intact. That is not harmful and it does mean that whatever is inside — the oil, the protein, most of the nutritional content — is largely unavailable.

Ground flaxseed is a different proposition. It behaves as a fine meal, it hydrates readily into a gel, and its contents are accessible.

The catch is that grinding exposes a large surface area of highly unsaturated oil to air, and ground flaxseed goes rancid noticeably faster than whole. Buy whole seed and grind it as you need it, in a spice grinder or a small blender — a few seconds is enough — or buy ground flax in small quantities and keep it in the freezer.

Rancid ground flax tastes sharp, bitter and faintly fishy, and it is unmistakable once you have met it.

What to use it for

• A "flax egg" — a tablespoon of ground flaxseed with three tablespoons of water, left for ten minutes until it thickens into something viscous and gloopy. It binds in the way an egg binds. It does not leaven and it does not enrich, so it works in flapjacks, burgers, cookies and dense loaves, and does not work in a sponge or a meringue.
• In bread, ground or whole, where it adds nuttiness and softens the crumb. Whole seeds on top of a loaf are decorative rather than nutritional.
• In porridge, yoghurt and smoothies, ground, a spoonful at a time.
• In crackers and seed loaves, where the gel binds a mixture with very little flour in it.
• As a thickener for a cold sauce or dressing, in small amounts.
• Not for frying. Flax oil has a very low smoke point and oxidises fast — it is a dressing oil kept in the fridge, not a cooking oil.

The details

Brown and golden

Two varieties. Brown is more common and slightly stronger tasting; golden is milder and paler, which matters in a light-coloured bake. Nutritionally very similar.

Flavour

Mild, nutty, faintly earthy. Not assertive, which is why it disappears into baking.

Flax oil

Cold-pressed, sold refrigerated, very high in ALA, and it goes rancid quickly. For dressings only.

Storage

Whole seed keeps for months in a cupboard. Ground flax belongs in the fridge or freezer and should be used within weeks.

Grinding

A spice or coffee grinder does it in seconds. A blender needs a decent quantity to work with.

Linseed and flaxseed

The same seed. "Linseed" is more common in Britain and for industrial uses; "flaxseed" in food marketing.

Flax and chia, side by side

They do very similar things and are usually presented as competitors, which is misleading.

Both form a mucilage gel in water, both bind in baking, both are significant sources of the plant omega-3 alpha-linolenic acid, and both are high in soluble fibre. In a "flax egg" or a "chia egg" they are close to interchangeable.

The differences are practical rather than nutritional. Chia works whole, so it needs no grinding and keeps better; flax must be ground, so it takes an extra step and goes off faster. Flax is generally cheaper. Chia stays visible as distinct pearls, which is desirable in a pudding and not in a cake; ground flax disappears.

For binding in baking, ground flax is usually the better and cheaper choice. For a pudding where you want the texture, chia. For a smoothie, either.

Common questions