Toasting nuts and seeds

Why

Toasting drives the remaining water out of nuts and seeds, makes them crisp, and starts browning their proteins and sugars in the Maillard reaction, which creates nutty, roasted aromas. Browning speeds up as the temperature rises, and because nuts contain little water to cool them, the stretch between golden and burnt is short; small, thin or oily seeds such as sesame, pine nuts or flaked almonds brown fastest. A hot pan or baking sheet keeps heating after it comes off the heat and the nuts go on darkening in it, which is why they are tipped out at once. Burnt nuts are bitter, whereas rancid ones taste of stale oil: the unsaturated fats in walnuts, pecans, pine nuts or linseed oxidise in air, light and warmth, and toasted nuts turn rancid even faster.

How to do it

• Toast small amounts in a single layer in a dry pan over medium heat, stirring constantly, usually for 3–5 minutes, and do not walk away.
• Spread larger amounts on a baking sheet and toast them in the oven at 175 °C for about 5–10 minutes; stir and check them early and often.
• They are done when fragrant and a shade darker; break one open, it should be light golden inside, not brown.
• Tip them straight onto a cold plate and spread them out; in a hot pan or on the baking sheet they would keep darkening.
• Watch sesame and pine nuts most closely; for tahini, toast sesame over low heat only until golden, as dark seeds would make the paste bitter.
• Store nuts sealed in a cool, dark place; use toasted ones soon or freeze them, and in the freezer they keep for about 1 month.

If it goes wrong

Burnt nuts cannot be saved, as the bitterness would spread through the whole dish; only if a few pieces have blackened and the rest taste fine, pick out the dark ones. Return under-toasted ones to the pan or baking sheet for just a moment. Do not use rancid nuts that taste of stale oil; neither toasting nor spices will hide the flavour. Throw away mouldy, blackened or shrivelled pieces, because moulds on nuts can produce aflatoxins, which toasting does not destroy, and if there are several mouldy ones, throw away the whole pack.