Zesting

Zest, pith and juice are three ingredients

The zest is the coloured layer, a fraction of a millimetre thick, packed with aromatic oils. It carries the smell of the fruit.

The pith is the white layer beneath it. It is bitter, and the bitterness is not subtle — it is why a badly zested cake tastes faintly medicinal.

The juice is water, acid and a little sugar with almost no aroma. A recipe using only juice tastes sharp rather than lemony, which is why a lemon cordial or a lemon cake made without zest disappoints.

Given how thin the coloured layer is, the whole technique is about depth of cut.

Four tools, four results

Rasp or microplane

A fine fluffy zest that disperses completely. The default, and the easiest to keep shallow.

Box grater, fine side

Similar but coarser, and it clogs. Rap it on the board to release what is stuck underneath.

Peeler

Wide strips with a little pith. For infusing into syrups, braises and cordials, then removing. Trim any white off the back with a knife.

Zester with holes

Long thin threads. Decorative and useful for a garnish or a candied peel.

A knife

For paring wide strips, and for removing pith from peeler strips.

Doing it well

1. Wash and dry the fruit. Scrub waxed citrus under warm water; buy unwaxed where you can.
2. Zest before you juice. Zesting a squeezed half is possible and miserable.
3. Move the fruit against the tool rather than the tool against the fruit. You can see what you are taking off.
4. Take one pass over any patch of skin and then move on. A second pass over the same spot is where the pith comes.
5. Work over the bowl the zest is going into. Oil sprays out as you grate, and that spray is a real part of the aroma.
6. For the strongest flavour in a sweet recipe, rub the zest into the sugar with your fingertips first. The crystals abrade the peel and the oil goes into the sugar rather than into the air.
7. Zest whatever you are not using and freeze it. It keeps for months and it is the part that cannot be bought.

Notes by fruit

• Lemon — thin skin, generous oil. The workhorse.
• Orange — thicker pith, so a shallower pass. Sweeter and less sharp than lemon.
• Lime — very thin skin and the most aromatic oil of the three. Easy to go through into pith.
• Grapefruit — thick pith and a resinous, faintly bitter zest that suits savoury dishes.
• Makrut lime — grown for its zest and leaves rather than juice. Intensely aromatic.
• Waxed fruit — scrub in warm water first, or the wax comes off with the zest.
• Bergamot, yuzu and calamansi — all zested for aroma rather than juiced, and worth it when you find them.

Common questions