Zest
Zest is the outermost, coloured layer of a citrus fruit's skin. It is full of aromatic oils, so a small amount gives a bright, intense citrus flavour without the sourness of the juice.
Anatomy of citrus peel
Citrus peel has two layers:
Flavedo (the zest). The thin, brightly coloured outer layer, dotted with tiny oil glands you can see as pores. Those glands hold essential oils dominated by limonene, with smaller amounts of compounds such as citral that give lemon its sharp, fresh scent.
Albedo (the pith). The spongy white layer underneath. It is rich in pectin and contains bitter compounds, such as naringin in grapefruit and limonin in many citrus. A little is harmless; a lot makes desserts taste bitter.
Good zesting takes the flavedo and leaves the albedo behind.
Why zest works
Citrus oils are fat-soluble and alcohol-soluble but barely water-soluble. That is why zest shines in butter-rich cakes, cream, olive oil dressings, and cocktails, and why simply squeezing juice into a dish does not give the same perfume. Rubbing zest into sugar before baking uses the sugar crystals' abrasive edges to rupture more oil glands, and the sugar then carries that aroma through the batter.
Yields
| Fruit | Finely grated zest |
|---|---|
| Medium lemon | About 1 tbsp (6 g) |
| Medium lime | About 2 tsp (4 g) |
| Medium orange | 1 1/2–2 tbsp (9–12 g) |
| Grapefruit | 2–3 tbsp |
Tools
- Rasp grater (Microplane): fine, fluffy zest that melts into batters and sauces.
- Channel zester: long, thin strands for garnish and cocktails.
- Vegetable peeler: wide strips for infusing syrups, braises, and custards, removed before serving.
- Box grater, finest holes: works, but tends to tear into the pith.
Chef Fizz says: Zest first, juice second. Trying to zest a squeezed lemon is like trying to paint a deflated balloon.
Tips
- Wash and dry first. Many citrus fruits are waxed. Scrub under warm water, or choose unwaxed fruit.
- Stop at the white. Rotate the fruit after each pass so you only take the colour.
- Zest over the bowl. Some of the oil sprays out as you grate.
- Add late for brightness. Long cooking drives off volatile oils; stir in fresh zest at the end of savoury dishes for the strongest aroma.
- Freeze extra. Zest freezes well for up to 3 months in a sealed bag.
Questions
How much zest does one lemon give?
A medium lemon gives about 1 tbsp (roughly 6 g) of finely grated zest. A medium orange gives about 1 1/2 to 2 tbsp, and a lime about 2 tsp.
How do you zest without a zester?
Use the finest side of a box grater, or peel strips with a vegetable peeler, trim off any white pith, and mince the strips finely with a sharp knife.
What is the difference between zest and peel?
Zest is only the coloured outer layer, called the flavedo. Peel usually means the whole rind, including the white pith (albedo) underneath, which is bitter.
Can I substitute lemon juice for lemon zest?
Not well. Juice adds sourness but little aroma, while zest adds aroma but no sourness. If you must, use about 2 tbsp juice or 1/2 tsp lemon extract per 1 tsp zest, and reduce other liquid slightly.