Makrut lime leaf

• bai makrutใบมะกรูด

  Thai

  Bai means leaf; makrut is the fruit. "Makrut lime leaf" is the preferred English name and the one used in this profile, because the older English name is a racial slur in South African usage.

• daun jeruk purut

  Indonesian

• daun limau purut

  Malay

• krauch soeuch

  Khmer

  Used in Cambodian cooking in similar roles to the Thai, particularly in kroeung pastes.

• la chanh

  Vietnamese

Aromatic rather than tasted. Whole leaves perfume a broth and are not eaten; finely shredded, the leaf is eaten and contributes a bright citrus-floral note with a slight bitterness and a tough, fibrous texture if the shredding was not fine enough.

Intensely citric — lime peel rather than lime juice — with a floral, faintly soapy edge and none of the sourness the smell suggests. Torn, it is one of the most immediately recognisable aromas in Southeast Asian cooking.

Deep glossy green on the upper surface, paler beneath, in the characteristic double-lobed shape. Dried leaves fade to a dull olive-brown, which is a reliable indicator of how little aroma is left.

Thick, glossy and leathery, and genuinely tough. A whole leaf is removed before serving; a shredded one must be cut very finely across the grain with a sharp knife, and the central rib is always discarded.

• Citronellal — The dominant compound and the sharp lime-peel character. It is volatile, which is why drying fails and freezing works.
• Citronellol and linalool — The floral notes sitting behind the citrus.
• Sabinene — A green, faintly peppery undertone shared with other Rutaceae leaves.

Tear it, and decide whether it is being eaten. The aromatic oil is inside the leaf rather than on it, so an intact leaf dropped into a broth releases very little — tearing or bruising is what makes it work. A whole torn leaf perfumes a soup or a curry and is lifted out before serving, exactly like a bay leaf and for the same reason: it is tough and unpleasant to chew. Where the leaf is to be eaten, in a salad or a fish cake, remove the central rib, stack the halves and shred as finely as the knife allows across the grain, because coarse shreds stay fibrous however long they cook. Use fresh or frozen; the dried leaf is a different and much weaker ingredient. And do not expect sourness — this is the smell of lime peel and none of the acidity, which is why a tom yum needs lime juice as well.

Thai, Indonesian, Malay, Cambodian and Vietnamese cooking: tom yum and tom kha, green and red curry pastes, rendang, soto, fish cakes, and shredded raw into salads. It works with chicken, prawns, fish, beef, coconut milk, galangal, lemongrass, chilli and lime, and its particular role is aroma without acidity — it supplies the smell of lime peel to a dish that gets its sourness from somewhere else, which is a distinction cooks unfamiliar with it routinely miss.

• infusing — Bruised or torn whole leaves give their aroma to a hot liquid within a few minutes. Tearing matters — an intact leaf dropped in whole releases very little, because the oil is inside the tissue.
• grinding — Pounded into a curry paste the leaf contributes aroma throughout rather than as a top note, and the fibre disappears into the paste. A blender leaves shreds a mortar would have broken down.
• frying — Fried briefly in hot oil the leaves crisp and the aroma moves into the fat, in the same way as curry leaf. Less common than infusing and very effective in a stir-fry.

Tear a leaf in half and smell it. A good fresh or frozen leaf gives an immediate sharp lime-peel hit; a tired one smells green and generic. For dried leaves, crumble one — if there is no smell in your palm there will be none in the pot.

• Blackened or slimy leaves, which is what happens to a bag sealed damp.
• Yellowing, which precedes aroma loss on a fresh leaf.
• Curled, brittle leaves that have dried out in the refrigerator rather than been dried deliberately.
• Dried leaves faded from olive to pale brown.

The choice here is fresh or frozen against dried, and it is not close. Frozen makrut lime leaf keeps almost all of its aroma for a year and goes from the freezer straight into a pot; dried leaf has lost most of the citronellal that makes it worth using and fades further within months. If the only option is dried, a curry with several other aromatics will survive it and a tom yum or a salad will not — and in those cases leaving it out and not pretending is often the better dish, since dried leaf adds a hay note the fresh leaf does not have.

• Deep glossy green with no yellowing or black spots, and an immediate sharp lime smell when a leaf is torn.
• Frozen leaf in preference to dried, always. Frozen is close to fresh and dried is close to nothing.
• Sold as fresh produce or from a freezer cabinet rather than from a spice shelf.
• Buy the large bag and freeze most of it — it costs little more and lasts a year.
• Look for the double-lobed shape, which confirms the species at a glance.

No grading standard exists at consumer level, and none of the spice-trade specifications apply because this is sold as fresh produce. Freshness and how recently the leaf was picked are the only quality variables and neither is stated.

Rutaceae

A thorny shrub or small tree bearing a distinctive double leaf — two lobes joined end to end, so that what looks like two leaves is one — and rough, deeply wrinkled green fruit. The double-lobed shape is the identifying feature and is unmistakable once seen.

Tropical Southeast Asia — the Malay peninsula, Indonesia and Thailand — where the tree has been cultivated domestically for centuries.

• TH — origin. The main commercial source of exported fresh and frozen leaf.
• ID — major producer
• MY — major producer
• VN — notable producer
• KH — notable producer

Leaves picked by hand year-round, mature rather than young — an older leaf carries more aromatic oil. Fruit is picked separately for its rind, which is a different product with a different market.

1. Picking and sorting — Mature leaves picked whole, sorted for damage, and packed on the stem or loose.Why: The fresh leaf is the product; everything below is preservation.
2. Freezing — Leaves frozen whole, which is now the main export route. The aromatic oil is held in leaf tissue rather than on the surface and survives freezing almost intact.Why: The preservation route that works. Frozen leaf is close enough to fresh that the difference is hard to detect in a cooked dish.
3. Drying — Air-dried, which costs most of the volatile oil. Widely sold and widely disappointing.Why: Shelf stability at a very high cost to the aroma — recorded because it is the form most readers will find on a spice shelf, and the one worth avoiding.

No consumer grading standard. Fresh and frozen leaf is judged on colour, gloss and how strongly it smells when torn, all of which a buyer can check directly and none of which is stated on a label.

A garden and smallholding crop far more than a plantation one, grown for both leaf and fruit and picked continuously. Commercial production for export is concentrated in Thailand and increasingly supplies frozen rather than dried leaf.

Tropical: warm, humid and frost-free. It grows readily as a container plant in temperate climates under glass, which is why keen cooks outside the tropics often keep one rather than buying leaves.

A domestic plant across maritime Southeast Asia for centuries, grown in gardens for both leaf and fruit and never a trade commodity — for the same reason as curry leaf, that it is worth having fresh and worth little dried. Its spread beyond the region followed Thai restaurant cooking in the late twentieth century and then air freight, and the frozen leaf that makes it genuinely usable outside the tropics is more recent still.

A modern fresh-produce and frozen trade rather than a spice one, centred on Thailand. The dried leaf has an older and larger commercial presence and a much poorer reputation, which is the same shape as the curry leaf trade and for identical reasons.

Recorded across Southeast Asian household tradition, including the fruit rind in hair and scalp preparations. Held as tradition and cultural context, not as a health claim.