Makrut lime leaf vs Bay leaf
The short answer
Both go in whole and are fished out, and there the similarity ends. Makrut lime leaf is intensely citric — its oil is nearly pure citronellal — and it gives its aroma up quickly, so it goes in near the end or is shredded raw. Bay is slow and resinous and needs long cooking to say anything. A Thai curry made with bay has no citrus at all, which is most of what a Thai curry is.
Side by side
| Makrut lime leaf | Bay leaf | |
|---|---|---|
| Botanical identity | Citrus hystrix DC. | Laurus nobilis L. |
| Part used | leaf, fruit | leaf |
| Origin | Tropical Southeast Asia — the Malay peninsula, Indonesia and Thailand — where the tree has been cultivated domestically for centuries. | The Mediterranean basin, where it has been cultivated and gathered since antiquity. |
| Flavour notes | citric, floral, aromatic, faintly bitter | resinous, camphorous, herbal, faintly bitter |
| Heat | Not established | Scoville does not apply |
| Flavour | 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. | On its own, bay is bitter, medicinal and frankly unpleasant — chewing a leaf is the fastest way to conclude it does nothing good. In a long simmer it does something quite different: it lifts and lengthens a savoury background without contributing anything identifiable as itself. It is a spice that is noticed by its absence, which is a rare and useful property. |
| Aroma | 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. | Resinous and faintly camphorous when a leaf is torn — eucalyptus and pine with a warm background. Whole and undisturbed it smells of very little, which is part of why bay is so often assumed to be inert. |
Which should you buy?
Makrut lime leaf
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.
Bay leaf
Buy whole leaf, in the smallest quantity sold, and replace it far sooner than you think. Bay is the spice most likely to be sitting in a cupboard doing nothing: it looks the same at six years as at six months, and because nobody can taste it directly nobody notices it has stopped working. Ground bay solves nothing — it fades faster and cannot be removed. If you have a garden, a bay tree is the one entry in this dataset you can realistically grow, and fresh leaf is both better and free.
Full detail on makrut lime leaf and bay leaf, including evidence grades and sources for every claim above.