Makrut lime leaves (kaffir lime, Thai lime, Mauritius papeda) come from the Makrut lime tree (Citrus hystrix). Both the size and color of the fruit are similar to the more common lime (Citrus x latifolia), but the Makrut lime contains much less juice and its skin is uneven and bumpy. Makrut lime leaves have a zesty lemon flavor and are predominantly used in Thai cooking.
What are Makrut lime leaves? The leaves of the Makrut lime are called Bai Makrut in Thailand. Although they look much like the more commonly known bay leaves, that’s where the similarity ends as the Makrut lime leaves are hourglass-shaped “double” leaves, with two leaves at the end of each stem that look like they are joined together, as one appears to grow from the tip of the other. Additionally, Makrut lime leaves tend to be eaten fresh, while bay leaves are almost always used dried.
Crush the leaves between your fingers to release a strong lemon aroma. Before cooking, rinse the fresh Makrut leaves thoroughly and make sure they are fully dry before using. Cook whole and remove shortly before eating. It is possible to eat the otherwise rather tough Makrut lime leaves by chopping them finely and cooking (e.g., in curries). This allows their full flavor to develop. The midrib and stem of more mature leaves sometimes tastes bitter. If this bothers you, you can remove these parts before cooking.
Fresh Makrut lime leaves are coated with a glossy green layer of wax. They make excellent garnishes for fruit salads, sundaes, lemonades, and cocktails. Sorbets and ice cream made with Makrut lime are refreshing for the palate.
Makrut lime leaves are associated with Thai and southeast Asian cooking. Their particular lemon flavor goes well with soups, salads, ragouts, rice, and vegetable dishes. The Thai soups Tom Yum (here is a recipe for a Vegan Tom Yum soup) and Tom Kha Gai owe their unique zesty flavor to the Makrut lime leaves. In Thailand and Cambodia, there are several well-known spice pastes that use Makrut lime leaves.
Although their flavor doesn’t last as long, Makrut lime leaves can also be bought dried or ground. If you don't have any Makrut lime leaves on hand, you can instead use fresh lime peel, lemongrass, or lime juice. Some people also replace Makrut lime leaves with lemon myrtle leaves (Backhousia citriodora).1 None of these, however, are perfect substitutes.
When brewed with hot water, fresh Makrut lime leaves can also be used to make tea. When cooled and sweetened, Makrut lime leaf tea is a refreshing summer beverage.
Ingredients: 2 stalks lemongrass (or 1 tablespoon lemongrass powder), 60 g fresh galangal (Thai ginger) (or 1 tablespoon ground), 60 g fresh ginger, 2 onions, 4 cloves of garlic, 2 teaspoons chili powder, 4 tablespoons lime juice, 3 tablespoons brown sugar, 3 tablespoons coconut oil (alternatively canola oil), 2 tablespoons salt, 8 fresh Makrut lime leaves
Preparation: Remove the hard lower part and the outer leaves of the lemongrass and cut the rest into small pieces. Peel the ginger, onions, and garlic and chop into large pieces. Chop tje Makrut lime leaves very finely (you can also use powder). Blend the ingredients in a high-speed blender and puree until completely mixed. Store the paste in a screw-top jar in the refrigerator for up to several days. The Thai Tom kha paste is used in curries and soups with the same name, usually in combination with coconut milk, chicken, or seafood. They can also be veganized using various vegetables.
It can be difficult to find fresh Makrut limes leaves in supermarket chains like Whole Foods Markets, Kroger, and Safeway (United States); Asda, Sainsbury’s, Tesco, Aldi, Lidl, and Holland & Barret (Great Britain); Metro, Extra Foods, and Goodness Me (Canada); and Coles, Woolworths, and Harris Farm (Australia). Well-stocked supermarkets sometimes carry dried or ground Makrut lime leaves. Fresh Makrut lime leaves are difficult to find, but the dried ones can almost always be found in specialty stores, Asian stores, and at Thai markets. Makrut lime leaves can also be ordered online, although even here the fresh leaves are more difficult to find than the dried ones.
Although there are organic Makrut lime leaves, the market for them is still very small. Try and buy organic when possible since high amounts of pesticide are used on citrus crops. You can also buy Makrut lime trees in garden centers. When kept in bright warm locations, the evergreen trees will provide you with fresh Makrut lime leaves year-round.
You can store fresh Makrut lime leaves in the vegetable drawer of your refrigerator for 2–3 days. If you have bought a larger quantity, you can freeze the leaves whole or chopped as this is the best way to preserve their flavor. They don’t go bad when stored in a plastic bag in the freezer.
Both the dried and ground Makrut lime leaves stay good for a long time when stored in a cool, dark, and hermetically sealed place, but they quickly lose their distinctive lemon flavor.
There are numerous species of the subgenus Archi-Citrus between the Himalayas and Malaysia, but Citrus hystrix prefers more maritime locations. Other known wild species include C. combra and C. macroptera. It is assumed that these primitive species are the predecessors of today’s cultivated species Citrus medica (citron), C. x limon (lemon, lime), C. x aurantium (bitter orange), C. x aurantiifolia (key lime), C. x sinensis (orange), and C. grandis (grapefruit).2
The penetrating lemon-like scent of the Makrut lime leaves comes from the essential oil they contain. Eighty percent of this is citronellal and up to 10 % citronellol. They also contain traces of limonene (a terpene) and nerol.
In countries where Makrut limes are grown, the juice and peel has been used as a shampoo for a long time. Shampoo made from Makrut limes is said to kill head lice (Pediculus humanus).3
There is evidence that an alcoholic extract of Makrut lime leaves is effective against herpes viruses.4
Studies have shown that extracts of Makrut lime leaves reduce cervical and neuroblastoma cell lines and are therefore suitable as an anticancer compound.5 Although no cytotoxic effect against leukemia cell lines has been found, further research into Citrus hystrix leaf extracts for use in chemotherapy is recommended.6
Furocoumarins (furanocoumarins) contained in the skin and flesh of Makrut lime can cause severe phytophotodermatitis. At least one case of this severe skin inflammation is known.7,8 These phytochemicals serve as phytoalexins (defense substances) of the plant. Furocoumarins (e.g., in the form of plant sap) that have reached the skin react with the UVA and UVB rays of sunlight. This leads to combustion-like symptoms, similar to those of the giant hogweed. Furocoumarins are carcinogenic when exposed to UV light because they form covalent bonds with the pyrimidine bases of DNA.9
The juice of the Makrut lime is used in Thailand and Cambodia as a laundry detergent.10
This dwarf lime tree originated in Asia and is most widespread in Southeast Asia.11 It is also cultivated in Central America and parts of Africa.
Makrut limes are shrubby, thorny evergreen trees that can reach a height of up to 2 m. The leaves are hourglass-shaped “double” leaves, with two leaves at the end of each stem. The small white flowers emit a strong smell. The limes have a diameter of about 5–6 cm, and the skin is thick and knobby. The fruit changes from green to yellow as it ripens. The main difference from a “normal” lime is the amount of juice. Makrut limes contain relatively little juice and more seeds. In this subgenus, the peel and flesh are difficult to separate from each other.2
If you buy a lime tree, you should repot it in a larger container. This requires a porous soil so that the thin roots can have optimal growing conditions. To provide for adequate drainage, place stones, fragments of clay, or expanded clay aggregate in the bottom of the pot and fleece on top of the soil because Makrut lime trees cannot tolerate waterlogging. Sprinkle potting soil on top (citrus mix or soil that is slightly acidic with a pH value of 5.5–6.5). Dip the roots briefly in lime-deficient water and then place back in the pot, pressing down a little. Rainwater is best for watering, but even this should only be in moderate amounts. The top layer of soil should never be wet and should only be watered again when completely dry.12
Pruning the tree regularly encourages branching and a more bushy plant. It is best to wear gloves because they are quite thorny. The best time for pruning is in the spring or anytime before blossoming. Dead branches and those growing inwards should be cut or pinched off with pruning shears that have been disinfected. You can cut branches that get too long at any time.12
In the summer, a sunny wind-protected place outside is suitable. During the winter, Makrut lime trees need to be kept in a bright frost-free location at temperatures of 5–10 °C, for example, an unheated winter garden, a staircase, a cellar, or a frost-free garage.
The leaf stalks of the Ichang lemon and Ichang Papeda (Citrus ichangensis) are hourglass-shaped like the Makrut lime (Citrus hystrix). The Makrut lime tree is frost-resistant (–15 °C) and according to Wikipedia popular as a slow-growing citrus rootstock for oranges.13 The aroma of the Ichang lemon leaves does not come close to that of the Makrut lime leaves. They are not poisonous.
Makrut lime leaves grow on the Makrut lime (Citrus hystrix), which is also known as the Kaffir lime, Mauritius Papeda, and Thai lime. Botanically, it belongs to the Sapindale order, the Rutaceae family, and the Citrus genus. The Makrut lime is classified as part of the subgenus Papeda and is therefore only distantly related to the better-known citrus fruits. This also explains the uncommon Latin name Citrus papeda.
Makrut limes are more commonly referred to as kaffir limes. Where the name kaffir lime comes from is not clear; however Kaffir is a racial slur used to describe black people during colonial times. In South Africa during the apartheid era, this term was as a slur to describe Black Africans and is forbidden there today. The Arabic meaning of Kaffir (infidel or village), meaning backward or outdated, further confuses the name’s origin.
Since Kaffir means infidel in Arabic, the use of this term is questionable and considered by many to be problematic. The leaves are often commonly called kaffir leaves (also considered to be problematic), lime leaves, and Indian or Indonesian lemon leaves. The leaves are also sometimes called Indonesian lime leaves.
In English, the names Makrut lime, Thai lime, Mauritius papeda, and Kaffir lime are common. In French, the fruit is called Combava. In Indonesia, the Makrut lime tree is called jeruk purut and the leaves daun jeruk purut.
Another use of Makrut lime leaves is to add them to a hot bath. You can also use the crushed leaves in an oil diffuser in the place of essential oil. If your skin is not too sensitive and no negative reactions occur, the leaves can be used as a light perfume. To do this, rub the crushed Makrut lime leaves into your hands and temples. The juice of the Makrut lime (fruit) is also used as a cleaning agent for clothes and hair (in Thailand and Cambodia). In Cambodia, the use of holy water with fruit slices of Makrut lime is common in religious ceremonies.14
Makrut lime leaves can also be used as an insecticide (e.g., as a substitute for mothballs and against mosquitoes).15