Fingerroot

Fingerroot is a perennial herb of the ginger family, Zingiberaceae. It grows 30–80 cm tall, with three or four broad leaves, up to 50 cm long, on short stems whose sheaths are tinged pink to red. The flowers are white to pink and open low down between the leaves.

The part we cook with is below ground. A small rhizome, dark brown outside and yellow inside, carries a bunch of long, tapering storage roots — the “fingers”, 5–30 cm long and up to 2 cm thick, with the same yellow flesh and fragrance. Botanically the fingers are roots, not rhizome; the Thai Herbal Pharmacopoeia lists the dried drug as root and rhizome.

In Thailand the plants are typically set in April–May and dug six to eight months later, when the leaves begin to yellow. Drying removes most of the weight: in one Thai study, 10 kg of fresh fingerroot gave 1.5 kg of coarse powder.

1. 1656–1688

   In King Narai’s recipes

   The medical recipes of King Narai of Ayutthaya list krachai with pepper, galangal, shallots and garlic — in an ointment, not a dish. It is the oldest Thai mention we found.

2. Late 17th century

   Drawn in Malabar

   Hendrik van Rheede pictures the plant in Hortus Malabaricus. In 1753 Linnaeus, who never saw it, named Curcuma rotunda from this plate.

3. 1810 · 1958

   Two names

   In 1810 William Roxburgh described Kaempferia pandurata from a plant in Calcutta, said to have come from Sumatra; the name is still found in older sources. In 1958 Rudolf Mansfeld placed it in the genus Boesenbergia, giving today’s name.

4. 1908–09

   In a Thai cookbook

   Mae Krua Hua Pa, generally regarded as the first printed Thai cookbook, uses krachai in an eel curry and in a Chinese-style nam ya.

5. 2021

   Thailand’s most wanted herb

   In 2020 a Thai team reported that a fingerroot extract slowed the COVID-19 virus in laboratory cells — not in people. By July 2021 the price of fresh krachai had risen from about 30–50 to 150–200 baht a kilo, and Michelin Guide Thailand called it “Thailand’s most wanted herb”. Mahidol University disowned product ads using its scientists’ images, and the Thai FDA reminded shoppers that food does not treat or cure disease.

Place and food culture

In Thai cooking, fingerroot is above all a partner for fish: long, thin strips of root go into fish curries to take away the fishy smell. Chef Chumpol Jangprai calls it essential to kaeng pa, the fiery, coconut-free jungle curry.

Krua.co’s classic nam ya paste, for fish curry on rice noodles, takes two cups of fingerroot but only seven slices of galangal. In Isaan, its nam ya pla ra names fingerroot the most important ingredient.

Descriptions of fingerroot differ more than for most spices. The Thai Herbal Pharmacopoeia says simply “spicy”, and Thai traditional texts add hot and bitter. Spice writer Gernot Katzer calls the flavour strong and dominating; chefs speak of a cooling, herbal aroma.

Where the aroma comes from

The aroma comes from a small amount of essential oil: 1–3 % of the dried root by one handbook, and at least 1.5 % by the Thai pharmacopoeia. In analyses of Thai samples, four compounds lead the oil, though which one comes first changes from sample to sample.

Cool

Camphor, eucalyptus

Herbal

Fresh and resinous

Warm spice

A peppery warmth

Bitter edge

Slight; add with care

Fingerroot and its relatives

Both recipes are written for fresh fingerroot. With powder, work ½–1 teaspoon, mixed to a paste with a little warm water, into the curry paste instead — our suggestion, as there is no published conversion — then taste.

Beyond Thailand

— fingerroot in other kitchens

Fingerroot is first of all a kitchen herb. In Thailand and Indonesia it also has a place in traditional practice, and researchers have studied its compounds.

What researchers are exploring now

Two trials in people, both with concentrated extracts rather than the spice:

Educational product information. Not medical advice. If you are pregnant, breastfeeding or taking medication, consult your doctor before using a new botanical product.