Thai oliang

Local names

Thai

โอเลี้ยงoliangoh-LEE-angFrom Teochew: 'o' black, 'liang' cold.

What it is

Oliang is not coffee with things added to the cup; it is a blend roasted and ground together before brewing. Robusta is combined with roasted grains and seeds — corn and soybean in the largest proportions, with sesame, and often cardamom or rice — and one widely sold commercial blend is around half coffee by weight. The result is brewed strong through a cloth sock filter, sweetened, and poured over ice.

What the additions do is not dilution in the pejorative sense. Roasted corn and soybean contribute their own caramelised, nutty, faintly smoky character and a body that survives ice, which coffee alone at the same strength does not. The drink tastes of the blend, not of coffee that has been stretched, and Thai drinkers who try oliang made from pure coffee generally report it as wrong rather than as better.

The practice belongs to the same family as Malaysian and Singaporean kopi and to the wider Southeast Asian tradition of sock-brewed dark blends — and it arrived by the same route, with Teochew-speaking Chinese migration, which the name itself records.

What makes it distinct: Roasted grains and seeds are part of the ground blend rather than the cup, so the additions are extracted alongside the coffee and cannot be separated from it.

Cultural context

Street and market coffee, sold from carts and small shops in plastic bags with straws as often as in glasses, and drunk cold in a hot climate. It sits alongside — not beneath — the espresso cafés that have grown in Bangkok and Chiang Mai; the two are different drinks with different customers and often the same customers at different hours.

Vessel and equipment

The tung dtom kaffee — a cotton bag on a metal ring with a long handle, the same family of object as the Malaysian kopi sock and the Caribbean colador.

Brewed in

• Cloth coffee filter

How it is made

Water passes down through a grounds bed held by cloth, which lets oils through.

Water is boiled separately and poured through the sock; the brewed coffee is then held hot or chilled depending on the stall.

1. Start from an oliang blend: robusta ground together with roasted corn, soybean and sesame, and often cardamom. This is done by the roaster, not the stall.
2. Load the sock with the ground blend and set it over a pot or jug.
3. Pour boiling water through and let it steep in the sock for several minutes, longer than a pour-over, so the grains as well as the coffee give up their character. (about 8 minutes)
4. Sweeten with sugar while the brew is still hot so it dissolves.
5. Pour over a full glass of ice and serve black. Condensed or evaporated milk turns it into oliang yen variants rather than oliang.

Sugar

Added to the hot brew, and generously. Unsweetened oliang would be unusual to the point of confusing an order.

Milk

None in oliang itself. Adding condensed milk makes a different, named drink; the black version is the one the word means.

Additions

Roasted corn, soybean and sesame in the blend — definitional; Cardamom, commonly; Rice or other grains, regionally; Ice, always

How it is served

A tall glass packed with ice, or a plastic bag with a straw for takeaway.

Served with: Patongo (fried dough sticks), Street food generally

When: Morning through afternoon; a heat-of-the-day drink.

Taste

Tendencies of the preparation, not a prediction about any particular cup.

Body

Medium-high

Clarity

Medium

Sediment in the cup

Low

Perceived strength

Medium-high

Bitterness tendency

Medium

Acidity tendency

Low

Sweetness tendency

High

Caffeine

Lower than the colour and strength suggest, and this is the useful thing to say about it. If half the blend by weight is corn, soybean and sesame — none of which contains caffeine — then a spoonful of oliang blend delivers roughly half the caffeine of a spoonful of coffee. Robusta pushes back the other way, carrying about twice arabica's caffeine per gram. The two effects partly cancel, and the result is an ordinary iced coffee's caffeine in a large, heavily diluted glass.

CoffeeHQ states no milligram figure for this preparation, because no measurement specific to it has been established. Inventing one would be easy and wrong.

What moves the number

• The grain-to-coffee proportion in the blend, which varies by brand and stall and is rarely stated
• Robusta, which raises caffeine per gram of the coffee component
• Ice melt, which dilutes as the glass stands

The displacement arithmetic is reliable; the blend proportions behind it are commercial and inconsistently published, so no figure is given.

How CoffeeHQ estimates caffeine

How it differs from

Nanyang kopi (Malaysian and Singaporean kopitiam coffee)

Close relatives — both are sock-brewed dark blends carried by Chinese migration into Southeast Asia — and they modify the coffee at different points. Kopi's additions are sugar and margarine applied to the beans in the roaster; oliang's are whole roasted grains and seeds blended in. Kopi is usually milky and hot; oliang is black and iced.

South Indian filter coffee

Both cut the coffee with a roasted non-coffee ingredient that regular drinkers expect and miss when absent — chicory in India, corn and soybean in Thailand — and both are held up as evidence of adulteration by people unfamiliar with them. Beyond that they share nothing: metal drip versus cloth sock, hot milk versus ice, decoction versus direct brew.

In practice

Common mistakes

• Making it from pure coffee, which produces a perfectly good iced coffee and not oliang
• Brewing it at drinking strength and then adding ice, which gives a watery glass
• Adding milk and still calling it oliang
• Letting the sock dry out between uses

Household and regional variation

Blend composition varies substantially between brands and stalls; so does whether cardamom is present at all.

Modern adaptations

Bottled and canned oliang, instant oliang powders, and espresso-machine versions in cafés. Some specialty roasters now sell single-origin Thai arabica that is explicitly not oliang.

Misconceptions

• That the grains are an adulterant or a wartime substitute. In this tradition they are the recipe, and the drink is not trying to be pure coffee.
• That it is Thai iced coffee with milk. That is a different, named drink; oliang is black.
• That it is unusually strong because it is very dark. Half of what is in the sock is not coffee.

Related preparations

• Nanyang kopi (Malaysian and Singaporean kopitiam coffee)
• Vietnamese phin coffee

Elsewhere on CoffeeHQ

• Iced coffee

History, culture and background

• South and Southeast Asian coffee traditions
• Coffee substitutes
• Roasting basics: from green bean to roasted coffee

Related in the catalogue

• Nanyang kopi (Malaysian and Singaporean kopitiam coffee)
• Cambodian iced coffee (kafe tuk doh ko)

Compare

• Cambodian iced coffee vs Thai oliang