003 · Field guide

豆乾 dòu gān · dried pressed tofu

What exactly is dougan?

You grew up calling a dozen different foods by one name. Here's the thing nobody says out loud: 豆乾 is an umbrella term, not a single food. What you taste as "texture" is really three physical variables: how hard it was pressed, how it was colored, and what it was even made from.

A market tray of golden-brown dougan squares beside a handwritten 豆干 price sign — Golden pressed dougan at a Taiwanese market. Note the cloth-weave imprint from pressing. Photo EHALAM BorG 600M · CC BY-SA 4.0

One word, six recipes

The core idea

Products sold as 豆乾 span at least six different production routes. Some are pressed bean curd, some are rolled bean-curd skin, some are deep-fried, some are fermented. And one of the most common, 百頁豆腐, isn't really tofu at all. The texture differences you notice aren't random. They track three things:

Water

How hard the block was pressed. Less water → firmer, chewier, more protein- and calcium-dense. This is the whole tofu-to-dougan move.

The braise

Caramel 糖烏 vs. soy braise vs. food dye vs. smoke. Sets the surface color, the saltiness, and how much the piece shrinks.

The base

Pressed curd? Skimmed skin (yuba)? Reconstituted soy-protein slurry? Fried or fermented derivative? Two pieces that look alike can come from totally different materials.

From soybean to dougan

The shared chain

Every product here branches off one early pipeline, then diverges. The single most important fact: dougan is just tofu that has been pressed harder and dried further.

黃豆soybeans

→

豆漿soy milk

→

豆花+ coagulant → curds

→

豆腐pressed → tofu

→

豆乾pressed again → dougan

then braise in caramel or soy or smoke or deep-fry or ferment

The coagulant stirred into the soy milk quietly decides texture and nutrition. 石膏 (gypsum) is cheap, sets a fine dense curd, and loads the piece with calcium, which is why dougan is calcium-rich at all: most of it comes from the gypsum, not the bean. 鹽滷 (nigari) sets a coarser curd. GDL adds no calcium and makes very soft tofu.

The firmness ladder

Water content ↓

Everything firmer than soft tofu sits on one ladder, and pressing is what moves a piece down it. Wettest at the top:

豆漿 soy milkno coagulant yet

~93% water · liquid

豆花 / 嫩豆腐GDL · soft tofu

~90% · silky, fragile

板豆腐gypsum/nigari · firm tofu

high but pressed · springy

白豆乾pressed twice

lower than tofu · firm, moist

五香 / 滷pressed + braised

lower still · chewy

黑豆乾 / 茶乾pressed + long braise

lowest of pressed · very chewy

豆皮 / 腐竹skimmed film, dried

under 60% · thin, dry

Bars below firm tofu are relative, not measured. Taiwanese sources only ever say "lower than tofu," never a standardized moisture %. Treat any exact figure for dougan with suspicion.

≈200

kcal / 100g

firm dougan, vs. board tofu ≈88

19 g

protein / 100g

vs. ≈8.5 g in board tofu

334 mg

calcium / 100g

up to 685 mg in dense 小方豆乾

The jump in protein and calcium density is purely the result of removing water. Nothing is added. It's concentrated.

All 13, side by side

Master comparison

"Base material" is the column that explains the most. It's the real reason two things that look similar can feel totally different. Scroll →

Variety	Base material	Texture	Color	Taste
白豆乾White dougan	Pressed bean curd	Firm, solid, still moist; perishable	Dull off-white	Pure soybean, unseasoned
黑豆乾Black dougan	Pressed bean curd	Dense, chewy, springy; tough skin	Coffee → near-black surface	Faintly sweet caramel
五香豆乾Five-spice	Pressed bean curd	Medium-firm (軟硬適中)	Light coffee-brown	Mild herbal-savory
滷豆乾 / 大溪Braised / Daxi	Pressed bean curd	Springy, firm; small air-holes	Soy-brown skin, cream interior	Savory, mellow, lightly smoky
茶乾 / 黃金Snack / golden	Heavily pressed curd	Firmest, densest, snappy	Golden-yellow to brown	Concentrated savory
煙燻豆乾Smoked	Pressed curd, smoked	Firm, dense, defined bite	Mahogany, glossy skin	Smoky, faintly sweet
豆乾絲 / 干絲Shredded	Pressed curd, cut to strands	Firm chewy strands; mushy if over-blanched	White to pale yellow	Mild soy; carries dressings
百頁豆腐Baiye tofu	Reconstituted soy protein	Smooth, bouncy like fish cake	White, square	Bland; a sponge for sauce; high fat
千張 / 百頁Thin sheet	Pressed/stacked curd sheet	Thin, pliable; soaks up soup	Pale yellow / cream	Nearly flavorless alone
油豆腐Fried tofu	Fried bean curd	Crisp skin, spongy or hollow interior	Golden/amber out, pale in	Rich, fried, slightly oily
豆包 / 豆皮Yuba	Skimmed soy-milk skin	Fresh: soft melt. Fried: crisp, porous	Pale yellow / golden fried	Strong clean soybean aroma
素雞Veg "chicken"	Rolled bean-curd skin	Chewy, firm; layered cross-section	Browned skin, pale layered inside	Savory braised
臭豆乾 / 臭豆腐Stinky	Fermented pressed curd	Crisp shell, airy porous interior	Grey to ink-dark; gold when fried	Pungent fermented, savory

The deep cuts

Profiles

Group A

The pressed-curd core: the "true" dougan

All start from the same pressed bean curd. What separates them is almost entirely the finishing step: how long they braise, what colors them, how much they dry afterward.

白豆乾

Plain white dougan · the raw form

Make: Board tofu cut and pressed a second time. Nothing added: no braise, no color, no smoke. This is the unfinished base of every type below.
Feel: Firm and solid, harder than board tofu but still full of moisture. Spoils fast. Left out a few hours it weeps water. That perishability is the original reason braising and coloring were invented.
Taste: Its whole selling point: clean, undiluted soybean aroma, nothing to mask it.
Color: 暗白色, dull off-white. The genuine, natural color of all dougan before anything is done to it.

黑豆乾

Caramel-braised black dougan

Myth to killIt's not made from black soybeans. Everyday black dougan is ordinary white dougan (yellow soybean) dyed dark by braising in caramel.

Make: Simmered in 糖烏: cane sugar slow-cooked until it carbonizes into a thick, faintly bitter caramel. Color depth is set by time in the pot: ~5 min for light, ~15 min for full black. Over-braise and it turns bitter, so timing is the maker's main skill.
Feel: Longer braise → more shrinkage and water loss → denser, chewier (較Q彈) than white, with a tough outer skin. Keeps longer, too.
Tell: With real 糖烏 the color sits on the surface only. A cut cross-section is still white. It bleeds slightly when wet-rubbed and tints standing liquid faint coffee.

五香豆乾

Five-spice dougan · the mainstream

Make: Braised in soy sauce, rock sugar, and a five-spice set: star anise (八角), licorice (甘草), cassia (桂皮), five-spice powder. Often the sugar is caramelized first, so color and flavor happen together.
Feel: Neither hard nor soft (軟硬適中): the most broadly popular eating texture. Craft detail: braising with no standing water keeps internal air-holes from forming, for a denser "軟Q" body.
Taste: Mild, savory, a faint Chinese-medicine herbal note. The default flavor of the whole category.

滷豆乾 / 大溪豆乾

Braised dougan, Daxi style

Make: No single recipe. One Daxi maker braises three times in salted black caramel, then three times in five-spice brine. Another stir-fries it in a ~100°C wok for ~80 min, then machine-dries it. Both saturate color and flavor through every layer.
Feel: Springy yet firm and substantial (彈牙紮實), soy-brown skin over a cream (米黃) interior carrying small air-holes. Firmer and heavier-flavored than white.
Note: The lore that Daxi's soft water makes it better is repeated everywhere, but the sources themselves frame it as legend (相傳), with no measured backing.

Sliced 現滷豆干 from Daxi (大溪), dressed and eaten as a snack. Cream interior, soy-brown skin. Photo bryan… · CC BY-SA 2.0

茶乾 / 黃金豆乾

Firm snack dougan · golden dougan

Name trap"茶乾" is not tea-flavored. The name just means small, very firm dougan eaten as a snack with tea. The firmness comes from heavy pressing; the golden color from caramel plus permitted yellow dye, not tea.

Make: Engineered mainly through press strength: the harder and longer the press, the flatter, drier, firmer, more sliceable it gets. Golden color added with caramel plus food yellow No. 4 (Tartrazine) or No. 5 (Sunset Yellow).
Feel: The firmest, densest, snappiest of the pressed types. Slices thin for stir-fries or eats as a chewy snack.
Taste: Concentrated and savory; the uncolored firm grade has the purest soybean aroma of any dougan, because nothing masks it.
Tell: A bright, vivid yellow signals added dye. Caramel can never produce a vivid yellow, only brown.

煙燻豆乾

Smoked dougan

Make: Seasoned dougan is steam-set, then smoked over wood, or over sugar (糖燻, where rock sugar adds both browning and aroma). The surface keeps darkening after it leaves the smoker, so it's pulled early; over-smoking turns it burnt and bitter.
Feel: Firmer and more defined than fresh tofu; the smoked skin adds its own layer of chew.
Taste: Smoky, salty enough in the skin to need little seasoning. Some compare the note to smoked cheese.

豆乾絲 / 干絲

Shredded dried tofu

Make: Exact same material as a block, just cut. A firm block is sliced into thin sheets, then into fine strands. So 干絲, 豆乾絲, and 豆腐絲 are the same thing: shredded pressed tofu, a soy-protein food. Not a noodle, despite the look.
Feel: Firm, springy strands when cooked right. Over-blanching makes them soft and mushy and kills the texture.
Note: Commercial strands are often treated with alkali (鹼) for texture, leaving a taste removed at home by blanching or a baking-soda soak (去鹼).

It looks like noodles. It's pressed tofu, sliced to strands. Photo Fumikas Sagisavas · CC0 / public domain

香干

Xiānggān · the mainland-Chinese cousin

Regional cousinAcross the strait, this same spiced-and-braised pressed curd is the everyday 香干 ("fragrant dry"). It sits outside the 13 above: a Chinese sibling included only to place the family, not a Taiwanese type.

Make: Pressed bean curd steeped or braised in a spiced soy brine: five-spice powder, star anise, fennel, plus caramel/soy color (醬色). It's the mainland name for the same spiced-and-pressed product Taiwan calls 五香豆乾 / 滷豆乾.
Feel: Firm and tight (質地緊實). Sliced thin, it holds its shape in a hot wok.
Color: Brown-red (棕紅) on the surface over a paler interior: the braise on the skin, the curd still light inside, exactly as with Taiwan's braised types.
Eat: Eaten ready-made or stir-fried, the classic being celery (芹菜炒香干). Tied especially to the Jiangnan region, though not only there; Hunan's 攸縣香干 is its own famed style.

香干: mainland-Chinese spiced, soy-braised pressed dried tofu. The brown braise sits on the skin; the cut faces stay paler inside. Photo Fumikas Sagisavas · CC0 / public domain

Group B

Skin & rolled forms: not pressed curd

These come from yuba (the skin skimmed off heated soy milk), not from pressed curd. That's why their cross-section is layered rather than solid, and why they feel different even when braised the same way.

豆包 / 豆皮

Yuba: bean-curd skin

Make: Hold soy milk at a simmer and proteins at the surface bond into a thin film. Lift it off. That's yuba. Folded layer over layer it becomes fresh 生豆包; fried low it becomes crisp 炸豆包.
Feel: Fresh: thin, soft, high-moisture, almost melt-in-mouth. Fried: puffed, crisp, porous. It drinks up soup and keeps at room temperature.
Taste: A rich, clean, concentrated soybean aroma, stronger than most pressed dougan, because so little is done to it.
Kin: 腐竹 is the same film dried far longer into hard, elastic rods.

Fresh yuba: soft folded sheets of skimmed soy-milk skin, here in a light broth. Photo pelican · CC BY-SA 2.0

素雞

Vegetarian "chicken"

Make: Sheets of yuba or 千張 are stacked, rolled tight into a cylinder, bound in cloth, tied hard, and steamed to set. On cooling, the layers bind into one body. Roll it loose and it falls apart.
Feel: Chewy, firm, springy, with a visibly layered cross-section, its defining structural signature, completely unlike the solid homogeneous body of block dougan.
Taste: Savory and braised: soy, sugar, sesame oil, five-spice. Often red-braised (紅燒) or pan-fried after steaming.

Soy-braised 素雞, sliced: rolled bean-curd skin set into a firm, layered body. Photo Fumikas Sagisavas · CC0 / public domain

千張 / 百頁

Thin bean-curd sheet

Don't confuseThis 百頁 is not 百頁豆腐 (Group C). Same character, entirely different foods.

Make: A thin, low-moisture bean-curd sheet. Sources disagree on the method: curd wrapped in many cloth layers and pressed very thin, vs. thin layers of soy milk heated into films and stacked. Both yield a thin layered sheet.
Feel: Thin and pliable, little chew: a vehicle that holds shape and soaks up soup.
Use: Shredded, tied into knots (千張結), used as wrappers, or rolled up into 素雞.

Thin 千張 sheets: low-moisture bean-curd film, unfolded in a tray. Photo Fumikas Sagisavas · CC0 / public domain

The same sheet tied into knots (千張結): the woven grid texture of the pressed film. Photo 汮汐 · CC BY-SA 4.0

Group C

The processed imposter

One of the most common things in the tofu aisle isn't tofu.

百頁豆腐

Baiye tofu

The headline百頁豆腐 is not tofu. It's a modern processed product, closer in principle to a fish cake (魚板) than to bean curd. Multiple authorities confirm it, including an NTU chemical-engineering reading of the label.

Make: Built from soy protein, starch, oil, water, and seasoning, then emulsified into a slurry, poured into molds, and steamed, like baking a cake. It's made from "reconstituted soy milk" (還原豆漿 = soy protein + water), not the raw soy milk that defines real tofu.
Feel: Smooth, dense, uniform, distinctly bouncy and springy (Q彈), the closest thing in the aisle to kamaboko. Pores let it absorb large amounts of sauce.
Numbers: ≈196 kcal, 13 g protein, 13 g fat per 100g: fat ≈ protein. Calcium is low (~33 mg) because it isn't set with calcium sulfate.
Tell: The "70% oil" claim is an exaggeration: fat is ~10–20% by weight. And it freezes and thaws with almost no texture change, rare among soy products.

百頁豆腐: white, square, uniform and bouncy. An emulsion that was never a curd. Photo FlipTable · CC BY-SA 3.0

Group D

Fried & fermented derivatives

Two more processes that restructure the protein entirely: frying flashes water to steam; fermenting loosens the body. Both start, though, from pressed firm tofu.

油豆腐

Fried tofu · 豆腐泡 / 三角油豆腐

Make: Firm tofu deep-fried in two stages: a low-temp fry to puff and expand, then a high-temp fry to set shape and color. Traditional shops keep two oil vats for it.
Feel: Crisp golden skin over a soft interior. Internal water flashes to steam and pushes the block into a honeycombed (蜂窩) sponge: small pieces go hollow, big blocks stay denser inside.
Taste: A rich, almost fried-chicken aroma. The skin's oil tastes greasy and blocks seasoning, so cooks blanch it (去油) first, which also re-opens the pores.

Cut 油豆腐 (atsuage style): the crisp fried skin against the pale, denser interior. Photo Potesara · CC BY-SA 2.5

臭豆乾 / 臭豆腐

Stinky tofu, the firm fried kind

Make: Pressed white tofu soaked in a fermenting brine (臭滷水): classically older amaranth (莧菜) steeped in rice-washing water. Microbes break down the protein, loosening structure and creating the smell.
Feel: Fries into a crisp shell over an airy interior riddled with holes: 外脆裡鬆. Started as a pressed block, so it needs longer frying and eats chewier than the soft type.
Caveat: Most mass-market fried stinky tofu now just soaks 6–8 hours in pre-made brine and doesn't truly ferment, which is why some of it tastes like ordinary fried tofu.

Taiwan-style fried 臭豆腐: crisp shell, airy holed interior, soy and pickled cabbage. Photo Richy · CC BY-SA 3.0

Reading the color

Cross-cutting

Color is the most misread property of dougan. The natural color of all pressed bean curd is dull off-white. Every brown, black, or yellow piece got that way by one of these:

Natural

The true color of all dougan before braising. Dull, dingy off-white.

糖烏 / 醬色

Carbonized cane-sugar caramel. Water-soluble → stays on the surface; only ever brown, never vivid.

醬油

Soy-sauce braise. Adds brown color plus salt and savor at the same time.

Food dye 4 / 5號

Tartrazine & Sunset Yellow. Penetrates the cross-section; vivid even yellow; doesn't bleed.

焦糖色素

Manufactured caramel color, four classes. Only Class I is truly "natural" caramel.

皂黃 / 二甲基黃

Illegal industrial dyes: the 2013 dougan scandal. Faked a bright cheap color fast.

How to read a piece by eye:

Brown surface, white core → natural caramel. The color is only skin-deep.

Colored all the way through → dye penetration, not caramel.

Vivid bright yellow → added dye. Caramel can't make this color.

Standing liquid turns coffee → caramel bleeding off the surface.

Why each one feels the way it does

Texture spectrum

Four physical processes move a soy product's texture. Most varieties are just combinations of them. Once you know which a piece has been through, its texture is predictable.

Pressing

Removes water, tightens the protein network. More pressing → firmer, drier, more sliceable, more protein- and calcium-dense. The whole tofu-to-dougan move.

Braising & drying

Shrink the piece through water loss and protein contraction. Longer cycles → denser, chewier, darker, longer-keeping. Why black dougan beats white for chew, and how 鐵蛋 iron eggs get small and rubbery.

Frying

Flashes internal water to steam, puffing the piece into a spongy or hollow interior under a crisp skin. Makes 油豆腐 and fried stinky tofu.

Fermenting & freezing

Loosen or restructure the protein into a porous, absorbent body: stinky tofu's holes, 凍豆腐's honeycomb.

Naming traps & honest gaps

Where sources fight

百頁豆腐 ≠ 百頁 / 千張. The first is the modern soy-protein-plus-starch-plus-oil block; the second is a thin plain bean-curd sheet. Same character, totally different foods. China renamed the first 千頁豆腐 precisely to stop the confusion.

干絲 vs. 豆乾絲 are interchangeable in Taiwan: the only real difference is fineness (knife-cut Huaiyang 干絲 is matchstick-thin; machine 豆乾絲 is coarser).

茶乾 is a name for firm snack dougan eaten with tea, not a tea-flavored product. Tea or turmeric as an ingredient in commercial golden dougan is unverified.

No standardized moisture % exists for dougan in the sources. They only say "lower than tofu." Treat any exact figure with suspicion.

大甲 · 關廟 · 鹽水 dougan didn't turn up as verified, physically-distinct types. Marketing copy for 大甲 recycles the wording used for Daxi. Don't assume they're separate varieties.

Daxi soft-water lore (that local water makes the dougan better) is presented by the sources themselves as legend, not measured fact.

百頁豆腐 fat and coagulant are disputed: fat best stated as ~10–20% (not "70% oil"); the coagulant is variously reported as calcium sulfate, none, or an unnamed improver.

Where this comes from

Sources & credits

Compiled from Taiwanese government, food-science, and journalism sources, focused on physical properties; cultural and regional history deliberately left out. Claims cross-checked where possible; conflicts flagged above.

Prefer it unabridged? This page distills a longer write-up. read the raw field guide →

Full source list (30+ references)

Production, coagulants, nutrition

農業部食農教育平臺 · fae.moa.gov.tw
自由時報食譜自由配 (tofu family / 油豆腐 / 百頁豆腐) · /4663, /6922, /10977, /7284
好食課 learneating · tofu calories & calcium, soy processing
康健雜誌 · commonhealth.com.tw
上下游 News&Market (coagulants) · /85991

Coloring, 糖烏, braised / Daxi

上下游 News&Market (糖烏 process, surface vs. cross-section) · /31443
PanSci 泛科學 (commissioned by 環境部) · /126916
環境部化學物質管理署 · moenv.gov.tw
玩咖 Playing / 自由時報 (Daxi 糖烏) · playing.ltn, food.ltn /7136
大溪豆干 · 維基百科
台灣麒麟 (大房豆干 process) · kirin.com.tw
徐仲飲食文化 (natural pigments) · hsuzong
ETtoday / 食藥署 · health.ettoday
得倫食品 (沙茶豆干 panel) · dl-food.com
香干 (regional cousin) · Chill Crisp · Tofu Products · The Woks of Life (五香豆干)

Shredded, sheet, 百頁豆腐

TechOrange / 謝玠揚台大化工博士 · "bean curd, not tofu"
CitiOrange (maker side) · hundred-layered beancurd
百頁豆腐 · 維基百科
今周刊 · businesstoday.com.tw
呂孟凡營養師 · dietitianbread.com
千張 · 維基百科 · 大煮干絲 · 維基百科
自由時報 (干絲去鹼) · /11934
小半天豆干味 · king-pin · 春豐豆類食品 · soypro.com.tw

Fried, yuba, rolled, fermented

食力 foodNEXT (fried-tofu mechanism) · foodnext.net
豆卜 · 維基百科
Cookpad Taiwan (豆皮 / 豆包 / 腐竹 / 千張) · cookpad.com/tw
夢幻廚房在我家 (素雞) · dreamchefhome.com
臭豆腐 · 維基百科
食力 foodNEXT (鐵蛋) · foodnext.net · 今周刊 (鐵蛋) · businesstoday

Photographs are reused under their licenses, self-hosted (nothing hotlinked): 豆乾 market by EHALAM BorG 600M (CC BY-SA 4.0); Daxi 現滷豆干 by bryan… (CC BY-SA 2.0); shredded by Fumikas Sagisavas (CC0); yuba by pelican (CC BY-SA 2.0); 素雞 by Fumikas Sagisavas (CC0); 百頁豆腐 by FlipTable (CC BY-SA 3.0); 油豆腐 by Potesara (CC BY-SA 2.5); 臭豆腐 by Richy (CC BY-SA 3.0); 千張 sheet by Fumikas Sagisavas (CC0); 千張結 (knotted) by 汮汐 (CC BY-SA 4.0); 香干 (xiānggān) by Fumikas Sagisavas (CC0). All via Wikimedia Commons. Guide compiled June 2026, physical-property focus.