Category Atlases · Article 13

Bread Atlas & Sourdough

A reference article · 2500 words · 12 cited sources · last reviewed August 2026

A bread style is a formula read as a set of levers. This atlas maps lean, enriched, rye, and world breads, then goes deep on the living microbial ecosystem that makes sourdough work.

Numbers are in baker’s percentages (ingredient ÷ total flour × 100). Contested/simplified claims are flagged.

Reading a formula as a style

A bread style is defined not by shape or name but by five formula levers.

Hydration (water as % of flour) is the primary lever: below ~55% = stiff, tight-crumb (bagels, pretzels, some pan breads); 60–70% = classic hearth; 70–85%+ = high-hydration open-crumb (ciabatta, country loaves); above 100% = batter (some ryes, injera). It governs enzyme mobility, gluten development rate, gas-cell wall thinness, and crumb openness (King Arthur, 2023).

Salt (~1.8–2.2%; ~2% default) tightens gluten (shielding glutenin’s charges), slows fermentation and enzymes, and improves crust color by sparing sugars from the yeast (Hamelman, 2004). Saltless Tuscan pane sciocco is slack, fast-fermenting, pale by design.

Preferment / leaven type (none, commercial yeast, poolish/biga/sponge, or sourdough) sets flavor complexity, acidity, dough strength, and timescale.

Fat and sugar convert lean (flour/water/salt/leaven: crackly, chewy hearth breads) into enriched (fat, sugar, eggs, dairy: tender, colored, soft, longer-keeping, but interfering with gluten and slowing fermentation).

These produce the classical dichotomies: lean vs enriched (fat/sugar axis), hearth vs pan (free-standing loaves need strong gluten and skilled shaping and bake on stone with steam; pan breads are supported and run softer/enriched), flatbread vs risen (gas retained by a developed network vs largely released).

The lean dough atlas

Lean dough is where technique, not ingredients, makes the bread.

French family. The baguette, ~65–68% hydration, T55/T65 (~11–11.5% protein), often on a poolish (equal-weight flour/water plus a pinch of yeast, 12–16 h) for nutty flavor and extensibility; defined by shaping to a taut sealed cylinder, proofed in a floured couche, scored at ~20–30° for ears (Reinhart, 2001). Pain de campagne adds 10–30% whole wheat/rye and a levain (fuller flavor, tighter-but-open crumb, longer keeping). Pain de mie is the French pan loaf, lightly enriched, lidded pullman tin, tight square tender crumb.

Italian family. Ciabatta, 75–85% hydration, often on a stiff biga (~50%), handled with folds not kneading, minimally shaped, wide-open glossy crumb (the defining move: preserving gas by handling wet dough gently). Focaccia, 75–90% hydration, pressed into oiled pan, dimpled for oil/brine. Pane (Pugliese, Altamura from durum semola), rustic rounds, 70–78%, long fermentation.

The rustic high-hydration open-crumb loaf (Robertson’s Tartine, 2010): 75–85% hydration, 10–20% whole grain, young sweet levain, long bulk with stretch-and-folds/coil folds, gentle two-stage shaping, long cold retard. Defined by building strength through folds and time rather than intensive mixing.

Bagels & pretzels invert every rustic instinct: low hydration (bagels ~50–57%), high-gluten flour (13–14%), malt/sweetener. Bagels are shaped, cold-retarded, then boiled (often with barley-malt syrup) to gelatinize the surface for chewy shine. Pretzels are dipped in food-grade lye (~3–4% NaOH) (or weaker baking-soda solution) for intense Maillard browning (laugengebäck = “lye pastry”).

Pizza doughs. Neapolitan (AVPN): Tipo 00, ~58–65% hydration, ~2.5–3% salt, tiny yeast, long ferment, baked 60–90 s at 430–485 °C. New York: ~60–65% hydration plus oil and sugar, higher-protein bread flour, cold-ferment 24–72 h, baked ~260–290 °C. Roman al taglio: ~75–85% hydration, long cold ferment, airy honeycomb.

Rye and whole-grain breads

Why rye behaves differently. Rye’s gluten proteins don’t form a functional viscoelastic network; structure is instead dominated by pentosans (arabinoxylans), ~7–8% of rye flour (vs ~2–3% in wheat), extraordinarily hydrophilic hydrocolloids (absorbing up to ~8× their weight in water) that form the primary gas-holding matrix (McGee, 2004; Hamelman, 2004). This is why rye doughs are sticky, dense, batter-like. Second, rye’s abundant α-amylase stays active to a higher temperature during baking; unchecked it degrades starch during gelatinization, giving a gummy, collapsed crumb. The corrective is acidification: pH below ~4.3 suppresses amylase, strengthens the matrix, and is why rye is almost always a sourdough (Gänzle, 2014; IREKS Kompendium).

Rye by percentage. Light rye (10–40%) behaves like flavored wheat bread. Past ~50%, sourdough is mandatory. High-percentage/100% ryes, German Roggenbrot, Vollkornbrot (whole-grain, soaked kernels) and pumpernickel (coarse whole rye, 12–24 h low-temperature steam bake whose color and sweetness come from starch caramelization plus Maillard, not coloring), are dense, moist, and rested 24+ hours before slicing.

The Detmolder multi-stage sour. The classical German method for controlled organism populations and acid balance. The three-stage (Dreistufenführung) runs a seed through Anfrischsauer → Grundsauer → Vollsauer, each at a defined temperature/hydration/time to favor different organisms: cooler, stiffer, longer stages favor acetic-forming heterofermentative bacteria (sharper); warmer, wetter, shorter stages favor lactic (milder). Typical staging runs ~24–26 °C stiff stages up to a warmer (~28–30 °C) full sour, ending near pH 3.5–3.8, TTA ~14–18 for a full rye (IREKS Kompendium). The multi-stage build tunes the lactic:acetic ratio with precision a single build cannot.

Whole-wheat handling, soakers, scalds. Bran and germ dilute gluten, sever strands, add enzyme/oxidative activity, absorb water slowly. Reinhart’s Whole Grain Breads (2007) “epoxy method” pairs a soaker (whole flour + water + salt, overnight: hydrates and softens bran, begins enzymatic sweetness) with a biga or levain (flavor and strength). A scald (Brühstück) pours boiling water over flour/grains to gelatinize starch and inactivate enzymes, pre-hydrating, sweetening, and dramatically improving moisture retention and shelf life. Sprouted grains add amylase and altered starch (sweetness, nutrition, gumminess risk). Seed/porridge breads fold cooked grains and soaked seeds in as internal soakers.

Enriched and soft breads

Enrichment trades open crumb and crackly crust for tenderness and shelf life; the science is interference with gluten plus retardation of staling. Sandwich/pain de mie: lightly enriched, fine even tender crumb. Milk breads / Japanese shokupan: cloud-like crumb from tangzhong/yudane (a cooked flour-liquid paste: ~5–10% of the flour whisked with ~1:5 flour:liquid and heated to ~65 °C, or ~1:1 with boiling water and rested); pre-gelatinized starch holds far more water, locking it into the crumb so the loaf is softer and stales slower without feeling wet. Brioche/babka (see Pâtisserie Doughs) emulsify large amounts of cold butter into developed gluten, usually with cold fermentation. Challah is egg-enriched but fat-lean and dairy-free, springy, richly colored. Potato rolls use potato starch/moisture for a pillowy crumb. Parker House uses buttered folded dough for soft layers.

Crumb-softening science. Four levers: higher effective hydration (tangzhong/scald), fat (interrupts gluten and starch retrogradation), sugar/humectants (bind water, slow amylopectin recrystallization, the chemical basis of staling), and enzymes/emulsifiers (commercial amylases, mono/diglycerides). Staling is primarily retrogradation, not moisture loss, which is why reheating partly refreshes stale bread (McGee, 2004).

Sourdough microbiology

What a starter is. A stable, self-perpetuating microbial ecosystem: a symbiosis of wild yeasts and lactic acid bacteria (LAB) in a flour-and-water medium. Stability is the product of selective pressure: each feeding is an ecological bottleneck favoring organisms adapted to that flour, hydration, temperature, and schedule. A mature starter holds roughly 10⁸–10⁹ LAB and 10⁶–10⁷ yeast cells/g, a ratio around ~100:1 bacteria to yeast (De Vuyst & Neysens, 2005; Gänzle, 2014).

The dominant organisms and the cross-feeding engine. The emblematic LAB is Fructilactobacillus sanfranciscensis (formerly Lactobacillus sanfranciscensis). Its partnership with sourdough yeasts is a textbook case of niche partitioning via cross-feeding. Flour’s principal fermentable sugar is maltose. F. sanfranciscensis preferentially metabolizes maltose and liberates glucose; the classic sourdough yeasts, Kazachstania humilis (formerly Candida milleri/humilis) and some Saccharomyces cerevisiae, are maltose-negative/slow, so they consume the glucose the bacterium leaves behind rather than competing for maltose. The two therefore don’t compete for the same carbon, precisely why the community is stable (Gänzle, 2014).

Homofermentative vs heterofermentative LAB, and the acid balance. Homofermentative LAB (e.g., Lactiplantibacillus plantarum) convert sugars almost entirely to lactic acid (mild, yogurt-like). Heterofermentative LAB (e.g., F. sanfranciscensis, Limosilactobacillus brevis) produce lactic + acetic acid + ethanol + CO₂ (acetic = sharp, vinegary tang). F. sanfranciscensis uses fructose as an electron acceptor, shunting toward more acetic acid when fructose is available. The lactic-to-acetic ratio (the “fermentation quotient”) is the master flavor dial: warm, wet, well-fed → lactic/mild; cool, stiff, less-fed → acetic/sharp (De Vuyst; Gänzle, 2014).

How conditions select the community. Every maintenance variable is a filter. Temperature: ~20–24 °C balances yeast and LAB; above ~28–32 °C, thermotolerant lactobacilli dominate and yeast is suppressed (why hot starters go acidic and lose lift). Hydration: liquid → lactic/faster/milder; stiff → acetic/yeast-favoring/buffered. Flour: whole-grain and rye carry more microbes/minerals/enzymes and ferment faster and more sourly. Feeding ratio/frequency: frequent high-dilution feeding keeps pH higher and flavor mild; infrequent feeding accumulates acid and selects acid-tolerant organisms.

The Landis et al. 2021 finding: geography matters less than expected. The largest citizen-science survey (500 starters across North America, Europe, Australasia; eLife, 2021) reframed folk wisdom: geography was a poor predictor (taxonomy did not correlate with geographic distance), and all process parameters together explained <10% of community variation. Fungal communities were dominated by S. cerevisiae (77% of samples); LAB plus acetic bacteria made up >97% of bacterial reads (L. plantarum and L. brevis the most common pair, 177 of 500). The cited surprise: acetic acid bacteria (distinct from acetic-acid-producing heterofermentative LAB) present at >1% in 147 starters, nearly absent from prior literature, strongly associated with slower rise (ρ = −0.51) and vinegary aromas (Landis et al., 2021).

pH and TTA. pH measures acid strength (a ripe starter ~pH 3.5–4.2); TTA (total titratable acidity) measures total acid quantity (mL of standard alkali to reach pH 8.5) and correlates better with perceived sourness and dough behavior. Rye bakers track TTA to hit the target acidification (~14–18 for a full rye sour) that controls amylase and structure.

Stabilization and what acidity does to the bread. A new starter passes through a chaotic early succession (a Leuconostoc/enterobacteria bloom) before acid-tolerant lactobacilli and their yeast partners lock in a stable low-pH climax within 1–3 weeks. That acidity then: strengthens gluten at mild levels but, in excess/prolonged, activates proteases that degrade it (why over-fermented sourdough goes soupy); builds complex flavor (acids plus esters/alcohols/aldehydes); extends shelf life (low pH plus acetic acid are antifungal/antibacterial); improves mineral bioavailability (acid activates flour phytase, degrading phytic acid that chelates iron/zinc/magnesium/calcium, a well-supported nutritional advantage); and slows staling.

Maintenance in practice. Keep a starter by discarding most and refreshing the rest at a chosen ratio. Stiff levains (~50–60% hydration) keep longer, taste more acetic, hold yeast vigor; liquid levains (100%+) act faster and taste more lactic. Retard at 3–5 °C to feed only weekly; dry (smear thin, dehydrate below ~40 °C) for shelf-stable, months-later revival.

Fermentation management for bread

Building/maintaining a levain. A levain is a bake-specific sourdough offshoot. Inoculate typically 10–25% of the levain’s flour as ripe starter (1:5:5 or 1:2:2 builds), fermented to peak ripeness (max leavening power, balanced acidity). A younger, sweeter levain gives milder flavor and stronger dough; a riper, more acidic levain gives more sour, weaker dough. The float test is unreliable (a stiff levain may not float when ready; a past-peak one may sink), so use time, volume rise, doming, and aroma instead (The Perfect Loaf; Modernist Bread, 2017).

Reading bulk fermentation. Judged by the dough, not the clock: percentage rise (many rustic doughs shaped at ~30–75% increase depending on flour/schedule), the aliquot jar (a straight-sided sample to read rise precisely, from Maurizio Leo/The Perfect Loaf), and dough feel (billowy, domed, jiggly, aerated, pulling from the container). Under-fermented gives dense, tight, pale, gummy; over-fermented slackens, loses shaping strength, bakes flat.

Building strength for open crumb. Instead of intensive kneading, use stretch-and-folds and coil folds every 30–50 min in early bulk, and, for extreme extensibility, lamination (stretching the dough thin on the bench and folding), aligning gluten while preserving gas, the method for reaching 80%+ hydration without collapse.

Pre-shape, bench rest, final shape. Divide, then loose pre-shape rounds (organize gluten), bench rest 15–30 min (relax), final shape with surface tension. Two-stage shaping lets a wet dough hold height.

Cold retard. Proofing (or bulk) at 3–6 °C for 12–48+ h develops flavor (LAB active while yeast slows), improves scoring and oven spring (cold firm dough scores cleanly, springs high), and decouples the bake from the clock.

Strength vs extensibility. The whole game: balance elasticity (strength/spring, from tightly-bound gluten) against extensibility (willingness to stretch thin without tearing). Open crumb needs high extensibility with just enough strength to hold gas in thin walls (over-strong forces a tight uniform crumb; too weak collapses). Hydration/autolyse raise extensibility; folds, salt, lower hydration raise strength.

Shaping, scoring and baking

Shaping and the skin. All hearth shaping builds surface tension, a taut outer skin holding height and directing oven spring. Boule (dragged tight round), bâtard (folded/rolled seam-sealed log), baguette (progressively elongated cylinder). A slack skin spreads flat.

Proofing vessels. Floured banneton (wicks surface moisture for a scorable skin, imprints coil) or linen couche (supports baguette sides). Poke test: a gentle dent that springs back slowly and incompletely is ready; fast = under-proofed; not at all = over-proofed.

Scoring, grigne, ear. Scoring controls where the loaf expands: a designed cut opens under oven spring rather than tearing randomly (a “blowout”). A shallow (~30°) angled cut lifts a flap that dries into the ear; the bloomed cut face is the grigne.

The bake. Steam (injected, or trapped under a Dutch oven lid) keeps the crust moist and elastic so the loaf expands fully before setting, and gelatinizes surface starch for gloss/crackle. Oven spring (first ~10–15 min): trapped gases expand, dissolved CO₂/ethanol vaporize, yeast makes a final burst before dying at ~55–60 °C; starch gelatinizes ~60–80 °C and gluten coagulates to set the crumb. Color comes from Maillard and caramelization once the surface passes ~150 °C. Lean hearth breads bake hot (230–250 °C); enriched cooler (170–200 °C) to avoid burning their sugars. Doneness: internal ~93–99 °C (lean), ~85–90 °C (soft enriched). Cooling finishes the bake: cutting hot gives gummy crumb; lean loaves cool 1–2 h, dense ryes a full day (Hamelman, 2004).

Crumb and quality

Open vs tight crumb. Open, irregular alveolation results from high hydration (thin extensible cell walls) plus adequate-not-excessive strength plus thorough fermentation plus gentle shaping/handling (preserving large gas pockets) and often cold retard. Tight even crumb (sandwich bread) comes from lower hydration, stronger/degassed dough, tighter shaping, pan support. Openness is a system property: hydration alone won’t deliver it if strength, fermentation, and handling don’t cooperate.

Common faults. Gummy/sticky crumb: under-baked; cut too hot; over-fermented (protease-degraded gluten); or unchecked rye amylase. Flat loaf/poor spring: over-proofed; weak gluten; slack shaping; insufficient steam. Dense/tight: under-fermented; under-hydrated; over-degassed; weak/dead leaven. Blowout: under-proofed and/or under-scored (spring with no designed exit). Pale crust: oven too cool; insufficient residual sugar (over-fermented or lean); too much steam held too long.

World breads: a survey

Tandoor/griddle breads of South/Central Asia. Naan (leavened, often yogurt/yeast-leavened enriched wheat) slapped onto a searing tandoor wall; roti/chapati (unleavened atta griddle breads); paratha (fat-laminated, flaky); puri (deep-fried, ballooning). Defining variable: heat source and whether leavened/enriched.

Pita and lavash. Pita: lean dough baked very hot (~230–260 °C) so a steam burst inflates a hollow pocket. Lavash: thin, large, lean, tandoor/griddle-baked, soft fresh and cracker-crisp dried.

Injera (Ethiopia/Eritrea). A fermented batter flatbread of teff (gluten-poor, iron-rich), poured thin and cooked one side on a clay mitad; days of wild fermentation give sourness and a honeycomb of “eyes”, simultaneously bread, plate, and utensil.

Steamed breads of China. Mantou (plain) and baozi (filled) are steamed, not baked: soft, white, cakey crumb with no crust (no dry-heat browning); historically leavened with wheat sourdough/old-dough, now often yeast.

Nixtamalized breads of the Americas. The tortilla is built on nixtamal: maize cooked/steeped in alkaline (lime) solution, which loosens the hull, transforms flavor, and liberates niacin (preventing pellagra). Masa is griddle-baked on a comal. Arepas (Colombia/Venezuela): thick maize cakes from pre-cooked maize flour.

Nordic rye and crispbreads. From dense moist sour whole-rye loaves to knäckebröd/crispbread: thin, dried, long-keeping rye flatbreads (the rye/acidification science in flat, shelf-stable form).

Laugengebäck. The pretzel family: lean low-hydration wheat dipped in food-grade lye for the mahogany, glossy, distinctive crust.

Panettone (Italy). The most elaborate enriched natural-leaven bread: a tall, domed Milanese Christmas bread on a stiff sweet sourdough (lievito madre / pasta madre), enriched with butter, egg yolks, sugar, and candied fruit, developed over multiple days and builds. Its light, shreddy, long-keeping crumb depends on a rigorously mild (low-acetic) stiff starter; hung upside-down to cool so the delicate structure doesn’t collapse.

Contested and simplified claims