Introduction to Baking Chemistry
Baking is applied chemistry where ingredients undergo physical and chemical transformations through heat application. Understanding these reactions helps troubleshoot problems, develop recipes, and consistently create superior baked goods. This cheat sheet provides comprehensive scientific insights into the chemistry that turns simple ingredients into complex, delicious creations.
Core Ingredients and Their Chemical Functions
Flour
| Type | Protein Content | Best Applications | Chemical Properties |
|---|---|---|---|
| All-Purpose | 10-12% | General baking | Moderate gluten formation |
| Bread Flour | 12-14% | Yeast breads, pizza | High gluten development, strong structure |
| Cake Flour | 7-9% | Tender cakes, pastries | Low gluten, chlorinated for acidity (pH 4.8-5.1) |
| Pastry Flour | 8-10% | Pie crusts, biscuits | Moderate-low gluten, tender results |
| Whole Wheat | 13-14% | Artisan breads, nutrition | Contains bran and germ, inhibits gluten |
| 00 Flour | 8-12% | Pizza, pasta | Very finely ground, variable protein |
| Rye Flour | 7-9% | Rye bread, pumpernickel | Low gluten, high pentosans (gummy substances) |
Flour Components
- Starch (65-75%): Gelatinizes at 140-158°F (60-70°C), absorbs moisture, provides structure
- Proteins (8-14%): Form gluten when hydrated and manipulated
- Pentosans (2-3%): Absorb water (up to 15x their weight), contribute to shelf life
- Enzymes: Amylases break down starch into sugars during fermentation
Leavening Agents
| Agent | Chemical Reaction | Activation | Applications |
|---|---|---|---|
| Baking Soda (NaHCO₃) | NaHCO₃ + H⁺ → Na⁺ + H₂O + CO₂ | Requires acid + moisture | Quick breads, cookies |
| Baking Powder | Double-acting:<br>1) NaHCO₃ + Acid → CO₂ (moisture)<br>2) Second acid reacts → CO₂ (heat) | Moisture, then heat | Cakes, muffins |
| Yeast | C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ | Fermentation (sugar consumption) | Breads, complex flavors |
| Steam | H₂O(l) → H₂O(g) | Heat above 212°F (100°C) | Puff pastry, choux |
| Whipped Proteins | Physical incorporation of air | Mechanical agitation | Soufflés, meringues |
Baking Powder Composition
- Sodium Bicarbonate (30%): Base component that releases CO₂
- Cream of Tartar (25-30%): Fast-acting acid that activates with moisture
- Sodium Aluminum Sulfate (15-30%): Heat-activated acid for second rise
- Cornstarch (15-25%): Prevents premature reactions by absorbing moisture
Fats & Oils
| Fat Type | Melting Point | Function | Best Uses |
|---|---|---|---|
| Butter | 90-95°F (32-35°C) | Flavor, tenderness, some moisture | Pastry, cakes, cookies |
| Shortening | 117°F (47°C) | Pure fat, tenderness, stability | Pie crusts, frostings |
| Lard | 97-113°F (36-45°C) | Flakiness, flavor | Pie crusts, biscuits |
| Oil | Liquid at room temp | Moisture, tenderness | Chiffon cakes, quick breads |
| Coconut Oil | 76°F (24°C) | Solid at room temp, vegan option | Vegan baking, frostings |
| Margarine | Variable | Water content varies (16-20%) | Variable results |
Fat Functions in Baking
- Tenderization: Inhibits gluten formation by coating flour proteins
- Aeration: Traps air during creaming for structure and leavening
- Flakiness: Creates layers in laminated doughs and pie crusts
- Moisture: Contributes to mouthfeel and perception of moistness
- Flavor Carrier: Dissolves and carries fat-soluble flavors
- Structure: Stabilizes foams and emulsions, particularly in cakes
Sweeteners
| Sweetener | Composition | Hygroscopicity | Effects on Baking |
|---|---|---|---|
| Granulated Sugar | 99.9% sucrose | Moderate | Structure, sweetness, tenderizes |
| Brown Sugar | Sucrose + molasses (1-3%) | High | Moisture, acidity (pH 5), flavor |
| Powdered Sugar | Sucrose + cornstarch (3%) | Low | Quick dissolution, fine texture |
| Honey | Fructose, glucose, water | Very high | Browning, moisture retention, flavor |
| Maple Syrup | Sucrose, glucose, water | High | Moisture, distinct flavor, browning |
| Corn Syrup | Glucose, maltose | Very high | Prevents crystallization, moisture |
| Invert Sugar | Glucose + fructose | Extremely high | Moisture, tenderness, shelf life |
| Molasses | Sucrose, invert sugars | Very high | Moisture, acidity, mineral content |
Sugar Functions
- Sweetness: Perception varies (fructose > sucrose > lactose > maltose)
- Structure: Stabilizes foams, creates bulk
- Tenderizing: Competes with flour for moisture, limits gluten development
- Moisture Retention: Hygroscopic nature improves shelf life
- Browning: Caramelization (>320°F/160°C) and Maillard reaction
- Fermentation: Food source for yeast
Eggs
| Component | Percentage | Function | Chemical Properties |
|---|---|---|---|
| Whole Egg | 100% | Structure, binding, leavening | Protein coagulation at 144-158°F (62-70°C) |
| White | 58% | Foam stability, binding | 90% water, 10% protein (primarily albumin) |
| Yolk | 30% | Emulsification, color, richness | 50% water, 34% fat, 16% protein |
| Shell | 12% | Protection | Calcium carbonate (CaCO₃) |
Egg Proteins and Their Roles
- Ovalbumin (54% of white): Primary structural protein, denatures at 176°F (80°C)
- Ovotransferrin (12%): Denatures at 140°F (60°C), initial setting
- Ovomucin (3.5%): Creates viscosity, stabilizes foams
- Lecithin (in yolk): Powerful emulsifier (lipoproteins), binds water and fat
Critical Chemical Reactions in Baking
Gluten Formation
Gliadin + Glutenin + H₂O + Energy → Gluten Network
- Hydration: Water activates glutenin and gliadin proteins
- Mechanical Action: Kneading/mixing forms disulfide bonds
- Factors that Increase Gluten:
- Higher protein flour
- Intense mixing/kneading
- Optimal hydration (60-65%)
- Acidic environment (to a point)
- Factors that Decrease Gluten:
- Fats coat proteins
- Sugars compete for water
- Enzymes (proteases) break down proteins
- Excessive acidity denatures proteins
Gelatinization
Starch + Water + Heat → Swollen Granules → Gel Structure
- Process: Starts at 140°F (60°C), peaks at 176°F (80°C)
- Structure: Amylose leaches out, amylopectin swells
- Factors Affecting Gelatinization:
- Sugar concentration (delays gelatinization)
- Fat content (inhibits water absorption)
- pH (acidic environments delay gelatinization)
- Salt (lowers gelatinization temperature)
Caramelization
C₁₂H₂₂O₁₁ (Sucrose) + Heat → Caramelans + Caramelens + Caramelins + H₂O + CO₂
- Temperature Range: 320-350°F (160-177°C)
- Products: Hundreds of compounds creating flavor complexity
- Flavor Notes: Butter, toffee, nuts, rum, butterscotch
- Color Range: Light amber to deep brown
- Enhanced By: Alkaline conditions, presence of dairy proteins
Maillard Reaction
Reducing Sugar + Amino Acid + Heat → Glycosylamine → Amadori Compounds → Melanoidins
- Temperature Range: 280-330°F (140-165°C)
- Reaction Speed Factors:
- Higher pH (alkaline) accelerates reaction
- Sugar type (glucose > fructose > sucrose)
- Amino acid type (lysine most reactive)
- Low moisture accelerates reaction
- Flavor Notes: Roasted, nutty, meaty, toasted
- Enhanced By: Adding milk, egg wash, or amino acid-rich ingredients
Fermentation
C₆H₁₂O₆ (Glucose) → 2C₂H₅OH (Ethanol) + 2CO₂ + Heat
- Optimal Temperature: 75-78°F (24-26°C) for flavor development
- Byproducts: Organic acids, alcohols, esters, aldehydes
- Processes:
- Alcoholic fermentation (yeast)
- Lactic acid fermentation (bacteria, sourdough)
- Acetic acid fermentation (extended fermentation)
- Contributes: Flavor complexity, texture, leavening, digestibility
Critical Temperature Points in Baking
| Temperature | Process | Application |
|---|---|---|
| 86-95°F (30-35°C) | Fats melt | Maintain cold for laminated doughs |
| 105-115°F (40-46°C) | Yeast most active | Fermentation temperature control |
| 140°F (60°C) | Starch gelatinization begins | Formation of crumb structure |
| 145°F (63°C) | Egg proteins begin coagulating | Structure setting in custards |
| 160-165°F (71-74°C) | Collagen converts to gelatin | Enriched dough doneness |
| 176°F (80°C) | Starch gelatinization complete | Crumb fully set |
| 195-205°F (90-96°C) | Lean dough doneness | Internal temperature for bread |
| 212°F (100°C) | Water converts to steam | Oven spring, leavening |
| 310-320°F (154-160°C) | Maillard reaction accelerates | Crust development |
| 320-350°F (160-177°C) | Caramelization begins | Browning of high-sugar doughs |
| 356°F (180°C) | Dextrinization of crust | Crisp, golden exterior formation |
pH and Its Effects on Baking
| Ingredient | Approximate pH | Effects in Baking |
|---|---|---|
| Cream of Tartar | 2.0 | Stabilizes egg whites, activates baking soda |
| Lemon Juice | 2.0-2.6 | Inhibits browning, tenderizes by breaking down gluten |
| Buttermilk | 4.4-4.8 | Activates baking soda, improves flavor and tenderness |
| Vinegar | 2.0-3.0 | Strengthens gluten in small amounts, breaks it down in larger amounts |
| Yogurt | 4.3-4.4 | Activates baking soda, adds tenderness |
| Chlorinated Cake Flour | 4.8-5.1 | Lower pH helps cake structure, faster setting |
| Milk | 6.5-6.7 | Enhances browning, slight buffering capacity |
| Water | 7.0 | Neutral |
| Egg Whites | 7.6-8.0 | Mild alkalinity stabilizes foam when intact |
| Baking Soda | 8.3-9.0 | Increases browning, neutralizes acidity |
| Egg Yolks | 6.0 | Slight acidity from phospholipids |
pH Effects on Baking Properties
- Acidic Environment (pH <7):
- Strengthens gluten (mild acidity)
- Weakens gluten (strong acidity)
- Inhibits enzymatic browning
- Enhances stability of whipped egg whites (with cream of tartar)
- Reduces gelatinization temperature of starch
- Prevents discoloration in fruits
- Alkaline Environment (pH >7):
- Enhances Maillard browning
- Creates distinct flavors (pretzels, alkaline noodles)
- Tenderizes by breaking down proteins
- Neutralizes bitter flavors
- Enhances yellow color in doughs and batters
Water Activity (aw) and Shelf Life
| Product | Water Activity (aw) | Shelf Life | Spoilage Concerns |
|---|---|---|---|
| Bread | 0.94-0.97 | 3-7 days | Mold, staling |
| Cakes | 0.78-0.87 | 7-10 days | Staling, moisture loss |
| Cookies | 0.3-0.6 | 21+ days | Rancidity, moisture gain/loss |
| Crackers | 0.1-0.3 | 6-12 months | Moisture gain, rancidity |
| Dried Fruit | 0.6-0.75 | 6-12 months | Mold (if too moist), hardening |
| Jam/Preserves | 0.80-0.85 | 12+ months | Mold, fermentation |
| Custards | 0.97-0.99 | 3-5 days refrigerated | Bacterial growth |
Controlling Water Activity
- Humectants: Sugar, honey, glycerin, invert sugar, corn syrup
- Dehydration: Baking longer at lower temperatures
- Salt: Binds water, reduces available water
- Preservatives: Acids like sorbic acid, propionic acid
- Fats: Create moisture barriers, limiting migration
Common Baking Problems and Their Chemical Solutions
Structure Problems
| Problem | Causes | Chemical Solutions |
|---|---|---|
| Tough Texture | Over-developed gluten | Increase fat, sugar or acidity; reduce mixing/kneading |
| Collapsed Cake | Underbaked; too much leavening | Increase flour protein; bake longer; reduce leavening |
| Dense Bread | Underfermented; insufficient gluten | Increase kneading; longer fermentation; add vital wheat gluten |
| Cookies Spread Too Much | Too much sugar or fat; warm dough | Increase flour; chill dough; reduce sugar or fat; add egg |
| Cookies Too Cakey | Too much egg; too little fat | Reduce egg; increase fat; reduce leavening |
| Soggy Pie Crust | Underbaked; filling too wet | Blind bake; add starch to filling; egg wash barrier |
Leavening Issues
| Problem | Causes | Chemical Solutions |
|---|---|---|
| Fallen Cake | Too much leavening | Reduce baking powder/soda (max 1-1.25 tsp per cup flour) |
| No Oven Spring | Overproofed dough; oven too cool | Shorter proof time; higher initial oven temperature |
| Bread Collapses | Underfermented; improper shaping | Develop gluten properly; ensure proper fermentation |
| Overly Dense Crumb | Too little leavening; improper fermentation | Increase leavening slightly; ensure proper proofing |
| Large Air Pockets | Uneven fermentation; improper shaping | Degas properly during shaping; consistent fermentation |
| Tunneling in Muffins | Overmixing; too much leavening | Mix just until combined; reduce leavening agent |
Flavor and Color Issues
| Problem | Causes | Chemical Solutions |
|---|---|---|
| Metallic Taste | Too much baking powder | Reduce baking powder; balance with acidic ingredients |
| Bitter Taste | Too much baking soda; unactivated soda | Balance with acidic ingredients; reduce baking soda |
| Pale Crust | Low sugar; high humidity | Increase sugar; brush with egg wash; increase oven temperature |
| Too Dark | Too much sugar; oven too hot | Reduce sugar; lower temperature; shield with foil |
| Bland Flavor | Insufficient salt; underfermentation | Increase salt (0.75-2% of flour weight); longer fermentation |
| Rancid Flavor | Oxidized fats; old flour | Fresh ingredients; store properly |
Moisture Control Issues
| Problem | Causes | Chemical Solutions |
|---|---|---|
| Dry Baked Goods | Overbaked; insufficient moisture retention | Add hygroscopic ingredients (honey, invert sugar); reduce baking time |
| Gummy Texture | Underbaked; too much liquid | Increase baking time; reduce liquid; adjust flour type |
| Staling | Retrogradation of starch | Add emulsifiers; include fats; add sugar or honey |
| Weeping Meringue | Underbaked; sugar too coarse | Bake longer at lower temp; use fine sugar; add cornstarch |
| Cracks in Cheesecake | Uneven baking; too much protein | Water bath; reduce temperature; add starch |
| Soaked Crust | Condensation during cooling | Cool properly before packaging; separate layers |
Advanced Ingredient Substitutions and Chemistry
Gluten-Free Baking
| Flour Type | Properties | Best Uses | Chemical Considerations |
|---|---|---|---|
| Rice Flour | Neutral taste, gritty texture | Cookies, shortbread | Needs binding agents; absorbs less water |
| Tapioca Starch | Chewy, glossy structure | Creates elasticity | Gelatinizes at lower temperature than wheat |
| Potato Starch | Light texture, moisture retention | Cakes, moisture addition | Do not boil; breaks down at high heat |
| Xanthan Gum | Provides elasticity (0.25-1% of flour weight) | Structure replacement | Hydrocolloid; can cause gumminess if overused |
| Psyllium Husk | Creates bread-like structure | Yeast bread | Forms gel matrix similar to gluten; highly hydrophilic |
| Almond Flour | Moisture, richness, no starch | Cookies, cakes | High fat content; browns quickly; needs protein binding |
Egg Replacers
| Replacer | Suitable For | Chemistry Mechanism | Substitution Rate |
|---|---|---|---|
| Flax/Chia Seeds | Binding, moisture | Soluble fiber forms gel | 1 Tbsp ground + 3 Tbsp water = 1 egg |
| Aquafaba | Meringues, foams | Proteins and saponins create stable foam | 3 Tbsp = 1 egg white |
| Applesauce | Moisture, binding | Pectin provides light binding | ¼ cup = 1 egg |
| Commercial Starch Blends | General baking | Modified starches + leavening | As package directs |
| Tofu, Silken | Moisture, protein | Similar protein structure to egg | ¼ cup pureed = 1 egg |
| Yogurt | Moisture, acidity | Protein content provides structure | ¼ cup = 1 egg |
Sugar Alternatives
| Alternative | Sweetness (Sucrose=1) | Hygroscopicity | Baking Adjustments |
|---|---|---|---|
| Erythritol | 0.7x | Very low | Doesn’t brown well; crystallizes; doesn’t tenderize |
| Allulose | 0.7x | Similar to sugar | Browns well; retains moisture; 1:1 replacement |
| Xylitol | 1x | Moderate | Doesn’t feed yeast; browns similarly to sugar |
| Monk Fruit Extract | 200-300x | None | Blend with bulking agents; no caramelization |
| Stevia | 200-350x | None | Needs bulking agents; can have bitter aftertaste |
| Date Sugar | 0.9x | High | Contains fiber; doesn’t dissolve completely |
| Coconut Sugar | 1x | Similar to brown sugar | More complex flavor; similar behavior to sugar |
Advanced Techniques and Their Chemistry
Lamination
- Process: Alternating layers of fat and dough through folding and rolling
- Chemistry: Fat layers prevent dough layers from adhering
- Steam Effect: Water in dough converts to steam, forcing layers apart
- Critical Factors:
- Temperature control (keep fat plastic but not melting)
- Optimal gluten development (strong but extensible)
- Fat composition (higher melting point preferred)
- Resting periods (gluten relaxation between folds)
Retarding (Cold Fermentation)
- Process: Slowing fermentation through refrigeration
- Chemistry:
- Yeast activity slows but doesn’t stop
- Amylase converts starch to maltose
- Enzymatic activity continues at reduced rate
- Acids develop through bacterial fermentation
- Benefits:
- Flavor development (more acetic acid, less lactic)
- Improved dough handling
- Enhanced digestibility
- Better starch gelatinization (due to amylase activity)
Pre-Ferments
| Type | Hydration | Fermentation Time | Chemical Contribution |
|---|---|---|---|
| Poolish | 100% | 8-16 hours | Mild acidity, extensibility, subtle flavor |
| Biga | 50-60% | 12-24 hours | Structure, complex flavor, extended shelf life |
| Pâte Fermentée | 60-65% | 8-12 hours | Balanced flavor, improved structure, enzymatic activity |
| Sourdough | Variable | 4-24 hours | Acidity, complex flavor, extended shelf life |
Sourdough Chemistry
- Microbial Composition:
- Lactobacillus bacteria (70-80% of microbes)
- Wild yeasts (primarily Saccharomyces and Candida species)
- Acidification:
- Lactic acid (milder, main acid at warmer temps)
- Acetic acid (sharper, increased at cooler temps)
- pH Range: 3.8-4.5 for mature starter
- Gluten Effects:
- Moderate acidity strengthens gluten
- Excessive acidity weakens gluten structure
- Extended fermentation activates proteolytic enzymes
- Starch Effects:
- Amylases break down damaged starch
- Lower pH enhances α-amylase activity
Sugar Cooking Stages
| Stage | Temperature | Chemical Change | Culinary Uses |
|---|---|---|---|
| Thread | 230-235°F (110-113°C) | Concentration begins | Syrups, glazes |
| Soft Ball | 235-240°F (113-116°C) | Supersaturated solution | Fudge, pralines |
| Firm Ball | 245-250°F (118-121°C) | Higher concentration | Caramels, soft candies |
| Hard Ball | 250-265°F (121-129°C) | Very little water remains | Nougat, marshmallows |
| Soft Crack | 270-290°F (132-143°C) | Minimal water content | Taffy, butterscotch |
| Hard Crack | 300-310°F (149-154°C) | Virtually anhydrous | Brittle, hard candy |
| Caramel | 320-350°F (160-177°C) | Caramelization begins | Caramel sauces, praline |
| Burnt Sugar | 350°F+ (177°C+) | Extensive caramelization | Caramel coloring |
Resources for Further Learning
Books on Food Science
- “How Baking Works” by Paula Figoni
- “On Food and Cooking” by Harold McGee
- “Bakewise” by Shirley Corriher
- “The Science of Good Cooking” by Cook’s Illustrated
- “Ratio” by Michael Ruhlman
Scientific Journals
- Journal of Cereal Science
- Food Chemistry
- Journal of Food Science
- International Journal of Food Science and Technology
- Journal of the Science of Food and Agriculture
Technical Baking Resources
- American Institute of Baking (AIB) Technical Bulletins
- Cereals & Grains Association publications
- AACC International Methods of Analysis
- Bakerpedia.com (online resource for baking science)
- Modernist Cuisine
Professional Organizations
- Bread Bakers Guild of America
- American Society of Baking
- Institute of Food Technologists (IFT)
- Research Chefs Association