Chapter 20 — Quiz
A mix of recall, application, and "explain why" questions. Answer key with explanations at the bottom. Total: 18 questions (14 multiple choice, 4 short answer).
Multiple Choice
1. Cocoa butter has how many distinct crystal polymorphs?
A) Two B) Four C) Six D) Eight
2. Which crystal form of cocoa butter is the desired form in tempered chocolate?
A) Form I B) Form III C) Form V D) Form VI
3. The melting point of Form V cocoa butter is approximately:
A) 17°C / 63°F B) 22°C / 72°F C) 33–34°C / 91–93°F D) 45°C / 113°F
4. During chocolate tempering, the chocolate is first heated to about 50°C / 122°F. The purpose of this step is:
A) To kill any microbes that might be in the chocolate B) To melt all crystal forms so the chocolate is crystallographically blank C) To caramelize the sugar in the chocolate D) To denature the proteins in the cocoa solids
5. Lindt's 1879 invention of the conche primarily addressed which problem in European chocolate?
A) Bitterness B) Gritty texture C) Spoilage D) Fat bloom
6. The cacao tree's botanical name Theobroma cacao translates from Latin as:
A) "Bitter water" B) "Food of the gods" C) "Sweet bean" D) "Tree of the Maya"
7. During cacao fermentation, the FIRST microbes to dominate are:
A) Acetic acid bacteria B) Lactic acid bacteria C) Yeasts D) Molds
8. Which of the following is the BEST description of fat bloom?
A) Mold growth on the surface of chocolate B) Cocoa butter migrating to the surface and recrystallizing in a different (often Form VI) crystal form C) Sugar dissolving and recrystallizing on the surface D) Oxidation of cocoa butter producing rancid off-flavors
9. Sugar bloom on chocolate is caused by:
A) Improper tempering at the start B) Storage at temperatures above 30°C / 86°F C) Moisture exposure that dissolves and then recrystallizes surface sugar D) Fat oxidation over long storage
10. Approximately what percentage of the world's cocoa is grown in West Africa, primarily Côte d'Ivoire and Ghana?
A) 20% B) 40% C) 70% D) 90%
11. A 70% dark chocolate is, by definition, approximately what percentage sugar by weight?
A) 5% B) 15% C) 30% D) 50%
12. Real white chocolate (US legal definition) must contain at least how much cocoa butter?
A) 5% B) 10% C) 20% D) 30%
13. The "cliff melt" sensation of high-quality dark chocolate refers to:
A) The cooling sensation as Form V crystals absorb latent heat of fusion B) The way the chocolate stays solid above body temperature C) The bitter aftertaste of high-cacao chocolate D) The sugar dissolving on the tongue before the cocoa butter melts
14. A chocolatier finds her chocolate "seized" into a stiff grainy mass while tempering. The most likely cause is:
A) Overheating past 50°C B) Even a small amount of water entering the melted chocolate C) Adding seed too late D) Stirring too vigorously
Short Answer
15. Briefly explain why Form V cocoa butter, rather than Form VI, is the target of chocolate tempering. (Form VI is more thermodynamically stable.)
16. Describe the seeding method of tempering in three steps.
17. Why is conching essential for the textural quality of bar chocolate? Reference the perceptual particle-size threshold.
18. Name two specific Indigenous Mesoamerican civilizations who developed cacao processing technology, and describe at least two of their pre-contact practices that are foundational to modern chocolate production.
Answer Key
1. C) Six. Cocoa butter polymorphs are labeled Forms I through VI, sometimes with Greek letters (γ, α, β'₂, β'₁, β₂, β₁).
2. C) Form V. Form V (also β₂) has a melting point around 33–34°C — solid at room temperature, melting cleanly at body temperature, glossy snap.
3. C) 33–34°C / 91–93°F. This melting point is the Goldilocks zone — above room temperature (so the chocolate is solid in your hand) but below body temperature (so it melts in your mouth).
4. B) To melt all crystal forms so the chocolate is crystallographically blank. Heating to 50°C is a "reset" — it ensures no residual unstable crystals from prior storage propagate into the new tempered batch. Microbes are not a relevant concern in chocolate at this stage.
5. B) Gritty texture. Conching reduces particle size from ~30–80 μm (perceptibly gritty) to ~15–25 μm (perceptibly smooth). It also refines flavor through prolonged agitation, but the dominant problem it solved was texture.
6. B) "Food of the gods." Theos (gods) + broma (food). Linnaeus chose this name in 1753 in deliberate reference to Mesoamerican religious framing of the plant.
7. C) Yeasts. Saccharomyces, Hanseniaspora, Pichia species dominate the first 24 hours, fermenting pulp sugars to ethanol. Lactic acid bacteria follow in days 2–4, and acetic acid bacteria in days 4–7.
8. B) Cocoa butter migrating to the surface and recrystallizing. Fat bloom is a physical phenomenon — fat in the wrong place. The chocolate is still safe to eat and can usually be re-tempered.
9. C) Moisture exposure that dissolves and then recrystallizes surface sugar. Cold chocolate moved to humid air condenses water on the surface; the water dissolves a thin layer of sugar; the water then evaporates leaving sugar crystals on the surface. Cannot be re-tempered out.
10. C) 70%. Côte d'Ivoire alone produces about 40% of world cocoa; Ghana adds another ~20%; nearby countries add the rest.
11. C) 30%. A 70% bar is 70% cacao products (cocoa solids + cocoa butter) plus ~30% sugar plus minor ingredients (lecithin, vanilla).
12. C) 20%. US FDA standards require at least 20% cocoa butter for the legal designation "white chocolate." Less = "white confection" or "white candy coating."
13. A) The cooling sensation as Form V crystals absorb latent heat of fusion. When the chocolate transitions from solid to liquid, it absorbs heat without changing temperature (the latent heat of fusion). This produces the characteristic cool sensation on the tongue.
14. B) Even a small amount of water entering the melted chocolate. Water causes cocoa solids and sugar to clump together with the water, crowding out the cocoa butter. A wet spatula, a drop of condensation, or steam from the bain-marie can do it.
15. Form V is the kinetically stable, desirable form — solid at room temperature, melts cleanly just below body temperature, glossy snap. Form VI is more thermodynamically stable but has a melting point above body temperature (so it doesn't melt cleanly in the mouth) and tends to develop fat bloom over time as Form V slowly converts to Form VI. Tempering arrests cocoa butter at Form V, a kinetically trapped state — stable enough for many months, but not the absolute thermodynamic minimum.
16. (1) Melt the chocolate completely to 45–50°C / 113–122°F to wipe out all crystal forms. (2) Add seed chocolate (already-tempered chunks, ~25% of the original weight) and stir constantly while the temperature drops. (3) Stop at 31–32°C / 88–90°F, removing any unmelted seed; the chocolate is now tempered and can be poured.
17. The human tongue can detect particle sizes above approximately 30 μm as graininess. Unconched chocolate has cacao particles of roughly 30–80 μm — perceptibly gritty. Conching reduces these to 15–25 μm, well below the perceptual threshold, producing the smooth mouthfeel we associate with quality chocolate. Conching also distributes cocoa butter evenly around all particles, refines flavor, and drives off volatile acids.
18. Several valid answers. Examples: Olmec (ca. 1500 BCE, Gulf Coast Mexico) — earliest evidence of cacao consumption; Maya (ca. 250 CE classical period and continuing) — sophisticated cacao beverages, kakaw word, religious and political uses; Mexica/Aztec (ca. 1300–1521 CE) — xocoatl drink, cacao as currency, Moctezuma's reported 50-cup-a-day consumption. Practices include: heap fermentation in banana leaves, sun-drying the fermented beans, roasting on clay or stone surfaces, grinding into a paste on heated stone (metate), preparation as a frothed beverage flavored with chili, vanilla, and other regional ingredients.