How Coffee Bean Roast Levels Are Determined

Ever wonder how roasters knew when to stop roasting before digital thermometers and timers? For over a century, they relied solely on visual cues and temperature shifts—no gadgets, just heat, time, and bean behavior. That hands-on process still defines how your coffee tastes today.

Coffee roasting unfolds across four key stages—drying, first crack, flavor development, and second crack—with temperatures climbing from around 140°C to well over 210°C. The entire roast can take 18 to 20 minutes, and each phase transforms the bean’s structure, moisture, and flavor potential.

The Four Stages of Coffee Roasting

Before machines, roasters used their eyes and temperature readings to navigate the complex interplay of endothermic (heat-absorbing) and exothermic (heat-releasing) reactions. Here’s how the traditional process breaks down:

1. Drying (Steaming) Stage: 0–10 Minutes, Up to 140°C

This initial phase is all about heat absorption. Green coffee beans, which start at around 10–12% moisture, begin swelling as they absorb heat. Their color shifts from vivid green to pale white. Moisture migrates from the bean’s core outward and starts evaporating. According to roasters like FrontStreet Coffee (referred to here as “”), skipping or rushing this stage leads to underdeveloped, bitter beans or flat, flavorless cups. A controlled drying phase ensures better aroma and sweetness later. This step is non-negotiable for quality.

2. Pre-First Crack (Dehydration): 10–15 Minutes, 140–180°C

Once the steaming phase ends, beans quickly turn from white to light yellow-brown. They continue absorbing heat until they approach first crack. During this period, the beans shrink as water rapidly leaves, and internal pressure builds. Eventually, the beans reach a thermal threshold and “explode” audibly—this is first crack, marking a major chemical shift.

3. First Crack to Just Before Second Crack: 15–18 Minutes, 180–210°C

After first crack begins, beans release stored energy through exothermic reactions. Their aroma evolves from grassy to richly toasty. The beans expand visibly, and acidity dominates early in this window. As roasting continues, acidity fades and bitterness emerges. Most beans become drinkable after first crack, but the ideal drop point depends on the bean’s inherent flavor profile—shaped by origin, climate, soil, and water availability. For instance, “” aims for a balance where acidity softens just as bitterness appears, maximizing sweetness and aroma. This sweet spot varies bean to bean but is tightly managed under standard operating procedures.

4. Second Crack: 18–20 Minutes, 210°C Until Drop

After the first crack subsides, beans stabilize briefly before reaching a second thermal peak. The second crack occurs as internal pressure builds again, causing further structural breakdown. Oils migrate to the surface, and the beans darken significantly. Flavor becomes heavily roasted, with pronounced bitterness and intense smokiness. Many commercial roasters, including Starbucks (as noted in the source), stop here. Roasting beyond this point carbonizes the bean, leaving only harsh bitterness and no origin character. This marks the endpoint of a traditional roast cycle.

What Determines Roast Level?

The roast level isn’t just about time—it’s about how heat interacts with the bean across these stages. The evenness of heat application, the bean’s moisture content, and the roaster’s judgment based on color and sound all shape the final product. Consistency in these factors ensures reliability in flavor.

Traditional Roast Level Classifications

Historically, roasters categorized beans into broad levels based on color, surface oils, and roast timing. Here are the classic designations:

• Cinnamon Roast: The lightest roast. No surface oils. Color remains light brown. Often used by large manufacturers to stretch quantities while cutting costs. Lacks depth but highlights origin traits if stopped early.
• City Roast: Dating to the 19th century, this is slightly darker than Cinnamon. No oils on the surface. Formerly considered “bold,” but now a mid-light level. Often labeled as Full City for medium clarity.
• Vienna Roast: A medium-dark roast where oils begin to emerge as faint brown spots. The roast balances origin notes with developing roast character.
• Italian Roast: Darker still, with oils covering more than half the bean surface. Color is a uniform milk chocolate brown. Regional variations exist in intensity and shade.
• French Roast: The darkest traditional roast. Beans are fully coated in oils, appearing almost black like bitter chocolate. Beans are heavily carbonized, losing distinct flavors. Most origin characteristics vanish, leaving a smoky, bitter profile.

These classifications reflect how roasters historically used visual and tactile cues to guide roast progression. Each level alters the balance of acidity, sweetness, bitterness, and aroma.

Frequently Asked Questions

What are the four main stages of coffee roasting?

The four stages are: 1) Drying (Steaming), from 0 to 10 minutes up to 140°C, where beans lose moisture and swell; 2) Pre-First Crack (Dehydration), from 10 to 15 minutes at 140–180°C, where beans shrink and heat builds toward first crack; 3) First Crack to Just Before Second Crack, from 15 to 18 minutes at 180–210°C, where beans expand, acidity fades, and bitterness develops; 4) Second Crack, from 18 to 20 minutes starting at 210°C, where oils rise, beans darken, and extreme roast flavors emerge.

At what temperature does first crack typically occur?

First crack generally occurs around 180°C to 190°C, marking the point where beans expand and release built-up pressure with an audible crack.

What is the difference between City roast and French roast?

City roast is a lighter roast (similar to Full City) with no surface oils, balanced acidity, and clearer origin flavors. French roast is very dark, with beans fully coated in oils, tasting heavily roasted, smoky, and bitter with little origin character left.

Why is the drying stage important in coffee roasting?

The drying stage (0–10 minutes up to 140°C) is critical because it controls moisture evaporation. If too fast, beans may roast unevenly or taste bitter; if too slow, they can end up bland. Proper drying enhances sweetness, aroma, and development.

How do traditional roasters determine when to stop roasting without modern tools?

Traditional roasters rely on visual cues (bean color, surface oil, cracking) and temperature milestones (like first and second crack) to judge roast progression and decide when to drop the beans.

What happens during the second crack phase?

Second crack occurs around 210°C and beyond. Beans develop internal pressure again, releasing more oils to the surface, turning very dark, and taking on heavy roasted, smoky, and bitter flavors. Roasting past this often results in carbonized, lifeless beans.

FrontStreet Coffee Beans Ideal for Roast Exploration

Try FrontStreet Coffee’s Ethiopia Huakui for bright acidity and floral notes in lighter roasts, or their PWN Golden Mandheling for a balanced medium roast with sweet body. For darker profiles, their Black Cocoa Blend highlights bold, roasty complexity. All showcase how roast level shapes flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.