Coffee roasting: types, importance, temperatures and how they influence flavour

Coffee roasting is an art and a science.

It is the most critical process in the transformation of the green bean into that perfect cup we all enjoy.

More than just a cooking process, roasting is where the magic of coffee is born: its unique aromas, flavours and textures develop through complex chemical reactions that occur under controlled heat.

In this comprehensive article, you’ll find out all about the types of coffee roasts, the exact temperatures for each level, and how each roast completely transforms the sensory profile of your coffee. From the lightest roasts that highlight the origin to the darkest roasts that create intense, smoky notes, I’ll guide you through each stage of the process.

Plus, I’ll show you how we at TecAIRE help brands roast with precision, no matter what roast profile they choose.

Coffee roasting is a thermal process that transforms green coffee beans into the aromatic and tasty beans we know. During this process, which can take between 8 and 20 minutes, more than 800 different chemical reactions occur that create the compounds responsible for the characteristic flavour, aroma and colour of roasted coffee.

Three main transformations take place during roasting:

• Maillard reaction: This is produced between 140°C and 165°C, creating components that provide sweet, caramelised and toasty notes. This reaction is responsible for the initial golden colour and the first complex flavour notes.
• Caramelisation of sugars: Between 160°C and 185°C, the natural sugars in the coffee caramelise, adding sweetness and body to the final coffee. This stage is crucial for the development of the flavour profile.
• Acid degradation: As temperature and roasting time increase, the natural acids in coffee degrade, reducing acidity and creating more complex and bitter compounds.

The level of roast directly influences five key aspects of the coffee:

• Acidity: Light roasts retain more natural acidity, while dark roasts significantly reduce it.
• Sweetness: Develops progressively until medium roast, where it reaches its optimum.
• Bitterness: Increases with darker roasts due to degradation of compounds and creation of new bitter elements.
• Body: Increases with roasting, especially through release of oils and caramelisation.
• Aroma: Each roasting level releases different volatile compounds, creating unique aromatic profiles.

According to the SCA, proper roasting is essential to fully evaluate and enjoy the sensory characteristics of coffee.

It is important to distinguish between roast coffee and torrefacto:

• Natural roasting: Only heat is applied to the grain, developing its natural characteristics.
• Torrefacto: Sugar is added during roasting (up to 15% of the weight of the grain), creating a caramelised layer on the outside.

Roasting, although popular in Spain, significantly modifies the original flavour of the coffee and can mask defects in lower quality beans.

There are three main categories of coffee roast types, each with a unique sensory profile and specific applications. The Specialty Coffee Association (SCA) establishes the colour and development parameters for each level.

Light roasting preserves as much of the original characteristics of the bean as possible, such as acidity, fruity and floral notes and a lighter body, highlighting its terroir and processing. It spends the least time in the roaster’s drum and at lower temperatures.

Technical characteristics:

• Color: Agtron 95-85
• Final temperature: 196°C – 205°C
• Development time: 15-20% of total roasting time
• Density: Higher, more compact grains

Sensory profile:

• Bright and pronounced acidity
• Light colour and dry surface.
• Fruity, floral or herbal notes
• Citrus, floral or herbal notes.
• Light to medium body
• Subtle and natural sweetness
• Higher caffeine retention (up to 5% more than dark roasts)

🔹 Who should use it?

Brands that seek to highlight the origin of their grains and offer complex and fresh profiles.

🔹 Example profile: Ethiopia, Kenya, high altitude Colombia.

Recommended methods: V60, Chemex or Aero Press, Kalita Wave, French Press (reduced time)

Medium roast represents the perfect balance between the characteristics of the origin and the flavours developed during roasting. It is one of the most popular, as it combines body, acidity and sweetness in a balanced way.

Technical characteristics:

• Color: Agtron 65-55
• Final temperature: 210°C – 220°C
• Development time: 20-25% of total time
• First crack completed, surface slightly shiny

Sensory profile:

• Medium brown colour with a slightly oily surface.
• More balanced flavour, with sweet and caramelised notes.
• Balanced and pleasant acidity
• Caramelised, chocolaty and nutty notes
• Medium to dense body
• Developed and complex sweetness
• Minimal and balanced bitterness
• Ideal for espresso and filtered coffee.

🔹 Who should use it?

Brands that want to offer a balanced experience, with complexity and sweetness.

🔹 Example profiles: Brazil, Guatemala, Costa Rica.

Recommended methods: Espresso, Moka, Dripper, French press

The dark roast develops intense and robust flavours, where the notes created by the roasting process predominate over those of the origin. Here, the flavours of the origin take a back seat to smoky, chocolaty and spicy notes.

Technical characteristics:

• Color: Agtron 45-35
• Final temperature: 225°C – 235°C
• Development time: 25-30% of total time
• Second crack started, surface accepted

Sensory profile:

• Very low acidity
• Dark colour with oily surface.
• Smoky, spicy, charred notes
• Dense, oily body
• Pronounced bitterness
• Notes of bitter chocolate, roasted nuts

🔹 Who should use it?

Brands that aim to offer an intense and strong flavour, or espresso blends.

🔹 Example profile: Robusta or Italian espresso blends.

Recommended methods: Espresso, Ristretto, Café au lait, Cappuccino

Precise temperature control during coffee roasting is essential for consistent results and specific profiles.

The roasting process is divided into several critical stages:

Drying phase (0-5 minutes)

• Temperature: 80°C – 160°C
• Grain loses moisture (initial 10-12%)
• Colour changes from green to pale yellow
• The first herbal aromas develop

Maillard phase (5-8 minutos)

• Temperature: 160°C – 196°C
• Intense Maillard reactions
• Colour evolves to light brown
• Development of complex aromas

First Crack (8-10 minutes)

• Temperature: 196°C – 205°C
• Internal steam expansion of the grain
• Characteristic “crack” sound
• Beginning of the development of roasted flavour

Post-crack development (10-15 minutes)

• Temperature: 205°C – 230°C
• Advanced caramelisation
• Release of oils
• Body development and acidity reduction

A successful roasting curve must consider:

• Rate of Rise (ROR): Rate of temperature increase, ideally decreasing.
• Development time: Percentage of total time after the first crack
• Crash cooling: Rapid cooling to stop the process instantly
• Airflow control: Airflow management to control the profile

The choice of coffee roast should be aligned with the brewing method to maximise the potential of each bean.

Filter methods work best with light to medium roasts:

• V60: Light-medium roast to bring out acidity and complex notes
• Chemex: Light roast to maximise clarity and flavour separation
• Kalita Wave: Medium roast for balance between acidity and body
• Aeropress: Versatile, but works excellently with medium roast.

Technical reason: The extended contact time and filtration allow delicate nuances to be extracted without over-extraction.

Espresso requires medium to dark roasts for several reasons:

• Extraction pressure: 9 bar requires grains that resist over-extraction.
• Contact time: 25-30 seconds need developed flavours
• Concentration: The profile should be intense to stand out in a small amount.

Specific recommendation: Medium-dark roast (Agtron 50-45) for espresso black, dark roast for coffee with milk.

Cold Brew: Medium-dark roast works best due to the extended extraction time (12-24 hours) which can create bitterness with light roasts.

Cápsulas: It depends on the system, but generally medium roast for domestic machines and medium-dark for professional systems.

The choice of coffee roast for your brand must consider multiple strategic and technical factors.

Origin of coffee:

• Etiopía, Kenia: Clear toast to highlight fruity acidity
• Colombia, Guatemala: Medium tastes for balance and sweetness
• Brasil, Indonesia: Medium-dark toast to enhance body and chocolatey notes

Coffee variety:

• Arabica: More versatile, works in all roasts
• Robusta: Best in dark roasts to control their natural intensity.
• Special varieties (Geisha, Bourbon): Clear roasts to preserve unique characteristics

Client profile:

• Traditional consumer: medium-dark, familiar and recognisable roast
• Coffee enthusiast: light-medium roast, complex and distinctive
• Wholesale market: medium roast, balanced and accessible

Speciality coffees:

• Prioritise expression of origin
• Clearer samples or specific profiles
• Traceability of the roasting process
• Detailed communication of the sensory profile

Retail coffees:

• Consistency and stability
• Medium samples for wide acceptance
• Scalable production capacity
• Accessible and familiar sensory profile

For more information on coffee roasting and evaluation standards, you can consult the official resources of the Specialty Coffee Association on their standards page.

1. Start with medium roast: more forgiving and versatile
2. Document everything: Each batch must have a record of temperature, time and profile.
3. Systematic tasting: Evaluates each roast 24 hours after roasting.
4. Ongoing training: Invest in SCA or similar courses.
5. Accurate equipment: calibrated thermometers and efficient cooling systems

The SCA suggests certain practices to ensure optimal roasting:

• Duration of roasting: Between 8 and 12 minutes for tasting samples.
• Post-roasting rest: Let the coffee rest for 8 to 24 hours before sensory evaluation.
• Consistency: Maintain uniform conditions during the roasting process to ensure reproducible results.

🔹 Thinking of scaling your brand and need a machine that respects your roasting profile?

👉 Discover our roasters for each type of roasting here

At TecAIRE we understand that coffee roasting is as much art as it is science, and our solutions are designed to give you total control over every variable in the process.

Our toasters incorporate advanced roasting control technology:

• PID control systems: Maintain accurate temperature with variations of less than 1°C.
• Real-time curve monitoring: ROR and grain temperature visualisation
• Programmable profiles: save and play back your favourite roasting curves
• Multiple temperature sensors: air, grain and ambient monitoring

Each roasting level requires specific control:

For light roasts:

• Precise airflow control for uniform development
• Quick cooling systems to stop the process exactly
• Real-time colour monitoring

For medium roasts:

• Automated temperature curve management
• Post-crack development control
• Batch homogenisation systems

For dark roasts:

• Smoke and Particulate Matter Management
• Temperature control in high ranges
• Prevention of localised over-roasting

TecAIRE electric roasters:

• More precise temperature control
• Ideal for light and medium roasts
• Reduced environmental impact
• Perfect for urban spaces

TecAIRE gas roasters:

• Increased production capacity
• Excellent for dark roasts
• Operating cost menor
• Traditional for classic profiles

Coffee roasting is much more than applying heat to a green bean. It is the process where your brand develops its unique sensory identity, where every decision on temperature, time and development translates into the experience your customers will remember. The essence of your coffee.

The types of coffee roasting you choose will define not only the taste of your product, but also your market positioning. A light roast connects you with consumers looking for complexity and origin, while a dark roast satisfies those who prefer intensity and tradition.

The difference between a good coffee and an exceptional coffee is in the details: those exact degrees of temperature, those precise seconds of development, that perfect curve that transforms the bean’s potential into sensory reality.

At TecAIRE, we not only offer you the tools to roast with precision, but the know-how and technical support to make every batch a perfect expression of your vision. Because we understand that behind every roast is a story, a passion and a commitment to excellence.

Coffee roasting is your flavour signature. Make it unforgettable.