Low-Temperature Coffee Roasting: No.1 secret of Excellent Coffee

The concept of low-temperature coffee roasting is always essential for anyone involved in coffee roasting. This is often similar to the slow roast. This article is going to cover the brief ideas of important coffee roasting variables temperature, time, roast profile, etc.

What is Low-Temperature Coffee Roasting?

What we know as the coffee bean is the green coffee seed. According to many studies and research, we came to understand that a coffee bean contains more than 800 volatiles compound.

Coffee roasting brings out the most flavorful contents from the coffee and prepares the coffee for brewing.
Several variables control the quality of coffee roasting. To master coffee roasting, you need to understand three core variables. These variables are time, temperature, and airflow.

Low-temperature coffee roasting is creating a larger temperature gradient at the roast profile for the inner core development. Many roasters can produce a much higher quantity in a short time with high temperatures. Trust me; it affects the taste of coffee badly.

Many roasters increase the roast time, especially it is practiced while roasting for espresso. After the first crack, the roasting duration is increased for the inner core development of the coffee beans.

But it would be great if you create a larger temperature gradient and this is the topic, I am covering low-temperature coffee roasting.

Don’t mess up!! If you intentionally extend the duration without considering other factors that may create baked flavor. So, Just avoid it.

The slow roasting process develops the essential oils of the coffee beans. It protects the surface of the beans from burning out and infuse coffee with flavorful contents.

Coffee Roasting Process Step by Step

We need to heat up the coffee roaster machine before pouring the beans into it. When the beans are fed into the roaster the temperature suddenly decreases.

When we put the green beans into the coffee roaster is called the charge temperature. This temperature varies from 180-200 degree celsius

Initially, beans start to absorb heat. It is very important to know the roast density and water content of the beans.

Too high temperature cause your beans to tip and scorch. It will also burn the outer surface only. From the turning point, it starts to go up, and the drying phase continues.

In the drying phase, coffee beans lose their moisture content and turn into pale yellow beans from the green beans. The drying phase doesn’t affect the taste of the beans that much. After the drying phase, the browning phase starts.

The Browning phase controls the flavor of roasted beans. Here, you should show the true skill of a slow roast. The result of slow roasting is awesome.

A low-temperature coffee roasting at a slow rate creates more Caramelization resulting in sweet and chocolaty flavor. You will hear the first crack just at the end of the browning phase when it all starts to create sounds like popcorn. We often call it Chorus.

Don’t just wait for the second crack. The flavor of roasted coffee beans after the second crack is charcoal and smokey flavor. If you are a big fan of typical Italian espresso or if you want a perfect chocolaty nutty aspect that is sweet, has a full mouth full and low acidity then this blend of the roasted coffee beans is just perfect for you.

Degrees of Coffee Roasting

Roast profile diagram to understand low-temperature coffee roasting
Credit: cafeculture.com

We came to know from the previous paragraph that coffee roasting undergoes three basic phases:

  • Drying Phase
  • Browing Phase
  • Development Phase

Within these three basic phases, degrees of coffee roasting determines the flavor and aroma. Certainly, flavor and aroma will be different for the different roast degrees.

According to a famous book “Coffee: Everything You Ever Wanted to Know About Coffee” by Jack Frisks, there are four main types of coffee roasting:

  1. Light Roasts
  2. Medium Roasts
  3. Medium-dark Roasts
  4. Dark Roasts

Light Roasts

The significant characteristics of light roasts are:

  • The lighter color is determined by the low roasting time of the beans
  • You don’t get a strong flavor as the roasting duration is less
  • More acidic and fruity flavor

Medium Roasts

You can recognize them with the following characteristics:

  • Medium brown texture
  • Coffee beans are roasted longer than the light roasts. It is less acidic and stronger than the light roast coffee
  • This category is more preferred in the USA. The caramelization of sugar causes it to be a sweety

Medium-Dark Roasts

  • It is the nonoily beans of medium roasts that fall between the black and darkened beans
  • It’s not roasted long enough to produce oil
  • If you are a fan of strong bitter coffee, don’t miss the medium-dark roast blend

Dark Roasts

  • Black in color and has the shiny and oily texture
  • Roasted for a longer duration
  • Sometimes you may find it burnt taste

Coffee Roasting Temperature Profile

If anyone wants to master a perfect roasting then he should master the charge temperature. A wrong charge temperature can cause either baked coffee or scorched coffee.

A prolonged roast at a low temperature helps to reduce the acidity. But there is a risk of getting the beans into flat or baked. Baked coffee beans can’t produce the necessary flavor or aroma.

Too much heat can scorch the coffee beans. It burns the outer surface of the green coffee beans. There is no doubt, it will serve a cup of dry and astringe cup of joe.

There is a graph that shows the temperature vs time of coffee roasting is known as a roast profile. Certainly, You can’t stick to a roast profile only. But to understand the basics of coffee roasting it helps the beginner.

Initially, the coffee beans absorb the temperature from the roaster machine. the charge temperature remains around 400 to 420 degrees F. The speed at which coffee absorbs energy is called the Rate Of Rise. Many of us call it RoR.

One must consider all six of the preceding variables (machine design, batch size, bean density, bean size, bean processing method, and intended roast time) when deciding an appropriate charge temperature for a batch. For example, in a 30 kg capacity classic drum roaster, one may charge a 12-minute, 25 kg batch of large, dense, washed Kenya AA beans at 430°F (221°C). In the same machine, the roaster may choose a 380°F (193°C) charge for a 15-minute, 20 kg batch of a small, low-density, naturally processed Brazilian. (Please ignore the unusual choice to roast the larger batch of Kenya so much faster than the Brazilian.)

All about the Roast Profile

What is the Best Roast for The Coffee

You can’t specify the best roast or best roast level for the coffee beans. It depends on your preference.

Yet, it varies with the quality of the beans and the cultivation area.

For roasting coffee beans, The arabica is always better than the robusta.

There are coffee beans that can’t take a full city roast. In some cases, coffee oils open up at dark roasts. you get a thin body from a darker or city roast. while the medium roast will have a rounded and full body. If you love to have a light sweet taste then go for the light roast of your green coffee beans.

Slow Roast vs Fast Roast Coffee

Basis Slow Roasting Fast Roasting
Roasting Time 14-20 Minutes As little as 90 seconds
Development Maximum aroma and flavor develop in slow roasting The inner core doesn’t develop. There is a possibility of getting burnt the outer surface
Purpose For brewing purposes, the slow roast is most preferred Used in laboratory experiments
Temperature Low-temperature coffee roasting after the first crack Significantly higher temperature gradients

Frequently Asked Questions

Why Slow Roast Coffee is Better?

The slow roasting process results in a more balanced, sweeter, and smoother coffee. This is possible because of the long, slow roasting time that allows for highlighting and suppression of various flavor compounds. If you’re looking for a smoother, less bitter cup of coffee, find a roast that’s been slow roasted.

How to Deal with the acidity of roasted coffee?

If you’ve ever roasted coffee, chances are you’ve heard of the terms “bright” and “acidic.” But what does that mean? What does a coffee taste like when it is bright or acidic? And how do you roast coffee for acidity?
To make it easy, roasting coffee for longer than the usual duration reduces acidity. Mastering the art of Slow roast coffee and low-temperature coffee roasting helps to attain that skill.


Low-temperature coffee roasting is a critical issue unless you understand how it works and when it starts! We have tried to give you a solution that can help you with everyday roasting.

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