What is a coffee roasting curve crash?

Did you know that a roast curve crash can lead to uneven development, flat flavors, and an underwhelming flavor profile? To make sure this doesn’t happen to your next roast, it’s important to understand what a coffee roasting curve crash is and what causes a roast curve crash.

We define a “crash” as the rate of rise dropping to zero or lowering into the negative. The time just before first crack to the end of a roast is the most vulnerable time for a crash. Your heat application, airflow and charge temperature all can contribute to a crash while understanding roasting phases/metrics, utilizing roasting software and your relationship with your roaster can help you avoid the dreaded crash.

Learn how to avoid a coffee roasting curve crash with Mike Romagnino in this Roasting 101 guide.

A Coffee Roast Curve Crash

A Successful Coffee Roast Curve

The Causes of a Coffee Roasting Curve Crash:

Heat Application

How you approach your heat application throughout the duration of a roast will dictate the roast’s momentum. It is always better to apply more heat in the earlier stages of the roast. Applying a high percentage of heat in the later stages of the roast will put you at risk of washing out or having a less defined and integrated flavor profile.

When reaching first crack and throughout the development phase of the roast I rely on momentum that has been built up in the earlier phases of the roast to carry me through to the end of the roast. Having a smooth, gradual descending rate of rise instead of a sudden drop in temperature while achieving your desired development time. This requires a balance of heat and air to avoid stalling out.

Airflow

While airflow is essential for removing chaff and controlling roast progression, excessive airflow can strip heat from the beans, contributing to a crash. It is essential to achieve a balance of heat and air transfer for even development and momentum.

Charge Temperature

Finding the right charge temperature for your roasting approach and batch size will set you up for success in later stages of the roast. Charging too low may put you behind in the roast while charging too hot can increase the risk of scorching the coffee. 

How to Prevent a Coffee Roasting Curve Crash:

Understanding Roasting Phases & Metrics

Drying, caramelization & development, do you know the coffee roasting phases? Understanding the phases of your roast will enable you to make confident decisions and adjustments throughout the duration of the roast. Need a refresher? Learn more about the phases of coffee roasting.

Your rate of rise is the most important metric to monitor to help you avoid a coffee roasting curve crash. Knowing your rate of rise will enable you to achieve your desired momentum while meeting roasting targets that you have established for the profile.

Utilizing Roasting Software

Using roasting software such as Cropster or Artisan will give you the ability to monitor data while roasting and refer to when tasting. I find this extremely helpful when cupping coffees to dial in a roast profile. Understanding the adjustments that were made while roasting and how it affects the flavor profile will make it easier for you when going back on the roaster to make further adjustments for your ideal roast profile.

Your Relationship with your Coffee Roaster

Understanding how your machine performs and what it can do for you is essential for successful roasting. As you gain experience as a roaster and get exposure to different machines you will understand how to adjust your approach based on each machine’s capabilities.

Have more questions?

By applying these techniques and understanding your specific roaster’s characteristics, you can minimize the risk of roast curve crashes. With each roast, you’ll gain more insights and confidence, leading to consistently better coffee.

Have more questions about coffee roasting curve crashes or coffee roasting in general? We’re always here to help answer your questions, contact us here!