First Crack vs. Second Crack: What They Mean for Your Roast
When it comes to roasting coffee, understanding the difference between the first crack vs. second crack can significantly enhance your skills. Coffee beans undergo several physical and chemical changes during the coffee roasting process. These changes are indicated by various sensory cues that specialty coffee roasters use to achieve the desired flavor profile and unlock their coffee beans’ hidden potential.
Two of the most distinctive indicators of the changes the coffee beans go through during roasting are the first crack and the second crack. Named after their audible popping sound, these two sound indicators mark the temperature thresholds in the coffee’s roast profile and flavor development. In this blog, we will discuss more on first crack vs. second crack and what they mean for your roast.
First Crack: What It Means For Your Roast
An average green coffee bean contains 10-12% moisture. Inside the roaster machine, as the temperature of the green coffee beans rises, the coffee beans’ water content turns into water vapor. As this hot steam forces itself out of the bean, we hear an audible crack sound, like popcorn popping. This usually happens around 196ºC, and at this stage, the beans start to expand and expel steam, carbon dioxide, and chaff.
The first crack is an important indicator, particularly for those looking for a particular degree of roast. Many specialty coffee roasters prefer to finish the roast shortly after the first crack, as the very light roast brings out the bright, natural characteristics of the roasted coffee beans. At this stage, the beans have a light brown color. Also, the beans usually start to become more fragrant and aromatic with a tinge of toasty scent. During cupping, lightly roasted coffee beans yield a brew with sharp acidity and less sweetness.
Second Crack: What Happens At This Stage
After the first crack, gas and pressure start to build up inside the coffee beans once again. In addition, the cellulose structure of the beans becomes more brittle and begins to break down, making way for a second crack. The second crack sound is quieter, similar to a softer crackling sound. It normally takes place around 224ºC, and at this stage, the oils and gasses within the beans start to migrate to the surface.
During the second crack, the coffee beans show all the characteristics of a dark roast. The color may darken further into dark brown or even black, with a noticeably oily surface. The aroma is significantly more intense, with a strong roasted bittersweet smell. The acidity is diminished, and caramel flavors emerge.
It is imperative for specialty coffee roasters to carefully monitor the roasting process at this stage, as the coffee beans’ characteristics change very rapidly. Roasting coffee beans too deep into the second crack may yield a burnt and smoky brew, with bitter charcoal taste.
The Roast Differences Between First Crack vs. Second Crack
The table below explains the differences between first crack vs. second crack.
FIRST CRACK | SECOND CRACK | |
Roast temperature | Around 196ºC | Around 224ºC |
Primary cause | Water vapor buildup | CO₂ buildup |
Sound | Corn kernel popping | Soft crackling |
Typical degree of roast | Very light roast | Dark roast |
Coffee bean appearance | Slightly expanded in size, light brown color, slightly oily on the surface | Significantly expanded in size, dark brown or black, very oily on the surface |
Coffee bean aroma | Fragrant, toasty, bread-like scent | Strong, bittersweet, more pungent |
Flavor | High acidity, natural flavor | Low acidity, thin body, more “roasty” flavor |
Amidst the differences of opinions and preferences about the first crack vs. second crack amongst specialty coffee roasters, the key to a successful roast is to find the sweet spot between the first crack and the second crack that corresponds with your desired roast profile.
Some tips that can help coffee roasters determine first crack vs. second crack:
- Listen carefully and pay close attention, as the transition between the first and second cracks can be quite subtle
- Track the temperature of the beans to mark the thresholds inside the roaster machine
- Keep an eye on the overall bean appearance and color
By combining these sensory observations, coffee roasters can effectively identify whether their coffee beans are in the first or second crack, and find the sweet spot that marks their targeted degree of roast.
In addition to a coffee roaster’s sensory instincts and experience, a powerful roaster machine helps to do the job right. Berto Roaster machines are equipped with data logging and profile replicator capabilities to ensure consistent quality at every batch. With Berto Roaster, it is easier than ever to meet the ever-growing demands of professional coffee roasters and their customers.
Ready to make Berto Roaster a part of your coffee journey? Get in touch with our team today.
Related Article
Sensory Coffee Roasting: Fine-tuning Your Senses
Related Article
Various Degrees of Coffee Roasts
Related Article
