Q-Grader Green Coffee Exam Process and Considerations: How to Identify Defective Coffee Beans

The CQI Q-Grader Coffee Cupping Exam: Understanding Green Bean Defect Classification

The CQI (Coffee Quality Institute) Q-Grader coffee cupping exam has always been the most rigorous and prestigious sensory evaluation test in the global coffee industry. This exam not only demands high sensory capabilities from candidates but also requires solid knowledge of coffee fundamentals.

To put it simply, you need to not only know how to taste coffee but also understand coffee basics. Among the various test sections, green bean selection—which might seem technically simple—is actually one of the sections with the highest failure rates! Let's first understand how this exam works!

Exam Requirements

Within a 1-hour time limit, candidates must continuously select three 350g boxes of washed green coffee beans, performing defect selection, scoring, and grading steps. Primary defects must not exceed 0 points (meaning no primary defect beans are allowed), and secondary defects must not exceed 5 points.

Wow! Isn't this exactly the same as SCA standards???

Good ingredients often only require the simplest cooking methods; similarly, the simplest exam sections often have the highest failure rates.

Let's analyze the requirements first!

Primary Defects: Not Exceeding 0 Points

This means no primary defect beans are allowed! Because even a single primary defect bean can affect the flavor of the entire coffee batch and, in severe cases, harm health with very serious consequences. According to SCA standards, primary defects include full black beans, full sour beans, dried fruit/pods, moldy beans, severely insect-damaged beans, foreign matter, and so on.

Except for severely insect-damaged beans, which require 5 beans to count as 1 point, all other primary defects count as 1 point each. So if just one primary defect bean is not picked out, it's game over.

Primary defect beans are typically very obvious defects that can be identified at a glance. Anything that doesn't belong to the coffee fruit is classified as foreign matter. The difficulty in the green bean selection exam lies in the assessment of secondary defect beans. Let's take a look at what these exam challenges look like.

Secondary Defects: Not Exceeding 5 Points

Secondary defects include partial black beans, partial sour beans, beans with shells, shell beans, broken/cut beans, parchment, slightly insect-damaged beans, and so on.

Most secondary defects are easy to identify, but the challenge comes from beans that appear to be partially sour and fully sour at the same time—how should these be classified? Should beans with only slight breakage be considered broken beans?

Let me share a simple method!

Three-Step Identification Method

1. First, examine the bean color—normal washed beans are green. If you encounter brown or darker-colored coffee beans, these are typically primary defects.

2. Next, assess the severity of the defect—if green beans show brown discoloration, first determine whether this brown color is silver skin. If it's silver skin, then it's a normal coffee bean. If not silver skin, determine whether the brown diseased portion has spread to more than 50% of the bean. If over 50%, it can be classified as fully black/sour beans; otherwise, it's partially black/sour beans.

3. Finally, consider the cause of the defect—if the defect was caused by machine crushing during coffee fruit processing or other reasons, such as the wet-hulling method used for Indonesian Mandheling coffee which causes surface damage to the beans. If it affects flavor, then classify it as a defect.

Finally, classify the various defect beans, calculate scores, and then grade the 350-gram batch. But even this simple math problem can trip people up! Remember! Remember! Remember! For primary defects, severely insect-damaged beans require 5 beans to count as 1 point!!!

Commercial Coffee Bean Quality

So, do the coffee beans we buy in our daily lives contain defects?

Green bean defects generally occur in the upstream stages of the coffee processing supply chain. Before export, green coffee beans undergo selection and grading. If there's even 1 point of primary defects, the batch will be classified as non-specialty coffee, affecting the price of the green coffee beans. Therefore, before export, the vast majority of defective beans are removed before reaching us consumers.

FrontStreet Coffee's beans are carefully selected by several skilled bakers before roasting, ensuring no green bean defects that might affect flavor before roasting. Therefore, the roasted coffee beans in your hands are already free of defects that could affect coffee flavor. Some beans broken during transportation are actually still specialty grade—they just look a bit less perfect~

Bonus Questions

1. Are all the coffee beans in the following images secondary defects?

Some beans with only slight breakage generally don't affect flavor and don't need to be picked out so meticulously. If you keep picking, all the beans will end up classified as defects!~!

2. Are the beans in the following image shell beans?

Whether they're shell beans—wouldn't you know by pulling them apart? (Teacher would disapprove of this behavior; destroying exam materials is not recommended!)

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