What are the Grind Value and Color Value of Coffee Beans? How to Determine the Roast Level of Coffee? Why Does Coffee Have Acidity?

Understanding Coffee Flavor: The Foundation

The flavors exhibited in coffee primarily stem from its genetic makeup (variety), growing environment, and processing methods! Once coffee beans have undergone these stages, they establish their inherent flavor characteristics. All that remains is waiting for the roaster's craft to transform them into a "delicious delicacy"!

The depth of roasting determines the flavor direction of coffee beans (sour, sweet, and bitter). Therefore, when purchasing beans or drinking coffee, besides the origin information of the beans, the degree of roast is also information that most friends pay attention to!

The Science Behind Roast Level Classification

Just as we distinguish between washed and natural processing by the "silver line" of coffee beans (a method of identifying coffee bean processing through appearance), the coffee industry initially determines roast levels through visual observation. This is because there's a scientific classification method in the industry that uses the color of roasted coffee beans as the basis for determining roast degree! Below is an Agtron color value card for your reference. It's a roasting classification table created by quantifying bean colors! The values here refer to Agtron color values (caramelization analysis values). The higher the value, the lighter the roast degree and color of the coffee beans; the smaller the value, the deeper the roast degree and color of the coffee beans.

Why FrontStreet Coffee Doesn't Use Standard Roast Labels

However, observant friends will notice that the beans sold by FrontStreet Coffee don't have roast level markings. With such classification methods already available, why doesn't FrontStreet Coffee label the roast degree of its beans? The reason is quite simple because this standard only distinguishes based on the color of coffee beans, and it's not suitable for certain special beans.

Limitations of Color-Based Roast Classification

For example, honey-processed and anaerobic-processed coffee beans are wrapped in substances like mucilage and fruit juice for extended periods during processing, causing a layer of sugar to adhere to the bean surface. The presence of these sugars causes more intense caramelization reactions on the bean's exterior. Therefore, although they may have very rich floral and fruity notes after roasting, their appearance takes on a darker color due to the sugar content. If we were to classify them using color values, they would be classified as dark roast coffee beans. For instance, the Sidra from Finca La Esperanza, although its color value reaches 61, even darker than the dark roast defined on the color chart, it possesses very abundant floral and fruit aromas!

A Better Approach: Flavor-Based Roast Classification

Therefore, this classification method has certain limitations, and we cannot use it as the standard for determining roast degrees. If we don't classify according to color values, disagreements will arise due to different understandings of roast degrees! For example, for the same bean, Roaster A might consider light roast to be when the beans come out at first crack, while Roaster B might consider light roast to be one minute after first crack (just an example). Different perceptions can lead to communication barriers, so FrontStreet Coffee recommends judging the degree of roast through taste and flavor descriptions.

Understanding Roast Levels Through Flavor Profiles

Nowadays, when we roast coffee, we generally consider the point when coffee becomes "ripe" to be at the "first crack." We can stop roasting at any time after the first crack and release the coffee. It's important to know that green coffee beans contain very rich organic acids, and most of these acidic substances gradually decompose as the roasting process progresses. Therefore, the earlier we release the beans, the more of these acidic substances are retained. Consequently, when we drink a cup of coffee with full acidity, we can define it as medium-light roast; the later the release time, the more acidic substances are lost, and the bitterness produced by caramelization reactions gradually replaces the dominant position of acidity! Therefore, if we drink a cup of coffee dominated by bitterness, we can define it as medium-dark roast coffee (excluding over-extraction)!

Practical Guide: Judging Roast Levels from Flavor Descriptions

Based on this standard, we can determine the roast degree of coffee beans ourselves through the flavor descriptions on the packaging labels! For example, most citrus fruits have relatively full acidity, so when such fruits appear in the flavor description section, we can preliminarily judge them as light to medium-light roast coffee beans; if the flavor labels contain descriptions like honeydew melon or complex fruits, we can preliminarily judge them as medium-light roast coffee beans leaning toward medium, because such coffee beans will have higher sweetness; if the flavor labels contain descriptions like chocolate, brown sugar, or yellow sugar, we can preliminarily determine them as medium-dark roast coffee beans leaning toward medium; if descriptions like dark chocolate, caramel, or pine appear, we can determine them as medium-dark roast coffee beans leaning toward dark~ Of course, this is only preliminary and can only provide us with a reference when purchasing beans. Remember not to generalize, as the final authentic roast information can only be obtained through tasting.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473