Nav: Home > Coffee >

Where Does the Sweetness in Coffee Come From? How Coffee Flavor Changes from Light to Dark Roast

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, Professional coffee knowledge exchange. For more coffee bean information, please follow Coffee Workshop (WeChat official account cafe_style). Green coffee beans contain a certain amount of monosaccharides. Although not all sugars have a sweet taste, these monosaccharides typically carry sweetness and react easily under the temperature catalysis of coffee roasting. Once most of the moisture inside the coffee beans evaporates, sugars will react with heat

Understanding Coffee Chemistry: From Green Beans to Perfect Roast

Professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style).

Green coffee beans contain a certain degree of monosaccharides. Although not all sugars are sweet, these monosaccharides typically carry sweetness and react easily under the catalytic effect of coffee roasting temperatures. Once most of the moisture within the coffee beans evaporates, sugars begin to react with heat in many different ways. Some undergo caramelization, causing certain coffee beans to exhibit caramel-like tones. It's particularly worth noting that these caramelized sugars will have reduced sweetness and ultimately become one source of bitterness. Additionally, some sugars interact with proteins within the coffee beans in what are known as Maillard Reactions - reactions that encompass phenomena including meat turning brown in ovens and the color changes that occur when roasting cocoa or coffee beans.

FrontStreet Coffee has learned that when coffee completely passes through the first crack stage, monosaccharides are almost completely non-existent - they may have all participated in various chemical reactions, ultimately transforming into more different coffee aromatic compounds. Coffee bean roasting progresses from light to dark, corresponding to: sharp and insipid -- gentle and rich -- monotonous and rough.

The Three Stages of Coffee Roasting

Sharp and Insipid (Astringent and Empty)

-- Under-roasted

Gentle and Rich

(High sweet aroma, soft acidity and bitterness, balance, lively brightness, mellow and smooth) -- Sufficiently roasted but not excessive

Monotonous and Rough

(Bitter, astringent miscellaneous flavors and monotonous rigidity) -- Over-roasted

The Honey Spot Extraction Concept

Corresponding to honey spot extraction (sufficient extraction without excess), it's worth introducing the honey spot roasting concept (sufficient roasting without excess).

The honey spot roasting area can be viewed as the honey spot roasting target, with honey spot roasting at its center.

The left side of the honey spot roasting area tends toward sweet and sour characteristics, while the right side leans toward sweet and bitter flavor profiles. The central area primarily features gentle richness, high balance, high sweet aroma intensity, soft acidity and bitterness, bright liveliness, and mellow smooth flavors.

When tasting coffee with sharp acidity, dead bitterness, astringent miscellaneous flavors, or even burnt bitterness and salty notes, one must examine extraction imbalance and roasting imbalance.

Limitations and Evolution of Extraction Theory

The SCA Honey Spot Extraction Gold Cup Theory emphasizes extraction yield and concentration but does not mention oil extraction, which can be considered a serious theoretical defect requiring supplementation and correction.

Therefore, it must also be emphasized that honey spot roasting seeks water-soluble substance balance (such as balance of small, medium, and large molecular substances), while also seeking full opening of oils and aromas, and achieving synchronization of both.

The evolution of honey spot extraction theory can be seeking balanced extraction of water-soluble substances, also seeking optimization of oil extraction, and achieving synchronization of both.

The Holy Grail of Coffee

The coffee holy grail is ultra-concentrated, with high concentration requirements demanding optimal balance between roasting and extraction, as well as sufficient oil and aroma. Only then will it be full of sweet aroma.

Aromatic substances are fat-soluble, with esters, aldehydes, ketones, alcohols, etc., present in oils. Roasting and extraction must重视 oils and aromatic substances, which correspond to regional flavors. Sweetness and aroma overlap, and sufficient sweet aroma can balance acidity and bitterness.

Coffee roasting and extraction should be viewed dichotomously - water-soluble substances and oils viewed separately for clarity, then comprehensively considering the synchronization of water-soluble balance and oil optimization.