The Sweet Symphony of Processing: How Methods Shape Coffee Sweetness at Similar Roasts

Question: When comparing coffees with similar roast levels, how does the processing method influence the perceived sweetness?

When comparing coffees that have undergone identical roasting, the method by which their cherries were processed can profoundly influence the perceived sweetness in the final cup. While roast level is a primary determinant of many flavor characteristics, the journey from cherry to bean unlocks different potentials for sweetness through various processing techniques.

Fermentation’s Sweet Influence

Fermentation, a critical stage in many coffee processing methods, has a notable impact on flavor development. Studies indicate that specific fermentation protocols can positively influence a coffee’s profile, contrasting with less beneficial treatments [2]. For instance, aerobic and anaerobic fermentation methods have been shown to enhance coffee quality by affecting parameters like pH and acidity, which indirectly contribute to the perception of sweetness [2]. The sugars and organic acids present in the coffee cherry undergo transformations during fermentation, leading to the formation of a complex array of volatile compounds that can contribute to a sweeter sensory experience [2, 4].

Pulp and By-product Contributions

The use of coffee pulp and other by-products in processing can also introduce unique sweetness profiles. Research into coffee pulp wines has identified specific volatile compounds, such as hexanoic acid ethyl ester, which imparts a sweet apple aroma, and β-damascenone, contributing strong floral and sweet notes [4]. These compounds, derived from the pulp, can significantly modify the overall flavor perception, adding layers of sweetness that might not be present in coffees processed without these elements [4]. This suggests that the retention or utilization of certain parts of the coffee cherry during processing can directly contribute to a sweeter final product.

Exploring Natural and Washed Contrasts

The distinction between natural and washed processing methods, for example, can lead to divergent sweetness profiles. Natural processing involves drying the coffee cherry with the fruit intact, allowing for greater interaction between the fruit sugars and the bean. This extended maceration period can lead to the development of more pronounced fruity and sweet characteristics [2]. In contrast, washed processing removes the fruit before drying, often resulting in a cleaner cup with brighter acidity. While not directly a measure of sweetness, the acidity of a coffee, influenced by processing, can play a role in how sweetness is perceived. For instance, a reduction in acidity, perhaps influenced by certain fermentation protocols, can make inherent sweetness more apparent [2, 8].

Sweetness Precursors and Volatile Compounds

Ultimately, the perceived sweetness in coffee at similar roast levels is a consequence of how processing methods influence the formation and transformation of flavor precursors and volatile compounds. Techniques that encourage the breakdown of complex sugars into simpler ones, or that foster the development of specific aromatic compounds like esters and ketones, will naturally lead to a perception of increased sweetness [2, 4]. Even subtle differences in fermentation time, temperature, or the specific microbial activity involved can cascade into significant variations in the final sensory attributes [2].

In conclusion, while the roast level lays the foundation for coffee’s flavor potential, the processing method acts as a crucial sculptor, fine-tuning the expression of sweetness. From the nuanced transformations during fermentation to the direct contributions of fruit pulp, the journey from cherry to green bean actively crafts the sweet notes we detect in our cup.

References

[1] — Ernesto Illy, Luciano Navarini — Neglected Food Bubbles: The Espresso Coffee Foam. — 2011-Sep — https://pubmed.ncbi.nlm.nih.gov/21892345/ [2] — Gustavo Galarza, Jorge G Figueroa — Volatile Compound Characterization of Coffee ( — 2022-Mar-21 — https://pubmed.ncbi.nlm.nih.gov/35335365/ [3] — Katarína Poláková, Alica Bobková, Alžbeta Demianová, Marek Bobko, Judita Lidiková, Lukáš Jurčaga, Ľubomír Belej, Andrea Mesárošová, Melina Korčok, Tomáš Tóth — Quality Attributes and Sensory Acceptance of Different Botanical Coffee Co-Products. — 2023-Jul-11 — https://pubmed.ncbi.nlm.nih.gov/37509767/ [4] — Rongsuo Hu, Fei Xu, Liyan Zhao, Wenjiang Dong, Xingyuan Xiao, Xiao Chen — Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines. — 2024-Jun-27 — https://pubmed.ncbi.nlm.nih.gov/38999011/ [5] — Rongsuo Hu, Fei Xu, Xiao Chen, Qinrui Kuang, Xingyuan Xiao, Wenjiang Dong — The Growing Altitude Influences the Flavor Precursors, Sensory Characteristics and Cupping Quality of the Pu’er Coffee Bean. — 2024-Nov-28 — https://pubmed.ncbi.nlm.nih.gov/39682914/ [6] — Mackenzie E Batali, Lik Xian Lim, Jiexin Liang, Sara E Yeager, Ashley N Thompson, Juliet Han, William D Ristenpart, Jean-Xavier Guinard — Sensory Analysis of Full Immersion Coffee: Cold Brew Is More Floral, and Less Bitter, Sour, and Rubbery Than Hot Brew. — 2022-Aug-13 — https://pubmed.ncbi.nlm.nih.gov/36010440/ [7] — Zachary R Lindsey, Joshua R Williams, James S Burgess, Nathan T Moore, Pierce M Splichal — Caffeine content in filter coffee brews as a function of degree of roast and extraction yield. — 2024-Nov-25 — https://pubmed.ncbi.nlm.nih.gov/39582028/ [8] — Laudia Anokye-Bempah, Timothy Styczynski, Natalia de Andrade Teixeira Fernandes, Jacquelyn Gervay-Hague, William D Ristenpart, Irwin R Donis-González — The effect of roast profiles on the dynamics of titratable acidity during coffee roasting. — 2024-Apr-08 — https://pubmed.ncbi.nlm.nih.gov/38589450/