In the future, Q grading may become an obsolete profession…for humans that is.
Typically, a buyer and “Q grader” will travel to the coffee plantation known as the origin to sample and then procure product for future shipment. Coffee cupping, or tasting, is the practice of noting the flavors and aromas of brewed coffee. It is a professional discipline, but can be done spontaneously by anyone or by professionals known as “Q graders”. This pre-sale process involves the roasting and tasting of all types of beans being considered before the final transaction is made.
This is a necessary, but expensive and time consuming process in the coffee business. However, with investments being made in tasting technology, the future need for highly experienced & (expensive to retain) “Q graders”/buyers could be in decline.
By studying the metabolites in high-quality beans, Suntory has developed a method to predict taste based on particular qualities they possess.
Beans that are at the height of their maturity (before they become overripe) produce coffees that taste more luscious than less ripe beans. In studying the various dimensions of metabolites in raw beans, Suntory found that “the maturity of raw beans could be predicted by looking at the amount of tryptophan they contained (immature fruits contain higher amounts of the amino acid tryptophan, which decreases as they mature). Higher amounts of tryptophan lead to unpleasant flavors in brewed coffee. In addition to this, they found that raw beans with high glycoside content tasted better when brewed.
The ability to determine coffee character before roasting and cupping would make the buying process that much more objective and easier, as it wouldn’t be dependent on the subjective sensory analysis of the evaluator.
Though most graders/buyers receive extensive training and cupping experience, they still have their own unique sensitivities, and ultimately receive training that varies in standardization and quality, meaning reliable results can vary. To overcome these limitations, Suntory created “an objective scale of taste not dependent on human sensation.”
Because coffee flavor develops from modifications to a large amount of metabolites in the green bean during the roasting process, the type and amount of metabolites in the raw product really matters. Finding the crucial metabolite that could predict coffee quality from raw beans is key. However, the metabolites that have the most impact on the taste of brewed coffee are sometimes found in small numbers, hence the need for a highly delicate measuring device. Using a medical diagnostic technique called metabolomics, Suntory, in collaboration with Dr. Hiroyuki Wariishi from Kyushu University, made it possible to analyze even the subtlest differences in thousands of coffee bean metabolites.
These technological advancements could allow for more consistency and ease in the selection of high quality raw coffee beans, and also make it possible to adjust “the relative amounts of the components that determine taste”.
“Generally, the quality of coffee beans is based on seller criteria, such as distribution prices and the grades given to different production areas. If we, as buyers of raw ingredients, have our own indicators to judge taste, we will be able to develop products that take advantage of certain bean characteristics.”