Abstract
Although from a food safety point, coffee is considered a shelf-stable product, changes in volatiles over time due to out-gassing and chemical reactions lead to perceivable differences in coffee aroma and “freshness”. Previous studies have looked at the impact of storage conditions on ground or brewed coffee. This study seeks to answer the question of how coffee consumers perceive the smell of coffee grounds of whole beans that have been stored under different conditions: freezer vs. room temperature for 9 weeks compared to a newly roasted control (stored for 1 day). Green beans from the same production lot were roasted to two different levels to also evaluate the impact of roast level on aroma changes. Using projective mapping (PM) followed by ultra-flash profiling (UFP), 48 coffee consumers evaluated, using only smell, 6 different freshly ground coffee samples presented in blind duplicates. In parallel, the profiles of 48 previously reported important coffee volatiles were measured by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) to relate chemical changes to perceivable sensory aroma changes. Overall, consumer product maps mimicked the instrumental measurements in that the lighter roast coffees showed smaller changes due to storage conditions compared to the dark roast samples. Consumers also perceived the frozen dark roast samples to be more similar to the newly roasted control than the samples stored at room temperature.
Highlights
Coffee consumption is a common ritual among a variety of cultures throughout the world.Aside from the energizing effects of caffeine, brewed coffee contains a complex mixture of tastes and aromas that make up the sensory experience of its unique flavor [1]
From a food safety point, coffee is considered a shelf-stable product, changes in roasted coffee aroma over time due to out-gassing and chemical reactions lead to perceivable differences in coffee aroma and “freshness” [4,6]
While previous studies looked at the impact of storage conditions on ground or brewed coffee, this study used coffee consumers to determine the impact of the roast level and storage conditions on the aroma of freshly ground coffee beans
Summary
Coffee consumption is a common ritual among a variety of cultures throughout the world.Aside from the energizing effects of caffeine, brewed coffee contains a complex mixture of tastes and aromas that make up the sensory experience of its unique flavor [1]. Many of the chemical compounds that contribute to the flavor of coffee are produced during roasting. The specific products of these reactions depend on the chemical makeup of the coffee beans and parameters in the roasting process, such as time and temperature. There is a growing industry of coffee producers who focus on roasting single-origin beans with specific roast parameters in order to highlight flavors and aromas that are unique to those beans. Producers of these specialty coffees suggest that their product is consumed within a few weeks in order to experience some aromas that can quickly dissipate during storage [4,5]
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