By Emma Bladyka, Coffee Science Manager, SCAA
Coffee is what is known in the food science field as a shelf-stable product, which after roasting does not spoil due to enzymatic or microbial processes (Illy and Viani 2005; Nicoli and others 1993; Anese and others 2006). However, in the specialty coffee industry, we are aware of the importance of chemical reactions and physical changes that occur after roasting (Nicoli and others 2009). Some of these changes are responsible for staling, or a perceptible negative flavor that increases over time, and affects the quality of the brew.
Capturing the exact nature, quantity and rate of staling is inherently challenging due to both to the diversity of flavors possible in the bean itself, and of the ephemeral nature of roasted coffee. The Specialty Coffee Association of America (SCAA) water quality handbook states “coffee’s flavor potential is constantly changing. As a result, when conducting a chemical or sensory analysis, coffee must be considered a moving target” (Beeman and others 2011). This concept epitomizes the problem with defining the science behind staling. The chemical and physical changes that occur in coffee after roasting make experimental control, repeatability, and data analysis all but impossible. However, this has not stopped a large cohort of researchers from tackling the challenge.