Identification of subthreshold chlorogenic acid lactones that contribute to flavor instability of ready-to-drink coffee

Abstract

Flavor instability of ready-to-drink (RTD) coffee during storage negatively impacts product quality. Untargeted liquid chromatography/mass spectrometry (LC/MS) analysis was applied to identify chemical compounds that degraded during storage and impacted the flavor attributes of RTD coffee. LC/MS chemical profiles of non-aged and aged coffee samples were modeled against the degree of difference sensory scores by orthogonal partial least squares with good fit (R²Y = 0.966) and predictive ability (Q² = 0.960). The top five predictive chemical features were subsequently purified by off-line multidimensional Prep-LC, revealing ten coeluting chlorogenic acid lactones (CGLs) compounds that were identified by LC/MS and nuclear magnetic resonance (NMR). The concentrations of eight CGLs significantly decreased in the coffee during the 4-month storage. Sensory recombination testing revealed the degradation of 3-O-caffeoyl-ɣ-quinide and 4-O-caffeoyl-ɣ-quinide significantly impacted the flavor stability of RTD coffee at subthreshold concentrations.

Keywords: Chlorogenic acid lactones; Degree of difference sensory evaluation; Flavor stability over storage; Ready-to-drink coffee; Untargeted chemical profiling.