Screening for Green Coffee with Sensorial Defects Due to Aging During Storage by MALDI-ToF Mass Fingerprinting

The sensorial quality of coffee can be impaired by prolonged storage. Aged coffee presents an off-note taste which is called “rested coffee flavor.” This quality reduction is accompanied by changes of the lipid profiles. Therefore, we tested the suitability of MALDI-ToF mass fingerprinting to discriminate between unrested (“fresh”) and rested Colombian Arabica (Coffea arabica) coffee samples. The samples represented different varieties, geographic regions, and processing. With an optimized sample preparation and data processing protocol, we obtained informative mass profiles of coffee oil. Principal component analysis (PCA) was insufficient to classify between unrested and rested samples. Thus, we developed a Random Forest model, which demonstrated a specificity of 72% to detect rested coffee across different days of sample analysis. For individual measurement days, 85–92% specificities were obtained. The high throughput of MALDI-ToF mass fingerprinting enables the broad screening of green coffee materials for quality monitoring and shelf-life studies.