Advanced instrumental characterization of the coffee extracts produced by pilot scale instant coffee process

Coffee, with production exceeding 10.3 million tonnes in 2018, is one of the most widespread commodities consumed world-wide. One of the increasingly popular coffee products is instant coffee, with consumption exceeding 1.6 million tonnes in 2017. In this work, we present how the combination of H-1 NMR and GC-MS allows the characterization of samples from the small pilot-scale instant coffee process. Results were compared with measurements for filter coffee made from the same coffee beans to better evaluate the effects of processing. In the coffee extracted at lower temperatures, a higher concentration of aroma compounds can be detected. This is particularly the case for compounds responsible for earthy (pyrazines) and woody (guaiacols) aroma notes. Also, for the coffee extracted at the highest temperature, a higher level of cyclotene giving undesired burnt and bready aroma is seen. The caffeine content in instant coffees was lower than in the filter coffee (49 +/- 13 up to 62 +/- 5 mg/100 mL brew for instant compared with 84 +/- 15 mg/100 mL brew for filter coffee). The same was observed for acetic acid, while the concentrations of citric and quinic acids are lower in the filter coffee than in the reconstituted instant coffee.

Automated summary

The production and characteristics of instant coffee are affected by the extraction temperature, with lower temperatures yielding higher concentrations of aroma compounds, and higher temperatures resulting in undesired burnt and bready aromas. Instant coffees have lower caffeine and acetic acid levels compared to filter coffee, while citric and quinic acid concentrations are lower in filter coffee.