Metabolomics and volatile fingerprint of yeast fermented robusta coffee: A value added coffee

Coffee fermentation is pivotal in post-harvest process to attain quality brew. Exploration of improved coffee profile was carried out by solid state fermentation with Yeast, Saccharomyces cerevisiae as starter (Y) on Robusta coffee (CXR variety). The microbial ecology, metabolism, volatomics and organoleptics of Y along with natural fermentation (NF) were evaluated. The proximate composition of mucilage was recorded to have 43.3 Kcal/100g. Fermentation was accelerated by Y populace (13 cfu log/g). The fermentation with Y was 52 h and NF 60h. The green beans displayed 12% moisture, uniform color, size and shape. Changes in alkaloids and chlorogenic acid content were insignificant. The GC-MS accorded additional 10 compounds in Y green coffee (GC), contributing 50.62% of total volatiles compared to NF. The aldehydes (30.1%), alcohols (13.8%), fatty acids (10.7%), and carboxylic acids (10%) are the major volatiles in Y fermented GC followed by Pyrazines and Furans in both the groups. The principal component analysis (PCA) of Y and NF volatilomics denoted 62.10% variance between GC and 99.38% in Roasted coffee (RC). The sensory contours 8 for Y, 6.5 in NF (scale of 0–10). Y can be a determining factor for flavour modulation and quality.