Biotechnological enhancement of coffee pulp residues by solid-state fermentation with Streptomyces. Py–GC/MS analysis

The ability of three Streptomyces strains to upgrade the nutritional value of coffee pulp residues from Nicaragua in solid-state fermentation (SSF) conditions was analyzed by Py–GC/MS. The presence in these residues of compounds such as polyphenols, tannins, chlorogenic acids and caffeine prevents their utilization as domestic fodder. The characteristic pyrolysis products derived from polyphenols and polysaccharides were identified both in control and treated coffee pulp being remarkable the decrease achieved in the total polyphenols derived compounds after the growth of the strains. The analysis of these compounds demonstrated that both monomethoxy- and dimethoxy-phenols were degraded. In addition, an increase in the microbial treated coffee pulp of protein content was detected by Kjeldahl method. In summary, changes evidenced in coffee pulp treated by Streptomyces through the application of analytical pyrolysis reveal the biotechnological interest of these bacteria to upgrade a usefulness and pollutant residue to be used for feeding purposes.