Solid-state fermentation as a sustainable method for coffee pulp treatment and production of an extract rich in chlorogenic acids

[Display omitted] •Saccharomyces cerevisiae was used to ferment coffee pulp.•Fermentation was investigated at laboratory scale and validated at pilot scale.•Fermentation increased chlorogenic acid content up to 400% in coffee pulp extract.•Sulfite at 0.5 wt% was selected to stabilize phenolics during the fermentation.•Use of ultrasounds was unable to enhance chlorogenic acid extraction. In this study, coffee pulp was used as carbon source in solid-state fermentation to produce a phenol-rich extract for industrial applications. Fermentations were carried out at laboratory (0.4 kg), semi-pilot (12 kg) and pilot (90 kg) scales in presence of 2.5 g kg−1 yeast strains and with three different coffee pulp materials. The extract stability was investigated using different stabilizing agents: SO2, ascorbic and acetic acids. Then, a study was conducted to determine the effect of ultrasound treatment on extraction yields. Results showed that higher concentrations of chlorogenic acids were obtained with fermentation without ultrasound treatment and by adding sulfite at 0.5 wt% at 8 h of fermentation. Despite of variations in coffee pulp composition, the process was validated at semi-pilot and pilot scales, providing an extract 400% richer in chlorogenic acids (600 mg kg of coffee pulp) and with lower sugar amounts to separate during the downstream processing.