Investigation of Enzymatic Hydrolysis of Coffee Silverskin Aimed at the Production of Butanol and Succinic Acid by Fermentative Processes Saverio Niglio 1 & Alessandra Procentese 2 & Maria Elena Russo 2 & Giovanni Sannia 3 & Antonio Marzocchella 1 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Coffee silverskin (CSS) is an agro-food waste obtained in large amount from the roasting phase of green coffee beans. Its potential use as biorefinery feedstock together with other agro-food wastes has been suggested, even though few experimental studies proved the production of bio-commodities at lab-scale from lignocellulosic sugars from CSS. The present work mainly aims at (i) the maximization of the sugar release by CSS pretreatment and hydrolysis; (ii) the fermentation of the CSS hydrolysate in order to produce butanol and succinic acid as bio-commodities having industrial interest. Alkali-pretreated CSS was enzy- matically hydrolyzed in glass bottles on a rotary shaker. Biomass loading (5–12.5%w v -1 ) and cellulase concentration (1–80 FPU gcellulose -1 ) were the operating conditions investigated to maximize the sugar release. Biomass loading at 10%w v -1 gave the best results in terms of sugar concentration and sugar yield. Curve fitting of experimental data was performed: increasing of hydrolysis rate and sugar concentration was observed increasing cellulase concentration. Biomass loading at 10%w v -1 and enzyme loading at 80 FPU g cellulose -1 were applied to produce the hydrolysate to use as the medium for fermentation tests: the sugars from CSS were the only carbon source. The batch fermentations by Clostridium acetobutylicum DSM 792 and Actinobacillus succinogenes DSM 22257 were characterized in terms of metabolite and sugar conversion. Butanol (2.2 g L -1 ) and succinic acid (20.8 g L -1 ) were produced, respectively. The results highlight the possibility of using CSS to produce fermentable sugars, solvents, and biochemicals of industrial interest. Keywords Biorefinery . Coffee silverskin . Enzymatic hydrolysis . Fermentation Abbreviations ABE Acetone-butanol-ethanol AFWs Agro-food wastes AIL Acid-insoluble lignin ASL Acid-soluble lignin CSS Coffee silverskin SA Succinic acid YE Yeast extract Introduction The use of biomass as a sustainable renewable resource represents a promising way to shift from a fossil-based to a bio-based society [1]. The set of combined processes that allow generating energy (biofuels) and bio-products from biomass is defined as a biorefinery. The molecules extracted and/or produced from bio-based resources have attracted great attention in the last year due to their char- acteristics. Biodegradability and biocompatibility are among the main properties of the bio-based products (biofuels and biochemicals) compared to fossil-derived products [2]. Three generations of biofuels have been de- veloped during the last years. Among these, second- generation biofuels can be produced from vegetal wastes. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12155-019-09969-6) contains supplementary material, which is available to authorized users. * Maria Elena Russo m.russo@irc.cnr.it 1 Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale, Università degli Studi di Napoli Federico II, P.le V. Tecchio 80, 80125 Naples, Italy 2 Istituto di Ricerche sulla Combustione - Consiglio Nazionale delle Ricerche, P.le V. Tecchio 80, 80125 Naples, Italy 3 Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant’Angelo, Via Cinthia, 80126 Naples, Italy BioEnergy Research https://doi.org/10.1007/s12155-019-09969-6