Novel processes and products from Mediterranean Biomass within the biorefinery framework

Doutoramento em Engenharia Florestal e dos Recursos Naturais / Instituto Superior de Agronomia. Universidade de LisboaIn the present context of environmental threats and the desired adoption of bioeconony, full resource use and sustainability principles, the valorisation of residual biomass to obtain value-added products within the biorefinery framework is showing has shown a great potential. In this work, a valorisation strategy centred on hemicellulosic oligosaccharides (OS) was developed using several forest, agricultural and agro-industrial residual materials relevant in the Mediterranean region, and in particular in the montado ecosystem, namely pine nut shells, almond shells, corncobs and extracted olive pomace. Autohydrolysis, microwave-assisted autohydrolysis and propylene glycol organosolv (PG-organosolv) processes were used for OS production with different process severity factors and the hydrolysate liquors were analysed for OS, monosaccharides, acids and furans. Comparing with PG-organosolv, autohydrolysis allowed a more selective removal of hemicelluloses. Overall, all the materials tested allowed the production of OS and optimal conditions with low monosaccharides and furan content could be selected. Microwave assisted autohydrolysis had a 15% better results for OS concentration and yield. The produced OS showed temperature (37 ºC / 100 ºC) and pH (1 and 11) stability and have therefore commercial potential. Different microwave heating conditions were tested, and the production of OS was favoured by slow heating, when the process is carried out under industrially relevant conditions (non-isothermal). Autohydrolysis liquors from corncobs with a high xylo-oligosaccharides (XOS) content were produced and used as growth media for Lactobacilli. Strain screening was carried out and six strains were selected that effectively assimilated XOS, thus being potentially considered probiotic strains. The best performing strains were inoculated in autohydrolysis OS-rich liquors from coffee grounds to obtain a symbiotic coffee-flavoured beverage.N/