Valorization of food processing wastes into the fucose-rich polysaccharide FucoPol

• Autor(a) principal: Freitas, Patrícia Castelo de
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/85966
• topic: Exopolysaccharide; FucoPol; Enterobacter A47; Food processing wastes; Subcritical water; Acid hydrolysis; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

The bacterium Enterobacter A47 is an exopolysaccharide (EPS) producer that has demonstrated the ability to use different carbon sources. It produces a fucose-rich exopolysaccharide, named FucoPol that is composed of fucose, glucose, galactose and glucuronic acid. This polymer has interesting properties at rheological, flocculation and emulsifying levels. In this work, apple pomace and grape pomace, two wastes generated by the beverage industry were tested as substrates for the cultivation of Enterobacter A47. Both wastes are rich in sugars, with low nitrogen content, which makes them suitable for production of FucoPol. The soluble fraction of apple pomace, obtained by centrifugation of the waste, resulted in the production of 6.10 g/L of EPS within 32 h of fed-batch cultivation, which corresponds to a volumetric productivity of 5.63 g/L.d. The use of filtered soluble fraction in batch mode resulted in a similar volumetric productivity but the polymer yield on a sugar basis was improved to 0.24 g/g. Grape pomace was processed into two sugar-rich materials using hot compressed water (HCW) and dilute acid hydrolysis. The HCW extract was not suitable for EPS production due to its low simple sugars concentration, but the acid hydrolysate resulted in the production of 3.92 g/L of EPS within 31 h of cultivation and a high polymer yield on a sugar basis of 0.39 g/g. The EPS produced was composed of fucose (39-42 mol %), glucose (27-29 mol %), galactose (26-27 mol %) and glucuronic acid (4-5 mol %), which is similar to the typical FucoPol composition, thus demonstrating that the polymer was not significantly affected by the use of the different substrates. The results obtained demonstrated that apple pomace and grape pomace can be used for the production of FucoPol, reaching high volumetric productivities, without impacting on the polymer’s composition. Since both substrates are low-cost, their use can contribute for the reduction of the production costs.