In vitro digestibility and fermentability of fructo-oligosaccharides produced by Aspergillus ibericus

The bifidogenic potential of fructo-oligosaccharides (FOS) produced by a newly isolated strain Aspergillus ibericus was studied. Their activity was compared to FOS produced by Aureobasidium pullulans and to a non-microbial commercial FOS sample (Raftilose® P95). FOS fermentability by a number of probiotic bacteria and their hydrolytic resistance to the simulated harsh conditions of the digestive system was evaluated. Aspergillus ibericus FOS sample effectively promoted probiotic bacteria growth. Overall, microbial-derived FOS promoted greater cellular growth compared to the commercial sample. FOS fermentation was both substrate and strain specific. The FOS structural differences identified may explain their distinct assimilation by the probiotics. [Fru(26)Glc] (possibly blastose) and a reducing trisaccharide (possibly [Fru(26)Glc(12)Fru], neokestose) were only found in microbial-derived FOS samples, while Raftilose® P95 was richer in inulobiose/inulotriose. 1-Kestose and nystose were only slightly hydrolyzed in the presence of gastric and intestinal fluid. FOS synthesized by Aspergillus exhibited great potential as food ingredients with likely prebiotic features.Clarisse Nobre, Sérgio Sousa, Elisabete Coelho and Ana Pinheiro acknowledge the Portuguese Foundation for Science and Technology (FCT) for their Post-Doc and Doc Grants (SFRH/BPD/87498/2012, SFRH/BD/105304/2014, SFRH/BPD/70589/2010, and SFRH/BPD/101181/2014, respectively). This study was supported by the FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte, also QOPNA research Unit (FCT UID/QUI/00062/2013) through national funds and where applicable co-financed by the FEDER, within the PT2020 Partnership Agreement, project Essence (POCI-01-0247-FEDER-010887) for financial support of Post-Doc grant of Elisabete Coelho and, multi‐purpose strategies for broadband agro‐forest and fisheries by‐products valorisation: a step forward for a truly integrated biorefinery SAICTPAC/0040/2015 (POCI-01-0145-FEDER-016403), Biomass and Bioenergy Research Infrastructure (01/SAICT/2016), also CBQF research centre by National Funds from FCT through project UID/Multi/50016/2013.