Fructooligosaccharides production by Aspergillus sp N74 in a mechanically agitated airlift reactor

Batch fructooligosaccharides (FOSS) production by fructosyltransferase from Aspergillus sp. N74 in a mechanically agitated airlift reactor was investigated. Two biomass concentrations (6 and 9.5 g L-1 in biomass dry weight) of Aspergillus sp. N74 were used for the evaluation of fructosyltransferase activity. The enzymatic reactions were carried out at the following conditions: initial sucrose concentration 70% (w/v), pH 5.5, 60 degrees C, 350 rpm, and superficial aeration rate 0.012 m s(-1); the reactor was operated in batch for 26 h. A biomass concentration and time reaction effect on FOS production and composition was observed. The obtained FOS yield (Y-Fos) for 6 g L-1 of biomass dry weight was 69% (43% 1-kestose and 26% nystose), while for 9.5 g L-1 of biomass dry weight a peak in the YFos of 70% was observed (43% 1-kestose, 25% nystose and 2% 1-beta-fructorianosyl nystose) after 4h of reaction, which was reduced to the 57% (18% 1-kestose, 33% nystose and 6% 1-beta-fructofuranosyl nystose) at the end of the reaction time. These results present the designed reactor and the native strain Aspergillus sp. N74 as an industrial alternative for the fructooligosaccharides production. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.