Production of fructo-oligosaccharides has received particular attention
recently due to its beneficial effects as prebiotics. Fermentative processes
appear to be a good technique for large scale production of FOS. However,
the result of such fermentations is a complex mixture containing salts and
low molecular weight sugars that do not contribute to the beneficial
properties of the higher molecular weight oligosaccharides, and so have to
be eliminated. Among the several strategies being studied to solve this
problem, the adorption onto activated carbon is a promising technique that
still requires further development. Thus, the aim of this work was the
purification of FOS from a fermentation broth using charcoal filters.
Microfiltration membranes (0,20 micrometers) were successfully used to
separate the biomass; nevertheless salts and other small sugars had to be
eliminated using a charcoal filter. Hence, 200 mL of fermentative broth
(without cells) was passed through the filter. Subsequently, the filter was
washed with water removing the salts and small sugars present in the
mixture. The oligosaccharides adsorbed onto the charcoal filter were
recovered using a 44% ethanol solution. An increased purity, from 30% to
97% (w/w) in total sugars, was achieved using this downstream process, as
compared to the initial mixture. The results gathered in this work suggest
that charcoal filters are a promising technology for the purification of FOS
from fermentation mixtures at an industrial scale, making clear the need for
further work in order to optimize this process
