This work is focused on the synthesis of the fructooligosaccharides (FOS) from 
sucrose and inulin, using free, immobilized and pre-treated immobilized 
inulinase from Kluyveromyces marxianus NRRL Y 7571 and Aspergillus niger in an 
aqueous-organic system. Initially, the influence of pre-treatment using four 
different gases, propane, n-butane, CO(2) and liquefied petroleum gas (LPG), was 
investigated towards FOS production and best results were found when both 
enzymes were previously treated with LPG. The best reaction yields were obtained 
when the immobilized enzymes were treated with LPG. Considering FOS synthesis 
using the enzyme from A. niger, yields of 26.62% of GF2 (kestose), 30.62% of GF3 
(nystose) and 8.47% of GF4 (fructosyl nystose) were achieved using sucrose as 
substrate. Using inulinases from K. marxianus NRRL Y 7571, 11.89% of GF2 and 
20.83% of GF3 were obtained, using inulin as substrate. However, promising 
results were achieved using the free form of inulinase from A. niger (77.19% of 
GF2; 14.03% of GF3 and 0.07% of GF4) using inulin as substrate.