Maximization of fructooligosaccharide production by two stage continuous process and its scale up.

Production of fructooligosaccharides (FOS) in a 2-stage continuous process was optimized using response surface methodology and subsequently scaled up. Fructosyl transferase (FTase) was produced by growing Aspergillus oryzae CFR 202 on a sucrose-containing medium, and then employed for the production of FOS with sucrose as substrate. FOS yield was optimized using as process variables fermentation time (36-108 h), KH2PO4 concn. (0.2-1%) and sucrose concn. (1-24%) in the fermentation medium, reaction time (1-24 h) and pH of the reaction mixture (5-6). Significant effects on FOS production were noted for reaction and fermentation times compared with KH2PO4 concn., sucrose concn. and reaction mixture pH. Max. FOS yield was obtained with a fermentation time of 108 h, 0.723% KH2PO4, 6.455% sucrose, a reaction time of 18 h and a reaction mixture pH of 5.15. The model exhibited coeff. of determination of 0.97 and regression probability was 6.98 x 10-16. Good agreement was obtained between predicted and actual max. FOS yield (58.9 vs. 56.4%, w/w). Contour plots were also used to predict the experimental conditions in order to provide more options for yields of >50%. This allowed maximization of FOS yield at 58%. Scaling up FOS production to a 10 l level generated results which were similar to those obtained for the shake flask experiments.