Kinetics and model development for enzymatic synthesis of fructo-oligosaccharides using fructosyltransferase

Experimental investigations were made to synthesize fructo-oligosaccharides (FOS) from sucrose using fructosyltransferase. The influence of various parameters such as temperature (45-55 °C), pH (4-5), initial sucrose concentration (ISC: 300-500 g/L) and enzyme concentration (4-32 U/mL) were varied. A maximum FOS yield of 60% was observed at ISC 500 g/L, pH 4.5 with enzyme activity 32 U/mL and at 55 °C. It was confirmed that 1-kestose (tri-) was the major product of FOS as compared to nystose (tetra-) and fructosylnystose (penta-saccharides). Further, the reaction rate increases with increase in temperature. From separate sets of experiments, it was observed that FOS formation was affected by glucose inhibition. Apart from the increase in the rate of FOS formation with increasing enzyme activity, the final values of FOS yield increase though till 16 U/mL and thereafter attain plateau. A kinetic model was also developed, based on Michaelis-Menten kinetics, and a five-step ten-parameter model, including glucose inhibition, was obtained. Model was solved using COPASI(®) (version 4.8) solver for kinetic parameter estimations followed by time course simulations.