Continuous production of inulo-oligosaccharides from chicory juice by immobilized endoinulinase

Abstract

Several carrier materials were examined for endoinulinase immobilization. A polystyrene carrier ma- terial (UF93 " ) gave the best immobilization capacity (217 units/g carrier) and operational stability. Carbohy- drate compositions in the reaction product were quite similar irrespective of the support materials even though each carrier material has different pore structure associ- ated with diffusional restriction. After immobilization the optimal pH for enzyme activity was shifted from 5.0 to 4.5, whereas optimal temperature (55 ∞C) was unaltered. Con- tinuous production of inulo-oligosaccharides from chicory juice was carried out using the polystyrene-bound endo- inulinase. The recommended operating conditions of the enzyme reactor for maximizing productivity were as fol- lows: feed concentration, 100 g/l chicory juice; flow rate, as superficial space velocity 2.0 h )1 ; temperature, 55 ∞C. The enzyme reactor was run for 28 days at 55 ∞C achieving an oligosaccharide yield of 82% without any significant loss of initial enzyme activity, where the volumetric productivity was 200 g/l AE h. Furthermore, there was no marked dif- ference in operational stability between the two reactors fed with pure inulin solution and with chicory juice as a substrate even though chicory juice contains a lot of im- purities.