Glutaraldehyde functionalization of halloysite nanoclay enhances immobilization efficacy of endoinulinase for fructooligosaccharides production from inulin

Abstract

Current work describes the enhancement of immobilization efficacy of Aspergillus tritici endoinulinase onto halloysite nanoclay using crosslinker glutaraldehyde. Under statistical optimized immobilization conditions, viz. glutaraldehyde 1.50% (v/v), enzyme coupling-time 2.20 h, glutaraldehyde activation-time 1.00 h and endoinulinase load 50 IU, maximum activity yield (65.77%) and immobilization yield (82.45%) was obtained. An enhancement of 1.15- and 1.23-fold in both enzyme activity yield and immobilization yield of endoinulinase was observed, when compared with APTES-functionalized halloysite nanoclay immobilized endoinulinase. Immobilized biocatalyst showed maximum activity at pH 5.0 and temperature 60 °C with broad pH (4.0–8.5) and temperature (50–75 °C) stability. Further, optimal hydrolytic conditions (inulin concentration 8.0%; endoinulinase load 80 IU; agitation 125 rpm and hydrolysis-time 13 h) supported fructooligosaccharides yield (95.44%) in a batch system. HPTLC studies blueprint confirmed 95.44% fructooligosaccharides containing 35.41% kestose, 26.19% nystose and 9.69% fructofuranosylnystose. The developed immobilized biocatalyst shown good stability of 8 cycles for inulin hydrolysis.