Inulinase immobilisation in PAA/PEG composite for efficient fructooligosaccharides production

Abstract

Inulinase was immobilised by entrapment method in polyacrylamide/polyethylene glycol composite and evaluated for its efficiency for short-chain fructooligosaccharides (3–6 degrees of polymerisation) production in batch hydrolysis system. Aqueous two-phase polymerisation technique was used to synthesise the composite, where aqueous polyethylene glycol 1000 containing the enzyme was used as dispersant with ammonium persulfate as initiator. The characteristics of free and immobilised inulinase were investigated and compared, and the results showed shift of pH and temperature optimum and change in stability caused by the immobilisation material. The immobilised preparation retained 50% of its initial activity after 20 successive batch cycles of 1 h each. The conversion degree of highly polymerised inulin to fructooligosaccharides (3–6 degrees of polymerisation) was 36% when using 30% PAA/PEG, w/v.

Highlights

• ATPS extracted inulinase was effectively immobilised in PAA/PEG composite.

• Immobilised enzyme showed good pH and thermal stability.

• Immobilised catalyst presents good retention of activity after 20 reuses.

• The entrapped enzyme is effective in producing FOS with the DP from 3 to 6 with proved prebiotic activities.

• The optimum conditions for batch operating mode were: 2% (w/v) inulin, 30% (w/v) PAA/PEG composite, pH = 4.4 and T = 40ºC.

Keywords:

• Inulinase
• immobilisation
• fructooligosaccharides
• polyacrylamide/polyethylene glycol composite
• characterisation

Disclosure statement

The authors have declared neither conflicts of interest nor competing financial interests. All authors have approved the manuscript.

Additional information

Funding

This work has been funded by Bulgarian National Science Fund under Project DN 06/11.