Abstract
In order to improve its stability and catalytic rate in flour, the immobilization of glucose oxidase (GOX) was investigated in this work. The enzyme was encapsulated in calcium alginate-chitosan microspheres (CACM) using an emulsification-internal gelation-GOX adsorption-chitosan coating method. The interaction between alginate and chitosan was confirmed by infrared spectroscopy (IR). The resultant CACM in wet state, whose morphology was investigated by scanning electron microscopy (SEM), was spherical with a mean diameter of about 26 μm. The GOX load, encapsulation efficiency and activity of the CACM-GOX were influenced by concentration of chitosan, encapsulation time and encapsulation pH. The highest total enzymatic activity and encapsulation efficiency was achieved when the pH of the adsorption medium was near the isoelectric point (pI) of GOX, approximately pH 4.0. In addition, the molecular weight of chitosan also evidently influenced the encapsulation efficiency. Storage stabilities of GOX samples were investigated continuously over two months and the retained activity of CACM-GOX was 70.4%, markedly higher than the 7.5% of free enzyme. The results reveal the great potential of CACM-GOX as a flour improver.
Highlights
Applying enzymes instead of chemical oxidants is a very interesting option to improve the bread-making performance of dough since they are considered as natural and non-toxic food components
Wet Calcium alginate (CaAlg) beads presented as spherical by optical micrographs (Figure 1a), calcium alginate-chitosan microspheres (CACM) coated with chitosans of 0.5% and 1.0% showed similar spherical shape (Figure 1b,c), while the existence of clustered alginate microspheres surrounded by chitosan coacervates was observed by microscope during coating CaAlg beads with chitosan of 2.0% (Figure 1d)
The necessary conditions for successful encapsulation of Glucose oxidase (GOX) into CACM microspheres using an emulsification-internal gelation-enzyme adsorption-coating by chitosan method with high residual activity had been established
Summary
Applying enzymes instead of chemical oxidants is a very interesting option to improve the bread-making performance of dough since they are considered as natural and non-toxic food components. Glucose oxidase (GOX) (EC 1.1.3.4) is the preferred enzyme alternative to chemical oxidizing agents for bread improvement and has been cited for commercial use. It is a dimeric protein with a molecular weight of 160 kDa, containing one tightly but noncovalently bound flavin adenine dinucleotide (FAD) per monomer as cofactor and glycosylated with a carbohydrate content of 16% (w/w). In the presence of oxygen, GOX catalyzes the oxidation of β-D-glucose to β-D-gluconolactone and generates hydrogen peroxide (H2O2). The generated H2O2 is able to oxidize thiol groups into disulfide bonds and catalyze the water-soluble pentosans in the dough to gel in the presence of peroxidase, which explains its improving effect on wheat flour [1,2,3,4,5,6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
