Enzymatic hydrolysis of starch into sugars is influenced by microgel assembly

Abstract

The use of alginate and chitosan polymer in the immobilization of Aspergillus oryzae ATCC 3940 fungal crude enzyme extract (CEE) amylase was presented. The assembly results change in the application of optimal pH and temperature hydrolysis to convert starch to sugar. Bead arrangement in three microgel supports: the internal support phase (IP), the external support phase (EP), and the internal and external support phase (UP). The best results were obtained using IP and EP. Reusing beads evaluated the stability of immobilized enzymes on IP support, remained active and bound during three cycles of reuse. For free and immobilized (IP) activity showed pH ranged from 5.0 to 7.0; optimum thermal enzymatic greater activity at 45 °C. The method of building the microgel influencing sugar reduction, in a single-step way to immobilize crude fungal amylase extracts can be used in industry.

Keywords: Alginate; Beads; Chitosan; Hydrolysis; Reducing sugars; Starch.

Scheme 1

Overall scheme of chitosan alginate bead hydrolysis.

Fig. 1

Beads produced with different combinations of alginate, chitosan, and amylases (with or without the addition of glutaraldehyde). The colored part of the beads represents the theoretical arrangement of the amylases in the beads. IP, internal phase (amylases were in the internal phase of the support); EP, external phase (amylases were in the external phase of the support); and UP, internal and external phase (amylases were both in the internal and external phase of the support).

Fig. 2

Concentrations of reducing sugars obtained in the enzymatic hydrolysis of 1% (w/v) starch solutions using the differentimmobilized amylase beads.

Fig. 3

Protein concentration in the supernatant after the beads dripping process.

Fig. 4

Reusability of immobilized amylases. (a) Concentration of residual starch obtained following enzymatic hydrolysis of a 1% (w/v) starch solution during three cycles of reuse with IP and IPG beads. ((b) Concentration of reducing sugars obtained following enzymatic hydrolysis of a 1% (w/v) starch solution during three cycles of reusewith IP beads.

Fig. 5

Effect of pH on IP, IPG beads and Free Enzyme (CEE) bead catalyzed reactions.

Fig. 6

All testes were conduced by hydrolisis of starch at temperatures ranging from 10 to 80 °C.

Fig. 7

Internal phase, internal phase and glutaraldehyde, and free enzyme are indicated in blue, red, and green, respectively. Representative FTIR results of the samples demonstrated Free enzyme (Crude enzymatic extract – CEE), shown in green, is retained in the carrier, both in IP (blue) and IPL (red).

Fig. 8

External morphology of the all formulated beads operating at 10–20 kV, with Back-scattered Electron Detector – BSED. (A) IP-magnification of 100×, (A1) IP-magnification of 1000×; (B) IPG-magnification of 100×, (B1) IPG-magnification of 1000×; (C) EP-magnification of 100×, (C1) EP-magnification of 1000× and (D) EPG-magnification of 100×, (D1) EPG-magnification of 1000×.