Fig 1.
Reaction scheme of ortho-nitrophenyl-β-D-galactopyranoside (ONPG) hydrolysis in the presence of β-galactosidase as a biocatalyst.
Fig 2.
Response obtained in tests of β-galactosidase solutions at different concentrations; test time 10 min; enzyme concentrations 1.0–100 mg.L-1.
Fig 3.
Visual response obtained after different times in the hydrogel-based test with immobilized ONPG performed for β-galactosidase in the concentration range of 5.1–323 mg.L-1.
Fig 4.
Visual response obtained after different times of the hydrogel-based test with immobilized ONPG, performed to test for β-galactosidase in the concentration range of 0.6–5.1 mg.L-1.
Fig 5.
Visual response obtained after different times in the hydrogel-based test with immobilized ONPG performed at a constant concentration of β-galactosidase (82 mg.L-1) prepared in a pH range from 4.0 to 9.0.
Fig 6.
Storage stability of ortho-Nitrophenyl-β-D-galactopyranoside (ONPG) in native form and immobilized in the gelatine-based hydrogel matrix.
Conditions: 4°C, 1–20 days.
Fig 7.
Storage stability of hydrogel-based test with immobilized ONPG.
Conditions: 4°C, 1–90 days. Test properties were examined by carrying out the β-galactosidase detection assay for 5 and 10 minutes.