Abstract:

Glucose oxidase (GOD), together with β-galactosidase (β-GAL), was immobilized onto yeast cell wall particulates, β-cyclodextrin glutaraldehyde particulates (β-CDP) and starch glutaraldehyde adhesive respectively to construct bi-enzyme membranes, whose lactose detection performances were tested using an SBA-40C biosensor. All bi-enzyme membranes performed a good detection capability, with a linear calibration range of 0.02%－2% lactose (R2 above 0.995) and a detection limit of 0.001 g/L and had a fast response, with response time within 20－40s. Among them, bi-enzyme membranes made with yeast cell wall particulates as a carrier had the widest linear calibration range of 0－10% and therefore could be widely used for the detection of lactose in raw milk and dairy products; β-CDP bi-enzyme membranes had a strong adsorption capacity to enzyme molecules and the response values were as high as 2500; bi-enzyme membranes made with starch glutaraldehyde adhesive as a carrier had a good homogeneity and were easy to prepare and could be used to detect lactose in milk.

Key words: immobilization carrier, yeast cell wall particulates, β-cyclodextrin glutaraldehyde particulates (β-CDP), starch glutaraldehyde adhesive, lactose membrane