lactis β-galactosidase was determined. The optimum substrate of the enzyme

interchanged from lactose to sucrose when it reacted with a certain concentration of

glutaraldehyde. Its mechanism was studied by detecting the changes in fluorescence

absorption. This is the first discovery that β-galactosidase can be converted to another

kind of enzyme which can catalyze sucrose to produce glucose rather than lactose. On

the basis of this phenomenon, an amperometric sucrose biosensor using β-galactosidase

modified by glutaraldehyde as the immobilized enzyme and poly-β-cyclodextrin as the

carrier was prepared. The response characteristic of the sucrose biosensor was also

studied. Under optimum conditions, the current response had a linear relationship with

the sucrose concentration in the range of 0–2 g/dL with a correlation coefficient of 0.9996

and a response time of < 30 s. The sucrose biosensor exhibited excellent diffusion and

stability, and retained its sensitivity after 7 d of continuous use. This sucrose biosensor

is expected to provide an effective and economical alternative for the quick and sensitive

detection of sucrose in the food and beverage industries in the future.