Antibacterial Activity of the Glucose Oxidase/Glucose System in Liquid Whole Egg.

The effect of glucose oxidase (GOX) in different GOX/glucose combinations on four commonly occurring microorganisms in liquid whole egg was evaluated. The addition of a combination of 500 U GOX and 0.5 g glucose in 100 ml liquid whole egg killed Salmonella enteritidis , Micrococcus luteus and Bacillus cereus inoculated at 103cells/ml after 5 days of storage at 7°C, and showed a bacteriostatic activity on Pseudomonas fluorescens . The latter possesses the strongest catalase activity of the four bacteria tested, enabling it to more rapidly break down the hydrogen peroxide produced enzymatically by the GOX/glucose system. The efficacy of the above-mentioned combination was tested on the natural contamination flora of liquid egg and compared to the effect of a simple β-d-glucono-δ-lactone (GDL) treatment (0.7 g/100 ml). The GOX/glucose combination prolonged the lag phase by 6 days. Subsequently, the bacterial flora started to develop, but growth remained retarded by 2 log units. Since GDL did not exert antibacterial activity, growth inhibition by the GOX/glucose system cannot be ascribed to a pH decrease as a result of the production of gluconic acid in the system.