Antibacterial activity of the glucose oxidase/glucose system in liquid whole egg

Abstract

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 103 cells/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-5-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. Copyright © International Association of Milk, Food and Environmental Sanitarians.