Microbial investigation of industrial liquid egg white

Although egg white is known as expressing efficient antimicrobial properties under physiological conditions, little is known on the microbial quality of industrial egg white. This issue is of great importance when egg white enters into the composition of highly perishable products, such as chilled egg-based desserts. Due to the high thermo-sensitivity of its constitutive proteins, liquid egg white is stabilized at low heat-treating times and temperatures (2 to 6 min at 55°C to 57°C in France). The remaining of heat-resisting bacteria may shorten the shelf-life of the desserts, with damaging health and economical consequences. The objective of this study was to investigate the microbial quality of raw and pasteurized liquid egg white products collected in a French company at two consecutive warm and cold seasons. A total of 63 samples were analyzed, including 30 raw and 33 pasteurized (at 57°C for 6 min) liquid egg white products. The level and type of bacterial contamination was evaluated by pour-plating in PCA (incubation for 24h at 30°C under aerobic conditions) and 16SrDNA sequencing of the colonies. The average counts were fairly low and a broad range of population was highlighted from one sample to another, namely 1.7 ± 1.6 log CFU/mL