Bacteriophage PCSE1 as a Potential Strategy Against Enteritidis in Liquid Egg Products.

Background/objectives: The consumption of liquid egg products is rising. While thermal pasteurization improves safety and shelf life, it can affect product quality. Furthermore, egg products continue to cause many foodborne illnesses, especially those caused by subspecies serovar Enteritidis ( Enteritidis). Bacteriophages (or phages) are an effective alternative to specifically fight foodborne bacteria. This study aimed to evaluate (i) the stability of phage vB_SeEM_UALMA_PCSE1 (PCSE1) under different conditions of temperature and pH; (ii) the effect of multiplicity of infection (MOI) and temperature on phage efficacy; (iii) the bactericidal effect of phage PCSE1 against Enteritidis in liquid whole eggs compared to thermal pasteurization; and (iv) the effect of both treatments on the physicochemical and functional properties of liquid whole eggs.

Methods: For this, stability tests, bacterial growth inhibition assays in culture media and liquid eggs, and physicochemical and functional analyses were conducted.

Results: Phage PCSE1 was (i) stable at pH 7 and 8, and at 4, 25, and 37 °C for 56 days; (ii) effectively prevented Enteritidis growth in TSB (reduction of 1.8, 4.5, and 4.5 log colony-forming units (CFU)/mL at 4, 10, and 25 °C, respectively, relative to the bacterial control); (iii) controlled Enteritidis in liquid whole eggs at 25 °C (reduction of 5.8 log CFU/mL relative to the bacterial control) comparable to pasteurization (reduction of 5.2 log CFU/mL); and (iv) preserved eggs' properties, contrarily to pasteurization.

Conclusions: These findings suggest PCSE1 is a promising strategy to fight Enteritidis in liquid egg products, though further studies on shelf-life are needed.