Effectiveness of a bacteriophage cocktail in reducing cheese early blowing caused by Escherichia coli

Gas production and subsequent food spoilage from the appearance of fissures, cracks or holes are undesirable consequences of saprophytic E. coli growth in cheese. Hence, the development of E. coli growth inhibitors is of special interest in soft and raw milk cheese production. This study investigates the inhibitory effect of a cocktail of four selected coliphages on the growth of E. coli in cheese and its ability to inhibit cheese early blowing. The microbiological analysis showed that the evolution of total bacterial counts during cheese-making and ripening was comparable among control and phage inoculated cheeses. Nevertheless these results also revealed a reduction in E. coli growth at the beginning of fermentation with phage treatment. Additionally, image analysis of cheese slices showed a noteworthy reduction in the number of cheese eyes and the area occupied by gas holes throughout cheese ripening. Thus, the use of bacteriophages as biocontrol agents provides an effective approach to combat cheese early blowing without noticeably altering the microbiological or physicochemical parameters of these fermented foods.