[Effect of the diluent on the aerobic bacterial count in raw minced meat and similar meats (author's transl)].

A report on the changes in the aerobic bacterial count in commercial minced meat, which appear when samples, decimally diluted with 0.85 per cent sodium chloride or with 0.85 per cent sodium chloride plus peptone (peptone physiological saline solution, p.ph.s.s.) are stored at room temperature for some time. When the higher dilutions (10(5) to 10(7) inclusive) were stored for periods of thirty minutes and more, significantly higher counts were recorded on using p.ph.s.s. and significantly lower counts were observed on using sodium chloride. Significantly higher counts were produced, however, when the two diluents were used following storage of the lowest dilution (10(1)) for a similar period. The dilutions have to be mixed again after each period of storage. The presence of "sublethally injured" bacteria in commercial minced meat is discussed. These bacteria may recover when a diluent having a sufficiently protective effect is used. Substances from the natural substrate are probably still active at the lowest dilution. A number of the injured bacteria which fail to multiply when the pour-plate method is used, will probably be able to produce colonies when the streak-plate method is adopted as more oxygen will be present in this case. Even when a rapid procedure is used in examining the samples (mixed agar method), the average number of colonies produced on using sodium chloride will be significantly smaller than that produced when p.ph.s.s. is used.