In this study, we examined rapid assay for coliforms test (presumptive test) using Petrifilm^TM RCC plates for cow milk and milk beverage. The study was conducted on 50 different coliforms and we checked how many hours the RCC plate could determine the coliforms using desoxycholate agar medium (20±2 hr incubation) as a control.

As a result, it was confirmed that 12 hr incubation on RCC plates was equivalent to make a positive determination of the coliforms presumptive test when freshly cultured bacteria were used. However injured bacteria were not considered. Further investigation of applying real food samples is needed.

While lactic acid bacteria are used in the production of fermented foods, they are also known to contaminate foods and cause spoilage, characterized by a sour taste and odor. Despite the availability of numerous commercially available media for lactic acid bacteria detection, their selectivity is low, allowing for the growth of microorganisms other than lactic acid bacteria. In this study, we investigated modifications to LA broth, an effective broth for detecting lactic acid bacteria, with the aim of expanding its use by selectively detecting lactic acid bacteria. First, we investigated the concentration of organic acid salts added to the broth using the bacterial strains. Next, the selectivity of the modified LA broth supplemented with organic acid salts for lactic acid bacteria was evaluated using commercially available foods and swab samples from plants. It was observed that the addition of sodium acetate and potassium sorbate to the LA broth created conditions for the detection of lactic acid bacteria, without interference from any other microorganisms. Based on these results, the modified LA broth was considered useful for the selective detection of lactic acid bacteria.