In this study, the traditional physiological and biochemical method, a VITEK automatic biochemical analyzer, the analytical profile index (API) biochemical identification system, real-time fluorescence quantitative polymerase chain reaction (real-time PCR) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) were used comparatively to identify the species of Pediococcus spp. in food. The results showed that the traditional physiological and biochemical method was the most accurate but time-consuming and labor-intensive; the VITEK automatic biochemical analyzer gave unstable results as the database states that Pediococcus acidilactici is negative for amygdalin reaction, whereas some strains actually test positive; the API biochemical identification system yielded accurate results at 24 h of culture, while deviations occurred when the culture period was extended to 48 h; real-time PCR was time-saving, accurate, and suitable for popularization; the MALDI-TOF MS method had the shortest operation time but high equipment requirements, making it difficult to popularize in primary-level institutions. In summary, the traditional physiological and biochemical method, real-time PCR, and MALDI-TOF MS can all serve as standard methods for the identification of Pediococcus spp. in food. The results of this study can provide a technical basis for the formulation of relevant national standards.

In order to ensure the quality of raw milk and enrich quality control strains for the acceptance evaluation of culture media for the detection of coliform bacteria in raw milk, three brands of violet red bile agar (VRBA), violet red bile agar with 4-methylumbelliferyl-β-D-glucuronidehydrate (VRBA-MUG), lauryl tryptose broth (LST) and brilliant green lactose bile broth (BGLB) were selected and evaluated for their physical indicators such as appearance, pH and moisture content as well as microbial indicators such as growth rate and selectivity using the methods specified in China’s national standard for quality requirements for culture media and reagents in food microbiological examination (GB 4789.28-2013). Besides, using Citrobacter freundii ATCC 43864 as a reference strain, seven strains of C. freundii were selected for acceptance evaluation of the four media. The results showed that the color of all three brands of dry powdered media was normal. Their moisture content was 5%–6%, and their pH was in line with the national standard. The growth rate of the seven tested strains of C. freundii was greater than 0.7 on the three brands of VRBA and VRBA-MUG, while only CMCC 48098 and CICC 22910 achieved turbidity of 2 on the three brands of LST and BGLB, and produced gas in the catheter; the same results were obtained with ATCC 43864. In summary, the three brands of VRBA, VRBA-MUG, LST and BGLB all comply with GB 4789.28-2013, and CMCC 48098 and CICC 22910 can be recommended as supplements to quality control strains for the acceptance evaluation of the four media.