In this study, an instant quality control sample for the detection of Salmonella enteritidis in meat products by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was developed. The homogeneity and stability of the quality control sample were verified by culture counting, MALDI-TOF-MS analysis and statistical analysis. The quality control sample was found to be white in color and spherical in shape. In the homogeneity test, the results of culture counting showed F = 0.75, which is less than the critical value, indicating that the homogeneity is consistent. The transport stability test showed that the number of viable bacteria in the quality control sample was stable and grew well at 37 and 25 ℃. The storage stability test showed that the resuscitation rate of the quality control sample was 90.6% after 28 days of storage at −20 ℃ and 89.0% after 28 days of storage at 4 ℃, indicating that the sample was stable in nature and could be stored stably for a long period of time. Similarly, the results of each MALDI-TOF-MS cycle were stable. In conclusion, the instant quality control sample for the rapid detection of S. enteritidis developed in this study has good homogeneity and stability, and can be used as a positive quality control sample for the detection and quality control of S. enteritidis.

In order to improve the detection efficiency of molds and yeasts in low-temperature yogurt, primers and probes were designed according to the sequences of the conserved gene elongation factor-1α (EF-1α) for molds and yeasts, respectively. A real-time fluorescence quantitative polymerase chain reaction (real-time PCR) method with TaqMan probe was established for the detection of molds and yeasts, respectively. The genomic DNA of fungi and lactic acid bacteria commonly found in low-temperature yogurt, were used as amplification templates for specificity testing. The sensitivity and repeatability were also tested, and the standard curves were constructed. The results showed that the designed primers and probes had good specificity; the sensitivity of the method was 10¹ and 10² CFU/mL for yeasts and molds, respectively; the coefficients of variation within and between groups in the repeatability test were less than 2%, indicating good reliability and stability; the correlation coefficients of the standard curves were higher than 0.99. Therefore, the real-time PCR method enables the rapid detection of molds and yeasts in low-temperature yogurt.