Study on the Enrichment Methods and Application of LAMP Technology for Detection of Listeria monocytogenes in Frozen Meat Products

In this study efficiency of four enrichment media (Fraser, Half Fraser, LB₁, LB₂) were evaluated for Listeria monocytogenes in frozen meat products, and their effects on the detection limit of Listeria monocytogenes by LAMP were assessed in frozen meat products. Combined with LAMP technology, the optimized method was applied to the detection of artificial contamination samples and samples from production line. The results showed that Half Fraser represented the best enrichment among the four media, which could increase the number of live Listeria monocytogenes from 6.4×10¹ CFU/mL to 9.4×10⁴ CFU/mL within 6 h. The detection limit of Listeria monocytogenes in frozen meat products reduced from 6.4×10⁴ CFU/g (without enrichment) to 6.4×10¹ CFU/g by LAMP with Half Fraser-enrichment. The reliability of the method was verified by using artificial contamination samples and actual samples from production line of the plant. The results obtained from Half Fraser-LAMP were consistent with the results from national standard method with an accuracy of 100%. The whole procedure of sample processing and testing was within 8 h, which could meet the on-site testing requirements of enterprises.