In the present study, an established multiplex PCR method was firstly applied to simultaneously identify pork, beef, chicken and mutton in meat products. Although this method was effectual toassay ordinary foods, it was not sensitive enough to identify further-processed ones. So, two strategies were attempted to increase the sensitivity of multiplex PCR: shortening primers and semi-nested multiplex PCR. When the primers of multiplex PCR were truncated to approximate 20 bp, it’s hardly to match good
specificity and identical efficiency on different templates. In contrast, semi-nested multiplex PCR exponentially reduced LOD, and was practical in the assay of further-processed foods.