Development of a magnetic separation method for rapid isolation and enrichment of bacteria in raw pork using chitosan functionalized magnetic Fe3O4@MIL-100(Fe) composites

In this study, a pretreatment method based on a magnetic capture probe for the rapid isolation and enrichment of bacteria from raw pork was developed. The chitosan immobilized Fe 3 O 4 @MIL-100(Fe) was prepared as a capture probe for total bacterial counts through the electrostatic interaction of positively charged chitosan and the negatively charged substances on the surface of bacteria. The interference of matrix in pork samples on this method was studied and removed by differential centrifugation. The results showed the capture probe had a great selectivity binding and magnetic separation properties for the tested six common bacteria in pork. Under the optimal conditions, the capture efficiency of the bacteria (10 5 CFU mL −1 ) from pork surface samples was all above 90%. The capture efficiency of the bacteria in a homogenate system was greatly decreased due to the interference of sarcoplasmic protein and myofibrillar protein in pork. The matrix effect was mitigated by a differential centrifugation method, and the capture efficiency of all six bacteria was >80%. The developed magnetic separation method took 40 min and showed good isolation and enrichment properties of bacteria. Thus, the proposed method is expected to provide a simple, convenient, and time-saving pretreatment method for the detection of total bacterial counts in pork.