Impacts of clarification techniques on sample constituents and pathogen retention

Authors: Armstrong, Cheryl; Gehring, Andrew; Paoli, George; Chen, Chinyi; He, Yiping; Capobianco, Joseph

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2019
Publication Date: 12/3/2019
Citation: Armstrong, C.M., Gehring, A.G., Paoli, G., Chen, C., He, Y., Capobianco Jr, J.A. 2019. Impacts of clarification techniques on sample constituents and pathogen retention. Foods. https://doi.org/10.3390/foods8120636.
DOI: https://doi.org/10.3390/foods8120636

Interpretive Summary: The sensitive detection of foodborne bacterial pathogens can be hampered by components within complex food matrices. Thus, several different methods have been developed to clean up samples prior to pathogen detection. The present study employs a systematic approach to compare the effects of four different techniques on pathogen recovery and the composition of the sample matrix. One outcome of this study is the discovery that the application of specific sequential sample processing methods can be employed to improve overall recovery of pathogenic bacteria. The results of the study will provide a reference framework to scientifically guide the pairing of the requirements of the downstream detection method with the most advantageous sample preparation techniques.

Technical Abstract: Determination of the microbial content in foods is important not only for safe consumption but also for food quality, value, and yield. There are a variety of molecular techniques currently available for both the identification and quantification of the microbial content within a sample; however, successful sample preparation often dictates the applicability of a given technique when investigating complex matrices such as foods. Because of the importance of sample preparation, the present study employs a systematic approach to compare the effects of four different separation techniques (glass wool, 50 µm polypropylene filters, graphite felt, and continuous flow centrifugation) on sample preparation. In order to define the physical effects associated with the use of these separation methods, a multifactorial analysis was performed where particle size and composition, both pre- and post- processing, were analyzed for four different food matrices including lean ground beef, ground pork, ground turkey and spinach. Retention of three important foodborne bacterial pathogens (Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes) was also examined to evaluate the feasibility of the aforementioned methods to be utilized within the context of foodborne pathogen detection. Data from the analyses delineated the range of particle sizes obtained and defined the unique compositional profiles that result from the different matrices and separation device utilized, which will allow for the coordination of putative sample preparation methods with the constraints of the down-stream detection platforms. In addition, it showed that the use of the methods in tandem may prove to be more beneficial than the use of any one method alone.