IAFP 2026

Primary Author: Evangelos Vandoros 

Introduction: Free DNA from non-viable cells can persist in powdered infant formula (PIF), dairy products, and environmental samples due to processing stresses, sanitation activities, or ingredient carryover. This residual DNA can be amplified by molecular detection assays and lead to false-positive results. A reliable solution for removing free-DNA prior to PCR testing is therefore needed to improve result interpretation while maintaining assay sensitivity. 

Purpose: This independent laboratory study evaluated whether the optional free-DNA removal step impacts the performance of the Thermo Scientific™ SureTect™ PCR Assay methods for detection of Cronobacter species, Listeria species, and Listeria monocytogenes across PIF, dairy, and environmental matrices. The objective was to demonstrate that inclusion of the solution does not reduce analytical sensitivity. 

Methods: Performance was assessed through an ISO 16140-2 comparative validation supported by AFNOR Technical Rules and AOAC Appendix J guidelines. Each SureTect assay was tested with and without the free-DNA removal solution and compared to the corresponding reference methods. Statistical analyses included determination of difference of probabilities of detection (dPOD) and relative limits of detection (RLOD). 

Results: Environmental sample dPODs at the fractional level were -0.20 for Listeria monocytogenes, 0.15 for Listeria species, and 0.00 for Cronobacter species when compared to the reference method. For PIF, fractional level dPODs were 0.00 for L. monocytogenes, 0.00 for Listeria species, and 0.05 for Cronobacter species.  

Significance: The data demonstrates that incorporating the free-DNA removal solution does not affect assay sensitivity and produces results where no statistically significant difference could be detected comparing to the reference methods. These validated workflows enable improved confidence in PCR testing by reducing false-positive risks without compromising detection performance. 

Primary Author: Rachael Trott

Introduction: Rapid and reliable pathogen detection is critical for powdered infant formula (PIF) manufacturers to ensure product safety and regulatory compliance. PCR-based testing offers sensitive and timely detection of foodborne pathogens. Heat treatment, low-moisture, and disinfectant use can result in residual free-DNA from nonviable organisms, leading to unconfirmable PCR-positive results. These false positives may cause unnecessary investigations, production delays, and product holds. This study evaluated whether use of the SureClean™ DNA Removal Kit prior to PCR could reduce false positives without compromising sensitivity. 

Method: PIF and environmental samples (N=280) were enriched, then post-enrichment aliquots were contaminated with free-DNA from multiple strains of Salmonella spp., Cronobacter spp., and Listeria monocytogenes at levels expected to generate false-positive PCR results. Samples were analysed by PCR before and after treatment with the DNA removal kit. Additional samples (N=150) were inoculated with low levels (<10 CFU) of live organisms, subjected to stress conditions, and tested pre- and post-treatment to assess impact to assay sensitivity. 

Results: Of 280 samples contaminated with free-DNA, 261 yielded PCR-positive results before treatment, while only 35 samples (13%) remained positive after treatment. Of 150 samples inoculated with live organisms, 103 were PCR-positive before treatment and 102 remained positive after treatment and were confirmed by culture media techniques. 

Conclusion: The use of a free-DNA removal step prior to PCR analysis significantly (P=<0.001) reduced unconfirmable PCR positive results in PIF and environmental samples, while maintaining detection of live stressed organisms at low levels. These findings demonstrate that incorporating free-DNA removal into PCR workflows can improve result reliability for PIF manufacturers, reducing investigations and production disruptions without compromising sensitivity. 

Primary Author: Dean Leak

Introduction: Molecular methods can detect DNA from non-viable microorganisms, leading to false-positive results in food safety testing. This study evaluates the SureClean™ DNA Removal Kit as a pre-analytical treatment to eliminate extracellular DNA while preserving DNA from viable cells, improving workflow specificity, confidence in results, and efficiency in food testing workflows. 

Method: The efficiency of a DNA removal solution was evaluated using samples artificially contaminated with non-viable DNA from Salmonella, Listeria, Vibrio, Cronobacter, and Staphylococcus species. PCR was performed before and after treatment, with Ct shifts analysed across 534 samples representing diverse matrices, including seafood, powdered infant formula and environmental samples. Sensitivity impact was assessed using Relative Level of Detection studies in SureTect™ workflows utilising large sample sizes and short enrichment times, comparing Ct shifts and detection rates between treated and untreated samples. 

Results: The DNA removal solution reduced false-positive results by 78.48%, with remaining positives showing greater than 2-log reductions in DNA. Sensitivity assessment across 270 samples demonstrated no impact on performance, with an average RLOD of 1.03 and no statistically significant difference between treated and untreated samples (P = 0.944). 

Conclusion: This study shows that the evaluated DNA removal solution effectively improves PCR result accuracy by selectively removing extracellular DNA. The solution performed reliably across diverse, high-risk food matrices, reducing false positives while maintaining assay sensitivity. RLOD studies confirmed unchanged detection performance under challenging SureTect™ conditions, demonstrating the solution’s value as a practical, robust enhancement to molecular food safety testing workflows. 

Primary Author: Marian Teye

Introduction: Beverage producers are under pressure to ensure product quality in the face of complex spoilage risks from diverse microorganisms. A rapid molecular detection method which enables detection in one reaction with a harmonized workflow significantly simplifies and streamlines testing, compared to traditional plating techniques.

Purpose: The purpose of this study was to verify performance of the SureTect™ Beverage Spoilage Multiplex PCR Assay for detection of yeast & molds, Brettanomyces spp., preservative resistant yeasts, lactic acid bacteria and acetic acid bacteria from diverse beverage products.

Method: Five matrix-microorganism combinations were tested. Matrices included electrolyte hydration, tea-based, sports energy, and juice-based drinks, with sample sizes ranging from 0.5L to 1.5L (in product bottles). A modified Relative Level of Detection (RLOD) study was performed vs. traditional plating methods with samples artificially contaminated with target organism microbial cocktails to achieve spike levels of 0, 1–5 and 5–20 CFU/sample. Samples were analysed using the PCR workflow following a single harmonized filtration and enrichment for all of the organisms of interest. Additionally, a panel of 183 inclusivity and 140 exclusivity isolates were tested.

Results: The modified RLOD study demonstrated comparable performance of the PCR workflow to the culture plating method across all matrix-microorganism combinations and inoculum levels tested. The time-to-result for the PCR workflow was 4 days shorter than the traditional method. Inclusivity of 98% and exclusivity of 95% was achieved.

Significance: The Beverage Spoilage Multiplex PCR Assay constitutes a comprehensive panel for detection of yeast and molds, Brettanomyces species, preservative resistant yeasts, lactic acid bacteria and acetic acid bacteria spoilage organisms, with a rapid and reliable workflow for the beverage industry.