Journal of food protection最新文献

Introduction: Listeria monocytogenes is a known food-borne risk associated with ready-to-eat (RTE) foods, including fish. An estimated 90% of cases of invasive human listeriosis result from ingestion of foods containing >2.0 × 10³ CFU/g, with growth after purchase being a significant factor. This study aimed to evaluate the biological characteristics, lytic spectra, and determine the biocontrol potential of a strictly lytic L. monocytogenes bacteriophage A511 in comparison with a commercial phage PGL (P100) on raw Scottish salmon fillets.

Methodology: The lytic spectra of phage A511 and the commercial phage PGL were determined using spot assays on a panel of 33 L. monocytogenes strains, and phage growth kinetics, such as burst and latent period, were evaluated using standard double agar layer methods. For the biocontrol study, ∼4 log₁₀ CFU/ml of L. monocytogenes were inoculated on raw Scottish salmon fillets, and the two individual lytic phages (viz., phage A511 and commercial phage PGL) at three phage application rates (final concentrations of 10⁵, 10^7, and 10⁹ PFU/g) were used to control experimental Listeria contamination of fresh Scottish salmon fillets stored at 4 °C and 10 °C.

Results: The phages A511 and PGL exhibited lytic spectra of 97% and 100%, respectively, against the strains tested while A511 produced burst sizes of ∼49 PFU/cell. There was a significant effect of phage titer (p < 0.0001) on the levels of L. monocytogenes, with reductions in bacterial numbers to below the limit of detection (i.e., no detectable counts were observed) after 1-day incubations at both 4 °C and 10 °C for both phage A511 and PGL applied at 10⁹ PFU/g, with enhanced reductions at 4 °C.

Conclusion: This study conducted a lab‑scale evaluation of the archival phage A511 on raw salmon in direct comparison with a commercial phage (PGL) under a unified dose-time-temperature framework. To our knowledge, a direct comparison of A511 and PGL on raw salmon using an identical experimental design has not been previously reported. While the findings demonstrate effective reduction of L. monocytogenes under controlled laboratory conditions, further work, including broader strain coverage, naturally contaminated lots, sensory and shelf‑life assessments, and multi‑batch validation, is required before commercial implementation can be fully assessed.

Cold-chain disruptions during the storage and distribution of raw poultry can significantly reduce product shelf-life and safety. This study evaluated the effects of short-term cyclic temperature abuse (TA) on the retail shelf-life of fresh chicken breast, using a multidisciplinary approach that combined food microbiology, machine learning (ML), metagenomics, and volatile compound (VC) analysis. Boneless, skinless chicken breast trays (n = 450) were obtained from a commercial poultry processor and transported under refrigeration (4 °C) to Auburn University. In three independent trials, trays were randomly assigned to one of three treatments: (1) Control at 4 °C for 24 h; (2) TA Cycle 1: alternating 30 min at 4 °C and 1 h at 30 °C; and (3) TA Cycle 2: alternating 30 min at 4 °C and 1 h at 37 °C. TA cycles lasted 7.5 h, after which all trays were stored at 4 °C. Samples were analyzed on days 0, 2, 4, 6, and 8 for aerobic, facultative anaerobic, and lactic acid bacteria (LAB) counts, and for VCs using an electronic nose. Rinsates from Trial 3 were stored at -80 °C for metagenomic analysis. TA Cycle 2 resulted in the highest spoilage rates, followed by TA Cycle 1. A neural network model moderately predicted bacterial growth (R² = 0.65-0.75 for aerobic and facultative anaerobic microorganisms; lower for LAB). Metagenomics demonstrated a shift toward Pseudomonas spp. dominance under TA conditions, while control samples retained microbial diversity. These findings underscore that even short-term TA significantly alters the microbiome and accelerates spoilage in raw poultry, emphasizing the importance of cold-chain integrity. Practical Relevance. This study shows that short, high-temperature abuse events from refrigeration failure, handling delays, or other supply chain disruptions can accelerate spoilage in raw chicken. By combining rapid spoilage-detection tools with predictive models, poultry producers and retailers may better monitor these events, helping to maintain cold-chain integrity and reduce losses.

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen and a common cause of foodborne infection. The stx genes are the main virulence factors and are classified into different subtypes. Some subtypes are more associated with severe infections than others, i.e. the HUS-associated stx_2a. Other virulence factors, such as eae, are also commonly observed, particularly from severe infections. Ruminants, in particular cattle, are recognized as the main reservoir for STEC; however, STEC is also isolated from pigs. In the present study, minced beef and pork were analyzed for STEC using two different approaches. Minced beef was analyzed for STEC of specific serogroups (O26, O91, O103, O121, O145, and O157), while for minced pork, all STECs were of interest. A specific real-time PCR screening for stx_2a was also employed. In total, 308 samples of minced beef and 157 of minced pork were collected and analyzed using ISO TS 13136:2012. After screening of minced beef, 28 samples met the criteria for isolation and STEC was isolated from two samples. Furthermore, after screening for and isolation of potentially stx_2a-positive STEC, STEC was isolated from two more samples. The isolates were characterized by whole genome sequencing as STEC O26:H11 (stx_1a, eae), O91:H21 (stx_2b), O22:H8 (stx_1a, stx_2a), and O178:H19 (stx_1a, stx_2a). This suggests that the occurrence of STEC in minced beef is most likely underestimated when only looking for STEC of specific serogroups. While 46 of 157 samples were positive for stx₁ and/or stx₂ in the screening of minced pork, STEC was not isolated from any of the samples. No samples were positive for stx_2a. While the occurrence of STEC of the specific serogroups in minced beef is low, it is difficult to draw any firm conclusions about the occurrence of STEC in minced pork. The results highlight the issue with PCR-positive/culture-negative results as observed for both sample types.

Rapid and accurate detection of Salmonella enterica serovars is critical for food safety monitoring, given their frequent involvement in egg-related foodborne disease outbreaks. In this study, unique genetic biomarkers for S. enterica, S. enterica serovars Enteritidis, Typhimurium, and Thompson were identified through comparative genomic analyses. Corresponding primer-probe sets were designed and evaluated using multiplex real-time PCR. The assay achieved amplification efficiencies between 90.7% and 94.2%, with strong linear correlations (R² > 0.998), and demonstrated high sensitivity with a detection limit of approximately 20 copies/µL. Specificity tests confirmed the absence of cross-reactivity with nontarget strains. Stability was further validated under accelerated aging conditions, with serovar-specific targets maintaining consistent detection, although the S. enterica marker exhibited modest variability (CV > 5%) for 12 days. Interference assessments revealed minimal inhibitory effects from common laboratory media, whereas egg matrices caused pronounced inhibition, particularly egg yolk. Subsequent analyses identified yolk granules as the primary source of inhibition, potentially associated with phosvitin and proteases. Further, DNA extraction methods influenced detection outcomes. The column-based extraction improved performance at higher yolk concentrations, whereas rapid heating-based extraction showed advantages at lower concentrations by denaturing inhibitory proteins and lipids. Lastly, application to artificially inoculated egg samples confirmed robust detection at ≥3 log CFU/mL, despite higher Ct values compared to tryptic soy broth controls. Collectively, this multiplex assay enables rapid, sensitive, and specific detection of major Salmonella serovars, while highlighting the importance of tailoring DNA extraction strategies to overcome matrix-associated inhibition in eggs.

The rise in Salmonella-related recalls and outbreaks linked to low-moisture foods (LMFs) necessitates the development of effective decontamination processes that do not compromise product quality. The objective of this study was to inactivate Salmonella spp. inoculated onto dried basil leaves, black peppercorns, walnuts, and chia seeds using gaseous ozone (O₃) treatments, and to evaluate the surrogate efficacy of Enterococcus faecium NRRL B-2354. Food products were inoculated with cocktails of Salmonella spp. and E. faecium and equilibrated to a water activity of 0.55. Two-gram samples of inoculated foods were treated in a customized chamber with ozone concentrations of 900-930 ppm and a relative humidity (RH) of 90% for 1-5 h, followed by mild heating (MH) at 40 °C for 4 h after the 3-h O₃ treatment. The 5-h O₃ treatment resulted in log reductions of 5.0 ± 0.6 for basil, 2.4 ± 0.2 for black pepper, 1.7 ± 0.3 for walnuts, and 1.1 ± 0.0 for chia seeds. The 3-h O₃ + MH treatment resulted in an additional 0.4-1.8-log reduction in Salmonella, compared with 3-h O₃ alone (p < 0.05), yielding reductions comparable to those of the 5-h O₃ treatment. E. faecium was a suitable surrogate for Salmonella only for dried basil leaves. In terms of quality, neither treatment significantly affected the color or total phenolic content of the four LMFs. Moderate, concentration-dependent reductions in antioxidant activity were observed for basil, black peppercorns, and chia seeds. The 3-h O₃ + MH treatment better preserved chia seed germination, walnut oxidative stability, and black pepper volatile compounds, whereas the 5-h O₃ treatment better maintained basil volatile compounds. The results of this study indicate that the combined effects of ozone, relative humidity, and mild heating can improve the microbial safety of LMFs during storage. However, the food matrix may be a limiting factor.

This study investigated whether the slightly acidic environment in the meat industry activates the Salmonella PmrA/B two-component regulatory system (TCS), thereby enhancing acid tolerance and cross-protection, by constructing a mutant strain lacking the response regulator PmrA. Results showed that deletion of pmrA not only reduced the acid tolerance induced by S. Typhimurium at pH 5.4 (the ultimate pH for beef cattle after slaughter), but also further reduced its cross-stress resistance to heat (55°C), osmotic (8% NaCl), oxidative (5 mM H₂O₂), and most the antibiotic stresses. Transcriptomics data revealed that down-regulation of genes mediating lipopolysaccharide modification and peptidoglycan synthesis led to reduced resistance to cationic antimicrobial peptides. Down-regulation of glycerophospholipid and lysine metabolic pathways, together with limited activation of genes in the glutathione metabolism pathway in the ΔpmrA mutant, was associated with reduced cross-resistance to osmotic, acid, and oxidative stresses. Furthermore, the down-regulation of several TCS genes related to envelope modification and the electron respiratory chain may have further impaired Salmonella cross-stress resistance and intestinal colonization. These findings highlight the critical role of PmrA/B TCS in Salmonella cross-protection and provide mechanistic insights for controlling pathogen persistence in meat processing environments.

Dry fermented sausages (DFSs) rely on nonthermal hurdles for safety, yet the impact of pathogen control measures has not been systematically evaluated. In this review, 207 datasets from 40 challenge studies were compiled and analyzed using inactivation modeling to quantify the impact of processing conditions on pathogen reduction during DFS manufacture. Factor analysis of log reduction times was conducted to elucidate interactions of processing conditions and how they impacted pathogen inactivation. Log-reduction times (LRTs) indicated that fermentation was the step with the most rapid pathogen inactivation, yielding significantly shorter LRTs than during drying or storage. However, the level of lethality achieved during fermentation alone was generally insufficient to reach commonly used validation benchmarks for Salmonella and STEC, indicating that fermentation, while a critical processing step, cannot function as the sole safety step. Regression tree analysis identified pathogen type, water activity (A_w), nitrite/nitrate concentration, and casing diameter as major determinants of inactivation during drying. The findings of the current work address Food Safety and Inspection Service (FSIS)-identified data gaps by quantifying pathogen inactivation across DFS processing steps and identifying the processing parameters that influence lethality, thereby supporting the development of effective multihurdle safety strategies.

Food service businesses in the state of North Carolina received support in the form of training, known as the Count On Me NC program, to safely reopen and manage the risk of COVID-19 infection at their establishments during the pandemic. This program was completed from May 2020 to December 2021 as per state government directives, establishments were required to undergo the lessons to resume operations. Businesses who completed the Count On Me NC modules received marketing material and a certificate of completion to be displayed. This study, completed in February 2023, assessed consumers' confidence related to Count On Me NC program completion by food businesses; it also determined the awareness of the existence of this training program during the COVID-19 pandemic. From the total responses (n=60), 36 consumers were aware of the Count On Me NC program and heard about this program in social media. The survey was used to investigate if the program would have influenced consumer decision-making to dine out at businesses that completed the program. Thirty one out of the 60 consumers reported that these type of programs and certifications would have influenced their decision on whether to dine out or not at a specific food service business. COVID-19 risk factors that concerned consumers the most were also identified, as well as measures they expected to be implemented to keep guests safe. Consumers reported to be most concerned about "crowded places and unmasked people". However, cleaning, disinfecting, and sanitizing was the practice consumers expected the most when dining out. The results of this study indicate that the Count On Me NC program effectively supported consumers' confidence, based on the fact that all reported concerns were covered throughout the training modules that the North Carolina food service industry completed. These results also showed a mixed understanding of COVID-19 infection mechanisms by consumers, and how their expectations of businesses' practices to keep consumers safe, did not match the science-based, recommended measures that would prevent infection based on risk.

Bacteriophages (phages) are highly specific viruses that infect bacteria, and they are increasingly explored as targeted biocontrol agents in meat and meat products, driven by the need for sustainable alternatives to conventional antimicrobials and by the growing challenge of antimicrobial resistance (AMR) along the meat production chain. This narrative review provides a critical synthesis of current knowledge on the application of bacteriophages in meat systems, addressing both food safety and spoilage control. Meat product is a complex microbial ecosystem that strongly influences quality, safety, and shelf life. Spoilage and pathogenic bacteria, including Brochothrix thermosphacta, Pseudomonas spp., Salmonella spp., Listeria monocytogenes, and Clostridium spp., represent major challenges for the meat industry. Phages can act as targeted and natural antimicrobials to control these microorganisms at multiple stages of production, processing, and storage. Conversely, the presence of phages in fermented meat products and processing environments may disrupt beneficial bacterial populations, including starter cultures, potentially leading to fermentation failures and economic losses. This review examines the multifaceted roles of bacteriophages in meat production and processing, discussing recent scientific advances, regulatory and safety considerations, technological applications, practical limitations, and future perspectives for their integration into meat safety and quality management strategies.