Journal of Food Safety最新文献

In the natural environment, ruminant livestock, including cattle, are the main reservoir of the outbreak–causing strains of Shiga toxin-producing Escherichia coli (STEC), where bacteriophages sustainably thrive as well. This study focuses on the characterization of STEC-specific bacteriophages isolated from cow manure samples in Maine farms and examines their prevalence with STEC hosts. Phenotypic features of representative isolates were characterized by using a transmission electron microscope. Similarly, host range, one-step growth curve, thermal stability, lytic capability, and genomic analyses were performed to fully characterize selected representative isolates. Results showed that representative bacteriophage isolates belong to Myoviridae (S6P10 and S14P12) and Siphoviridae (S19). The most prevalent and common bacteriophages (46%) were specific to the O26 serogroup. The farm C sampling site had highly heterogenous bacteriophage populations that were specific to six STEC serogroups. The most prevalent bacteriophage isolate (S1P5, Escherichia phage vB_EcoM-S1P5QW) was verified to have a double-stranded DNA genome (166,102 bp) with 266 CDs of which 130 have known functions. The majority of the diverse bacteriophage isolates had strong lytic capabilities and a narrow host range that could withstand selected temperature conditions (−20, 37, and 62°C). Results of bacterial screening showed that STEC host strains were not detected in Farms A, C, and E, but were detected on Farms B and D. In conclusion, the highly-diverse bacteriophage ecology found in cow manure samples may have been an important element in shaping the population of STEC serogroups, specifically in its natural environment, which can provide useful tools for potential antibiotic-free therapeutics and diagnostic technologies.

For fresh foods, the purpose and benefits of modified atmosphere packaging (MAP) generally include the preservation of antioxidants, the extension of shelf life, deferral of microbial spoilage, and retention of product color. Commercial MAP products frequently involve a mixture of nitrogen, oxygen, and carbon dioxide, affecting consumer acceptability, cost-effectiveness, and hygienic food safety issues. This study investigated a novel active MAP formulation for strawberries in retail packaging which ensures changes in quality-related physicochemical characteristics [including hardness, moisture, vitamin C, total soluble solids (TSS), titratable acid, and appearance] during low-temperature storage, whereas samples of different storage times were assessed for shelf life by sensory evaluation. The innovative active MAP formulation of 0.8 g of sodium ascorbate, 2.6 g of sodium carbonate, and 1.6 g of ferrous sulfate achieved atmosphere equilibrium in packaged strawberries in <48 h, compared to 5–6 days in the control group. Strawberries treated with active MAP maintained their moisture, firmness, vitamin C, TSS, and titratable acid contents better than the control group (p < 0.05). The strawberries showed softening and waterlogging of tissue and 50% moldiness by the 14th day, while the control group lost commercial value by the 8th. New applications of similar commodities in food are unavailable based on current knowledge. Therefore, the scope of fresh food applications covered in this study and the refinement of other functions will be helpful directions for future research.

In this study, gelatin-based encapsulation of different bioactive compounds including essential oils (EOs) and bacteriocins, produced by lactic acid bacteria was established to evaluate the microbial, physiochemical, and sensory qualities of meatballs. Determination of minimum inhibitory concentration followed by checkboard method showed citrus extract, Mediterranean formulation, Cinnamon and thyme EOs had inhibitory concentrations between 20 and 5000 ppm and synergistic effect against common contaminant and pathogenic bacteria in meat. The bacteriocins produced by Lactobacillus curvatus and Pediococcus acidilactici showed antimicrobial activity between 10,000 and 80,000 ppm against Leuconostoc mesenteroides, Carnobacterium divergens, Lactobacillus curvatus, Listeria inocua, Listeria monocytogenes, and Pseudomonas aeruginosa. Encapsulation of the bioactive compounds in gelatin kept the bioactive content to greater extent. The encapsulated bioactive compounds were effective to inhibit the microbial growth, retard the lipid oxidation and color changes, and preserve the sensorial attributes of meatballs. It can be concluded that gelatin-based encapsulation of Cinnamon EOs and bacteriocins is effective to extend the shelf-life of meatballs.

The antibacterial packaging films were produced from poly (vinyl alcohol) (PVOH), agarose, and cinnamon (Cinnamon cassia) oil (CO). The mechanical, antibacterial, water- and UV-barrier properties of the resulting films were fully characterized. Our findings revealed that increasing amount of CO slightly affected the color of resulting film, while the dispersion of CO in polymeric matrix was influenced by CO concentration. UV-barrier property of PVOH/agarose was enhanced by adding a small amount of CO. Tensile strength of the resulting films insignificantly changed (8.94–10.23 MPa) with raising CO content while the flexibility remarkably dropped from 92.63% to 75.49%. Remarkably, the PVOH/agarose containing 1.5% (v/v) CO presented strong inhibition against Pseudomonas aeruginosa, Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus due to the presence of cinnamaldehyde in CO and this inhibitory efficiency was maintained for up to 7 days. Furthermore, the PVOH/agarose film enriched with 1% (v/v) CO was applied for enhancing the storability of bread slices during 50-day storage at room temperature.

Foodborne pathogens are a persistent threat to food and consumer safety. To mitigate outbreaks and contamination incited by these pathogens, the development of novel preventative safety controls and biorational inactivation measures are paramount. The objectives of this research were to evaluate the efficacy of pyrrolidine-based amide derivatives of decanoic (DEPY), lauric (LAPY), myristic (MYPY) and palmitic (PAPY) fatty acids for in-vitro inhibition and inactivation of various Gram-positive bacterial strains including Listeria monocytogenes (typically associated with foodborne illness), Bacillus subtilis, and Streptococcus mutans and Streptococcus sobrinus (both normally present in the oral cavity and involved with dental caries). Compared to no treatment (control), significant differences (P < 0.05) in the growth of Listeria strains were seen in-vitro with increased inhibition at higher amide concentrations (10,000–20,000 ppm). Furthermore, in-vitro growth inhibition of B. subtilis, S. sobrinus, and S. mutans was also observed with an effectiveness of LAPY>MYPY>PAPY>DEPY. In co-inoculation assays, LAPY treatment significantly reduced Listeria growth from 1.55 to >5.0 Log CFU/mL when a concentration range of 5 to 250 ppm was applied. Moreover, Listeria populations on pathogen-inoculated produce were significantly (P < 0.05) reduced from 0.51 to >3.00 Log CFU/g with greater inactivation on carrots compared to alfalfa, soybean, and pistachio. These results demonstrated the potential value of these FA amides against Gram-positive pathogenic bacteria. Biorational applications of antibacterial FA amides on fresh produce as a postharvest intervention process offers a great potential for enhancement of food safety.

Malathion is one of the commonly used organophosphate pesticides known to attack the central nervous system, posing a risk to humans and other animals upon exposure. The surface enhanced Raman spectroscopy (SERS) has been identified as an indispensable tool for chemical and biomolecular sensing. In this work, the facile fabrication of activated carbon (AC)-based colloidal SERS active substrate dubbed AC@AgNPs was designed by trapping AgNPs on the surface of AC for detection of varying concentrations of malathion. Apart from the higher concentrations of malathion, the rest of the normal Raman spectra of malathion standard solutions exhibited weak Raman signals. The intensity of peaks for 0.47 mg L⁻¹ were nearly non-existent which is an indication that the malathion pesticide could only be detected up to 0.95 mg L⁻¹ when using silica wafer. On the contrary, all the SERS spectra of malathion in wheat extracts adsorbed on AC@AgNPs substrate exhibited strong Raman signals. Quantitative analysis of malathion was performed by regression models developed using PLSR built with the raw spectra (no pretreatment), SNV-PLSR, and SNV-CARS-PLSR. The model with the most remarkable performance was established by using SNV-PLSR with r = 0.9869 and RPD = 4.61. This research shows that the proposed method can rapidly detect malathion residues in wheat, suggesting that it could be adopted for production process monitoring of other related food products to guarantee their safety for human and animal consumption.

Polymerase chain reaction (PCR) is widely used in several research areas and routine laboratory analyses, including foodborne pathogens detection. We aimed to investigate the knowledge about PCR-based methods and foodborne pathogens among undergraduate and graduate Brazilian students and professionals. A cross-sectional survey was carried out using an online questionnaire as data collection method. The questionnaire was validated and distributed through email and social networks. Data from 1246 respondents was collected. The knowledge scores were verified by correspondence analysis and discussed, 75.8% of the participants answered that they knew a foodborne pathogen and 71.4% of the participants answered that they did not study molecular biology techniques during undergraduate course. The highest level of knowledge was found among professionals with Masters' and PhD degrees. In conclusion, participants are not knowledgeable about PCR-based methods and the level of academic training influences the knowledge of analytical foundations. Most participants did not study PCR and its application in detecting foodborne pathogens during undergraduate course. We suggested that undergraduate courses in Food Engineering and in Food Science and Technology include mandatory molecular biology classes in academic programs.

In this study, the characteristics of Listeria monocytogenes isolated from enoki mushroom (Flammulina velutipes) collected from May to July 2019 were analyzed. The isolates were analyzed for strain characteristics, hemolysis, antibiotic resistance, heat resistance, and virulence genes (inlA, inlB, actA, plcB, and hlyA) were analyzed, and whole genome sequencing (WGS) analysis was performed for the strain with the highest risk. Seven isolates were obtained from some enoki mushroom samples. All isolates were β-hemolytic and had virulence genes. Antibiotic resistance test showed multi-drug resistance in L. monocytogenes strain SMFM2019-FV15 and SMFM2019-FV16. L. monocytogenes SMFM2019-FV16 showed higher heat resistance than the other isolates. According to the results L. monocytogenes SMFM2019-FV16 was selected as the strain with the highest risk. WGS for L. monocytogenes SMFM2019-FV16 showed that it had 14 antibiotic resistance genes and 43 virulence genes, and 35 single nucleotide variants in the 43 virulence genes were observed. These results indicate that these genetic variations might be related to the high risk of L. monocytogenes SMFM2019-FV16.

Campylobacter spp. cannot grow in raw milk, but it is able to transform into a viable but non-culturable (VBNC) state enabling the survival in such harsh conditions. In this study, Campylobacter jejuni survival in raw milk was investigated taken into consideration colony-forming units (CFUs) and VBNC cells. CFU from two different strains of C. jejuni (DSM 4688 and BfR-CA-18043) were enumerated at three temperatures (5°C, 8°C, and 12°C). In parallel, a viability real-time PCR was conducted to quantify intact and putatively infectious units (IPIUs) (comprising CFU and VBNC bacteria). The data generated were used to model the viability of C. jejuni during raw milk storage. Here, a one-step fitting approach was performed using parameter estimates from an intermediate two-step fit as starting values to generate tertiary models. Different primary model equations (Trilinear and Weibull) were required to fit the CFU and the IPIU data. Strain-specific linear secondary models were generated to analyze the effect of storage temperature on the maximum specific inactivation rate of the CFU data. The time of the first decimal reduction parameter of the IPIU models could be modeled by a strain-independent linear secondary model. The developed tertiary models for CFU and IPIU differ significantly in their predictions, for example, for the time required for a one log₁₀ reduction. Taken into consideration that VBNC could revert to a culturable state during the raw milk storage, our results underline the importance of considering IPIU and not only CFU to avoid underestimation of the survival of C. jejuni in raw milk.

Cross-contamination in the poultry slaughtering process can lead to thespread of zoonotic bacteria like Salmonellaenterica. Surfaces of equiptment may facilitate contamination of carcasses due to bacterial adherence and transfer. In this study, attachment, proliferation, and detachment of Salmonella Enteritidis and Escherichia coli were comparatively investigated on uncoated and silica-coated stainless-steel surfaces. The conditions occurring in the slaughtering workflow were imitated on laboratory scale, for example, spilling of contaminated liquid onto equipment surfaces, pressing or sliding of carcasses against surfaces during the slaughtering procedure, and cleaning of contaminated stainless-steel surfaces with water or detergent. Growth on stainless-steel surfaces was measured for 8 h. The applied silica coating led to a partly higher repelling effect without impact on proliferation for the target organisms on stainless steel. Further development of the coating and daption to the exact circumstances as well as more extending testing under real conditions would be the next steps.