Journal of Food Safety最新文献

Staphylococcus aureus is an opportunistic zoonotic pathogen which secretes 24 different types of enterotoxins (SEs) and enterotoxin-like (SEls) proteins. Classical enterotoxins (SEA–SEE) are responsible for >95% of food poisoning outbreaks, of which SEA alone is responsible for >75% of them. This study was undertaken to develop a sandwich enzyme-linked immunosorbent assay (ELISA) for sensitive, specific, and quantitative detection of staphylococcal enterotoxins-A in food. Optimization of sandwich ELISA was attempted in two ways: rabbit polyclonal anti-SEA as a capture antibody and mouse monoclonal anti-SEA as a detector antibody, and vice versa. In the optimization of sandwich ELISA, mouse monoclonal anti-SEA as a capture antibody and rabbit polyclonal anti-SEA as a detector antibody yielded the highest sensitivity of 0.5–0.75 ng mL⁻¹. The developed assay was found to be highly specific and exhibited equivalent sensitivity to a commercial kit. The developed sandwich ELISA may be utilized for the detection of staphylococcal enterotoxin-A in food as a cheap alternative to available commercial kits. The developed sandwich ELISA may be useful for microbiological quality assurance of foods, especially in resource-limited developing countries.

Using stable chlorine dioxide (ClO₂) combined with slightly acidic electrolyzed water (SAEW), the quality variations of cold-stored large yellow croaker (Pseudosciaena crocea) were studied. The results of microbial indicators demonstrated that ClO₂ and SAEW treatment inhibited microbial growth. Moreover, ClO₂ + SAEW treatment had lower values of pH, malondialdehyde content, total volatile basic nitrogen, and higher water-holding capacity than those in other groups. From the results of free amino acids and trimethylamine, ClO₂ + SAEW treatment could delay the breakdown of umami amino acids and the accumulation of bitter amino acids in large yellow croaker. According to the results of microbial indexes and K-value, compared with sterile distilled water treatment, the shelf life of large yellow croaker with ClO₂ + SAEW treatment was extended for an additional 4 days. Therefore, ClO₂ + SAEW treatment is a potential method to preserve the flavor and quality of large yellow croaker during cold storage.

This study aimed to optimize minimal thermal treatment conditions for sour cherry juice using response surface methodology. The effects of ultrasound power (UP; 54, 35, 14 W), ultrasound time (UT; 8, 5, 3 min), ohmic electrical field strength (OE; 40, 30, 20 V/cm) and ohmic time (OT; 8, 5, 3 min) on total phenolic content (TPC), antioxidant activity (AA), color values (L*, a*, b*, $��∆�E�$), total monomeric anthocyanin content (TMAC), polymeric color (PC), color density (CD), polymeric color ratio (PC%), total mesophilic aerobic bacteria (TMAB) and yeast-mold count (YM) were investigated. UP significantly affected TPC, L*, a*, b*, and $��∆�E�$, while OE affected TPC, TMAC, PC, PC%, and TYC. UT affected TPC, L*, AA, CD, PC and PC%, and OT level affected TPC and b* values. The optimum points were determined by considering maximum TPC as 28.7564, maximum AA as 6.7714, maximum TMAC as 4.9616, maximum L* as 21.3839, maximum a* as 5.5396, maximum b* as 3.4260, maximum color density as 27.1412, minimum polymeric color as 17.3148, minimum PC% as 4.9253, minimum TYC as 1.9251 and minimum TMBC as 2.3301. The optimum levels were found to be 54 W, 8 min, 27.06 V/cm and 8 min. Improvements in TPC, TMAC and AA were determined after ultrasound-ohmic combination thermal treatment. Although ohmic (OH) has the effect of maintaining juice quality, its effectiveness is impacted by the electrochemical properties of food. By using ultrasound, the electrical conductivity values of juices were increased; thus, ultrasound improved the electrochemical properties of sour cherry juice. Further studies are needed to evaluate the effects of ultrasound-ohmic combination for juice processing on a large scale.

Moisture content detection has guiding significance for the storage and quality detection of rice. To detect moisture content rapidly and non-destructively, hyperspectral imaging technology (400-1000 nm) was employed to analyze rice with different moisture content, and Savitzky–Golay mixed standard normalized variable algorithm (SG-SNV) was used for spectral data pretreatment. Furthermore, a modified supervised locality preserving projections (MSLPP) method was proposed to extract spectral features. The modeling results showed that MSLPP had better spectral feature extraction performance. Finally, to improve prediction accuracy, the equilibrium slime mold algorithm (ESMA) was introduced to obtain the optimal parameters (c, g) of the support vector regression (SVR) model. And MSLPP–ESMA–SVR model had higher prediction accuracy and stronger robustness, with R²_p reaching 0.9755 and root mean square error of prediction reaching 0.8597%. Therefore, hyperspectral imaging technology combined with MSLPP–ESMA–SVR model is feasible to detect rice moisture content.

The current observational study aims to determine the extent to which main food safety principles are addressed in Slovenian cooking shows and whether the type of main actor or television channel significantly impacts adherence to good hygiene practices. In general, our results show that food handling presented to the audience in Slovenian TV cooking shows often deviates from the main food safety recommendations. A comparison between amateur and professional chefs has shown notable but statistically insignificant differences. While in the area of personal hygiene, more deviations were found among amateur than among professional chefs (p = 0.011), we can observe the opposite in the area of preparation practices, albeit with insignificant difference (p = 0.884). The current study provides further evidence that there is a large gap between what viewers see and what they should have seen in television cooking shows from a food safety perspective.

This cross-sectional study determined the occurrence of virulence and antimicrobial resistance genes in Salmonella strains recovered from chicken obtained from informal markets in Gauteng province, South Africa. The study also assessed the relationship between these characteristics, the source, the type of samples, and the serotypes of Salmonella isolates. A total of 151 samples (cloacal swabs, chicken carcasses, and carcass drips) were randomly collected from 47 informal market outlets in six townships in Gauteng province. Salmonella spp. was isolated and identified based on ISO 6579:2002 methods and confirmed by polymerase chain reaction (PCR) targeting invA gene fragment. Conventional PCR was used to detect 12 virulence and 18 antimicrobial resistance (AMR) genes in Salmonella spp. The most frequently detected virulence genes were invA (100%), shdA (91%), mgtB (87.7%), and sopE (81%), but considerably low for spvC (2.2%), sefC (1.5%), and pefC (0.4%). The differences in detection frequency were statistically significant (p < 0.05). Tetracycline-resistant genes tetA (34.7%) and tetB (16%) were the most frequently detected, while Beta-lactam-resistant genes blaTEM (0.4%), blaCMY-2 (0.4%) and quinolones resistant gene qnrS (0.4%) were detected in low frequency (p < 0.05). The locations of the outlets and the types of samples were significantly associated with detecting some virulence and AMR genes. Significant but moderately to substantial positive correlations were observed for qnrS, sul2; shdA, and mgtB genes. The pipA and spiC were, however, substantially negatively correlated. Our findings show that detecting these virulence and AMR genes in Salmonella isolates serves as a potential health hazard to the public, environment, and poultry farming in Gauteng, South Africa.

Food contamination with plasmid-mediated antibiotic-resistant Escherichia coli has not been thoroughly investigated. This study aimed to clarify the prevalence of colistin-resistant AmpC/extended-spectrum β-lactamase (ESBL)-producing E. coli harbouring mcr (COL-ESBL-EC) and to determine antibiotic resistance by comparison with AmpC/ESBL-producing E. coli (ESBL-EC) and colistin-resistant E. coli harbouring mcr (COL-EC). Sixty chicken meats were tested for COL-ESBL-EC contamination. The result showed that 64 COL-ESBL-EC were isolated from 66.7% of the samples, and compared with ESBL-EC and COL-EC were isolated before. The genotypes of the COL-ESBL-EC showed bla_CTX-M-55/TEM, bla_CTX-M-55, bla_CMY-2, and bla_CTX-M-65 were predominant. The COL-ESBL-EC results showed a similar trend for bla_CTX-M identification to that of ESBL-EC. The mcr was investigated, and mcr-1 was detected in COL-ESBL-EC and COL-EC. Antibiotic susceptibility testing revealed that many strains of COL-ESBL-EC and ESBL-EC were resistant to quinolones, and fosfomycin (FOS). These results suggest that COL-ESBL-EC has simultaneously acquired AmpC/ESBL-related, quinolone, and FOS resistance genes in COL-EC.

The aim of this work was to evaluate the resistance of two pathogenic bacteria (Listeria monocytogenes and Salmonella enterica subsp. enterica serotype Senftenberg), and three airborne food-spoiling filamentous fungi (Hyphopichia burtonii, Penicillium nordicum, and Aspergillus brasiliensis ATCC 16404) to gaseous ozone on stainless steel. Tests were carried out by exposing inoculated tiles to gaseous ozone in a laboratorial chamber at concentrations up to 50 mg/L and at times up to 180 min (bacteria) or 300 min (filamentous fungi). For bacteria, the resistance to gaseous ozone of L. monocytogenes proved markedly higher than that of S. enterica. Their D-values increased by seven times (from 27.3 to 200.7 min for the strain of L. monocytogenes studied; from 7.3 to 48.0 min for the Salmonella species studied) when the ozone concentration were reduced from 12 to 4 mg/L. For filamentous fungi, a substantial effect was observed only at 50 mg/L on single-layered inocula: at these conditions, A. brasiliensis ATCC 16404 proved the most resistant strain to gaseous ozone, its D-value (134.4 min) being higher than those registered for the tested strains of H. burtonii (9.9 min) and P. nordicum (17.1 min). The results demonstrated that the use of gaseous ozone as a sanitizing agent for environments and working surfaces seems to be a potential alternative to chemical sanitizers against the two pathogens studied, whereas it seemed effective against the three filamentous fungi studied only in limited circumstances.

The laboratory inoculation techniques should ideally mimic the real-life environment to reliably estimate the decimal reduction time (D-value) of bacteria for process validation. This study aims at investigating the influence of the inoculation method on the D-value of Salmonella in black pepper powder. Whole black peppercorns were either inoculated prior to grinding (pre-grinding procedure) or ground and then inoculated (post-grinding procedure). The ground black pepper was thermaly treated at 80°C for 0-30 min. The D80°C values of Salmonella inoculated by pre-grinding and post-grinding procedures were 5.5 ± 0.8 and 3.9± 0.3, respectively. Salmonella and E. faecium were significantly (p⟨0.05) more thermally resistant in ground black pepper when inoculated pre- rather than post-grinding. Therefore, inoculation protocol must be considered by spice industries while validating the pasteurization process. E. faecium is a suitable surrogate for Salmonella because of its higher decimal reduction time for both inoculation methods.

This study investigated the impact of incorporating gas [air, carbon dioxide (CO₂), and nitrogen (N₂)] UFB on the potency of chlorine (Cl₂; 50, 100, and 200 ppm) and peracetic acid (PAA; 20, 40, and 80 ppm) antimicrobial (AM) solutions against fresh (3 days) and aged (30 days) E. coli O157:H7 biofilms on polypropylene, silicone, and stainless-steel surfaces. The biofilms were statically grown on polypropylene, silicone, and stainless-steel coupons (7.62 × 2.54 cm) at 25°C for 3 or 30 days by immersing in a 3-strain cocktail of E. coli. The incorporation of air, CO₂, and N₂ UFB in AM solutions resulted in significantly increased log reductions (2.1–3.7 logs) in fresh and aged E. coli biofilms on all surfaces compared to solutions without UFB, except for N₂ UFB on aged stainless-steel biofilms and air UFB on aged polypropylene biofilms, which resulted in similar log reductions as solutions without UFB (1.5–2.1 logs).