Journal of Food Safety最新文献

Trehalose exhibits broad-spectrum antibacterial and antioxidant activities and plays a vital role in delaying postharvest decay in fruits. In this study, we utilized transcriptomic and metabolomic approaches to investigate the metabolic regulation of phenols and amino acids in Kyoho grapes (Vitis vinifera × labrusca var. Kyoho) following treatment with trehalose. Physiological assessments showed that trehalose significantly reduced the decay rate, weight loss, and decay severity compared to the controls over 19 days of storage. Integrative analysis revealed that many differentially expressed genes (DEGs) and metabolites (DEMs) were enriched in the phenolic and amino acid biosynthesis pathways, and trehalose treatment upregulated genes and enhanced metabolite flux within these pathways. Trehalose-treated grapes displayed improved disease resistance and delayed senescence, likely due to the coordinated modulation of metabolite expression. Overall, exogenous trehalose treatment effectively prolonged the preservation of Kyoho grapes by orchestrating complex molecular and metabolic responses. This study advances the theoretical understanding of grape preservation and offers promising strategies for improving postharvest storage.

Antimicrobial resistance is a public health threat and the horizontal transfer of plasmids harboring antimicrobial resistance genes is a concern. This study aimed to determine the prevalence of plasmid-mediated cefotaxime (CTX) and meropenem (MEM)-resistant bacteria in dried foods imported to Japan from Southeast Asia. A total of 68 imported dried foods were purchased and mixed with buffered peptone water. After culturing in the mixing medium, the bacterial broth was spread on CHROMagar ECC containing CTX or MEM. Typical Enterobacterales colonies were selected, and antimicrobial susceptibility was determined using the disc diffusion method. Isolated colonies showing CTX or MEM antimicrobial resistance were subjected to DNA extraction using the boiling method, and bacterial species were identified using 16S rRNA sequencing. Multiplex PCR was conducted to detect genes encoding extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase enzymes. Whole-genome sequencing indicated the complete genome of the ESBL-producing strain. Seven CTX-resistant strains of Enterobacter, Atlantibacter, Stenotrophomonas, and Pseudomonas; and three strains of Enterobacter and Stenotrophomonas MEM-resistant bacteria were isolated. After antimicrobial susceptibility testing, a CTX-resistant strain of Atlantibacter hermannii, VT10-S, was identified as an ESBL producer. The total genome size of A. hermannii VT10-S was 4,423,010 bp; it harbored a 97,668 bp IncFIB plasmid encoding bla_CTX-M-27. Conjugation assays indicated that the IncFIB plasmid could be transferred to Escherichia coli isolated from humans. Humans may harbor ESBL-producing E. coli from the consumption of food imported from Southeast Asia.

Salmonellosis remains a significant public health concern, often linked to egg consumption. This study evaluated Salmonella inactivation in omelets, scrambled eggs, and poached eggs. Egg yolks were contaminated with a Salmonella cocktail and incubated at 37°C for 24 h, achieving approximately 8 log CFU/g. These eggs were used to prepare omelets in a frying pan for 5–7 min, testing different cooking times due to the lack of a standard. Scrambled eggs were cooked on direct heat for 3–8 min, followed by 1 min off the heat. Poached eggs were cooked in boiling water for up to 8 min, following Le Cordon Bleu recipes. Salmonella survivors were quantified on xylose lysine deoxycholate (XLD) agar and confirmed by ISO 6579:2022. Scrambled eggs and omelets showed Salmonella levels below the limit of enumeration after 5 min of cooking, when fully coagulated. However, poached eggs made with refrigerated eggs required longer cooking to achieve equivalent Salmonella inactivation compared with those at room temperature. Eggs stored at room temperature (28°C) showed a mean reduction of 7.4 log CFU/g after 5 min, whereas, eggs stored at 5°C achieved a similar 7.6 log CFU/g reduction only after 7 min. At 5 min, the difference in Salmonella inactivation between poached eggs prepared from room-temperature and refrigerated eggs was 4.4 log CFU/g. These results demonstrate that lower egg storage temperature delays heat penetration and requires longer cooking to achieve equivalent microbial reduction, emphasizing the importance of controlling both initial contamination level and cooking time, especially for poached eggs with partially coagulated yolks considered ready-to-eat.

Salmonella and Clostridium represent foodborne pathogens that infect livestock, as well as cause gastroenteritis in humans consuming tainted pork and poultry products. Free chemical zinc oxide (ZnO), at doses much higher than nutritional zinc requirements, has been routinely added to livestock feed in order to suppress infections and promote animal growth; however, unabsorbed zinc (excreted in feces) may accumulate in the environment and/or foster antimicrobial resistant (AMR) strains of bacteria. Here, NutriClay^Zn is described as an analog of montmorillonite clay (MMT) that suppresses growth of multidrug-resistant Salmonella enterica and single-drug resistant Clostridium perfringens. Zinc amended to the interlayer of MMT was found to be the active constituent of NutriClay^Zn, and release of zinc from NutriClay^Zn was quantified by inductively coupled plasma mass spectrometry. Two-log growth suppression of Salmonella enterica by NutriClay^Zn was significantly (p < 0.05) better than the mere one-log inhibition by concurrent equimolar (1.4 mM) free chemical ZnO positive controls. Moreover, the magnitude of NutriClay^Zn efficacy was significantly (p < 0.05) enhanced by subtherapeutic doses of antioxidants, while NutriClay^Zn administered alone prevented growth of Clostridium perfringens. These findings suggest that NutriClay^Zn could be developed as an alternative to free chemical ZnO for control of enterotoxigenic AMR bacteria that threaten the safety of key dietary protein sources for humans.

The bullfrog (Rana catesbeiana) is a popular and economically valuable amphibious product. Its nutrition, flavor, and dietary safety are of significant importance to consumers, but could be affected by different farming modes (traditional, industrial, and ecological modes). It is critical to compare the bullfrogs cultured under different cultivation modes to determine the most economically viable system that yields superior-quality products. The results showed that bullfrogs from all three farming modes exhibited high protein content (17.12–19.92 g/100 g ww) and low-fat content (1.76–1.67 g/100 g ww). Notably, the muscle of bullfrogs from all three modes met the criteria for ideal amino acid profiles. The ecologically farmed bullfrogs exhibited the highest muscle quality, with an essential amino acid to total amino acid (EAAs/TAAs) ratio of 46.87% and an essential amino acid to non-essential amino acid (EAAs/NEAAs) ratio of 88.20%. The polyunsaturated fatty acid to saturated fatty acid ratio (PUFAs/SFAs) indicated that the industrial (1.01) and ecological (1.08) farming modes were healthier than the traditional mode (0.84). Additionally, bullfrogs from the ecological farming mode exhibited the lowest concentrations of off-flavor compounds (GSM: 0.39 ± 0.04 ng/g ww, MIB: 0.45 ± 0.02 ng/g ww). Industrial farming also suppressed the accumulation of these off-flavor substances in bullfrogs. Regarding dietary safety, the levels of the five heavy metals in bullfrog muscle were below regulatory limits, except for chromium (Cr) with a dietary hazard index (HI) < 1. Five classes of antibiotics (sulfonamides, quinolones, tetracyclines, macrolides, and chloramphenicol) were detected in bullfrogs from different modes, with total concentrations of 34.55, 43.06, and 27.33 ng/g dw, respectively, posing no significant dietary risks. Using a comprehensive four-dimensional evaluation system (nutrition, safety, flavor, and economics), the advantages of the three farming modes were analyzed from both producer and consumer perspectives. The findings further confirmed that ecologically farmed bullfrogs exhibit superior quality, while industrial farming provided a more economical option without significantly compromising bullfrog quality.

Consuming food contaminated with harmful microorganisms poses a significant public health risk, often occurring on indoor food contact surfaces like cutting boards in home kitchens. The study aimed to experimentally determine the survival of Salmonella on commonly used cutting board surfaces (glass, wood, polyethylene) and its potential to cause cross-contamination of food samples (salami) over varying intervals and contact times. Salmonella bacteria persisted on polyethylene and glass cutting boards for up to 4 h, whereas on wooden surfaces, they were detected only up to 2 h. The transfer rates of bacteria to salami were found to vary depending on the type of board material and bacterial strain, with wooden boards demonstrating the lowest transfer rates. Additionally, the transfer rate increased proportionally with longer contact times. The study highlights that all types of cutting boards have the potential to transfer bacteria to food, although wooden boards showed lower transfer rates compared to polyethylene and glass surfaces.