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International Journal of Food... Jun 2024Nowadays, the discovery of alternative natural antimicrobial substances such as bacteriophages, essential oils, and other physical and chemical agents is developing in...
Nowadays, the discovery of alternative natural antimicrobial substances such as bacteriophages, essential oils, and other physical and chemical agents is developing in the food industry. In this study, nine bacteriophages were isolated from various parts of raw chickens and exhibited lytic activities against L. monocytogenes and various Listeria spp. The characterization of phage vB_LmoS-PLM9 was stable at 4 to 50 °C and pH range from 4 to 10. Phage vB_LmoS-PLM9 had a circular, double-stranded genomic DNA with 38,345 bp having endolysin but no antibiotic resistance or virulence genes. Among the eight essential oils tested at 10 %, cinnamon bark, and cassia oils showed the strongest antilisterial activities. The combined use of phage vB_LmoS-PLM9 and cinnamon oils indicated higher efficiency than single treatments. The combination of phage (MOI of 10) and both cinnamon oils (0.03 %) reduced the viable counts of L. monocytogenes and inhibited the regrowth of resistant cell populations in broth at 30 °C. Furthermore, treatment with the combination of phage (MOI of 100) and cinnamon oil (0.125 %) was effective in milk, especially at 4 °C by reducing the viable count to less than lower limit of detection. These results suggest combining phage and cinnamon oil is a potential approach for controlling L. monocytogenes in milk.
PubMed: 38878706
DOI: 10.1016/j.ijfoodmicro.2024.110797 -
International Journal of Food... Jun 2024To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C...
To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm to levels below the limit of detection (LOD; <1.65 log CFU/cm) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.
PubMed: 38878705
DOI: 10.1016/j.ijfoodmicro.2024.110800 -
Journal of the Science of Food and... Jun 2024This study evaluated for the first time the potential of orange passion fruit as a base for alcoholic and acetic fermentations, with a view to assessing its profile of...
Orange passion fruit (Passiflora caerulea L.) as a new raw material for acetic fermentation: evaluation of organic acids and phenolic profile, in vitro digestion, and biological activities.
BACKGROUND
This study evaluated for the first time the potential of orange passion fruit as a base for alcoholic and acetic fermentations, with a view to assessing its profile of organic acids and polyphenols, in vitro digestion, and biological activities.
RESULTS
In terms of aliphatic organic acids, malic acid was the majority in the wine (3.19 g L), while in the vinegar, it was acetic acid (46.84 g L). 3,4-Dihydroxybenzoic acid (3,4-DHB) was the major phenolic compound in the wine and vinegar samples (3443.93 and 2980.00 μg L, respectively). After the in vitro gastrointestinal simulation stage, the wine showed high bioaccessibility for the compounds sinipaldehyde (82.97%) and 2,4-dihydroxybenzoic acid (2,4-DHBA, 81.27%), while the vinegar exhibited high bioaccessibility for sinipaldehyde (89.39%). Through multivariate analysis, it was observed that 3,4-DHB was highly concentrated in the different digested fractions obtained from the wine. In contrast, in the vinegar, the stability of isorahmenetin and Quercetin 3-o-rhamnoside was observed during the in vitro digestion simulation. Lastly, the vinegar stood out for its inhibition rates of α-amylase (23.93%), α-glucoside (18.34%), and angiotensin-converting enzyme (10.92%). In addition, the vinegar had an inhibitory effect on the pathogenic microorganisms Salmonella enteritidis, Escherichia coli, and Listeria monocytogenes.
CONCLUSION
Orange passion fruit has proved to be a promising raw material for the development of fermented beverages. Therefore, this study provides an unprecedented perspective on the use and valorization of orange passion fruit, contributing significantly to the advancement of knowledge about fermented products and the associated nutritional and functional possibilities. © 2024 Society of Chemical Industry.
PubMed: 38877535
DOI: 10.1002/jsfa.13663 -
Food Research International (Ottawa,... Aug 2024This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent...
Metagenomic analysis of the bacterial microbiome, resistome and virulome distinguishes Portuguese Serra da Estrela PDO cheeses from similar non-PDO cheeses: An exploratory approach.
This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent chromogenic methods were also used for certain groups/microorganisms. Eight samples of raw ewe's milk cheese were obtained from four producers: two producers with cheeses with a PDO (Protected Designation of Origin) label and the other two producers with cheeses without a PDO label. Agar-based culture methods were used to quantify total mesophiles, Enterobacteriaceae, Escherichia coli, Staphylococcus, Enterococcus and lactic acid bacteria. The presence of Listeria monocytogenes and Salmonella was also investigated. The selected isolates were identified by 16S rRNA gene sequencing and evaluated to determine antibiotic resistance and the presence of virulence genes. The eight cheese samples analyzed broadly complied with EC regulations in terms of the microbiological safety criteria. The HTS results demonstrated that Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus plantarum, Lacticaseibacillus rhamnosus, Enterococcus durans and Lactobacillus coryniformis were the most prevalent bacterial species in cheeses. The composition of the bacterial community varied, not only between PDO and non-PDO cheeses, but also between producers, particularly between the two non-PDO cheeses. Alpha-diversity analyses showed that PDO cheeses had greater bacterial diversity than non-PDO cheeses, demonstrating that the diversity of spontaneously fermented foods is significantly higher in cheeses produced without the addition of food preservatives and dairy ferments. Despite complying with microbiological regulations, both PDO and non-PDO cheeses harbored potential virulence genes as well as antibiotic resistance genes. However, PDO cheeses exhibited fewer of these virulence and antibiotic resistance genes compared to non-PDO cheeses. Therefore, the combination of conventional microbiological methods and the metagenomic approach could contribute to improving the attribution of the PDO label to this type of cheese.
Topics: Cheese; Microbiota; Portugal; Food Microbiology; Animals; Metagenomics; Bacteria; RNA, Ribosomal, 16S; Drug Resistance, Bacterial; Sheep; High-Throughput Nucleotide Sequencing; Milk; Enterococcus
PubMed: 38876593
DOI: 10.1016/j.foodres.2024.114556 -
Food Research International (Ottawa,... Aug 2024Listeria monocytogenes, a widespread food-borne pathogen, utilizes diverse growth substrates including mono- and di-saccharides via PEP-phosphotransferase (PTS) systems....
Listeria monocytogenes, a widespread food-borne pathogen, utilizes diverse growth substrates including mono- and di-saccharides via PEP-phosphotransferase (PTS) systems. We evaluated a collection of L. monocytogenes isolates of different origins for their ability to utilize lactose, a disaccharide composed of galactose and glucose and the main carbon source in milk and dairy products. Notably, the dairy-associated outbreak strain F2365 could not utilize lactose efficiently, conceivably due to a frameshift mutation (lacR) resulting in a truncated LacR. Transcriptional activator LacR is involved in the expression of two PTS systems, encoded by the lpo operon lmo1718-1720 in combination with lmo2708 and the lmo2683-2685 operon, and linked to lactose and/or cellobiose metabolism in L. monocytogenes. Via experimental evolution of the ancestral strain F2365, an evolved isolate F2365 EV was obtained which showed enhanced growth and metabolism of lactose. Using the lactose-positive model strain L. monocytogenes EGDe as a control, HPLC experiments showed that EGDe and F2365 EV could consume lactose and utilize the glucose moiety, while the galactose moiety was exported from the cells. Genome sequencing of F2365 EV found the original lacR mutation was still present but an additional point mutation lmo2766 had occurred, resulting in an amino acid substitution in the putative regulator Lmo2766. The lmo2766 gene is located next to operon lmo2761-2765 with putative PTS genes in the genome. Notably, comparative RNAseq analysis confirmed that the lmo2761-2765 operon was strongly upregulated in F2365 EV in the presence of lactose but not in EGDe and F2365. Conversely, the LacR-regulated lpo operon, lmo2708, and lmo2683-2685 operon were only upregulated in EGDe. Additional growth and HPLC experiments, using mutants constructed in lactose-positive L. monocytogenes EGDe, showed reduced growth of the EGDe lacR mutant with no utilization of lactose, while the double mutant EGDe lacRlmo2766 showed enhanced growth and lactose utilization. Hence, these results demonstrate that an amino acid substitution in the Lmo2766 regulator activates a previously silent lactose utilization pathway encoded by PTS operon lmo2761-2765, facilitating the growth and metabolism of L. monocytogenes with lactose as a substrate. This finding enhances our understanding of the metabolic capabilities and adaptability of L. monocytogenes, offering a broader view of the lactose utilization capacity of this pathogen.
Topics: Listeria monocytogenes; Lactose; Operon; Bacterial Proteins; Disease Outbreaks; Gene Expression Regulation, Bacterial; Food Microbiology; Milk; Animals; Dairy Products
PubMed: 38876592
DOI: 10.1016/j.foodres.2024.114554 -
Journal of Food Protection Jun 2024The efficacy of a sanitizer in biofilm removal may be influenced by a combination of factors such as sanitizer exposure time and concentration, bacterial species,...
The efficacy of a sanitizer in biofilm removal may be influenced by a combination of factors such as sanitizer exposure time and concentration, bacterial species, surface topography, and shear stresses. We employed an inline biofilm reactor to investigate the interactions of these variables on biofilm removal with chlorine. The CDC bioreactor was used to grow E. coli O157:H7 and L. monocytogenes biofilms as a single species or with Ralstonia insidiosa as a dual-species biofilm on stainless steel, PTFE, and EPDM coupons at shear stresses 0.368 and 2.462 N/m for 48 hours. Coupons were retrieved from a CDC bioreactor and placed in an inline biofilm reactor and 100, 200, or 500 ppm of chlorine was supplied for 1- and 4 min. Bacterial populations in the biofilms were quantified pre- and posttreatment by plating on selective media. After chlorine treatment, reduction (Log CFU/cm) in pathogen populations obtained from three replicates was analyzed for statistical significance. A 1-min chlorine treatment (500 ppm), on dual-species E. coli O157:H7 biofilms grown at high shear stress of 2.462 N/m resulted in significant E. coli O157:H7 reductions on SS 316L (2.79 log CFU/cm) and PTFE (1.76 log CFU/cm). Similar trend was also observed for biofilm removal after a 4-min chlorine treatment. Single species E. coli O157:H7 biofilms exhibited higher resistance to chlorine when biofilms were developed at high shear stress. The effect of chlorine in L. monocytogenes removal from dual-species biofilms was dependent primarily on the shear stress at which they were formed rather than the surface topography of materials. Besides surface topography, shear stresses at which biofilms were formed also influenced the effect of sanitizer. The removal of E. coli O157:H7 biofilms from EPDM material may require critical interventions due to difficulty in removing this pathogen. The inline biofilm reactor is a novel tool to evaluate the efficacy of a sanitizer in bacterial biofilm removal.
PubMed: 38876365
DOI: 10.1016/j.jfp.2024.100314 -
Journal of Food Protection Jun 2024The current study assessed (i) the microbiological safety level profiles (MSLPs) of milkmen's hands and milking containers and (ii) the influence of hygiene and handling...
The current study assessed (i) the microbiological safety level profiles (MSLPs) of milkmen's hands and milking containers and (ii) the influence of hygiene and handling practices on MSLPs of raw and cultured milk, from six informal dairy farms in Zimbabwe. Interviews and direct observations were carried out during the assessment of hygiene and handling practices at six farms designated A to F. Microbiological criteria of the following six microbiological parameters: Total Bacterial Counts (TBCs), Coliform Counts (CCs), Total Escherichia coli Counts (TECs), Salmonella spp., Listeria monocytogenes and Klebsiella pneumonia, were used to determine contamination level (CL) at four different critical sampling locations (CSLs). The CSLs were raw milk (CSL1), cultured milk (CSL2), milkmen's hands (CSL3), and milking containers (CSL4). The microbiological criteria of the six microbiological parameters were used to score CLs as: intolerable (0), poor to average (1), average (2), and good (3). MSLPs at each CSL for the six farms were computed based on the CL scores to a maximum score of 18. A total of 192 samples were collected and analyzed. Salmonella spp. and L. monocytogenes were not detected at all the CSLs. All the farms failed to achieve a maximum MSLP score of 18 at all the CSLs. The relationship between MSLPs and hygiene and handling practices was tested using point-biserial correlation coefficients. The correlation study revealed that handling and hygiene practices (such as the duration between milking and storage, the type of milking container utilized at farms, the frequency of cleaning the milking parlor, the water source for hand and equipment washing, and the use of hand sanitizers) generally influenced the MSLPs on the farms. Both training and improvement in infrastructure are needed to improve the quality of milk and its products produced and sold in the informal value chain in Zimbabwe.
PubMed: 38871224
DOI: 10.1016/j.jfp.2024.100313 -
Journal of Food Protection Jun 2024In recent years, there have been numerous recalls of frozen vegetable products due to Listeria monocytogenes contamination, which causes listeriosis. In pregnant women,...
In recent years, there have been numerous recalls of frozen vegetable products due to Listeria monocytogenes contamination, which causes listeriosis. In pregnant women, listeriosis can cause miscarriage, stillbirth, and other serious complications. Manufacturing guidelines are created with the intention that frozen vegetables will be cooked prior to consumption. However, consumers may prepare and eat frozen vegetables without prior cooking. Therefore, it is necessary to assess behaviors that could be risky for L. monocytogenes exposure. A 10-question online survey was distributed to women between the ages of 18-54 to investigate frozen vegetable consumption behaviors. The prevalence of uncooked frozen vegetable consumption, reading preparation instructions, and listeriosis knowledge was assessed. Data were analyzed using logistic and ordered logit regression. Of 1,001 complete responses, 531 (53%) indicated that they consumed frozen vegetables in the past week, and of those 35.6% (n = 189) indicated that they consumed frozen vegetables without prior heating. Women who had not heard of listeriosis and had not read preparation instructions had significantly higher odds of uncooked frozen vegetable consumption (Odds Ratio (OR): 2.30, 95% Confidence Interval (CI): 1.48, 3.55; OR: 1.85, 95% CI: 1.13, 3.01, respectively). These results will guide future research on safe food handling practices for frozen vegetable products. The findings support the need for updating public health guidelines to include frozen vegetables as foods that are risky for listeriosis in pregnancy. Additionally, these findings have implications for future research to inform food policy governing labeling regulation on frozen vegetable products to reflect current consumer behavior.
PubMed: 38871223
DOI: 10.1016/j.jfp.2024.100315 -
Meat Science Jun 2024Present study is focused on exploring in vitro antimicrobial activity of ginseng extract (GE) against Staphylococcus aureus, Salmonella Typhimurium and Listeria...
In vitro antimicrobial activity of ginseng extract against Staphylococcus aureus, Salmonella Typhimurium and Listeria monocytogenes and its inhibitory effects on these pathogens in cooked ground beef.
Present study is focused on exploring in vitro antimicrobial activity of ginseng extract (GE) against Staphylococcus aureus, Salmonella Typhimurium and Listeria monocytogenes and their biofilm forming ability, then determining its antimicrobial efficiency during the storage (4 and 10 °C) of cooked ground beef contaminated with these pathogens. Results revealed that the minimum inhibitory concentration (MIC) for S. aureus, S. typhimurium and L. monocytogenes were 90, 70 and 40 mg/mL, respectively. GE was also able to inhibit biofilm production by S. aureus and L. monocytogenes, whereas S. typhimurium did not produce biofilm with or without GE application. On the other hand, the results of GE aplication in ground beef indicated that GE incorporation at 0.5% or more reduced S. aureus and S. Typhmurium counts in cooked ground beef at the end of 30 d storage at 4 °C (P < 0.05). Using 1% or more GE totally inhibited S. Typhmurium after 15 d storage at 4 °C (P < 0.05). However, GE application did not affect S. aureus or S. Typhmurium counts in cooked ground beef stored at 10 °C. Furthermore, incorporation of 0.5% or more GE generally inhibited L. monocytogenes growth in cooked ground beef at the end of storage at both 4 and 10 °C (P < 0.05). In general, pH was lower in samples with GE than those without GE regardless of differences in the type of tested pathogen, storage time and temperatures (P < 0.05). Although similar a was generally obtained on processing day, lower a was observed in GE containing groups at the end of storage for both storage temperatures (P < 0.05). Oxidation reduction potential (ORP) in all groups generally increased during storage at both storage temperatures (P < 0.05). In conclusion, our results demonstrated that GE has an important role in controlling growth of tested pathogens and may be used as a natural agent by the meat industry to inhibit the growth of food-borne pathogens in cooked processed meat products during storage.
PubMed: 38870594
DOI: 10.1016/j.meatsci.2024.109559 -
Journal of Medicinal Food Jun 2024Antioxidant-related parameters and anti-inflammatory and antimicrobial activities against were assessed in eight North East Spain poplar propolis samples. Propolis...
Antioxidant-related parameters and anti-inflammatory and antimicrobial activities against were assessed in eight North East Spain poplar propolis samples. Propolis extracts (PEs) were obtained using 70% ethanol (PEE) and methanol (PME). Yield and total phenol compounds were higher in PEE. Phenolic acids were analyzed by a high-performance liquid chromatograph-diode array detector. Caffeic and ferulic acids were quantified in all PEE and PME. All samples contained p-coumaric acid (quantified in 6 PEE and in 3 PME). Ascorbic acid was detected in all propolis, but mainly quantified in PME (≤0.37 mg/g PE). Biological properties were tested on PEE. As for antiradical activities, trolox equivalent antioxidant capacity (TEAC) [against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], ranged between 578 and 4620 µmol trolox/g, 2,2-diphenyl-1-picrylhydrazyl (DPPH) (against DPPH free radical), between 0.049 and 0.094 mg/mL, antioxidant activity against hydroxyl (OH) radical (AOA), between 0.04 and 11.01 mmol uric acid/g, and oxygen radical absorbance capacity (ORAC) against peroxyl (ROO) radical between 122 and 3282 µmol trolox/g. Results of TEAC, AOA, and ORAC were significantly correlated. IC anti-inflammatory activity ranged from 1.08 to 6.19 mg/mL. Propolis showed higher inhibitory activity against CECT934 and CP101 by agar well diffusion ( < .05) (10.5 and 10.2 mm, respectively) than against CP102 (7.0 mm). Data of this research show that North East Spain propolis may be of interest for pharmaceutical and food industry use.
Topics: Propolis; Anti-Inflammatory Agents; Phenols; Listeria monocytogenes; Antioxidants; Spain; Anti-Infective Agents; Anti-Bacterial Agents; Plant Extracts
PubMed: 38868932
DOI: 10.1089/jmf.2023.0206