The combined effect of weakly acidic electrolyzed water (WAEW) and modified atmosphere packaging (MAP) treatments on the quality of puffer fish (Takifugu obscurus ) during cold storage was studied on aspects of microbiological activity, texture, total volatile basic nitrogen (TVB‐N), trimethylamine (TMA), free amino acids (FAAs), thiobarbituric acid reactive substance (TBARS), ATP‐related compounds and K value, volatile organic compounds (VOCs), and organoleptic properties. As a result, significantly (p < .05) higher inhibitory effects on total viable counts (TVC), H2S‐producing bacteria (including Shewanella putrefaciens ), Pseudomonas spp., and lactic acid bacteria (LAB) were observed in WAEW‐treated puffer fish packaged in 60%CO2/5%O2/35%N2 atmosphere than that in air package and vacuum package with/without WAEW‐treated samples. In addition, chemical results showed that WAEW together with MAP treatments were highly efficient in maintaining lower TVB‐N, TMA, and TBARS values in refrigerated puffer fish. Moreover, the presence of WAEW combined with MAP treatments showed positive effects on retarding the relative content of fishy flavor compounds, such as 1‐octen‐3‐ol, 1‐penten‐3‐ol, hexanal, heptanal, nonanal, decanal, (E )‐2‐octenal, and 2,3‐butanedione. As a whole, the combined effect of WAEW and MAP on refrigerated puffer fish is advisable to maintain better quality and extend the shelf life.
Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Pseudomonas, Pseudomonas aeruginosa, Pseudomonas fluorescens, Research, Shewanella, Technology, Uncategorized
This study evaluated the in vitro and in vivo antibacterial activities of methanol and ethyl acetate extracts of Camellia sinensis (Green tea) against Escherichia coli implicated in urinary tract infections. Antibacterial activities of these plant extracts were tested against 10 multi-drug resistant E. coli isolates obtained from clinical specimens of UTI patients. Forty-five (45) Wister albino rats were used for this study and exactly 0.1 ml of standardized (0.5 McFarland’s) E. coli suspension was each inoculated into the 45 rats through intra-urethral route and observed after 48 h. This was followed by oral administration of different concentrations of methanol and ethyl acetate extracts of C. sinensis, and ciprofloxacin antibiotic for 14 days. Phytochemical screening of extracts showed the presence of bioactive components. Results revealed that methanol extract was better than ethyl acetate extract of C. sinensis in the treatment of UTI caused by E. coli. Body weight, white blood cell count, and erythrocyte sedimentation rate level returned to normal values after treatment with methanol extract of C. sinensis at 200 mg/kg body weight when compared to ethyl acetate extract of C. sinensis. This study has shown that C. sinensis possess bioactive ingredients with antimicrobial activities. Information from this study adds to the current information on the potential health benefits of green tea. Thus, further studies on other plant products should be explored so as to understand their potential health benefits and as alternative therapeutics in the treatment of bacterial infections.
Salmonella typhimurium is able to form biofilms as a resistance mechanism against antimicrobials; therefore, it represents a problem for assuring food safety and highlights the importance of research on anti‐biofilm technologies. In this study, S. typhimurium biofilms were inactivated with the combination of clove essential oil (CEO) and ultraviolet light (UV‐C). The volatile composition of the CEO determined by gas chromatography showed eugenol as the major constituent (82%). A combination of CEO with UV‐C achieved a complete bacterial reduction (6.8 log/cm2) on biofilms with doses of 1.2 mg/ml and 76.41 mJ/cm2, respectively. Individually, the CEO at 1.2 mg/ml caused a reduction of 1.8 log CFU/cm2 of attached bacteria cells on stainless steel, while UV‐C individually used at 620.4 mJ/cm2 caused a 2.9 log CFU/cm2 reduction compared to control biofilms. In conclusion, this study demonstrated a synergistic effect of combining CEO and UV‐C irradiation to inactivate biofilms of S. typhimurium .
Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized
Home canning is an excellent way to preserve garden produce and share it with family and friends. But it can be risky—or even deadly—if not done correctly and safely.
It’s summertime and time to harvest the delicious produce you’ve been growing. You may be thinking about home canning as a way to preserve your garden goodies. But beware! If home canning is not done the proper way, your canned vegetables and fruits could cause botulism.
What is botulism?
Botulism is a rare but potentially deadly illness caused by a poison most commonly produced by a germ called Clostridium botulinum. The germ is found in soil and can survive, grow, and produce a toxin in certain conditions, such as when food is improperly canned. The toxin can affect your nerves, paralyze you, and even cause death.
You cannot see, smell, or taste botulinum toxin—but taking even a small taste of food containing this toxin can be deadly.
Posted in botulism, Clostridium botulinum, food contamination, food death, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, Food Poisoning Death, Food Safety, Food Technology, Food Temperature Abuse, Food Testing, Food Toxin, Research, Uncategorized
Researchers have developed synthetic microbial spores that can be safely introduced onto objects and surfaces at a point of origin, such as a field or manufacturing plant, and be detected and identified months later. The approach can help determine the source of foodborne illnesses.
Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Technology, Food Testing, Spores, Uncategorized
A quantitative risk assessment comprising the elements hazard identification, hazard characterization, exposure assessment, and risk characterization has been prepared to assess the effect of different mitigation strategies on the number of human cases in Denmark associated with thermophilic Campylobacter spp. in chickens. To estimate the human exposure to Campylobacter from a chicken meal and the number of human cases associated with this exposure, a mathematical risk model was developed. The model details the spread and transfer of Campylobacter in chickens from slaughter to consumption and the relationship between ingested dose and the probability of developing campylobacteriosis. Human exposure was estimated in two successive mathematical modules. Module 1 addresses changes in prevalence and numbers of Campylobacter on chicken carcasses throughout the processing steps of a slaughterhouse. Module 2 covers the transfer of Campylobacter during food handling in private kitchens. The age and sex of consumers were included in this module to introduce variable hygiene levels during food preparation and variable sizes and compositions of meals. Finally, the outcome of the exposure assessment modules was integrated with a Beta-Poisson dose-response model to provide a risk estimate. Simulations designed to predict the effect of different mitigation strategies showed that the incidence of campylobacteriosis associated with consumption of chicken meals could be reduced 30 times by introducing a 2 log reduction of the number of Campylobacter on the chicken carcasses. To obtain a similar reduction of the incidence, the flock prevalence should be reduced approximately 30 times or the kitchen hygiene improved approximately 30 times. Cross-contamination from positive to negative flocks during slaughter had almost no effect on the human Campylobacter incidence, which indicates that implementation of logistic slaughter will only have a minor influence on the risk. Finally, the simulations showed that people in the age of 18-29 years had the highest risk of developing campylobacteriosis.
Posted in Campylobacter, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Uncategorized
We compared the fate of cold‐stressed (CS) or tetracycline‐resistant (TR) Vibrio parahaemolyticus, Vibrio vulnificus , and Vibrio cholerae in precooked shrimp during frozen storage. The recovery ability of viable but nonculturable (VBNC) Vibrio cells was compared at 25°C. Each suspension of nonstressed (NS), CS, or TR Vibrio cells inoculated into cooked shrimps were subjected to frozen storage at −20°C or three freeze–thaw cycles. CS and TR cells were more rapidly converted to VBNC state than NS cells. Most of VBNC Vibrio cells were observed as viable cells after frozen storage. Although there were differences in the recovery extent of cells depending on the types of stress and strain, VBNC cells were resuscitated at 25°C. The most resistant to tetracycline and the lowest injury rate were observed in V. cholerae cells during frozen storage.
Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Uncategorized, Vibrio, Vibrio cholera, Vibrio parahaemolyticus, Vibrio vulnificans, Vibrio vulnificus
The safety of current UK industry practice (including shelf-life) for chilled, vacuum/modified atmosphere-packed fresh red meat (beef, lamb and pork) held at 3°C–8°C has been evaluated with respect to non-proteolytic Clostridium botulinum. UK industry typically applies a retail pack shelf-life at 3°C–8°C to 13 days for fresh red meat, with a maximum of 23 days for beef, 27 days for lamb, and 18 days for pork. An exposure assessment established that current commercial practice for fresh red meat provided strong protection with more than 1010 person servings marketed in the UK without association with foodborne botulism. A challenge test demonstrated that spores of non-proteolytic C. botulinum inoculated on chilled vacuum-packed fresh red meat did not lead to detectable neurotoxin at day 50 for beef, day 35 for lamb, or day 25 for pork (i.e. <40 pg type B toxin and type E toxin g−1 of meat). The products were visually spoiled many days before these end points. The exposure assessment and challenge test demonstrated the safety of current UK industry practices for the shelf-life of fresh, vacuum-packed beef, lamb and pork held at 3°C–8°C with respect to C. botulinum, and that botulinum neurotoxin was not detected within their organoleptic shelf-life.
Litsea cubeba essential oil (LC‐EO) has been reported as antibacterial agents, but there are few studies about its possible antibacterial mechanism. The antibacterial activities and the underlying mechanisms of LC‐EO against Escherichia coli O157: H7 and Salmonella enterica were investigated. The results showed that the LC‐EO was more effective against gram‐negative bacteria. The inhibition zone for E. coli O157: H7 and S. enterica were 3.1 ± 0.8 and 4.5 ± 0.6 mm, respectively. The minimum inhibitory concentration of LC‐EO against both bacteria was 0.9 μg/ml, while the minimum bactericidal concentrations were 4.5 and 9 μg/ml. Gas chromatography–mass spectrometry analysis confirmed that citral (86.8%) was the main component of LC‐EO. The results of a time–kill analysis illustrated that treatment with LC‐EO led to a rapid decrease in viable bacterial cell number. The release of electrolytes and nucleic acids from the bacterial cells increased with the dose of LC‐EO. Propidium iodide uptake revealed that LC‐EO caused cell membrane damage. Scanning electron and transmission electron microscopy showed that LC‐EO caused damage to the cell walls and membranes, resulting in cell deformation, atrophy, and large central voids. Thus, LC‐EO may provide the basis for the development of new natural food preservatives.
Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Salmonella, STEC E.coli, Technology, Uncategorized
Journal of Food Protection
Biofilm formation by Escherichia coli O157:H7 and Salmonella enterica at meat processing plants poses a potential risk of meat product contamination. Many common sanitizers are unable to completely eradicate biofilms formed by these foodborne pathogens because of the three-dimensional biofilm structure and the presence of bacterial extracellular polymeric substances (EPSs). A novel multifaceted approach combining multiple chemical reagents with various functional mechanisms was used to enhance the effectiveness of biofilm control. We tested a multicomponent sanitizer consisting of a quaternary ammonium compound (QAC), hydrogen peroxide, and the accelerator diacetin for its effectiveness in inactivating and removing Escherichia coli O157:H7 and Salmonella enterica biofilms under meat processing conditions. E. coli O157:H7 and Salmonella biofilms on common contact surfaces were treated with 10, 20, or 100% concentrations of the multicomponent sanitizer solution for 10 min, 1 h, or 6 h, and log reductions in biofilm mass were measured. Scanning electron microscopy (SEM) was used to directly observe the effect of sanitizer treatment on biofilm removal and bacterial morphology. After treatment with the multicomponent sanitizer, viable E. coli O157:H7 and Salmonella biofilm cells were below the limit of detection, and the prevalence of both pathogens was low. After treatment with a QAC-based control sanitizer, surviving bacterial cells were countable, and pathogen prevalence was higher. SEM analysis of water-treated control samples revealed the three-dimensional biofilm structure with a strong EPS matrix connecting bacteria and the contact surface. Treatment with 20% multicomponent sanitizer for 10 min significantly reduced biofilm mass and weakened the EPS connection. The majority of the bacterial cells had altered morphology and compromised membrane integrity. Treatment with 100% multicomponent sanitizer for 10 min dissolved the EPS matrix, and no intact biofilm structure was observed; instead, scattered clusters of bacterial aggregates were detected, indicating the loss of cell viability and biofilm removal. These results indicate that the multicomponent sanitizer is effective, even after short exposure with dilute concentrations, against E. coli O157:H7 and S. enterica biofilms.
- No viable biofilm cells were detected after treatment with the multicomponent sanitizer.
- Prevalence of both pathogens was low after treatment with the multicomponent sanitizer.
- SEM analysis revealed that treatment dissolved the EPS matrix and destroyed the biofilm.
Posted in Biofilm, E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Salmonella, STEC E.coli, Technology, Uncategorized