Category Archives: Technology

Research – Isolation and characterization of a virulent bacteriophage for controlling Salmonella enteritidis growth in ready-to-eat mixed-ingredient salads

Posted on April 6, 2021 by | Leave a comment

Journal of Food Protection

Recently, ready-to-eat vegetable salads have gained popularity worldwide. However, the microbial safety of ready-to-eat salads is a health concern, primarily due to Salmonella enteritidis contamination during the growing, harvesting, processing, and handling of produce. This study aimed to develop a bacteriophage-based strategy to control S. enteritidis growth in mixed-ingredient salads. A lytic Salmonella-specific phage SapYZU01 was isolated from a soil sample from a suburban vegetable field in Yangzhou, China. SapYZU01 exhibited characteristics such as a short latent period, a large burst size, and a lytic effect against 13 S. enteritidis strains isolated from various sources (human, pork, deli, chicken, and chicken meat). The SapYZU01 genome did not contain virulence or antibiotic resistance genes. SapYZU01 significantly decreased the viability of S. enteritidis cells in iceberg lettuce, chicken meat, and mixed-ingredient (lettuce+chicken) salads at 37 and 25 °C. Furthermore, bacterial counts in the salad decreased significantly (by 4.0 log colony-forming units (CFU)/g) at 25 °C upon treatment of contaminated lettuce with SapYZU01 at an MOI of 100 prior to salad preparation. Bacterial counts were decreased by 3.8 log CFU/g at 25 °C in (lettuce+chicken) salads treated with SapYZU01 at an MOI of 100 after the salad preparation. In contrast, treating cooked chicken meat with SapYZU01 at an MOI of 100 before mixing it with contaminated lettuce decreased the bacterial count of the salad by 1.2 log CFU/g at 25 °C. These findings indicate the potential application of SapYZU01 as a natural biocontrol agent against S. enteritidis in mixed-ingredient salads. Furthermore, the application of lytic bacteriophage SapYZU01 in mix-ingredient salads should considered the bacteriophage treatment method in addition to the bacteriophage concentration.

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Posted in Bacteriophage, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology

Research – Efficacy of Bacteriophage Cocktail to Control E. coli O157:H7 Contamination on Baby Spinach Leaves in the Presence or Absence of Organic Load

Posted on March 14, 2021 by | Leave a comment

MDPI

Fruits and vegetables are high in nutrients that are essential for a healthy lifestyle. However, they also harbor an extensive array of microorganisms such as bacteria, which can be beneficial, neutral, or pathogenic. Foodborne pathogens can contaminate produce at any stage from the farm to the consumer’s table. Appropriate washing techniques using sanitizers can reduce the risk of pathogen contamination. Issues related to maintaining concentration, efficacy, and other problems have been a challenge for the food industry and, when left unresolved, have led to different outbreaks of foodborne illnesses. In this study, the efficacy of a lytic bacteriophage cocktail was examined for its ability to infect and reduce the contamination of Escherichia coli O157:H7 (E. coli O157:H7), in media with a high organic load, using a microplate technique. The study was conducted for 3 h to determine if the bacteriophage cocktail could reduce the pathogen in the presence of a high organic load. A significant (p < 0.05) reduction in the population of E. coli O157:H7 was observed, representing a 99.99% pathogen reduction at the end of 3 h. Fresh spinach leaves were washed in sterile potable or organic water (~9000 ppm organic load) containing E. coli O157:H7 and a bacteriophage cocktail to study the effectiveness of bacteriophages against the foodborne pathogen. Results indicated that the bacteriophage significantly (p < 0.05) reduced the contamination of E. coli O157:H7 in both situations. The study also demonstrated the bacteriophages’ ability to infect and reduce the pathogen in an organic-rich environment. This characteristic differs from commercially available sanitizers that have demonstrated a tendency to bind with the available organic load. Thus, these studies highlight the advantage of employing bacteriophages during produce wash to eliminate foodborne pathogen contamination on fruits and vegetables. View Full-Text

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Posted in Bacteriophage, E.coli O157, E.coli O157:H7, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, STEC, STEC E.coli, Technology

Research – Effect of Chlorine Dioxide Treatment on Human Pathogens on Iceberg Lettuce

Posted on March 13, 2021 by | Leave a comment

MDPI

In the vegetable processing industry, the application of chlorine dioxide (ClO2) as a disinfectant solved in washing water to eliminate undesirable microorganisms harmful to consumers’ health and the shelf life of produce has been discussed for years. The disinfection efficacy depends on various factors, e.g., the location of microorganisms and the organic load of the washing water. The present study analyzed the sanitation efficacy of various concentrations of water-solved ClO2 (cClO2: 20 and 30 mg L−1) on Escherichia coli (1.1 × 104 cfu mL−1), Salmonella enterica (2.0 × 104 cfu mL−1) and Listeria monocytogenes (1.7 × 105 cfu mL−1) loads, located on the leaf surface of iceberg lettuce assigned for fresh-cut salads. In addition, it examined the potential of ClO2 to prevent the cross-contamination of these microbes in lettuce washing water containing a chemical oxygen demand (COD) content of 350 mg L−1 after practice-relevant washing times of 1 and 2 min. On iceberg leaves, washing with 30 mg L−1 ClO2 pronouncedly (1 log) reduced loads of E. coli and S. enterica, while it only insignificantly (<0.5 × log) diminished the loads of L. monocytogenes, irrespective of the ClO2 concentration used. Although the sanitation efficacy of ClO2 washing was only limited, the addition of ClO2 to the washing water avoided cross-contamination even at high organic loads. Thus, the application of ClO2 to the lettuce washing water can improve product quality and consumer safety. View Full-Text

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Posted in E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Pathogen, pathogenic, Research, Salmonella, Technology

Research – Acoustic Water Could Cut Salad-Related Food Poisoning

Posted on March 4, 2021 by | 1 comment

Technology Networks

Eurofins Food Testing UK

A new study has shown that gentle streams of water carrying sound and microscopic air bubbles can clean bacteria from salad leaves more effectively than current washing methods used by suppliers and consumers. As well as reducing food poisoning, the findings could reduce food waste and have implications for the growing threat of anti-microbial resistance.

A diet containing uncooked salad, fruit and vegetables is key to reducing a range of conditions, including cardiovascular diseases, Type II diabetes and certain types of cancer.

However, salad and leafy green vegetables may be contaminated with harmful bacteria during growing, harvesting, preparation and retail leading to outbreaks of food poisoning which may be fatal in vulnerable groups.

Because there is no cooking process to reduce the microbial load in fresh salads, washing is vital by the supplier and the consumer.

Washing with soap, detergent bleach or other disinfectants is not recommended and the crevices in the leaf surface means washing with plain water may leave an infectious dose on the leaf. Even if chemicals are used, they may not penetrate the crevices.

In this new study, published in the journal Ultrasound in Medicine and Biology, scientists used acoustic water streams to clean spinach leaves directly sourced from the field crop, then compared the results with leaves rinsed in plain water at the same velocity.

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Posted in food contamination, Food Hazard, Food Hygiene, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Safety, Food Technology, Food Testing, Research, Technology

Research – Short Wave Ultraviolet Light (UV-C) Effectiveness in the Inactivation of Bacterial Spores Inoculated in Turbid Suspensions and in Cloudy Apple Juice

Posted on February 21, 2021 by | Leave a comment

MDPI

Liquid foods might present interferences in their optical properties that can reduce the effectiveness of short-wave ultraviolet radiation (UV-C) treatments used for sterilization purposes. The effect of turbidity as UV-C interference factor against the inactivation of bacterial spores was analysed by using phosphate-buffered saline solutions (PBS) of different turbidity values (2000, 2500, and 3000 NTU) which were adjusted with the addition of apple fibre. These suspensions were inoculated with spores of Bacillus subtilis and Alicyclobacillus acidoterrestris. While higher UV-C doses increased the inactivation rates of spores, these were reduced when turbidity values increased; a dose of 28.7 J/mL allowed inactivation rates of B. subtilis spores of 3.96 Log in a 2000-NTU suspension compared with 2.81 Log achieved in the 3000-NTU one. Spores of B. subtilis were more UV-C-resistant than A. acidoterrestris. Cloudy apple juice inoculated with A. acidoterrestris spores was processed by UV-C at different doses in a single pass and with recirculation of the matrix through the reactor. Inactivation increased significantly with recirculation, surpassing 5 Log after 125 J/mL compared with 0.13 Log inactivation after a single-pass treatment at the same UV-C dose. UV-C treatments with recirculation affected the optical properties (absorption coefficient at 254 nm and turbidity) of juice and increased browning as UV-C doses became higher.

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Posted in Bacterial Spores, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Spores, Technology

Research – Natural Antimicrobials Suitable for Combating Desiccation-Resistant Salmonella enterica in Milk Powder

Posted on February 18, 2021 by | Leave a comment

MDPI

Some Salmonella enterica strains survive well in low-water activity (low-aw) foods and cause frequent salmonellosis outbreaks in these products. Methods are needed to overcome such desiccation-resistant Salmonella and to improve the safety of low-aw foods. Building on a recent finding, we hypothesized that natural antimicrobial food additives, which are active against cytoplasmic membrane, could overcome this desiccation resistance phenomenon, and thus, sensitize the pathogen to drying and mild processing. Food additives were screened for the ability to cause leakage of intracellular potassium ions; retention of these ions is vital for protecting Salmonella against desiccation. Two antimicrobial food additives, carvacrol and thymol, caused considerable potassium leakage from the desiccation-resistant S. enterica serovars, Tennessee and Livingstone. Thus, carvacrol and thymol were investigated for their ability to sensitize the desiccation-adapted S. enterica to heat treatment. The combined use of food additives, at their minimum inhibitory concentrations, with heat treatment at 55 °C for 15 min caused 3.1 ± 0.21 to more than 5.5 log colony forming unit (CFU)/mL reduction in desiccation-adapted S. enterica, compared to 2.4 ± 0.53–3.2 ± 0.11 log CFU/mL reduction by sole heat treatment. Carvacrol was the additive that caused the greatest potassium leakage and sensitization of Salmonella to heat; hence, the application of this compound was investigated in a food model against Salmonella Typhimurium ASD200. Addition of carvacrol at 200 or 500 ppm into liquid milk followed by spray-drying reduced the strain’s population by 0.9 ± 0.02 and 1.3 ± 0.1 log CFU/g, respectively, compared to 0.6 ± 0.02 log CFU/g reduction for non-treated spray-dried milk. Additionally, freeze-drying of milk treated with high levels of carvacrol (5000 ppm) reduced the population of Salmonella Typhimurium ASD200 by more than 4.5 log CFU/g, compared to 1.1 ± 0.4 log CFU/g reduction for the freeze-dried untreated milk. These findings suggest that carvacrol can combat desiccation-resistant S. enterica, and thus, potentially improve the safety of low-aw foods. View Full-Text

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology

Research – Light technology kills eggshell pathogens

Posted on January 27, 2021 by | Leave a comment

KMA Land

hazegg.jpg

Pulsed ultraviolet light can be an alternative to some of the antimicrobial technologies now used in the poultry industry to kill pathogens, according to researchers at Pennsylvania State University. By reducing the microbial load on eggshells, foodborne illness associated with eggs and poultry meat can be reduced while chick health is maintained.

Paul Patterson, a professor of poultry science at Penn State, said the technology has merit for commercial application. The research team applied components of standard egg processing to a conveyor and sanitized eggs in a commercial setting, he said.

In the study eggshells were inoculated with nonpathogenic bacterial strains used for research. They were treated with pulsed ultraviolet light derived from a xenon flashlamp. Eggs were exposed on a modified egg-carrying conveyor that provided complete rotation of eggs under the flashlamp.

The researchers found that pulsed ultraviolet light treatment inactivated two different microbial strains with greater energy.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Safety, Food Technology, microbial contamination, Microbiology, Research, Technology

Research – Impact of a Combination of UV-C Irradiation and Peracetic Acid Spray Treatment on Brochothrix thermosphacta and Yersinia enterocolitica Contaminated Pork

Posted on January 23, 2021 by | Leave a comment

MDPI

Efficient ways of decontamination are needed to minimize the risk of infections with Yersinia (Y.) enterocolitica, which causes gastrointestinal diseases in humans, and to reduce the numbers of Brochothrix (B.) thermosphacta to extend the shelf-life of meat. While many studies have focused on a single treatment of peracetic acid (PAA) or UV-C-irradiation, there are no studies about a combined treatment on meat. Therefore, in the present study, pork was inoculated with either Y. enterocolitica or B. thermosphacta, and was treated with a combination of 2040 mJ/cm2 UV-C irradiation followed by a 2000 ppm PAA spray treatment (30 s). Samples were packed under modified atmosphere and stored for 1, 7, or 14 days. The samples were examined for Y. enterocolitica and B. thermosphacta content, chemical and sensory effects, and meat quality parameters. For Y. enterocolitica, a significant reduction of up to 2.16 log10 cfu/cm2 meat and for B. thermosphacta, up to 2.37 log10 cfu/cm2 meat was seen on day 14 after UV-C/PAA treatment compared to the untreated controls.

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Posted in Brochothrix thermosphacta, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Technology, Yersinia, yersinia enterocolitica

Research – Nanocrystals that eradicate bacteria biofilm

Posted on January 17, 2021 by | Leave a comment

Science Daily

The COVID-19 pandemic is raising fears of new pathogens such as new viruses or drug-resistant bacteria. To this, a Korean research team has recently drawn attention for developing the technology for removing antibiotic-resistant bacteria by controlling the surface texture of nanomaterials.

A joint research team from POSTECH and UNIST has introduced mixed-FeCo-oxide-based surface-textured nanostructures (MTex) as highly efficient magneto-catalytic platform in the international journal Nano Letters. The team consisted of professors In Su Lee and Amit Kumar with Dr. Nitee Kumari of POSTECH’s Department of Chemistry and Professor Yoon-Kyung Cho and Dr. Sumit Kumar of UNIST’s Department of Biomedical Engineering.

First, the researchers synthesized smooth surface nanocrystals in which various metal ions were wrapped in an organic polymer shell and heated them at a very high temperature. While annealing the polymer shell, a high-temperature solid-state chemical reaction induced mixing of other metal ions on the nanocrystal surface, creating a number of few-nm-sized branches and holes on it. This unique surface texture was found to catalyze a chemical reaction that produced reactive oxygen species (ROS) that kills the bacteria. It was also confirmed to be highly magnetic and easily attracted toward the external magnetic field. The team had discovered a synthetic strategy for converting normal nanocrystals without surface features into highly functional mixed-metal-oxide nanocrystals.

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Posted in Biofilm, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Technology

Research – Bacteria Broadly-Resistant to Last Resort Antibiotics Detected in Commercial Chicken Farms

Posted on January 16, 2021 by | Leave a comment

MDPI

Resistance to last resort antibiotics in bacteria is an emerging threat to human and animal health. It is important to identify the source of these antimicrobial resistant (AMR) bacteria that are resistant to clinically important antibiotics and evaluate their potential transfer among bacteria. The objectives of this study were to (i) detect bacteria resistant to colistin, carbapenems, and β-lactams in commercial poultry farms, (ii) characterize phylogenetic and virulence markers of E. coli isolates to potentiate virulence risk, and (iii) assess potential transfer of AMR from these isolates via conjugation. Ceca contents from laying hens from conventional cage (CC) and cage-free (CF) farms at three maturity stages were randomly sampled and screened for extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, carbapenem-resistant Acinetobacter (CRA), and colistin resistant Escherichia coli (CRE) using CHROMagar™ selective media. We found a wide-spread abundance of CRE in both CC and CF hens across all three maturity stages. Extraintestinal pathogenic Escherichia coli phylogenetic groups B2 and D, as well as plasmidic virulence markers iss and iutA, were widely associated with AMR E. coli isolates. ESBL-producing Enterobacteriaceae were uniquely detected in the early lay period of both CC and CF, while multidrug resistant (MDR) Acinetobacter were found in peak and late lay periods of both CC and CF. CRA was detected in CF hens only. blaCMY was detected in ESBL-producing E. coli in CC and CF and MDR Acinetobacter spp. in CC. Finally, the blaCMY was shown to be transferrable via an IncK/B plasmid in CC. The presence of MDR to the last-resort antibiotics that are transferable between bacteria in food-producing animals is alarming and warrants studies to develop strategies for their mitigation in the environment. View Full-Text

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Posted in Antibacterial, Antibiotic Resistance, antimicrobial resistance, Antimicrobials, E.coli, Enterobacteriaceae, ESBL, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, Technology