Category Archives: Research

Research – Hazards in Seafood Notified in the Rapid Alert System for Food and Feed (RASFF) in 1996–2020

Posted on January 6, 2024 by | Leave a comment

MDPI

Abstract

Seafood covering fish, crustaceans, molluscs and cephalopods is broadly recognised for its nutritional value and popularity, but it can pose some hazards to health to the potential consumer. The aim of the study was to analyse Rapid Alert System for Food and Feed (RASFF) notifications for seafood over the period 1996–2020 by hazard, year, product, notifying country, country of origin, notification type, notification basis, distribution status and action taken. The research applied cluster analysis using the joining and two-way joining methods. The main reported hazards were micro-organisms (Listeria, Salmonella, Escherichia coli, Vibrio, norovirus, mesophiles, Enterobacteriaceae and histamine), heavy metals (mercury and cadmium), veterinary products (nitrofuran, chloramphenicol and leucomalachite green), controls (poor temperature control and hygienic state), parasites (Anisakis) and additives/allergens (sulphite). The reported seafood products originated mainly from European and Asian countries and were notified on the basis of official or border controls, respectively. In order to minimize or eliminate risks, it is important to have the right activity of control authorities, appropriate legislation at the European and national levels and awareness at the different stages of the food chain.

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Posted in E.coli, Enterobacteriaceae, Food Microbiology Research, Food Technology, Histamine, Listeria, Listeria monocytogenes, Norovirus, RASFF, Research, Salmonella, Uncategorized, Vibrio

Research – Biocontrol of L. monocytogenes with Selected Autochthonous Lactic Acid Bacteria in Raw Milk Soft-Ripened Cheese under Different Water Activity Conditions

Posted on January 6, 2024 by | Leave a comment

MDPI

Abstract

The effect of selected autochthonous Lactic Acid Bacteria (LAB) against Listeria monocytogenes was evaluated in two elaborations of soft-ripened cheese performed under high and low relative humidity (RH) elaborations, to achieve aw ranging from 0.97 to 0.94 in ripened cheeses. Two selected autochthonous strains of Lacticaseibacillus casei 31 and 116 were used. In each elaboration, 8 batches were physicochemically and microbiologically evaluated throughout the ripening process. The aw and pH decreased during ripening to final values ranging from 0.944 to 0.972 aw and 5.0 to 5.3 pH, respectively. LAB was the only microbial group that increased throughout the ripening in high and low RH elaborations. In batches that were uninoculated with LAB strains, L. monocytogenes was either maintained at the initial inoculation level or showed a slight reduction by the end of the ripening process. However, in LAB-inoculated batches in the two elaborations, steady decreases of L. monocytogenes were observed throughout maturation. L. casei 31 alone or in combination with strain 116 provoked reductions of 2 to 4 log CFU/g in L. monocytogenes over 60 days of ripening, which could be enough as a strategy for biocontrol to deal with the usual contamination by L. monocytogenes during cheese processing.

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Posted in Food Microbiology Research, Food Technology, LAB, lactic acid bacteria, Lactobacillus, Listeria, Listeria in Cheese, Listeria monocytogenes, Raw Milk, raw milk cheese, Research

Research – Positive and negative aspects of bacteriophages and their immense role in the food chain

Posted on January 6, 2024 by | Leave a comment

Nature

Abstract

Bacteriophages infect and replicate inside a bacterial host as well as serve as natural bio-control agents. Phages were once viewed as nuisances that caused fermentation failures with cheese-making and other industrial processes, which lead to economic losses, but phages are now increasingly being observed as being promising antimicrobials that can fight against spoilage and pathogenic bacteria. Pathogen-free meals that fulfil industry requirements without synthetic additives are always in demand in the food sector. This study introduces the readers to the history, sources, and biology of bacteriophages, which include their host ranges, absorption mechanisms, lytic profiles, lysogenic profiles, and the influence of external factors on the growth of phages. Phages and their derivatives have emerged as antimicrobial agents, biodetectors, and biofilm controllers, which have been comprehensively discussed in addition to their potential applications in the food and gastrointestinal tract, and they are a feasible and safe option for preventing, treating, and/or eradicating contaminants in various foods and food processing environments. Furthermore, phages and phage-derived lytic proteins can be considered potential antimicrobials in the traditional farm-to-fork context, which include phage-based mixtures and commercially available phage products. This paper concludes with some potential safety concerns that need to be addressed to enable bacteriophage use efficiently.

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Posted in Bacteriophage, Food Microbiology Research, Food Technology, Phage, Research, Technology

Research – Novel Methods for the Mitigation of Human Pathogens and Mycotoxin Contamination of High Value California Specialty Crops

Posted on January 6, 2024 by | Leave a comment

ARS USDA

Successful execution of these Objectives will contribute to field by: improving our knowledge of how microbial populations can affect and impact food safety and public health and delineating how pathogens are transmitted and disseminated in and among plant crops allowing for future development of improved/alternate interventions and control strategies

(Objectives 1-4); developing novel intervention strategies using sustainable, natural fungicide alternatives that eliminate aflatoxigenic fungi; enhancing our knowledge regarding the prevalence of azole-resistant aspergilli with enhanced aflatoxin production

(Objective 5); and developing novel methods to control invasive insect pests and reducing the need for the use of radioisotopes for irradiation

(Objective 6). These Objectives, if successful, will allow growers to produce a safer food supply and reduce the use of toxic chemicals (pesticides) and enhance environmental quality.

Objective 1: Identify and characterize agricultural soils that suppress the persistence of the human pathogenic bacteria Salmonella enterica, Listeria monocytogenes and Escherichia coli O157:H7.

Objective 2: Examine the microbiomes, potential for human pathogen colonization, and effectiveness of biological control agents on lettuces grown in indoor vertical hydroponic systems.

Objective 3: Examine the effects of bacterial biocontrol candidate strains on population dynamics of black Aspergillus spp. on grapes and raisins.

Objective 4: Identification and utilization of antifungal metabolites from microbial sources as interventions. •

Sub-objective 4A: Identification of antifungal metabolites from candidate biocontrol bacteria collected from raisin grape vineyards. •

Sub-objective 4B: Isolation and characterization of bacteria with antifungal activities from pistachio orchards.

Objective 5: Development of resistance management augmenting fungal and mycotoxin elimination. •

Sub-objective 5A: Determine the prevalence of azole-resistant aspergilli (A. flavus, A. parasiticus) that produce increased levels of mycotoxins in California tree nut orchards. •

Sub-objective 5B: Develop new intervention strategies for the control of azole-resistant Aspergillus species utilizing natural products/derivatives as fungicide alternatives.

Objective 6: Investigate novel methods to address mycotoxin contamination of tree nuts through control of fungal and insect vectors. •

Sub-objective 6A: Evaluate X-ray based irradiation as an alternative to gamma irradiation for SIT. •

Sub-objective 6B: Investigate high pressure steam as a tool for orchard sanitation through destruction of overwintering NOW larvae in pistachio mummies.

Objective 7: The use of previously approved natural products as an accelerated chemical interventions strategy to inhibit food-associated mycotoxins, fungal pathogens, and their insect pest transmitters. •

Sub-objective 7A: Identify previously approved natural products that inhibit mycotoxins and fungal pathogens frequently found in food contaminations. •

Sub-objective 7B: Identify previously approved natural products that immunosuppress insect pests and increase their sensitivity to microbes.

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Posted in Aflatoxin, Aflatoxin B1, Alternaria Toxin, Animal Feed Aflatoxin, Animal Feed Mould Toxin, Aspergillus Toxin, Food Microbiology Research, Food Pathogen, Food Toxin, Fusarium Toxin, Mold Toxin, Mould Toxin, Mycotoxin, Ochratoxin, Ochratoxin A, Pathogen, pathogenic, Research, Toxin

Research – Evaluation of the Effectiveness of Aeration and Chlorination during Washing to Reduce E. coli O157:H7, Salmonella enterica, and L. innocua on Cucumbers and Bell Peppers

Posted on January 6, 2024 by | Leave a comment

MDPI

Abstract

The attachment strength of bacteria to surfaces can affect the efficacy of sanitizers during washing. This study aimed to determine the effectiveness of chlorination and aeration in the removal of pathogens from the surface of produce. Cucumbers and bell peppers were inoculated with Listeria innocua, Escherichia coli O157:H7, or Salmonella enterica; afterwards, the produce was washed with or without chlorinated water (100 ppm) for 3 min in combination with or without aeration. Cucumbers washed with chlorinated water, with or without aeration, presented significant reductions of L. innocua (3.65 log CFU/cm2 and 1.13 log CFU/cm2, respectively) (p < 0.05). Similarly, bell peppers washed in chlorinated water with aeration (1.91 log CFU/g) and without aeration (2.49 log CFU/g) presented significant reductions of L. innocua. A significant reduction of L. innocua was observed on bell peppers washed with non-chlorinated water with aeration (2.49 log CFU/g) (p < 0.05). Non-chlorinated water was also effective in significantly reducing the level of Salmonella enterica (p < 0.05) on cucumbers and bell peppers. Washing with chlorinated water with aeration reduced Salmonella enterica levels from 4.45 log CFU/cm2 on cucumbers to below the detectable limit (0.16 log CFU/cm2). The highest reduction of Salmonella enterica from bell peppers occurred after washing with chlorinated water with aeration (2.48 log CFU/g). E. coli O157:H7, L. innocua, and Salmonella enterica levels present in non-chlorinated water after washing contaminated produce with or without aeration were significantly greater than those in chlorinated water (p < 0.05). After treatment, the population levels of all pathogens in chlorinated water with or without aeration were below the detectable limit for bell peppers (<1.10 log CFU/mL) and cucumbers (<1.20 log CFU/mL). Using chlorine in combination with forced aeration during washing minimizes cross-contamination of bacterial pathogens.

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Posted in E.coli O157, E.coli O157:H7, Food Microbiology Research, Food Technology, Hurdle Technology, Research, STEC, STEC E.coli, Technology

Research – ‘UK should break licensing impasse and maximise the potential of phages’

Posted on January 4, 2024 by | Leave a comment

The Microbiologist

In a major new report the UK’s Science, Innovation & Technology Committee has called for steps to develop the potential of bacteria-killing viruses – called bacteriophages or phages for short – that can provide an alternative to antibiotics that are attracting growing resistance.

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Posted in Bacteriophage, Food Microbiology Research, Food Technology, Phage, Research, Technology

Research – Lactic acid bacteria and spoilage bacteria: Their interactions in Escherichia coli O157:H7 biofilms on food contact surfaces and implications for beef contamination

Posted on January 2, 2024 by | Leave a comment

Wiley Online

Abstract

This research explores the interaction between Shiga toxin-producing Escherichia coli (STEC) O157:H7 and bacteria species commonly found in beef processing environments, specifically Carnobacterium, Lactobacillus, Comamonas, Raoultella, and Pseudomonas. The study investigated how various environmental conditions impact the formation of biofilms and the ability of O157:H7 to transfer from multispecies biofilm onto beef surfaces. For this purpose, a mixture of lactic acid bacteria (LAB), spoilage bacteria (106 CFU/mL), and E. coli O157 (103 CFU/mL) were combined as follows: LAB (T1): Carnobacterium piscicola + Lactobacillus bulgaricus + O157:H7, an spoilage bacteria (T2): Comamonas koreensis + Raoultella terrigena + O157:H7, an spoilage bacteria (T3): Pseudomonas aeruginosa + C. koreensis strain + O157:H7 and only O157:H7 as control (T4). Multispecies biofilms were developed on thermoplastic polyurethane (TPU) and stainless steel (SS) coupons at 10 and 25°C for 6 days, washed and stored for 6, 30, and 60 days at wet (60%–90% RH) and dry (20%–50%, RH) conditions. To evaluate O157:H7 transfer, beef cubes (3 × 3 × 1 cm) were placed on the coupons, followed by a 50-g weight (7.35 kPa). The experiment was repeated three times in triplicate for each strain combination. Results demonstrate that biofilms formed at 10°C were generally weaker (less biomass) than those at 25°C. Regardless of temperature, more viable O157:H7 cells were transferred to beef from moist biofilms on TPU surfaces. At 25°C, T3 biofilm exhibited the lowest O157:H7 transfer to beef by 1.44 log10 CFU/cm2 (p < 0.01). At 10°C, none of the multispecies biofilm (T1–T3) affected the number of O157:H7 transfers to beef (p > 0.05). Notably, O157:H7 was not detected on food contact surfaces with 30 and 60-day-old dry biofilms (T1–T4). Through enrichment, E. coli O157:H7 was recovered from multispecies biofilms T1, T2, and T3. Findings from this study imply that multispecies biofilms contribute to the persistence of O157:H7 under dry conditions, regardless of temperature. These results underscore the intricate influence of multiple environmental factors—including surface type, biofilm age, humidity, temperature, and the presence of other bacterial species—on the risk of beef contamination facilitated by biofilms.

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Posted in Biofilm, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Lactobacillus, microbial contamination, Microbial growth, Microbial Spoilage, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Pseudomonas, Research

Research – Impact of High-Pressure Processing (HPP) on Listeria monocytogenes—An Overview of Challenges and Responses

Posted on January 2, 2024 by | Leave a comment

MDPI

Abstract

High-pressure processing (HPP) is currently one of the leading methods of non-thermal food preservation as an alternative to traditional methods based on thermal processing. The application of HPP involves the simultaneous action of a combination of several factors—pressure values (100–600 MPa), time of operation (a few–several minutes), and temperature of operation (room temperature or lower)—using a liquid medium responsible for pressure transfer. The combination of these three factors results in the inactivation of microorganisms, thus extending food shelf life and improving the food’s microbiological safety. HPP can provide high value for the sensory and quality characteristics of products and reduce the population of pathogenic microorganisms such as L. monocytogenes to the required safety level. Nevertheless, the technology is not without impact on the cellular response of pathogens. L. monocytogenes cells surviving the HPP treatment may have multiple damages, which may impact the activation of mechanisms involved in the repair of cellular damage, increased virulence, or antibiotic resistance, as well as an increased expression of genes encoding pathogenicity and antibiotic resistance. This review has demonstrated that HPP is a technology that can reduce L. monocytogenes cells to below detection levels, thus indicating the potential to provide the desired level of safety. However, problems have been noted related to the possibilities of cell recovery during storage and changes in virulence and antibiotic resistance due to the activation of gene expression mechanisms, and the lack of a sufficient number of studies explaining these changes has been reported.

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Posted in Food Microbiology Research, High Pressure, HPP, Listeria, Listeria monocytogenes, Research

Research – Association between the Presence of Resistance Genes and Sanitiser Resistance of Listeria monocytogenes Isolates Recovered from Different Food-Processing Facilities

Posted on December 31, 2023 by | Leave a comment

MDPI

Abstract

Sanitisers are widely used in cleaning food-processing facilities, but their continued use may cause an increased resistance of pathogenic bacteria. Several genes have been attributed to the increased sanitiser resistance ability of L. monocytogenes. This study determined the presence of sanitiser resistance genes in Irish-sourced L. monocytogenes isolates and explored the association with phenotypic sanitiser resistance. The presence of three genes associated with sanitiser resistance and a three-gene cassette (mdrL, qacH, emrE, bcrABC) were determined in 150 L. monocytogenes isolates collected from Irish food-processing facilities. A total of 23 isolates contained bcrABC, 42 isolates contained qacH, one isolate contained emrE, and all isolates contained mdrL. Additionally, 47 isolates were selected and grouped according to the number and type of resistance genes, and the minimal inhibitory concentration (MIC) of these isolates for benzalkonium chloride (BAC) was determined experimentally using the broth microdilution method. The BAC resistance of the strain carrying the bcrABC gene cassette was significantly higher than that of strains lacking the gene cassette, and the BAC resistance of the strain carrying the qacH gene was significantly higher than that of strains lacking the qacH gene (p < 0.05). Isolates harbouring both the qacH and bcrABC genes did not show higher BAC resistance. With respect to environmental factors, there was no significant difference in MIC values for isolates recovered from different processing facilities. In summary, this investigation highlights the prevalence of specific sanitiser resistance genes in L. monocytogenes isolates from Irish food-processing settings. While certain genes correlated with increased resistance to benzalkonium chloride, the combination of multiple genes did not necessarily amplify this resistance.

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Posted in Disinfection Resistance, Food Microbiology Research, Food Technology, Listeria, Listeria monocytogenes, Research, Technology

Research – Predictive Mapping of Antimicrobial Resistance for Escherichia coli, Salmonella, and Campylobacter in Food-Producing Animals, Europe, 2000–2021

Posted on December 30, 2023 by | Leave a comment

cdc

Abstract

In Europe, systematic national surveillance of antimicrobial resistance (AMR) in food-producing animals has been conducted for decades; however, geographic distribution within countries remains unknown. To determine distribution within Europe, we combined 33,802 country-level AMR prevalence estimates with 2,849 local AMR prevalence estimates from 209 point prevalence surveys across 31 countries. We produced geospatial models of AMR prevalence in Escherichia coli, nontyphoidal Salmonella, and Campylobacter for cattle, pigs, and poultry. We summarized AMR trends by using the proportion of tested antimicrobial compounds with resistance >50% and generated predictive maps at 10 × 10 km resolution that disaggregated AMR prevalence. For E. coli, predicted prevalence rates were highest in southern Romania and southern/eastern Italy; for Salmonella, southern Hungary and central Poland; and for Campylobacter, throughout Spain. Our findings suggest that AMR distribution is heterogeneous within countries and that surveillance data from below the country level could help with prioritizing resources to reduce AMR.

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Posted in Antibacterial, Antibiotic Resistance, antifungal, antimicrobial resistance, Antimicrobials, Campylobacter, E.coli, Food Microbiology Research, Multi Drug Resistant, Research, Salmonella