Category Archives: Research

Research – Recent Trends in Active Packaging Using Nanotechnology to Inhibit Oxidation and Microbiological Growth in Muscle Foods

Posted on October 8, 2023 by | Leave a comment

MDPI

Muscle foods are highly perishable products that require the use of additives to inhibit lipid and protein oxidation and/or the growth of spoilage and pathogenic microorganisms. The reduction or replacement of additives used in the food industry is a current trend that requires the support of active-packaging technology to overcome novel challenges in muscle-food preservation. Several nano-sized active substances incorporated in the polymeric matrix of muscle-food packaging were discussed (nanocarriers and nanoparticles of essential oils, metal oxide, extracts, enzymes, bioactive peptides, surfactants, and bacteriophages). In addition, the extension of the shelf life and the inhibitory effects of oxidation and microbial growth obtained during storage were also extensively revised. The use of active packaging in muscle foods to inhibit oxidation and microbial growth is an alternative in the development of clean-label meat and meat products. Although the studies presented serve as a basis for future research, it is important to emphasize the importance of carrying out detailed studies of the possible migration of potentially toxic additives, incorporated in active packaging developed for muscle foods under different storage conditions.

Leave a comment

Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Research

Research – Comparison of Antibacterial Activity of Phytochemicals against Common Foodborne Pathogens and Potential for Selection of Resistance

Posted on October 8, 2023 by | Leave a comment

MDPI

Abstract

Antimicrobial resistance is now commonly observed in bacterial isolates from multiple settings, compromising the efficacy of current antimicrobial agents. Therefore, there is an urgent requirement for efficacious novel antimicrobials to be used as therapeutics, prophylactically or as preservatives. One promising source of novel antimicrobial chemicals is phytochemicals, which are secondary metabolites produced by plants for numerous purposes, including antimicrobial defence. In this report, we compare the bioactivity of a range of phytochemical compounds, testing their ability to directly inhibit growth or to potentiate other antimicrobials against Salmonella enterica Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus. We found that nine compounds displayed consistent bioactivity either as direct antimicrobials or as potentiators. Thymol at 0.5 mg/mL showed the greatest antimicrobial effect and significantly reduced the growth of all species, reducing viable cell populations by 66.8%, 43.2%, 29.5%, and 70.2% against S. enterica Typhimurium, S. aureus, P. aeruginosa, and L. monocytogenes, respectively. Selection of mutants with decreased susceptibility to thymol was possible for three of the pathogens, at a calculated rate of 3.77 × 10−8, and characterisation of S. enterica Typhimurium mutants showed a low-level MDR phenotype due to over-expression of the major efflux system AcrAB-TolC. These data show that phytochemicals can have strong antimicrobial activity, but emergence of resistance should be evaluated in any further development.

Leave a comment

Posted in Antibacterial, Antibiotic Resistance, antifungal, antimicrobial resistance, Antimicrobials, Drug Resistance, Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Research

Research – Fate of Planktonic and Biofilm-Derived Listeria monocytogenes on Unwaxed Apples during Air and Controlled Atmosphere Storage

Posted on October 7, 2023 by | Leave a comment

MDPI

Abstract

Multiple recalls and outbreaks involving Listeria monocytogenes-contaminated apples have been linked to the post-harvest packing environment where this pathogen can persist in biofilms. Therefore, this study assessed L. monocytogenes survival on apples as affected by harvest year, apple cultivar, storage atmosphere, and growth conditions. Unwaxed Gala, Granny Smith, and Honeycrisp apples were dip-inoculated in an 8-strain L. monocytogenes cocktail of planktonic- or biofilm-grown cells (~6.5 log CFU/mL), dried, and then examined for numbers of L. monocytogenes during air or controlled atmosphere (CA) (1.5% O2, 1.5% CO2) storage at 2 °C. After 90 days, air or CA storage yielded similar L. monocytogenes survival (p > 0.05), regardless of harvest year. Populations gradually decreased with L. monocytogenes quantifiable in most samples after 7 months. Apple cultivar significantly impacted L. monocytogenes survival (p < 0.05) during both harvest years with greater reductions (p < 0.05) seen on Gala compared to Granny Smith and Honeycrisp. Biofilm-derived cells survived longer (p < 0.05) on L. monocytogenes-inoculated Gala and Honeycrisp apples compared to cells grown planktonically. These findings should aid in the development of improved L. monocytogenes intervention strategies for apple growers and packers.

Leave a comment

Posted in Biofilm, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria monocytogenes, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Research

Research – Anti-Biofilm Activity of Laurel Essential Oil against Vibrio parahaemolyticus

Posted on October 7, 2023 by | Leave a comment

MDPI

Abstract

Vibrio parahaemolyticus is a primary seafood-associated pathogen that could cause gastroenteritis. It can attach to various surfaces and form a biofilm, which poses serious threats to food safety. Hence, an effective strategy is urgently needed to control the biofilm formation of V. parahaemolyticus. Laurel essential oil (LEO) is used in food, pharmaceutical and other industries, and is commonly used as a flavoring agent and valuable spice in food industries. The potential antibiofilm effects of LEO against V. parahaemolyticus were examined in this study. LEO obviously reduced biofilm biomass at sub-inhibitory concentrations (SICs). It decreased the metabolic activity and viability of biofilm cells. Microscopic images and Raman spectrum indicted that LEO interfered with the structure and biochemical compositions of biofilms. Moreover, it also impaired swimming motility, decreased hydrophobicity, inhibited auto-aggregation and reduced attachment to different food-contact surfaces. RT-qPCR revealed that LEO significantly downregulated transcription levels of biofilm-associated genes of V. parahaemolyticus. These findings demonstrate that LEO could be potentially developed as an antibiofilm strategy to control V. parahaemolyticus biofilms in food industries.

Leave a comment

Posted in Biofilm, essential oils, Food Microbiology Research, Food Technology, Hurdle Technology, Research, Technology, Vibrio, Vibrio parahaemolyticus

Tools to Enumerate and Predict Distribution Patterns of Environmental Vibrio vulnificus and Vibrio parahaemolyticus

Posted on October 7, 2023 by | Leave a comment

MDPI

Abstract

Vibrio vulnificus (Vv) and Vibrio parahaemolyticus (Vp) are water- and foodborne bacteria that can cause several distinct human diseases, collectively called vibriosis. The success of oyster aquaculture is negatively impacted by high Vibrio abundances. Myriad environmental factors affect the distribution of pathogenic Vibrio, including temperature, salinity, eutrophication, extreme weather events, and plankton loads, including harmful algal blooms. In this paper, we synthesize the current understanding of ecological drivers of Vv and Vp and provide a summary of various tools used to enumerate Vv and Vp in a variety of environments and environmental samples. We also highlight the limitations and benefits of each of the measurement tools and propose example alternative tools for more specific enumeration of pathogenic Vv and Vp. Improvement of molecular methods can tighten better predictive models that are potentially important for mitigation in more controlled environments such as aquaculture.

Leave a comment

Posted in Food Microbiology Research, Research, Vibrio, Vibrio parahaemolyticus, Vibrio vulnificans, Vibrio vulnificus

Research – Phenotypic and Genotypic Characteristics of Non-Hemolytic L. monocytogenes Isolated from Food and Processing Environments

Posted on October 5, 2023 by | Leave a comment

MDPI

Abstract

Increasingly, Listeria monocytogenes (LM) with atypical phenotypic and genotypic characteristics are being isolated from food, causing problems with their classification and testing.
From 2495 soil, food, and swab samples from the food industry, 262 LM isolates were found. A total of 30 isolates were isolated, mainly from soil and plant food, and were classified as atypical LM (aLM) because they lacked the ability to move (30/11.4%) and perform hemolysis (25/9.5%). The isolation environment affected aLM incidence, cell size, sugar fermentation capacity, antibiotic sensitivity, and the number of virulence genes.
Therefore, despite several characteristics differentiating all aLMs/non-hemolytic isolates from reference LMs, the remaining phenotypic characteristics were specific to each aLM isolate (like a fingerprint). The aLM/non-hemolytic isolates, particularly those from the soil and meat industries, showed more variability in their sugar fermentation capacity and were less sensitive to antibiotics than LMs. As many as 11 (36.7%) aLM isolates had resistance to four different antibiotics or simultaneously to two antibiotics. The aLM isolates possessed 3–7 of the 12 virulence genes: prfA and hly in all aLMs, while iap was not present.
Only five (16.7%) isolates were classified into serogroups 1/2c-3c or 4a-4c. The aLM/non-hemolytic isolates differed by many traits from L. immobilis and atypical L. innocua. The reference method of reviving and isolating LM required optimization of aLM. Statistical analyses of clustering, correlation, and PCA showed similarities and differences between LM and aLM/non-hemolytic isolates due to individual phenotypic traits and genes.
Correlations were found between biochemical traits, antibiotic resistance, and virulence genes. The increase in the incidence of atypical non-hemolytic LM may pose a risk to humans, as they may not be detected by ISO methods and have greater antibiotic resistance than LM. aLM from LM can be distinguished based on lack of hemolysis, motility, growth at 4 °C, ability to ferment D-arabitol, and lack of six specific genes.

Leave a comment

Posted in Food Microbiology Research, Listeria, Listeria monocytogenes, Research

Research – EU audits investigate Egypt and India’s Aflatoxin problem

Posted on October 5, 2023 by | Leave a comment

Food Safety News

The European Commission’s health and safety unit has published findings from two assessments looking at controls on aflatoxins in nuts in Egypt and India.

A DG Sante audit in Egypt in September 2022 was due to continuing Rapid Alert System for Food and Feed (RASFF) notifications for aflatoxins in peanuts. There were 41 in 2021 and at least 34 in 2022. A few operators are behind the majority of rejections, said auditors. Local officials said the rise in alerts was related to increased exports.

Each consignment of peanuts originating in or coming from Egypt must be accompanied by a health certificate and results of official sampling and analysis verifying compliance with EU aflatoxin limits. Imports are also subject to checks at a frequency of 30 percent.

Leave a comment

Posted in Aflatoxin, Aspergillus Toxin, Food Microbiology Research, Food Toxin, Mold Toxin, Mould Toxin, Mycotoxin, Research

Research – Combining High-Pressure Processing and Supercritical Carbon Dioxide for Inactivation of Listeria innocua

Posted on October 5, 2023 by | Leave a comment

MDPI

Abstract

The effect of high-pressure treatment with supercritical CO2 on the inactivation of Listeria innocua in a fish soup was investigated. The soup was inoculated with L. innocua, packaged in modified atmosphere with 50:50 or 95:5 CO2:N2, high-pressure processed (300, 350, 400 and 600 MPa, 2 min) under subcritical (T < 304 K) or supercritical conditions (T > 304 K) and stored at 4 °C for up to 53 days. Treatment at 400 and 600 MPa had a significant (p < 0.05) effect on L. innocua under both supercritical and subcritical conditions. In contrast, pressurization at 350 MPa and supercritical conditions were needed to significantly (p < 0.05) inactive L. innocua. Increased levels of CO2 in the headspace significantly (p < 0.05) reduced the bacterial load during processing, and supercritical conditions had a significant (p < 0.01) interaction with both CO2 levels and pressure. Increased storage time gave significantly increased levels of L. innocua at 400 and 600 MPa. In addition, high levels of CO2 significantly decreased (p < 0.001) growth. However, 350 MPa under supercritical conditions seemed to set the L. innocua in a permanent lag phase, with slow and steadily decreasing numbers of bacteria during storage. All the design variables resulted in significant inactivation of L. innocua, and supercritical conditions combined with high levels of CO2 inhibited the recovery of L. innocua to a large degree.

Leave a comment

Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Listeria, Listeria innocua, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Research

England and Wales – Listeriosis in England and Wales: summary for 2020

Posted on October 3, 2023 by | Leave a comment

Gov UK

Main points for 2020

This report summarises the number, demographics and clinical outcomes of confirmed cases of listeriosis in England and Wales in 2020:

A total 124 cases of listeriosis were reported in England and Wales.

Incidence rates of listeriosis were highest in people aged 80 years and over.

Overall, the crude incidence of listeriosis was lower in men than women, but reported cases among men aged 60 to 69 were 4 times higher than in women aged 60 to 69.

Pregnancy associated infections accounted for a fifth of all reported cases and, a 34.8% of pregnancy-associated cases resulted in stillbirth or miscarriage.

Among non-pregnancy associated cases of listeriosis, death was reported for 29 cases (29.3%), of whom 17 (17.2%) were known to have listeriosis recorded as a cause of death on the death certificate.

Incidence of listeriosis varied geographically, with the lowest incidence in the North West (0.15 per 100,000 population) and the highest in the East Midlands (0.27 per 100,0000 population).

There were 2 listeriosis outbreaks investigated in England, including a national outbreak associated with smoked salmon.

Listeriosis is a foodborne disease caused by the bacterium Listeria monocytogenes. These bacteria are widely distributed in the environment and infection usually occurs after consumption of contaminated raw, chilled, or ready-to-eat foods, and can cause sporadic infection and outbreaks of disease. People with listeriosis have been reported to develop symptoms between 1 to 70 days after consuming food contaminated with Listeria monocytogenes.

Compared to other foodborne pathogens, infections in humans are relatively rare, with 2,621 confirmed cases of listeriosis reported across 28 EU member states in 2019, and a median of 160 cases in England and Wales each year (2010 to 2019). However, listeriosis can cause severe clinical outcomes in vulnerable groups, including those aged over 60 years, pregnant women and their unborn or newborn babies, and people with impaired immunity. In these groups, listeriosis can present as infection of the bloodstream or brain. Due to the severity of infection and high case fatality rate, listeriosis is an important public health concern.

National surveillance of listeriosis in England and Wales has been undertaken since 1992. This report summarises the number, demographics and clinical outcomes of confirmed cases of listeriosis in England and Wales reported in 2020.

Leave a comment

Posted in Food Illness, Food Microbiology Research, Foodborne Illness, Foodborne Illness Death, foodborne outbreak, foodbourne outbreak, Illness, Listeria, Listeria monocytogenes, Listeria Smoked Fish, listeriosis, outbreak, Research

Research – Cooked rice safety: A review of status and potential of radiative pasteurization

Posted on October 1, 2023 by | Leave a comment

Wiley Online

Abstract

Microbial contamination in cooked rice-based foods poses a global concern due to rice’s widespread consumption. This review aims to consolidate information on harmful microorganisms associated with such foods from various countries and their adverse effects on consumers. Additionally, it explores the reported causes of microbial contamination in cooked rice-based dishes and proposes an intervention strategy for safer consumption. The findings highlight that ready-to-eat cooked rice-based foods may harbor unsafe levels of microorganisms like Bacillus cereus, Staphylococcus aureus, and Aspergillus spp. A recommended solution is the application of microwave pasteurization. This method involves cooking rice in pasteurized packaging, minimizing human contact, and effectively controlling harmful microorganisms. Microwave pasteurization emerges as a promising approach to ensure the safe consumption of cooked rice-based foods by reducing microbial contamination levels.

Leave a comment

Posted in Aspergillus, Aspergillus Toxin, Bacillus, Bacillus cereus, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Pasteurisation, Research, Staphylococcal Toxin, Staphylococcus aureus