Category Archives: Research

Research – Application of ultra-fine bubble technology to reduce Listeria monocytogenes contamination of fresh produce

Center for Produce Safety

Summary

Water used for washing or hydrocooling can act as a source of produce contamination with Listeria monocytogenes. Since this could lead to human infections, controlling L. monocytogenes in hydrocooling water and produce is critical for food safety. Commercial disinfectants (chlorine, quaternary ammonium compounds) are not completely effective in killing L. monocytogenes in wash water or on produce, especially in presence of organic load.

This proposal aims to investigate the potential of a new technology that employs water containing ultra-fine gas bubbles (size ~ 1 micrometer or less) for washing produce (celery, gala apples, romaine lettuce). We will generate ultra-fine ozone (UFO) bubbles in water using a high energy shear method and test the potential of resulting solution to rapidly kill (in 30 to 60 sec) L. monocytogenes in wash water and on produce surface. In addition, the efficacy of UFO bubble water to synergistically improve the Listeria killing potential of aforementioned commercial disinfectants will be tested. The anti-listerial efficacy of UFO bubble water will also be tested in presence of organic load. Successful completion of this project will provide the produce industry with novel antimicrobial treatment for disinfecting wash water and produce in single pass or re- circulated hydrocooling systems.

Technical Abstract

The widespread distribution of Listeria monocytogenes in agricultural environments such as soil, manure and water results in frequent contamination of food processing areas. Although good agricultural practices partially reduce contamination, however, due to the open nature of farming, it is extremely difficult to completely prevent pathogen influx. Water used for washing or hydrocooling can act as a source of equipment and produce contamination with L. monocytogenes. Since this could lead to human infections, controlling L. monocytogenes in hydrocooling water and on the surface of fresh produce is critical for food safety. Currently used commercial disinfectants (chlorine, peracetic acid, quaternary ammonium compounds) are not completely effective in killing L. monocytogenes in wash water or on the surface of produce, especially in presence of organic load. Moreover, the presence of chemical residues and the formation of harmful organochlorine compounds is an occupational concern due to associated health risks, including cancer. Therefore, there is a need for developing novel strategies that could be employed (either alone or in combination with currently used commercial disinfectants) to control L. monocytogenes in wash water and on surface of fresh produce, vegetables and fruits.

This proposal aims to investigate the potential of a new technology that employs water containing ultra-fine gas bubbles (size ~ 1 micrometer or less) for washing produce (celery, gala apples, romaine lettuce). We will generate ultra-fine ozone (UFO) bubbles in water using a high energy shear method and test the potential of resulting solution to rapidly kill (in 30 to 60 sec) L. monocytogenes in wash water and on produce surface. In addition, the efficacy of UFO bubble water to synergistically improve the Listeria killing potential of aforementioned commercial disinfectants will be tested. The anti-listerial efficacy of UFO bubble water will also be tested in presence of organic load.

Potential impact from anticipated outcomes: Successful completion of this project will provide the produce industry with novel antimicrobial treatment for disinfecting wash water and produce in dump tanks, and single pass or re-circulated hydrocooling systems. This intervention will translate into increased microbiological safety of fresh produce.

Research – Frozen Vegetable Processing Plants Can Harbour Diverse Listeria monocytogenes Populations: Identification of Critical Operations by WGS

MDPI

Frozen vegetables have emerged as a concern due to their association with foodborne outbreaks such as the multi-country outbreak of Listeria monocytogenes serogroup IVb linked to frozen corn. The capacity of L. monocytogenes to colonize food-processing environments is well-known, making the bacteria a real problem for consumers. However, the significance of the processing environment in the contamination of frozen foods is not well established. This study aimed to identify potential contamination niches of L. monocytogenes in a frozen processing plant and characterize the recovered isolates. A frozen vegetable processing plant was monitored before cleaning activities. A total of 78 points were sampled, including frozen vegetables. Environmental samples belonged to food-contact surfaces (FCS); and non-food-contact surfaces (n-FCS). Positive L. monocytogenes samples were found in FCS (n = 4), n-FCS (n = 9), and the final product (n = 1). A whole-genome sequencing (WGS) analysis revealed two clusters belonging to serotypes 1/2a-3a and 1/2b-3b). The genetic characterization revealed the presence of four different sequence types previously detected in the food industry. The isolate obtained from the final product was the same as one isolate found in n-FCS. A multi-virulence-locus sequence typing (MVLST) analysis showed four different virulence types (VT). The results obtained highlight the relevant role that n-FCS such as floors and drains can play in spreading L. monocytogenes contamination to the final product. View Full-Text

Research – Microbiome of Lettuce Might Hold Secret to Better Food Safety

Growing Produce

Eurofins Food Testing UK

Researchers at the University of Georgia Center for Food Safety are preparing to launch a study on E. coli colonization from a new angle: the microbiome of lettuce.

By studying the interactions between EcO157 and the lettuce microbiome — the entire community of microorganisms like bacteria that live on the surface of lettuce — researchers hope to better understand how the microbiome may affect the pathogen’s fate during produce processing.

Center for Food Safety Professor Xiangyu Deng, lead researcher on the project, says, “We want to really figure out the interactions between the pathogen and potential biocontrol organisms indigenous to lettuce.”

In other words, how does E. coli interact with other microorganisms on lettuce, and how can we use those interactions to control foodborne outbreaks?

The focus of the research, to start this year, will be how the microbiome interacts with EcO157. The team will use a new microscopic approach to create a biogeographic map of the microbiome.

“Clearly the microbiome interacts with EcO157, and that interaction has an implication for food safety,” Deng adds. “We want to understand the mechanism behind this interaction.”

Research – Temperature, Time, and Type, Oh My! Key Environmental Factors Impacting the Recovery of Salmonella Typhimurium, Listeria monocytogenes, and Tulane Virus from Surfaces 

Journal of Food Protection

Environmental monitoring (EM) programs are designed to detect the presence of pathogens in food manufacturing environments with the goal of preventing microbial contamination of food. Nevertheless, limited knowledge exists regarding the influence of environmental conditions on microbial recovery during EM. This study utilizes a commercially-available polyurethane foam (PUF) EM tool to determine the influence of environmental factors on the recovery of foodborne pathogens. The specific objectives of this study were to determine if environmental conditions and surface composition impact the recovery of sought-after microorganisms found in food processing environments. These data are compared across 1) microorganism type, 2) surface type, 3) environmental temperature and relative humidity, and 4) exposure time. Two bacteria ( Listeria monocytogenes , Salmonella Typhimurium) and one human norovirus surrogate (Tulane virus [TV]) were inoculated onto three non-porous surfaces (polypropylene, stainless steel, neoprene). Surfaces were held in an environmental chamber for 24 or 72 h at 30°C/30%, 6°C/85%, and 30°C/85% relative humidity (RH). Data indicate that microbial recovery from environmental surfaces significantly (p ≤ 0.05) varies by microorganism type, environmental conditions, and exposure time. For instance, all microorganisms were significantly different from each other, with the greatest mean log reduction being TV and the lesser reduction being L. monocytogenes at 4.94 ± 1.75 log 10 PFU/surface and 2.54 ± 0.91 log 10 CFU/surface, respectively. Overall, these data can be used to improve the effectiveness of EM programs and underscores the need to better comprehend how EM test results are impacted by food manufacturing environmental conditions.

Australia – Australia Food Recall Statistics 2021

FSANZ

Microbe

76.PNG

USA – New Era of Smarter Food Safety: FDA’s Foodborne Outbreak Response Improvement Plan

FDA

New Era of Smarter Food Safety - FDA's Foodborne Outbreak Response Improvement Plan Cover

Tackling foodborne outbreaks faster and revealing the root cause are essential for the prevention of future outbreaks. We have a plan to do that.

Foodborne disease remains a significant public health problem in the United States. The FDA’s Foodborne Outbreak Response Improvement Plan (FORIP), described in this document, is an important step that the FDA is taking to enhance the speed, effectiveness, coordination, and communication of outbreak investigations. (Unless stated otherwise, this report focuses exclusively on the response to human food and not animal food.)

Our ultimate goal is to bend the curve of foodborne illness in this country.

Ireland – People urged to cook frozen fruit and vegetables because of Listeria findings

Food Safety News

Listeria monocytogenes has been detected in a number of frozen vegetables tested in Ireland.

The Food Safety Authority of Ireland (FSAI) said findings show a potential risk of illness for consumers who have non-ready-to-eat (RTE) frozen vegetables, fruits or herbs without cooking.

After a 2015 to 2018 listeriosis outbreak in Europe traced to uncooked non-RTE frozen sweetcorn and other vegetables, a national microbiological survey on frozen vegetables, fruits and herbs sold in Ireland was done between August and November 2019 by the FSAI. More than 50 people were sick from five countries and 10 died in the outbreak linked to vegetables made by Greenyard in Hungary.

Of 906 samples tested for Listeria monocytogenes in Ireland, 27 were positive, and 21 were non-RTE frozen vegetables. It was detected in four samples of RTE frozen fruits and two RTE frozen vegetables.

Research – Microbial Consortium Associated with Crustacean Shells Composting

MDPI

Soil microbes play an essential role in the biodegradation of crustacean shells, which is the process of sustainable bioconversion to chitin derivatives ultimately resulting in the promotion of plant growth properties. While a number of microorganisms with chitinolytic properties have been characterized, little is known about the microbial taxa that participate in this process either by active chitin degradation or by facilitation of this activity through nutritional cooperation and composting with the chitinolytic microorganisms. In this study, we evaluated the transformation of the soil microbiome triggered by close approximation to the green crab shell surface. Our data indicate that the microbial community associated with green crab shell matter undergoes significant specialized changes, which was reflected in a decreased fungal and bacterial Shannon diversity and evenness and in a dramatic alteration in the community composition. The relative abundance of several bacterial and fungal genera including bacteria FlavobacteriumClostridiumPseudomonas, and Sanguibacter and fungi MortierellaMycochlamys, and Talaromyces were increased with approximation to the shell surface. Association with the shell triggered significant changes in microbial cooperation that incorporate microorganisms that were previously reported to be involved in chitin degradation as well as ones with no reported chitinolytic activity. Our study indicates that the biodegradation of crab shells in soil incorporates a consortium of microorganisms that might provide a more efficient way for bioconversion. View Full-Text

Research – Microbial Safety and Sensory Analyses of Cold-Smoked Salmon Produced with Sodium-Reduced Mineral Salts and Organic Acid Salts

MDPI

Cold-smoked (CS) salmon contains high levels of sodium salts, and excess dietary sodium intake is associated with an array of health complications. CS salmon may also represent a food safety risk due to possible presence and growth of the foodborne pathogen Listeria monocytogenes which may cause fatal human infections. Here we determine how reformulated CS salmon using commercial sodium-reduced salt replacers containing KCl (e.g., Nutek, Smart Salt, SOLO-LITE) and acetate-based preservative salts (Provian K, proviant NDV) affect sensory properties, quality, and microbial safety. Initial sensory screening of sodium-reduced CS salmon was followed by L. monocytogenes growth analyses in selected variants of reformulated CS salmon, and finally by analyses of CS salmon variants produced in an industrial smokehouse. Projective mapping indicated overall minor sensory changes in sodium-replaced samples compared with a conventional product with NaCl. Growth of L. monocytogenes was temperature-dependent (4 °C vs. 8 °C storage) with similar growth in sodium-reduced and conventional CS salmon. The addition of 0.9% of the preservative salts Provian K or Provian NDV gave up to 4 log lower L. monocytogenes counts in both sodium-reduced and conventional cold-smoked salmon after 29 days of chilled storage. No changes in pH (range 6.20–6.33), aw levels (range 0.960–0.973), or weight yield (96.8 ± 0.2%) were evident in CS salmon with salt replacers or Provian preservative salts. Analyses of CS salmon produced with selected mineral salt and preservative salt combinations in an industrial salmon smokery indicated marginal differences in sensory properties. Samples with the preservative salt Provian NDV provided L. monocytogenes growth inhibition and low-level total viable counts (<2.8 log/g) dominated by Photobacterium and Carnobacterium during storage. Production of sodium-reduced CS salmon with inhibiting salts provides a simple method to achieve a healthier food product with increased food safety.

Research – Removal of Ochratoxin A from Grape Juice by Clarification: A Response Surface Methodology Study

MDPI

This study achieved maximum removal of ochratoxin A (OTA) during the grape juice clarification process with minimal reduction in antioxidant compounds (phenolic acid, flavonoids, and antioxidant capacity by FRAP) by the RSM method. Independent variables included three types of clarifiers—gelatin, bentonite, and diatomite (diatomaceous earth)—at a concentration level of 0.25–0.75% and clarification time of 1–3 h. OTA was measured by high-performance liquid chromatography with fluorescence detection. Clarifying agent concentration and clarification time affected the reduction amount of OTA and antioxidant compounds in grape juice. There was a direct linear correlation between the reduction amounts of OTA and antioxidant compounds and capacity with the concentration of bentonite, gelatin, and diatomite, and the clarification time. The reduction amount of OTA and antioxidant capacity followed the linear mode. However, the decreased phenolic acid and flavonoid values followed the quadratic model. The study results showed that if the concentrations of bentonite, gelatin, and diatomite and clarification time were 0.45, 0.62, 0.25%, and 1 h, respectively, the maximum amount of OTA reduction (41.67%) occurred. Furthermore, the phenolic acid, flavonoid, and antioxidant activity decrease amounts were at their lowest levels, i.e., 23.86, 7.20, and 17.27%, respectively. View Full-Text