Richard A Holley

Richard A Holley
University of Manitoba | UMN · Food and Human Nutritional Sciences

About

221
Publications
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9,293
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Publications

Publications (221)
Article
Full-text available
The novel coronavirus (COVID-19) pandemic has caused sequential ripples of public health con-cern worldwide. Restaurant owners and workers have been significantly affected by safety reg-ulations which have governed the activities of both employees and consumers. The objective of this study was to investigate the knowledge, attitude, and practices (...
Article
Several types of cheeses including white brined cheese have been linked to listeriosis outbreaks worldwide. This study aimed to (i) investigate the in vitro inhibitory activity of zinc oxide (ZnO) nanoparticles (NPs) at concentrations of 0.0125–0.1% against three Listeria monocytogenes strains at 10 or 37°C, (ii) evaluate the antimicrobial efficien...
Article
Hummus is a popular dip in the Middle East region prepared by mixing the boiled chickpeas with tahini and other ingredients, and because its consumption has increased world-wide some notoriety has developed following an increase in the incidence of hummus-related illness outbreaks and recalls. The objectives of the current research were (i) to stud...
Article
The study aimed to evaluate the antimicrobial activity of 0.5 or 1% (w/w) chitosan and 1% (w/w) garlic against Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes in hummus dip stored at 4, 10, or 25°C for 28, 21, or 7 days, respectively. In hummus without garlic, at all storage temperatures and storage periods, 0.5% chitosan decre...
Article
Full-text available
Tahini (sesame paste) is a traditional food. Numerous foodborne outbreaks have been associated with it. This study aimed to (i) explore the efficiency of 2450 MHz microwave heating at 220, 330, 440, 550, and 660 W on the inactivation of Salmonella spp, Escherichia coli O157:H7, and Listeria monocytogenes in tahini; (ii) determine the impact of desi...
Article
Recently, the consumption of hummus has become popular in the United States, European countries, and Canada, and unfortunately, several foodborne outbreaks and recalls have been reported due to its contamination with Listeria monocytogenes and Salmonella enterica. The current study aimed to investigate the inhibitory activity of 0.5, 1.0, and 1.5%...
Article
Full-text available
A conductometric immunosensor was developed for the detection of one of the most common foodborne pathogens, Escherichia coli O157:H7 (E. coli O157:H7), by conductometric sensing. The sensor was built based on a polyaniline/zinc oxide (PANI/ZnO) nanocomposite film spin-coated on a gold electrode. Then, it was modified with a monoclonal anti-E. coli...
Article
Full-text available
Exopolysaccharides (EPSs) are metabolites synthesized and excreted by a variety of microorganisms, including lactic acid bacteria. EPS serve several biological functions such as interactions between bacteria and their environments, protection against hostile conditions including dehydration, the alleviation of the action of toxic compounds (bile sa...
Article
This study aimed to evaluate the survival or growth behavior of L. monocytogenes and S. aureus in ready-to-eat vegetable salads including Arabic salad (tomato-cucumber salad) with or without 0.5% (w/w) salt and 1% (v/w) lemon juice, tahini salad, coleslaw salad, toum sauce salad (aioli) stored at 4, 10, and 24 °C for 5 d. L. monocytogenes showed gr...
Article
This study aimed to investigate the survival of the foodborne pathogen Escherichia coli O157:H7 in white-brined cheeses as influenced by the presence of Lactobacillus reuteri. The white cheeses were made from pasteurized bovine milk inoculated with E. coli O157:H7 (cocktail of 3 strains) to achieve ~5 log10 cfu/g with absence or presence of Lb. reu...
Article
Full-text available
Purpose People with food allergies rely to a great extent on restaurant staff to have a safe meal. The purpose of this paper is to acquire novel data to evaluate knowledge, attitudes and practices of food allergy among the restaurant's staff and factors that could be associated with these domains. Design/methodology/approach A cross-sectional stud...
Article
Full-text available
Tahini is a common food product in the Mediterranean area that is used as a main ingredient in variety of ready-to-eat foods. The objective of the current study was to investigate the inhibitory effect of thyme oil (TO) or cinnamon oil (CO) on E. coli O157:H7 viability in tahini and diluted tahini at different storage temperatures. Addition of 2.0%...
Article
The Canadian Food Inspection Agency is developing an Establishment-based Risk Assessment (ERA) model for commercial and on-farm mills involved in the manufacture, storage, packaging, labeling, or distribution of livestock feed (ERA–Feed Mill model). This model will help inform the allocation of inspection resources on the basis of feed safety risk,...
Article
Full-text available
Tahini (sesame seed paste) is a low water activity product that has been involved in several salmonellosis outbreaks. The objectives of the study were to examine over a year the impact of aw and storage temperature of tahini on the viability of Salmonella serovars previously stressed by drying or heat exposure. Tahini samples adjusted to aw values...
Article
Full-text available
The coronavirus disease 2019 (COVID-19) is a clinical syndrome caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2). COVID-19 was declared a pandemic by the World Health Organization (WHO) on March 11, 2020 due to its rapid and extensive spread among many countries through its very contagious nature and its high mortality among t...
Article
Full-text available
The COVID-19 pandemic represents a major public health, economic, political, and scientific concern in most countries around the globe where COVID-19 cases and deaths have been confirmed. This study assessed the attitudes, anxiety, and behavioral practices of university students in Jordan regarding COVID-19 during the early period of the infection...
Article
Staphylococcus aureus is a major foodborne pathogen that causes severe disease in humans. It is commonly found in milk and dairy products, particularly in fresh brined cheese. Our aim was to investigate the behavior of Staph. aureus and enterotoxin production during the storage of white-brined cheese prepared with or without a starter culture and s...
Article
Oily, low water activity (OL aw) products including tahini (sesame seed paste), halva (tahini halva), peanut butter, and chocolate, have been recently linked to numerous foodborne illness outbreaks and recalls. This review discusses the ingredients used and processing of OL aw products with a view to provide greater understanding of the routes of t...
Article
Full-text available
Background: Coronavirus disease 2019 (COVID-19) has rapidly spread worldwide, and it was officially declared to be a pandemic by the World Health Organization (WHO) March 11, 2020. Most countries over the entire globe have reported some COVID-19 cases. The current study aimed to assess student knowledge about COVID-19 at different Jordanian univers...
Article
The study aimed to determine D and z-values of Escherichia coli O157:H7 strains and Salmonella spp. in camel lean meat burger (CM) and camel meat burger with hump fat (CMF). Two E. coli O157:H7 strains, S. Typhimurium and S. Copenhagen were mixed individually with CM and CMF samples, placed in sterile pouches and exposed to water bath heat treatmen...
Article
This study aimed to evaluate growth behaviour of Escherichia coli O157:H7, Salmonella spp., and background microbiota in ground lean camel meat during refrigerated storage for up to 7 d, and determine thermal inactivation parameters (D and z-values) of the pathogens in the meat. Fresh ground camel meat samples were individually inoculated with two...
Article
Tahini is a popular food product in the Middle East region and is used as a major ingredient in several ready-to-eat food products. Tahini and its products have been linked to foodborne illness outbreaks and product recalls worldwide as a result of Salmonella spp. contamination. The objectives of the current study were to investigate: i) the effect...
Article
The present study tested the antibacterial activity, expressed as minimum bactericidal concentration (MBC), of zinc oxide nanoparticles (ZnO‐NPs), copper oxide nanoparticles (CuO‐NPs) and their combination with or without rosemary, clove or cinnamon extract against Escherichia coli O157:H7 and Listeria monocytogenes. The NPs were characterized by s...
Article
Abstract The antimicrobial activity of different essential oils was screened against five Salmonella serotypes using disk diffusion. Cinnamon (Cinnamomum zeylanicum) and thyme (Thymus vulgaris) essential oils exhibited the highest activity with inhibition zones of 22.5–38.5 mm in diameter. These oils were also investigated for their ability to cont...
Article
Full-text available
The production of safe and healthy food products represents one of the main objectives of the food industry. The presence of microorganisms in meat and products containing meat can result in a range of human health problems, as well as economic losses to producers of these products. However, contaminated meat products continue to initiate serious a...
Article
Escherichia coli O157:H7 is a toxigenic serotype of E. coli and has been associated with foodborne outbreaks involving meat products, vegetables and fresh produces worldwide. Salts for curing are usually employed as antimicrobials in the production of pork sausages. However, salts do not have a significant inhibitory effect on enterobacteria. Due t...
Article
The objective of the current study was to evaluate the antimicrobial action of different concentrations of acetic (0.3% and 0.4%) or citric (1% and 1.4%) acids and their combinations (1% citric acid plus 0.4% acetic acid and 1.4% citric acid plus 0.3% acetic acid) against Salmonella Typhimurium, Escherichia coli O157:H7 and Staphylococcus aureus in...
Article
Full-text available
Curing processes for pork meat in the U.S. currently require individual validation of methods to demonstrate inactivation of Trichinella spiralis, a nematode parasite historically associated with pork. However, for protozoan parasites, no such strictures exist. It has been assumed, with little evidence, that curing processes required to inactivate...
Article
Full-text available
Salmonella is a persisting contaminant in poultry products that may pose a potential risk to consumers. Thus, developing decontamination strategies to eliminate or reduce this pathogen in chicken is crucial. The objective of the current study was to investigate the antimicrobial activity of malic acid (MA) and acetic acid (AA) or their combination...
Article
Hummus (chickpea dip) is a ready-to-eat product which has been implicated in several foodborne outbreaks and food recalls. This study aimed to screen the antimicrobial activity of allyl isothiocyanate (AITC) against 5 strains of each of Salmonella enterica and Listeria monocytogenes using a disc diffusion method. Additionally, the antimicrobial act...
Article
The Canadian Food Inspection Agency (CFIA), as part of the modernization of its inspection system, is developing a risk assessment model with the goal of evaluating the most important food safety-related risk factors associated with the various types of food establishments under its jurisdiction. Ultimately, this new risk assessment model will assi...
Article
Shelf life and safety of minimally processed food are crucial for both consumers and the food industry. This study investigates the in vitro and in situ efficiency of electrospun chitosan-based nanofibers (CNFs) as inner part of a multilayer packaging in maintaining the quality of unprocessed red meat. Activated CNF-based packaging (CNFP) were obta...
Article
The effectiveness of 30 to 400 ppm chlorine dioxide (CDO), acidified sodium chlorite (ASC) and peroxyacetic acid (PAA) to control Escherichia coli O157:H7 in beef was examined. Ground beef made from treated meat was vacuum packaged and stored at 4 °C for 4 d. CDO or ASC concentration by storage time interaction for inactivation of E. coli O157:H7 w...
Article
Full-text available
The growth behaviour of foodborne pathogens (Staphylococcus aureus, Listeria monocytogenes, E. coli O157:H7 and Salmonella spp.) was investigated in pasteurised camel milk and compared with pasteurised bovine milk at different incubation temperatures. This study also aimed to compare the growth patterns of these four foodborne pathogens in pasteuri...
Article
Escherichia coli O157:H7 is a foodborne pathogen that causes hemorrhagic colitis and hemolytic uremic syndrome. The low dose of infection and severity of the disease represent a concern to public health. Natural compounds have been widely applied as food additives to replace synthetic preservatives. The aim of this study was to determine the effici...
Conference Paper
Full-text available
Introduction: The Canadian Food Inspection Agency (CFIA) is modernizing its risk-based approach to oversight by developing the establishment-based risk assessment model to enhance a more effective and efficient allocation of inspection activities to highest risk areas. Its initial developmental stages involved the selection/refinement of key risk f...
Article
Full-text available
Curing processes are one method by which pork products, which are considered ready to eat (RTE) and have not been otherwise tested or treated, can be rendered safe from risk for exposure to Trichinella muscle larvae (ML). Curing processes in the U.S. currently require individual validation of methods to demonstrate inactivation of Trichinella. This...
Article
Cinnamaldehyde is a natural antimicrobial compound that has been found to damage the cytoplasmic membrane, inhibit septum development and cause cell elongation, as well as induce oxidative stress in Escherichia coli. Thus, cinnamaldehyde may be of value as a natural compound to enhance susceptibility of drug resistant E. coli to antibiotics in live...
Article
Full-text available
The effects of chitosan (C) coating with or without lysozyme (L) or natamycin (N) on shelf-life, microbial quality, and sensory properties of Halloumi cheese held at 3 °C or 25 °C in 5%, 10% or 15% (w/v) NaCl were examined. Coatings increased cheese shelf-life by ≥ 5 days than the control when brined in 5% and 10% NaCl at 3 °C but did not affect th...
Chapter
In an effort to eat healthfully, consumers have increased their consumption of fruits and vegetables over the past three decades only to find that produce, in spite of its minimal processing and perishability is now almost as frequently implicated as a vehicle of foodborne illness as food of animal origin. It is apparent that produce can be easily...
Article
Full-text available
This study was conducted to evaluate the survival of 7 Shiga-toxigenic Escherichia coli (STEC) in fresh cold-pressed juice and the antimicrobial efficacy of 4 essential oils (EO: achillea, rosemary, sage, and thyme). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each EO was determined using microdilution...
Article
The growth response of Cronobacter spp. to different levels of NaCl and pH was investigated using response surface methodology. Brain heart infusion (BHI) broth containing 0 to 10% (w/v) NaCl at pH values of 4.5 to 8.0 was inoculated with a cocktail of 5 Cronobacter spp. The mixtures were incubated at 37°C and were sampled at intervals of 0, 2, 4,...
Article
Full-text available
E. coli O157:H7 is an emerging public health concern worldwide because of its low infectious dose and ability to survive under adverse conditions. Tests were conducted to determine the ability of unstressed E. coli O157:H7 cells or those stressed by acid, cold, salt exposure or starvation to survive on the surfaces of rocket leaves after contaminat...
Article
Unlabelled: Listeria monocytogenes is an important foodborne pathogen that can cause infection in children, pregnant women, the immunocompromised and the elderly. Antibiotic resistance in this species would represent a significant public health problem since the organism has a high fatality/case ratio and resistance may contribute to failure of th...
Article
Ready-to-eat meats are considered foods at high risk to cause life-threatening Listeria monocytogenes infections. This study screened 5 L. monocytogenes strains for their ability to hydrolyze sinigrin (a glucosinolate in Oriental mustard), which formed allyl isothiocyanate (AITC) and reduced L. monocytogenes viability on inoculated vacuum-packed, c...
Article
In addition to its nutritional and therapeutic properties, camel milk has the ability to suppress the growth of a wide range of foodborne pathogens, but there is a lack of information regarding the behavior of these pathogens in products such as yogurt produced from camel milk. The objective of the current study was to investigate the behavior of L...
Article
Full-text available
The antimicrobial activity of a methanolic extract of amurca (olive oil lees) was determined against both Gram-positive (L. monocytogenes and S. aureus) and Gram-negative (E. coli O157:H7 and S. enteritidis) foodborne pathogens at 10 °C or 37 °C using microdilution and disk diffusion methods, and its relative activity was compared to selected antib...
Data
##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Data
Sequences were screened for chimeras by the submitter using Uchime 4.2.40. ##Assembly-Data-START## Sequencing Technology :: Sanger dideoxy sequencing ##Assembly-Data-END##
Article
This work examined Escherichia coli O157:H7 strain 02-0304 for putative genes responsible for sinigrin hydrolysis. Sinigrin is a glucosinolate present in Oriental mustard (Brassica juncea), and its hydrolysis is mediated in plants by the enzyme myrosinase. Sinigrin hydrolysis by plant or bacterial myrosinase yields allyl isothiocyanate (AITC) which...
Article
Lactic acid pre-treatment was examined to enhance the antimicrobial action of electron (e-) beam irradiation of beef trim. Meat samples were inoculated with Escherichia coli O157:H7, non-O157 VTEC E. coli or Salmonella cocktails and treated with 5% lactic acid at 55 °C. Samples were packaged aerobically or vacuum-packed, kept at 4 °C and treated wi...
Article
Prevalence of antibiotic resistance of Listeria monocytogenes isolated from a variety of foods has increased in many countries. L. monocytogenes has many physiological adaptations that enable survival under a wide range of environmental stresses. The objective of this study was to evaluate effects of osmotic (2, 4, 6, 12% NaC), pH (6, 5.5, 5.0) and...
Article
Enterococcus species are part of the normal intestinal flora of a large number of mammals including humans and consequently, they can be used as indicators of faecal contamination in food and water for human consumption. Their presence in large numbers in foods may indicate a lapse in sanitation and their ability to serve as a genetic reservoir of...
Article
Factors, including pH, temperature, glucose concentration, and iron compounds, affect the activity of plant myrosinase and, consequently, endogenous glucosinolate degradation. These factors also may affect glucosinolate degradation by bacterial myrosinase. Therefore, this study examined the effect of temperature (4 to 21°C), glucose (0.05 to 1.0%),...
Article
A total of 270 samples of raw and processed meat products were collected at retail in Amman, Jordan and tested for the presence of Listeria spp. by conventional bacteriological methods. L. monocytogenes isolates were confirmed by PCR using L. monocytogenes virulence gene primers actA, hlyA, iap, inlA, inlB, inlC and inlJ. The overall occurrence of...
Article
Since tahini and its products have been linked to Salmonella illness outbreaks and product recalls in recent years, this study assessed the ability of Salmonella Typhimurium to survive or grow in commercial tahini and when hydrated (10% w/v in water), treated with 0.1%–0.5% acetic or citric acids, and stored at 37, 21 and 10 °C for 28 d. S. Typhimu...
Article
Unlabelled: The effects of microencapsulating cardamom essential oil (CEO) in whey protein isolate (WPI) alone and combined with guar gum (GG) and carrageen (CG) on microencapsulation efficiency, oil chemical stability, and microcapsule structure were investigated. Freeze-dried microcapsules were prepared from emulsions containing (w/w): 15% and 3...