Layal Karam | American University of Beirut (original) (raw)

Papers by Layal Karam

Foods

Hummus is a traditional and very popular Mediterranean ready-to-eat (RTE) food, with growing popu... more Hummus is a traditional and very popular Mediterranean ready-to-eat (RTE) food, with growing popularity worldwide. However, it has a high water activity and is susceptible to microbial growth and post-process contamination that limit its quality and shelf-life. For this purpose, the present study compared the use of several antimicrobials, alone or in combination, for hummus preservation during storage (4 °C), for up to 45 days. The chemical preservative potassium sorbate 0.09% (S) was evaluated, along with three natural antimicrobials: garlic 1.25% (G); vinegar 5% (V); natamycin 0.002% (N); or their combination: garlic 1.25%–vinegar 5% (GV); vinegar 5%–natamycin 0.002% (VN); garlic 1.25%–natamycin 0.002% (GN); and garlic 1.25%–vinegar 5%–natamycin 0.002% (GVN) to increase the shelf-life of hummus. A thymol and carvacrol mixture 0.2% (O) was also assessed to preserve and develop a new oregano-flavored hummus. All treatments that included vinegar used alone or in combination had sign...

Journal of Food Quality and Hazards Control, 2020

Background: Controlling and reducing the food-borne illnesses remain one of the most challenging ... more Background: Controlling and reducing the food-borne illnesses remain one of the most challenging problems encountered by food authorities worldwide. This study was conducted to assess the microbiological quality of chicken breast, chicken liver, local and imported offal, and ground beef meat products sold in the Lebanese retail market. Methods: Thirty-five chicken breast and liver samples produced by ISO 22000 certified and non-certified companies were purchased from the market. Chicken samples were tested for Total Aerobic Count (TAC), Total Coliforms (TC), Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes. Twenty offal and ground beef meat samples were collected as sold in bulk from the market and were analyzed for Escherichia coli O157:H7. Statistical analysis was performed using SPSS statistical software v. 23.0. Results: The results showed that 20, 100, 20, 80, and 0% of the analyzed chicken breast samples were rejected for TAC, TC, S. aureus, Salmonella spp., ...

Journal of Peptide Science, 2013

Study of peptides adsorption on surfaces remains a current challenge in literature. A complementa... more Study of peptides adsorption on surfaces remains a current challenge in literature. A complementary approach, combining X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate the antimicrobial peptide nisin adsorption on hydrophilic and hydrophobic surfaces. The native low density polyethylene was used as hydrophobic support and it was grafted with acrylic acid to render it hydrophilic. XPS permitted to confirm nisin adsorption and to determine its amount on the surfaces. ToF-SIMS permitted to identify the adsorbed bacteriocin type and to observe its distribution and orientation behavior on both types of surfaces. Nisin was more oriented by its hydrophobic side to the hydrophobic substrate and by its hydrophilic side to the outer layers of the adsorbed peptide, in contrast to what was observed on the hydrophilic substrate. A correlation was found between XPS and ToF-SIMS results, the types of interactions on both surfaces and the observed antibacterial activity. Such interfacial studies are crucial for better understanding the peptides interactions and adsorption on surfaces and must be considered when setting up antimicrobial surfaces.

Food Science and Technology

Thyme intake assessment is gaining significance because thyme is becoming a global staple food an... more Thyme intake assessment is gaining significance because thyme is becoming a global staple food and its use has been on the rise. In our study, a food frequency questionnaire (FFQ) was developed to assess thyme intake in Lebanon. Out of the total 1555 adult participants, 1523 persons (97.9%) consumed at least one thyme product among the14 assessed thyme-containing products. The mean consumption of thyme products was estimated to be 425.5 g/day, providing an estimated 31.4 g/day of thyme. Thyme pie had the highest mean intake (72.5 g/day) and represented the highest thyme contribution (10.4 g/day) among all thyme products, while crackers with thyme had the lowest mean intake (3.7 g/day) and the lowest thyme contribution (0.2 g/day). The mean consumption values for thyme products were significantly different between participants of different genders, age categories, socioeconomic and demographic levels. This study highlighted the importance of a food frequency questionnaire as a tool for data collection about the consumption patterns.

Reactive and Functional Polymers, 2013

ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the... more ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the surface properties and the surface treatments allowing the modification of such properties. In order to investigate the factors affecting such adsorption, the native low density polyethylene (LDPE) was modified using Argon/Oxygen (Ar/O2) plasma, nitrogen (N2) plasma and plasma-induced grafting of acrylic acid (AA). The films were studied by various characterization techniques. The chemical surface modification was confirmed by X-ray photoelectron spectroscopy (XPS), the wettability of the surfaces was evaluated by contact angle measurements, the surface charge was determined by the zeta potential measurements, and the changes in surface topography and roughness were revealed by atomic force microscopy (AFM). Nisin was adsorbed on the native and the modified surfaces. The antibacterial activity, the nisin adsorbed amount, and the peptide distribution were compared for the four nisin-functionalized films. The highest antibacterial activity was recorded on the Ar/O2 followed by AA then by N2 treated films and the lowest activity was on the native film. The observed antibacterial activity was correlated to the type of the surface, hydrophobic and hydrophilic interactions, surface charge, surface topography, nisin adsorbed amount, and nisin distribution on the surfaces.

Active food packaging and antimicrobial surfaces are innovative solutions for increasing food-bor... more Active food packaging and antimicrobial surfaces are innovative solutions for increasing food-borne diseases and changes in food habits. This review describes the different methods for setting up active packaging, with specific focus on antimicrobial surfaces developed by peptide adsorption. The key elements in the study of peptide adsorption on surfaces are the peptide nature, the surface properties and the interactions between them. Nisin, a well-known peptide, was reviewed and can be considered as a model for peptide studies. Plasma surface treatments were evaluated as potential versatile tools to provide specific functional groups and various surface characteristics needed to optimize and understand the adsorption behavior. The surface characterization methods were screened and discussed in terms of their relevance to investigate the interactions between peptides and surfaces, confirm each modification step and evaluate the antimicrobial activity of surfaces. For each factor, th...

PurposeThe purposes of this study were to analyze fruits, vegetables, water and soil for organoch... more PurposeThe purposes of this study were to analyze fruits, vegetables, water and soil for organochlorine pesticide (OCP) residues and to assess the food exposure of these pesticides in Qatar.Design/methodology/approachPesticides were quantified in dates, leafy vegetables, fruiting vegetables, water and soil samples using a gas chromatography-electron capture detector and gas chromatography-mass spectrometry. These pesticides were α-benzene hexachloride (BHC), ß-BHC, heptachlor, aldrin, g-chlordane, endosulfan I, α-chlordane, dieldrin, endrin and methoxychlor. Additionally, food exposure risk assessment was performed by estimating daily intakes of OCP.FindingsMost analyzed samples contained at least one OCP residue. Endosulfan was the only pesticide that was not detected. The concentrations of OCP in samples were below the maximum residue level (MRL) except endosulfan. Among all the samples analyzed, ˜18% of those exceeded the MRL with respect to the concentrations of methoxychlor and...

International Journal of Food Microbiology

Spices and herbs are widely used in almost all types of food preparation and their microbial cont... more Spices and herbs are widely used in almost all types of food preparation and their microbial contamination may cause spoilage and pose public health risk. Thus, the aim of this study was to assess the effect of packaging, source and a food safety management system (FSMS) on the microbiological quality of spices and dried herbs in a developing country, like Lebanon. For this, a total of 96 composite samples of thirteen most commonly consumed types of spices and dried herbs were collected twice at three-month interval. Each type was purchased in 5 common brands from 4 categories: packaged in companies with FSMS, packaged in companies without FSMS, packaged imported, and unpackaged. Total aerobic mesophilic bacteria (TAMB), sulfite reducing anaerobic bacteria, C. perfringens, coliforms, E. coli, yeasts and molds were found in 89%, 43%, 18%, 15%, 1% and 54% of the samples, respectively. All samples were negative for Salmonella. One per cent, 4%, 6%, 1% and 7% of the samples had unacceptable levels of TAMB, coliforms, sulfite reducing anaerobic bacteria, E. coli, yeasts and molds, respectively. Among the four categories, imported samples had the lowest microbiological load, followed by locally packaged in companies with FSMS, then locally packaged in companies without FSMS and the highest microbiological load was for the unpackaged spices and dried herbs. This study highlighted the importance of storage conditions, good hygienic practices, process controls and FSMSs in the spices and dried herbs sector.

International Journal of Food Microbiology

The objective of the study was to assess the antimicrobial effect of active essential oil compone... more The objective of the study was to assess the antimicrobial effect of active essential oil components (EOs) namely (carvacrol (CA), cinnamaldehyde (CI) and thymol (TH)) on Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 in chicken tawook during storage at 4 and 10 °C. A marinade consisting of ingredients commonly used in the chicken tawook recipe was prepared and mixed with 1% and 2% v/v CA, CI or TH. The marinade with or without EOs was added to fresh chicken breast cubes inoculated with the foodborne pathogens. Afterward, marinated chicken "tawook" was stored at 4 and 10 °C covered with cling wrap to mimic chill and mild abuse storage conditions for up to 7 days. At 10 °C, the marinade decreased L. monocytogenes numbers on day 4 and 7 by about 2.4 log10 CFU/g as compared to unmarinated samples. Adding EOs to chicken tawook did not change L. monocytogenes numbers during storage at 4 and 10 °C. For Salmonella spp., the marinade decreased the numbers during 10 °C storage on day 4 and 7 by about 4.9 log10 CFU/g as compared to unmarinated samples. At 4 °C, EOs at 2% decreased Salmonella spp. on day 7 by 0.5 log10 CFU/g. One percent CI significantly decreased Salmonella by 1.5 log10 CFU/g, at day 4 of storage. At 10 °C, 1% CA, 2% CI, 1% and 2% TH decreased Salmonella spp. in the samples by 0.5 log10 CFU/g on day 7. The marinade decreased E. coli O157:H7 numbers on the chicken samples during 10 °C storage on day 4 and 7 by about 3.3 log10 CFU/g as compared to unmarinated samples. Regardless of storage day at 4 °C, EOs decreased E. coli O157:H7 populations in chicken tawook by ≤2.4 log10 CFU/g compared to samples without EOs, where the decrease was ≤1.4 log10 CFU/g. Moreover, no significant decrease in E. coli O157:H7 populations could be attributed to the addition of EOs in samples which were stored at 10 °C. Increasing the concentration of EOs from 1 to 2% seemed to have no significant effect in reducing the tested foodborne pathogen populations.

Journal of Dairy Science

Dairy product safety is a global public health issue that demands new approaches and technologies... more Dairy product safety is a global public health issue that demands new approaches and technologies to control foodborne pathogenic microorganisms. Natural antimicrobial agents such as nisin can be added to control the growth of pathogens of concern in dairy foods, namely Listeria monocytogenes and Staphylococcus aureus. However, several factors affect the antimicrobial efficacy of nisin when directly added into the food matrix such as lack of stability at neutral pH, interaction with fat globules, casein, and divalent cations. To overcome these limitations, new and advanced strategies are discussed including nisin encapsulation technology, addition to active packaging, bioengineering, and combination with other antimicrobials. This review highlights advanced technologies with potential to expand and improve the use of nisin as a dairy preservative.

Journal of Food Protection

The effects of vacuum packaging, chitosan (1.5%, w/v), and natamycin (10 mg/L, w/v) on phyllo pas... more The effects of vacuum packaging, chitosan (1.5%, w/v), and natamycin (10 mg/L, w/v) on phyllo pastry quality were studied by monitoring microbiological, chemical, and sensory changes. Five lots were prepared with or without vacuum packaging, chitosan, and natamycin: A, air packaged (control); V, vacuum packaged; VC, vacuum packaged with chitosan; VN, vacuum packaged with natamycin; and VCN, vacuum packaged with both chitosan and natamycin. Based on the sensory acceptability data, a shelf life of 6 (A), 12 (V), 14 (VN), 16 (VC), and 17 (VCN) days was obtained at 4°C. VCN treatment resulted in a shelf life extension of 11 days compared with the shelf life of the control. Microbiological data revealed that the combination of chitosan and natamycin resulted in significant reductions of microbial species (mesophilic total viable counts, yeasts and molds, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae, and enterococci) of 1 to 3 log CFU/g on the final day (day 18) of st...

International Journal of Food Microbiology

The demand for marinated chicken worldwide, is continuously growing. To date, limited data on add... more The demand for marinated chicken worldwide, is continuously growing. To date, limited data on addition of active components of Essential Oils (EOs) to marinades for chicken preservation are available. The antimicrobial effect of carvacrol and thymol, added at 0.4 and 0.8% v/w to marinated fresh chicken, stored in air and under vacuum packaging (VP), for 21 days at 4 °C, was examined. The samples were monitored for microbiological (total viable count (TVC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Pseudomonas spp., total coliforms, Escherichia coli, yeasts and molds) and sensory attributes (odor characteristics). Our data supports that among the tested microorganisms, Pseudomonas spp., LAB and B. thermosphacta were the most dominant microbiota in the marinated chicken samples. Additionally, the use of active EOs components, especially the higher concentration (0.8% v/w) in combination with VP, retarded the growth of spoilage microbiota and resulted in a significant reduction of about 2.9-3.1 log cfu/g and a microbiological shelf-life extension of marinated chicken by >6 days, as judged by TVC data. Interestingly, the combination of active components of EOs at the lower concentration (0.4% v/w) and packaging (air or vacuum) resulted in a significant sensorial shelf-life extension of 15 and >21 days, as compared to the controls' shelf-life of 9 days. The results of our study demonstrated the potential of the active components, carvacrol and thymol, as natural effective antimicrobial hurdles to control the growth of spoilage microorganisms in marinated chicken meat.

Journal of the Taiwan Institute of Chemical Engineers

Abstract In order to prevent microbial contamination and food-borne illnesses, antimicrobial acti... more Abstract In order to prevent microbial contamination and food-borne illnesses, antimicrobial active packaging represents an innovative option. The aim of this paper was to optimize the experimental parameters of the plasma treatment. Such pre-treatment can be used to develop an active packaging film by adsorbing a natural antimicrobial peptide “Nisin” on the surface of a commonly used polymer in the agro-food sector “low density polyethylene (LDPE)”. Cold nitrogen (N2) plasma treatment was used to functionalize LDPE and generate a hydrophilic polymer suitable for the adsorption of the peptide. The experimental design technique allowed determining the optimal conditions of the plasma treatment. The lowest contact angle and highest hydrophilic character were obtained for a gas flow rate of 500 cm3/min, a generator power of 300 W and an exposure time of 300 s. The surface characterization techniques X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), contact angle and surface free energy measurements were used to confirm the surface modification after cold plasma treatment. The antimicrobial tests permitted to validate the efficiency of the active packaging films. The plasma treated films showed higher antimicrobial activity after nisin adsorption as compared to the native ones.

Food microbiology, 2017

This study explores the effects of chitosan and natamycin on the quality of fresh "Phyllo&qu... more This study explores the effects of chitosan and natamycin on the quality of fresh "Phyllo" - a dough-based wheat product, by monitoring the microbiological, physicochemical and sensory parameters. Four different lots of phyllo samples stored under aerobic packaging conditions, in the absence or presence of the aforementioned antimicrobials, were prepared and stored at 4 °C. Microbiological data suggested that, the combination of chitosan and natamycin resulted in significant reductions (1-3 log cfu/g) of the microbial species examined (mesophilic total viable counts; TVC), yeasts/molds, psychrotrophic and lactic acid bacteria (LAB), Enterobacteriaceae and coliforms) by day 10. The pH values of treated phyllo samples were lower on final day 10, as compared to the untreated phyllo, and of the Hunter color parameters (L*, b* and a*) that were evaluated, mostly the combined treatment of chitosan and natamycin maintained the original lightness (L*) and color (yellowness) stabil...

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La mondialisation du commerce alimentaire et les changements des modes de consommation presentent... more La mondialisation du commerce alimentaire et les changements des modes de consommation presentent de nouveaux defis majeurs en securite alimentaire. La mise au point d’emballages alimentaires actifs, par adsorption de peptides antimicrobiens sur des materiaux, est une approche innovante et proactive pour ameliorer la securite, la qualite et la duree de vie des produits emballes. L’adsorption de peptides en surface et l’activite antimicrobienne des supports fonctionnalises dependent principalement des proprietes de surface, des traitements de surface permettant de modifier ces proprietes et des interactions peptides-materiaux-bacteries. Dans cette these, le choix de l’agent antimicrobien s’est porte sur la nisine, bacteriocine a activite antilisteria, produite par des souches de Lactococcus lactis subsp. Lactis. L’emballage choisi etait le polyethylene a basse densite, un support frequemment utilise dans le secteur agro-alimentaire. Plusieurs procedes de traitements plasma froid ont ete mis au point pour developper des surfaces presentant des caracteristiques differentes et des fonctionnalites specifiques necessaires a l’etude des mecanismes d’adsorption. Des techniques physico-chimiques de caracterisation ont permis d’une part, de mettre en evidence la fonctionnalisation des supports par les traitements de surface et par la nisine et d’autre part, d’etudier les interactions aux interfaces. L’etude antimicrobienne a ete menee pour comparer et confirmer l’activite antimicrobienne des differents emballages traites. Ces analyses ont egalement ete effectues contre des pathogenes alimentaires et a basse temperature pour evaluer une possible application industrielle de ces emballages.

International Journal of Food Microbiology

Controlling spoilage of the popular ethnic marinated beef "Shawarma" is crucial to achi... more Controlling spoilage of the popular ethnic marinated beef "Shawarma" is crucial to achieve high quality, extend shelf-life, reduce food waste and meet the need of the globalized supply chain. Active essential oil (EO) components (thymol and carvacrol) were added at 0.4% and 0.8% (w/w) to preserve marinated beef, stored under aerobic or vacuum packaging. Microbiological and sensory (odor) parameters were assessed during 21 days at 4 °C. The treatments with higher EO concentration achieved higher antimicrobial activity than the lower ones and significantly reduced the mesophilic total viable count (TVC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Pseudomonas spp., total coliforms, Escherichia coli, yeasts and molds. The higher EO concentration extended the microbiological shelf-life by 6 days, as judged by TVC and compared to the controls (aerobic and vacuum packaging) but was unacceptable sensorially. The lower EO concentration increased the microbiological shelf-life by 3 days and the sensorial shelf-life by 9 and > 12 days, under aerobic and vacuum conditions, respectively.

Foods

Hummus is a traditional and very popular Mediterranean ready-to-eat (RTE) food, with growing popu... more Hummus is a traditional and very popular Mediterranean ready-to-eat (RTE) food, with growing popularity worldwide. However, it has a high water activity and is susceptible to microbial growth and post-process contamination that limit its quality and shelf-life. For this purpose, the present study compared the use of several antimicrobials, alone or in combination, for hummus preservation during storage (4 °C), for up to 45 days. The chemical preservative potassium sorbate 0.09% (S) was evaluated, along with three natural antimicrobials: garlic 1.25% (G); vinegar 5% (V); natamycin 0.002% (N); or their combination: garlic 1.25%–vinegar 5% (GV); vinegar 5%–natamycin 0.002% (VN); garlic 1.25%–natamycin 0.002% (GN); and garlic 1.25%–vinegar 5%–natamycin 0.002% (GVN) to increase the shelf-life of hummus. A thymol and carvacrol mixture 0.2% (O) was also assessed to preserve and develop a new oregano-flavored hummus. All treatments that included vinegar used alone or in combination had sign...

Journal of Food Quality and Hazards Control, 2020

Background: Controlling and reducing the food-borne illnesses remain one of the most challenging ... more Background: Controlling and reducing the food-borne illnesses remain one of the most challenging problems encountered by food authorities worldwide. This study was conducted to assess the microbiological quality of chicken breast, chicken liver, local and imported offal, and ground beef meat products sold in the Lebanese retail market. Methods: Thirty-five chicken breast and liver samples produced by ISO 22000 certified and non-certified companies were purchased from the market. Chicken samples were tested for Total Aerobic Count (TAC), Total Coliforms (TC), Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes. Twenty offal and ground beef meat samples were collected as sold in bulk from the market and were analyzed for Escherichia coli O157:H7. Statistical analysis was performed using SPSS statistical software v. 23.0. Results: The results showed that 20, 100, 20, 80, and 0% of the analyzed chicken breast samples were rejected for TAC, TC, S. aureus, Salmonella spp., ...

Journal of Peptide Science, 2013

Study of peptides adsorption on surfaces remains a current challenge in literature. A complementa... more Study of peptides adsorption on surfaces remains a current challenge in literature. A complementary approach, combining X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate the antimicrobial peptide nisin adsorption on hydrophilic and hydrophobic surfaces. The native low density polyethylene was used as hydrophobic support and it was grafted with acrylic acid to render it hydrophilic. XPS permitted to confirm nisin adsorption and to determine its amount on the surfaces. ToF-SIMS permitted to identify the adsorbed bacteriocin type and to observe its distribution and orientation behavior on both types of surfaces. Nisin was more oriented by its hydrophobic side to the hydrophobic substrate and by its hydrophilic side to the outer layers of the adsorbed peptide, in contrast to what was observed on the hydrophilic substrate. A correlation was found between XPS and ToF-SIMS results, the types of interactions on both surfaces and the observed antibacterial activity. Such interfacial studies are crucial for better understanding the peptides interactions and adsorption on surfaces and must be considered when setting up antimicrobial surfaces.

Food Science and Technology

Thyme intake assessment is gaining significance because thyme is becoming a global staple food an... more Thyme intake assessment is gaining significance because thyme is becoming a global staple food and its use has been on the rise. In our study, a food frequency questionnaire (FFQ) was developed to assess thyme intake in Lebanon. Out of the total 1555 adult participants, 1523 persons (97.9%) consumed at least one thyme product among the14 assessed thyme-containing products. The mean consumption of thyme products was estimated to be 425.5 g/day, providing an estimated 31.4 g/day of thyme. Thyme pie had the highest mean intake (72.5 g/day) and represented the highest thyme contribution (10.4 g/day) among all thyme products, while crackers with thyme had the lowest mean intake (3.7 g/day) and the lowest thyme contribution (0.2 g/day). The mean consumption values for thyme products were significantly different between participants of different genders, age categories, socioeconomic and demographic levels. This study highlighted the importance of a food frequency questionnaire as a tool for data collection about the consumption patterns.

Reactive and Functional Polymers, 2013

ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the... more ABSTRACT Setting up antibacterial materials by nisin adsorption on surfaces depends mainly on the surface properties and the surface treatments allowing the modification of such properties. In order to investigate the factors affecting such adsorption, the native low density polyethylene (LDPE) was modified using Argon/Oxygen (Ar/O2) plasma, nitrogen (N2) plasma and plasma-induced grafting of acrylic acid (AA). The films were studied by various characterization techniques. The chemical surface modification was confirmed by X-ray photoelectron spectroscopy (XPS), the wettability of the surfaces was evaluated by contact angle measurements, the surface charge was determined by the zeta potential measurements, and the changes in surface topography and roughness were revealed by atomic force microscopy (AFM). Nisin was adsorbed on the native and the modified surfaces. The antibacterial activity, the nisin adsorbed amount, and the peptide distribution were compared for the four nisin-functionalized films. The highest antibacterial activity was recorded on the Ar/O2 followed by AA then by N2 treated films and the lowest activity was on the native film. The observed antibacterial activity was correlated to the type of the surface, hydrophobic and hydrophilic interactions, surface charge, surface topography, nisin adsorbed amount, and nisin distribution on the surfaces.

Active food packaging and antimicrobial surfaces are innovative solutions for increasing food-bor... more Active food packaging and antimicrobial surfaces are innovative solutions for increasing food-borne diseases and changes in food habits. This review describes the different methods for setting up active packaging, with specific focus on antimicrobial surfaces developed by peptide adsorption. The key elements in the study of peptide adsorption on surfaces are the peptide nature, the surface properties and the interactions between them. Nisin, a well-known peptide, was reviewed and can be considered as a model for peptide studies. Plasma surface treatments were evaluated as potential versatile tools to provide specific functional groups and various surface characteristics needed to optimize and understand the adsorption behavior. The surface characterization methods were screened and discussed in terms of their relevance to investigate the interactions between peptides and surfaces, confirm each modification step and evaluate the antimicrobial activity of surfaces. For each factor, th...

PurposeThe purposes of this study were to analyze fruits, vegetables, water and soil for organoch... more PurposeThe purposes of this study were to analyze fruits, vegetables, water and soil for organochlorine pesticide (OCP) residues and to assess the food exposure of these pesticides in Qatar.Design/methodology/approachPesticides were quantified in dates, leafy vegetables, fruiting vegetables, water and soil samples using a gas chromatography-electron capture detector and gas chromatography-mass spectrometry. These pesticides were α-benzene hexachloride (BHC), ß-BHC, heptachlor, aldrin, g-chlordane, endosulfan I, α-chlordane, dieldrin, endrin and methoxychlor. Additionally, food exposure risk assessment was performed by estimating daily intakes of OCP.FindingsMost analyzed samples contained at least one OCP residue. Endosulfan was the only pesticide that was not detected. The concentrations of OCP in samples were below the maximum residue level (MRL) except endosulfan. Among all the samples analyzed, ˜18% of those exceeded the MRL with respect to the concentrations of methoxychlor and...

International Journal of Food Microbiology

Spices and herbs are widely used in almost all types of food preparation and their microbial cont... more Spices and herbs are widely used in almost all types of food preparation and their microbial contamination may cause spoilage and pose public health risk. Thus, the aim of this study was to assess the effect of packaging, source and a food safety management system (FSMS) on the microbiological quality of spices and dried herbs in a developing country, like Lebanon. For this, a total of 96 composite samples of thirteen most commonly consumed types of spices and dried herbs were collected twice at three-month interval. Each type was purchased in 5 common brands from 4 categories: packaged in companies with FSMS, packaged in companies without FSMS, packaged imported, and unpackaged. Total aerobic mesophilic bacteria (TAMB), sulfite reducing anaerobic bacteria, C. perfringens, coliforms, E. coli, yeasts and molds were found in 89%, 43%, 18%, 15%, 1% and 54% of the samples, respectively. All samples were negative for Salmonella. One per cent, 4%, 6%, 1% and 7% of the samples had unacceptable levels of TAMB, coliforms, sulfite reducing anaerobic bacteria, E. coli, yeasts and molds, respectively. Among the four categories, imported samples had the lowest microbiological load, followed by locally packaged in companies with FSMS, then locally packaged in companies without FSMS and the highest microbiological load was for the unpackaged spices and dried herbs. This study highlighted the importance of storage conditions, good hygienic practices, process controls and FSMSs in the spices and dried herbs sector.

International Journal of Food Microbiology

The objective of the study was to assess the antimicrobial effect of active essential oil compone... more The objective of the study was to assess the antimicrobial effect of active essential oil components (EOs) namely (carvacrol (CA), cinnamaldehyde (CI) and thymol (TH)) on Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 in chicken tawook during storage at 4 and 10 °C. A marinade consisting of ingredients commonly used in the chicken tawook recipe was prepared and mixed with 1% and 2% v/v CA, CI or TH. The marinade with or without EOs was added to fresh chicken breast cubes inoculated with the foodborne pathogens. Afterward, marinated chicken "tawook" was stored at 4 and 10 °C covered with cling wrap to mimic chill and mild abuse storage conditions for up to 7 days. At 10 °C, the marinade decreased L. monocytogenes numbers on day 4 and 7 by about 2.4 log10 CFU/g as compared to unmarinated samples. Adding EOs to chicken tawook did not change L. monocytogenes numbers during storage at 4 and 10 °C. For Salmonella spp., the marinade decreased the numbers during 10 °C storage on day 4 and 7 by about 4.9 log10 CFU/g as compared to unmarinated samples. At 4 °C, EOs at 2% decreased Salmonella spp. on day 7 by 0.5 log10 CFU/g. One percent CI significantly decreased Salmonella by 1.5 log10 CFU/g, at day 4 of storage. At 10 °C, 1% CA, 2% CI, 1% and 2% TH decreased Salmonella spp. in the samples by 0.5 log10 CFU/g on day 7. The marinade decreased E. coli O157:H7 numbers on the chicken samples during 10 °C storage on day 4 and 7 by about 3.3 log10 CFU/g as compared to unmarinated samples. Regardless of storage day at 4 °C, EOs decreased E. coli O157:H7 populations in chicken tawook by ≤2.4 log10 CFU/g compared to samples without EOs, where the decrease was ≤1.4 log10 CFU/g. Moreover, no significant decrease in E. coli O157:H7 populations could be attributed to the addition of EOs in samples which were stored at 10 °C. Increasing the concentration of EOs from 1 to 2% seemed to have no significant effect in reducing the tested foodborne pathogen populations.

Journal of Dairy Science

Dairy product safety is a global public health issue that demands new approaches and technologies... more Dairy product safety is a global public health issue that demands new approaches and technologies to control foodborne pathogenic microorganisms. Natural antimicrobial agents such as nisin can be added to control the growth of pathogens of concern in dairy foods, namely Listeria monocytogenes and Staphylococcus aureus. However, several factors affect the antimicrobial efficacy of nisin when directly added into the food matrix such as lack of stability at neutral pH, interaction with fat globules, casein, and divalent cations. To overcome these limitations, new and advanced strategies are discussed including nisin encapsulation technology, addition to active packaging, bioengineering, and combination with other antimicrobials. This review highlights advanced technologies with potential to expand and improve the use of nisin as a dairy preservative.

Journal of Food Protection

The effects of vacuum packaging, chitosan (1.5%, w/v), and natamycin (10 mg/L, w/v) on phyllo pas... more The effects of vacuum packaging, chitosan (1.5%, w/v), and natamycin (10 mg/L, w/v) on phyllo pastry quality were studied by monitoring microbiological, chemical, and sensory changes. Five lots were prepared with or without vacuum packaging, chitosan, and natamycin: A, air packaged (control); V, vacuum packaged; VC, vacuum packaged with chitosan; VN, vacuum packaged with natamycin; and VCN, vacuum packaged with both chitosan and natamycin. Based on the sensory acceptability data, a shelf life of 6 (A), 12 (V), 14 (VN), 16 (VC), and 17 (VCN) days was obtained at 4°C. VCN treatment resulted in a shelf life extension of 11 days compared with the shelf life of the control. Microbiological data revealed that the combination of chitosan and natamycin resulted in significant reductions of microbial species (mesophilic total viable counts, yeasts and molds, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae, and enterococci) of 1 to 3 log CFU/g on the final day (day 18) of st...

International Journal of Food Microbiology

The demand for marinated chicken worldwide, is continuously growing. To date, limited data on add... more The demand for marinated chicken worldwide, is continuously growing. To date, limited data on addition of active components of Essential Oils (EOs) to marinades for chicken preservation are available. The antimicrobial effect of carvacrol and thymol, added at 0.4 and 0.8% v/w to marinated fresh chicken, stored in air and under vacuum packaging (VP), for 21 days at 4 °C, was examined. The samples were monitored for microbiological (total viable count (TVC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Pseudomonas spp., total coliforms, Escherichia coli, yeasts and molds) and sensory attributes (odor characteristics). Our data supports that among the tested microorganisms, Pseudomonas spp., LAB and B. thermosphacta were the most dominant microbiota in the marinated chicken samples. Additionally, the use of active EOs components, especially the higher concentration (0.8% v/w) in combination with VP, retarded the growth of spoilage microbiota and resulted in a significant reduction of about 2.9-3.1 log cfu/g and a microbiological shelf-life extension of marinated chicken by >6 days, as judged by TVC data. Interestingly, the combination of active components of EOs at the lower concentration (0.4% v/w) and packaging (air or vacuum) resulted in a significant sensorial shelf-life extension of 15 and >21 days, as compared to the controls' shelf-life of 9 days. The results of our study demonstrated the potential of the active components, carvacrol and thymol, as natural effective antimicrobial hurdles to control the growth of spoilage microorganisms in marinated chicken meat.

Journal of the Taiwan Institute of Chemical Engineers

Abstract In order to prevent microbial contamination and food-borne illnesses, antimicrobial acti... more Abstract In order to prevent microbial contamination and food-borne illnesses, antimicrobial active packaging represents an innovative option. The aim of this paper was to optimize the experimental parameters of the plasma treatment. Such pre-treatment can be used to develop an active packaging film by adsorbing a natural antimicrobial peptide “Nisin” on the surface of a commonly used polymer in the agro-food sector “low density polyethylene (LDPE)”. Cold nitrogen (N2) plasma treatment was used to functionalize LDPE and generate a hydrophilic polymer suitable for the adsorption of the peptide. The experimental design technique allowed determining the optimal conditions of the plasma treatment. The lowest contact angle and highest hydrophilic character were obtained for a gas flow rate of 500 cm3/min, a generator power of 300 W and an exposure time of 300 s. The surface characterization techniques X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), contact angle and surface free energy measurements were used to confirm the surface modification after cold plasma treatment. The antimicrobial tests permitted to validate the efficiency of the active packaging films. The plasma treated films showed higher antimicrobial activity after nisin adsorption as compared to the native ones.

Food microbiology, 2017

This study explores the effects of chitosan and natamycin on the quality of fresh "Phyllo&qu... more This study explores the effects of chitosan and natamycin on the quality of fresh "Phyllo" - a dough-based wheat product, by monitoring the microbiological, physicochemical and sensory parameters. Four different lots of phyllo samples stored under aerobic packaging conditions, in the absence or presence of the aforementioned antimicrobials, were prepared and stored at 4 °C. Microbiological data suggested that, the combination of chitosan and natamycin resulted in significant reductions (1-3 log cfu/g) of the microbial species examined (mesophilic total viable counts; TVC), yeasts/molds, psychrotrophic and lactic acid bacteria (LAB), Enterobacteriaceae and coliforms) by day 10. The pH values of treated phyllo samples were lower on final day 10, as compared to the untreated phyllo, and of the Hunter color parameters (L*, b* and a*) that were evaluated, mostly the combined treatment of chitosan and natamycin maintained the original lightness (L*) and color (yellowness) stabil...

Http Www Theses Fr, Jul 8, 2013

La mondialisation du commerce alimentaire et les changements des modes de consommation presentent... more La mondialisation du commerce alimentaire et les changements des modes de consommation presentent de nouveaux defis majeurs en securite alimentaire. La mise au point d’emballages alimentaires actifs, par adsorption de peptides antimicrobiens sur des materiaux, est une approche innovante et proactive pour ameliorer la securite, la qualite et la duree de vie des produits emballes. L’adsorption de peptides en surface et l’activite antimicrobienne des supports fonctionnalises dependent principalement des proprietes de surface, des traitements de surface permettant de modifier ces proprietes et des interactions peptides-materiaux-bacteries. Dans cette these, le choix de l’agent antimicrobien s’est porte sur la nisine, bacteriocine a activite antilisteria, produite par des souches de Lactococcus lactis subsp. Lactis. L’emballage choisi etait le polyethylene a basse densite, un support frequemment utilise dans le secteur agro-alimentaire. Plusieurs procedes de traitements plasma froid ont ete mis au point pour developper des surfaces presentant des caracteristiques differentes et des fonctionnalites specifiques necessaires a l’etude des mecanismes d’adsorption. Des techniques physico-chimiques de caracterisation ont permis d’une part, de mettre en evidence la fonctionnalisation des supports par les traitements de surface et par la nisine et d’autre part, d’etudier les interactions aux interfaces. L’etude antimicrobienne a ete menee pour comparer et confirmer l’activite antimicrobienne des differents emballages traites. Ces analyses ont egalement ete effectues contre des pathogenes alimentaires et a basse temperature pour evaluer une possible application industrielle de ces emballages.

International Journal of Food Microbiology

Controlling spoilage of the popular ethnic marinated beef "Shawarma" is crucial to achi... more Controlling spoilage of the popular ethnic marinated beef "Shawarma" is crucial to achieve high quality, extend shelf-life, reduce food waste and meet the need of the globalized supply chain. Active essential oil (EO) components (thymol and carvacrol) were added at 0.4% and 0.8% (w/w) to preserve marinated beef, stored under aerobic or vacuum packaging. Microbiological and sensory (odor) parameters were assessed during 21 days at 4 °C. The treatments with higher EO concentration achieved higher antimicrobial activity than the lower ones and significantly reduced the mesophilic total viable count (TVC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Pseudomonas spp., total coliforms, Escherichia coli, yeasts and molds. The higher EO concentration extended the microbiological shelf-life by 6 days, as judged by TVC and compared to the controls (aerobic and vacuum packaging) but was unacceptable sensorially. The lower EO concentration increased the microbiological shelf-life by 3 days and the sensorial shelf-life by 9 and > 12 days, under aerobic and vacuum conditions, respectively.