Targeted Next-Generation Sequencing Assay for Direct Detection and Serotyping of Salmonella from Enrichment.

In this study, an automated, targeted next-generation sequencing (tNGS) assay to detect and serotype Salmonella from sample enrichments was evaluated. The assay generates millions of reads to detect multiple Salmonella-specific genes and serotype-specific alleles, detecting all Salmonella spp. tested to date, and serotyping 62 common Salmonella serotypes. Accuracy was tested on 291 pure reference cultures (251 Salmonella, 40 non-Salmonella), 21 artificially contaminated poultry carcass rinse samples, and 363 naturally contaminated poultry environmental samples. Among the 291 pure reference cultures, the automated tNGS assay resulted in 100% detection accuracy, 100% serotyping accuracy for the claimed serotypes, and 0% false positives. The limit of detection was estimated at 5 × 104 CFU/mL by testing enumerated cultures of strains representative of six serotypes. In cocontamination studies with mixtures of two serotypes (Enteritidis, Typhimurium, Kentucky, Infantis, and Newport) at a 1:1 ratio, tNGS detected both serotypes with 100% accuracy. The assay demonstrated 100% accuracy in artificially contaminated poultry carcass rinse sample enrichments. Targeted NGS was highly effective in detecting Salmonella in samples collected from poultry production facilities. Results demonstrated that tNGS could detect Salmonella and provide accurate serotyping information consistent with conventional serology. These findings highlight the reliable and efficient performance of a fully automated tNGS Salmonella assay in detecting and identifying Salmonella strains in complex matrices, reducing the time to results from 4 to 5 days required by the traditional isolation and serotyping to 10-12 h for tNGS after primary enrichment.

The power, potential, benefits, and challenges of implementing high-throughput sequencing in food safety systems.

The development and application of modern sequencing technologies have led to many new improvements in food safety and public health. With unprecedented resolution and big data, high-throughput sequencing (HTS) has enabled food safety specialists to sequence marker genes, whole genomes, and transcriptomes of microorganisms almost in real-time. These data reveal not only the identity of a pathogen or an organism of interest in the food supply but its virulence potential and functional characteristics. HTS of amplicons, allow better characterization of the microbial communities associated with food and the environment. New and powerful bioinformatics tools, algorithms, and machine learning allow for development of new models to predict and tackle important events such as foodborne disease outbreaks. Despite its potential, the integration of HTS into current food safety systems is far from complete. Government agencies have embraced this new technology, and use it for disease diagnostics, food safety inspections, and outbreak investigations. However, adoption and application of HTS by the food industry have been comparatively slow, sporadic, and fragmented. Incorporation of HTS by food manufacturers in their food safety programs could reinforce the design and verification of effectiveness of control measures by providing greater insight into the characteristics, origin, relatedness, and evolution of microorganisms in our foods and environment. Here, we discuss this new technology, its power, and potential. A brief history of implementation by public health agencies is presented, as are the benefits and challenges for the food industry, and its future in the context of food safety.

Validation of the Modified Clear Safety Salmonella for Detection of Salmonella enterica in Selected Poultry and Pet Food Matrixes and on Stainless Steel: AOAC Performance Tested MethodSM 111802.

BACKGROUND: The Clear Safety Salmonella method was modified to improve sample preparation, PCR reagents, library preparation, flow cell quality control, library loading mix, priming mix, and sequencing kit reagents and steps. OBJECTIVE: To evaluate the modified Clear Safety Salmonella method (manual and automated) via independent and method developer validation studies according to current AOAC INTERNATIONAL Validation Guidelines. METHOD: Performance of the modified Clear Safety Salmonella method (manual and automated) was assessed for selectivity (using 105 inclusive and 30 exclusive strains), probability of detection in matrixes, product consistency, stability, and robustness. The modified Clear Safety Salmonella method was compared with the appropriate reference method for Salmonella detection on 4 inch × 4 inch stainless steel environmental surfaces, and in chicken carcass rinse (30 mL), raw ground chicken (375 g), dry pet food (375 g), and ready-to-eat deli turkey breast (375 g). RESULTS: The modified Clear Safety Salmonella method (manual and automated) demonstrated no statistically significant differences between the candidate and reference method probability of detection or between the presumptive and confirmed results for all target food matrixes and the stainless steel surface. Additionally, the modified method (manual and automated) detected all 105 inclusivity organisms and excluded all 30 exclusivity organisms. The product consistency and kit stability studies showed no statistical differences between lots or over the term of the kit's shelf life. In robustness studies, changes in enrichment time, diluted sample volume, and sample volume for PCR did not show any statistical difference in terms of assay performance. CONCLUSIONS: The modified Clear Safety Salmonella method (both manual and automated) is statistically equivalent to or better than the reference methods. HIGHLIGHTS: The Clear Safety Salmonella method utilizes PCR amplification and targeted next-generation sequencing technology to selectively detect Salmonella enterica.

Validation of the Clear Safety Listeria Method for Detection of Listeria Species in Hot Dogs and on Environmental Surface Matrixes: AOAC Performance Tested MethodSM 091901.

BACKGROUND: The Clear Safety Listeria method utilizes polymerase chain reaction (PCR) amplification and targeted next-generation sequencing technology to detect Listeria species (L. monocytogenes, L. innocua, L. ivanovii, L. marthii, L. grayi, L. welshimeri, and L. seeligeri) in hot dogs and on selected environmental surfaces. OBJECTIVE: The aim was to validate the candidate method according to current AOAC guidelines. METHOD: The candidate method was compared to the reference method for hot dogs and the environmental surfaces. The method was also evaluated for inclusivity and exclusivity using 50 inclusivity strains and 30 exclusivity strains for each reported target. Product consistency and stability was tested and robustness was evaluated with changes in enrichment temperature, volume of sample treatment, and aliquot volume for PCR. RESULTS: The candidate method demonstrated no statistically significant differences using the probability of detection model between candidate and reference methods or between presumptive and confirmed results for all environmental surfaces and hot dogs. Additionally, the candidate method detected all inclusivity organisms and excluded all exclusivity organisms for each reported target. Product lots were shown to be consistent and data supported the kit's shelf life. Finally, the robustness study demonstrated no statistical differences when the volume of sample or the aliquot volume for PCR was altered. Increasing the incubation temperature to 37 ± 1 °C resulted in greater recovery of L. monocytogenes as compared to 35 ± 1 °C and 30 ± 1 °C. CONCLUSIONS: The Clear Safety Listeria method is statistically equivalent to the reference methods for the detection of L. monocytogenes and Listeria spp. in hot dogs and on selected environmental surfaces. HIGHLIGHTS: The Clear Safety Listeria method is an automated, highthroughput NGS-based method capable of detecting Listeria species in the hot dog and environmental samples within 28h.

Utilizing the Microbiota and Machine Learning Algorithms To Assess Risk of Salmonella Contamination in Poultry Rinsate.

ABSTRACT: Traditional microbiological testing methods are slow, and many molecular-based techniques rely on culture-based enrichment to overcome low limits of detection. Recent advancements in sequencing technologies may make it possible to utilize machine learning to identify patterns in microbiome data to potentially predict the presence or absence of pathogens. In this study, 299 poultry rinsate samples from various points in the processing chain were analyzed to determine if microbiota could inform about a sample's risk for containing Salmonella. Samples were culture confirmed as Salmonella positive or negative following modified U.S. Department of Agriculture Microbiological Laboratory Guidebook protocols. The culture confirmation result was used as a reference to compare with 16S sequencing data. Prechill samples tested positive (71 of 82) at a higher frequency than postchill samples (30 of 217) and contained greater microbial diversity. Due to the larger sample size, postchill samples were analyzed more thoroughly. Analysis of variance identified a significant effect of chilling on the number of genera (P < 0.001), but analysis of similarities failed to provide evidence for microbial dissimilarity between pre- and postchill samples (P = 0.001, R = 0.443). Various machine learning models were trained by using postchill samples to predict if a sample contained Salmonella on the basis of the samples' microbiota preenrichment. The optimal model was a random forest-based model with a performance as follows: accuracy (88%), sensitivity (85%), and specificity (90%). Although the algorithms described in this article are prototypes, these risk-based algorithms demonstrate the potential and need for further studies to provide insight alongside diagnostic tests. Combining risk-based information with diagnostic tools can help poultry processors make informed decisions to help identify and prevent the spread of Salmonella. These data add to the growing body of literature exploring novel ways to utilize microbiome data for predictive food safety.

Home Food Safety Practice and Household Food Insecurity: A Structural Equation Modeling Approach.

BACKGROUND: Food safety and food security are interrelated concepts with a profound impact on the quality of human life. The current study, for the first time, was set to identify associations between home food safety practice and household food insecurity a structural equation modeling approach. METHODS: In this cross-sectional study, urban households were selected from among 10 health centers of five districts of Tehran, Iran (2015). The following questionnaires were completed: socioeconomic status (SES), food security and food safety. Structural Equation Modeling (SEM) was applied for predicting the relationships between SES, food insecurity, and food safety in households. RESULTS: Food security was observed in 56% of households. Mild, moderate and severe food-insecure households were determined to be 29%, 12%, and 3%, respectively. In addition, the scores of home food safety practice in 37.5%, 33% and 29.5% of the households were classified as desirable, acceptable and weak, respectively. Low-educated mothers having husbands with low educational and occupational level had a weaker food safety practice compared to high-educated ones. Based on the SEM results, an inverse association between food safety practice and food insecurity score was observed (t= -2.89, ɣ = 0.16). CONCLUSION: Food insecurity and undesirable food safety practice were relatively prevalent among households. In addition, the economic and social factors could inversely affect both food insecurity and food safety practices.

Preparation and Characterization of Nanoparticle ß-Cyclodextrin:Geraniol Inclusion Complexes.

The aim of the present study was to formulate ß-cyclodextrin (ß-CD) nanoparticles loaded with geraniol (GR) essential oil (EO) with appropriate physicochemical properties. Complexation of GR with ß-CD was optimized by evaluation of four formulations, using the co-precipitation method, and the encapsulation efficiency (EE), loading, size, particle size distribution (PDI) and zeta potential were investigated. Further characterization was performed with nuclear magnetic resonance spectroscopy (1H NMR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and infra-red (IR) spectroscopy analysis. Results showed that the physicochemical properties of the nanoparticles were affected by GR content in formulations that yielded nanoscale-size particles ranging from 111 to 258 nm. The highest encapsulation efficiency (79.4 ± 5.4%) was obtained when the molar ratio of EO to ß-CD was 0.44: 0.13 with negative zeta potential (-21.1 ± 0.5 mV). The 1H-NMR spectrum confirmed the formation structure of the EO and ß-CD nanoparticle complex. Complexation with geraniol resulted in changes of IR profile, NMR chemical shifts, DSC properties, and SEM of ß-cyclodextrin. Inclusion complex of essential oil with ß-cyclodextrin was considered as promising bioactive materials for designing functional food.

Characterization and oxidative stability of purslane seed oil microencapsulated in yeast cells biocapsules.

BACKGROUND: Purslane seed oil, as a potential nutritious source of omega-3 fatty acid, is susceptible to oxidation. Encapsulation in yeast cells is a possible approach for overcoming this problem. In the present study, purslane seed oil was encapsulated in non-plasmolysed, plasmolysed and plasmolysed carboxy methyl cellulose (CMC)-coated Saccharomyces cerevisiae cells and measurements of oil loading capacity (LC), encapsulation efficiency (EE), oxidative stability and the fatty acid composition of oil-loaded microcapsules were made. Furthermore, investigations of morphology and thermal behavior, as well as a Fourier transform-infrared (FTIR) analyses of microcapsules, were performed. RESULTS: The values of EE, LC were approximately 53-65% and 187-231 g kg-1, respectively. Studies found that the plasmolysis treatment increased EE and LC and decreased the mean peroxide value (PV) of microencapsulated oil. The presence of purslane seed oil in yeast microcapsules was confirmed by FTIR spectroscopy and differential scanning calorimetry analyses. The lowest rate of oxidation belonged to the oil-loaded plasmolysed CMC-coated microcapsules (16.73 meqvO2 kg-1 ), whereas the highest amount of oxidation regardless of native oil referred to the oil-loaded in non-plasmolysed cells (28.15 meqvO2 kg-1 ). CONCLUSION: The encapsulation of purslane seed oil in the yeast cells of S. cerevisiae can be considered as an efficient approach for extending the oxidative stability of this nutritious oil and facilitating its application in food products. © 2017 Society of Chemical Industry.

Development of a Home Food Safety Questionnaire Based on the PRECEDE Model: Targeting Iranian Women.

Food safety is an essential public health issue for all countries. This study was the first attempt to design and develop a home food safety questionnaire (HFSQ), in the conceptual framework of the PRECEDE (predisposing, reinforcing, and enabling constructs in educational diagnosis and evaluation) model, and to assess its validity and reliability. The HFSQ was developed by reviewing electronic databases and 12 focus group discussions with 96 women volunteers. Ten panel members reviewed the questionnaire, and the content validity ratio and content validity index were computed. Twenty women completed the HFSQ, and face validity was assessed. Women who were responsible for food handling in their households (n =320) were selected randomly from 10 health centers and completed the HFSQ based on the PRECEDE model. To examine the construct validity, a principal components factor analysis with varimax rotation was used. Internal consistency was determined with Cronbach's α. Reproducibility was checked by Kendall's τ after 4 weeks with 30 women. The developed HSFQ was considered acceptable with a content validity index of 0.88. Face validity revealed that 95% of the participants understood the questions and found them easy to answer, and 90% confirmed the appearance of the HFSQ and declared the layout acceptable. Principal component factor analysis revealed that the HFSQ could explain 33.7, 55.3, 34.8, and 60.0% of the total variance of the predisposing, reinforcing, practice, and enabling components, respectively. Cronbach's α was acceptable at 0.73. For Kendall's τc, r = 0.89, with a 95% confidence interval of 0.85 to 0.93. The HFSQ developed based on the PRECEDE model met the standards of acceptable reliability and validity, which can be generalized to a wider population. These results can provide information for the development of effective communication strategies to promote home food safety.

Effect of nanocomposite packaging containing ZnO on growth of Bacillus subtilis and Enterobacter aerogenes.

Recent advances in nanotechnology have opened new windows in active food packaging. Nano-sized ZnO is an inexpensive material with potential antimicrobial properties. The aim of the present study is to evaluate the antibacterial effect of low density Polyethylene (LDPE) containing ZnO nanoparticles on Bacillus subtilis and Enterobacter aerogenes. ZnO nanoparticles have been synthesized by facil molten salt method and have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocomposite films containing 2 and 4 wt.% ZnO nanoparticles were prepared by melt mixing in a twin-screw extruder. The growth of both microorganisms has decreased in the presence of ZnO containing nanocomposites compared with controls. Nanocomposites with 4 wt.% ZnO nanoparticles had stronger antibacterial effect against both bacteria in comparison with the 2 wt.% ZnO containing nanocomposites. B. subtilis as Gram-positive bacteria were more sensitive to ZnO containing nanocomposite films compared with E. aerogenes as Gram-negative bacteria. There were no significant differences between the migration of Zn ions from 2 and 4 wt.% ZnO containing nanocomposites and the released Zn ions were not significantly increased in both groups after 14 days compared with the first. Regarding the considerable antibacterial effects of ZnO nanoparticles, their application in active food packaging can be a suitable solution for extending the shelf life of food.

Antioxidant and antimicrobial carboxymethyl cellulose films containing Zataria multiflora essential oil.

The present study describes the physical, antioxidant, and antimicrobial properties of biodegradable films prepared by incorporating different concentrations (1, 2, and 3% v/v) of Zataria multiflora Boiss (avishan-e shirazi) essential oil (ZEO) into carboxymethyl cellulose (CMC) film. The films' tensile strength, elongation at break, water-vapor permeability, optical characteristics, microstructure, and antimicrobial and antioxidant properties were investigated. The results indicated that the film containing 1% ZEO had the highest tensile strength and elongation at break. The control film showed the lowest water-vapor permeability. The resulting optical data showed that the control films were transparent in appearance; transparency was significantly reduced by an increase in ZEO concentration. Solubility in water decreased with increased ZEO. Films with ZEO, especially at higher concentrations, were more effective against all tested bacteria than the control film. Those films incorporating essential oil revealed antioxidant properties as well; this effect was greatly improved when the proportion of ZEO was increased. The results indicated that the antioxidant and antibacterial activity of ZEO is retained when it is used in CMC film. These properties with some good physical characteristics suggest applications for ZEO-incorporated film in a wide range of food products.

Investigation of the Effects of Inulin and ß-Glucan on the Physical and Sensory Properties of Low-Fat Beef Burgers Containing Vegetable Oils: Optimisation of the Formulation Using D-Optimal Mixture Design.

In this study, the D-optimal mixture design methodology was applied to determine the optimised proportions of inulin, ß-glucan and breadcrumbs in formulation of low-fat beef burgers containing pre-emulsified canola and olive oil blend. Also, the effect of each of the ingredients individually as well as their interactions on cooking characteristics, texture, colour and sensory properties of low-fat beef burgers were investigated. The results of this study revealed that the increase of inulin content in the formulations of burgers led to lower cooking yield, moisture retention and increased lightness, overall acceptability, mouldability and desired textural parameters. In contrast, incorporation of ß-glucan increased the cooking yield, moisture retention and decreased lightness, overall acceptability, mouldability and desired textural parameters of burger patties. The interaction between inulin and ß-glucan improved the cooking characteristics of the burgers without significantly negative effect on the colour or sensory properties. The results of the study clearly stated that the optimum mixture for the burger formulation consisted of (in g per 100 g): inulin 3.1, ß-glucan 2.2 and breadcrumbs 2.7. The texture parameters and cooking characteristics were improved by using the mixture of inulin, ß-glucan and breadcrumbs, without any negative effects on the sensory properties of the burgers.

Characterization of nanobiocomposite kappa-carrageenan film with Zataria multiflora essential oil and nanoclay.

In this study, we aimed to improve the physical, mechanical and water-vapor permeability (WVP) properties of kappa-carrageenan (KC) films by including montmorillonite (MMT) nanoclay in the film-forming solution. To further improve these properties, the combined effect of Zataria multiflora Boiss essential oil (ZEO) and MMT was also investigated. The incorporation of MMT improved the physical and mechanical properties of KC film. Film made from KC alone had a tensile strength (TS) of 26.29MPa, while the KC film with 10% nanoclay had a TS of 34.67. Further analysis was provided by X-ray diffraction and scanning electron microscopy that confirmed the dispersion of MMT in the KC matrix. It was also shown that the combined effect of nanoclay and ZEO significantly improved the TS and EB of KC films. ZEO decreased the WVP of the nanocomposite films; for example, 3% ZEO reduced WVP by around 78%. The antimicrobial activity of nanocomposite films was also studied using the overlay and vapor-phase methods; the films effectively inhibited the growth of five pathogens tested. Thus, the incorporation of both nanoclay and ZEO into KC films is a promising way to manufacture films with better mechanical, antimicrobial and WVP properties.

Preparation and characterization of alginate and alginate-resistant starch microparticles containing nisin.

Delivery systems with sustained release of nisin have been proposed to improve stability and long-term effectiveness of this bacteriocin in foods. In this study, nisin was encapsulated in alginate (Alg) and alginate-resistant starch (Alg-RS) microparticles and its release was investigated. Studies found that the nisin concentration has significant influence on encapsulation efficiency (EE), loading capacity (LC) and size of both microparticles. Furthermore, encapsulation efficiency and loading capacity values were more increased by the addition of resistant starch to the alginate formulation. The highest encapsulation efficiency was obtained with Alg-RS microparticles prepared using initial nisin to alginate weight ratio of 25% w/w (59.77 ± 2.26%). Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results confirmed the presence of nisin in the microparticles. The in vitro nisin release from these microparticles followed a controlled-release pattern consistent with a Fickian diffusion mechanism. The release rate from Alg-RS microparticles was less than that from the Alg microparticles.

Simultaneous determination of sorbic and benzoic acids in milk products using an optimised microextraction technique followed by gas chromatography.

A rapid and reliable method for direct determination of sorbic and benzoic acids in milk products was developed by dispersive liquid-liquid microextraction (DLLME) and gas chromatography with flame ionisation detector (GC-FID). A response surface methodology (RSM) based on a central composite design (CCD) was applied for optimisation of the main variables, such as volume of extraction and dispersive solvents, pH and salt effect. The primary extraction of sorbic and benzoic acids were performed in 8 mL NaOH (0.1 M) in a closed-vessel system. Carrez solutions (potassium hexaferrocyanide and zinc acetate) were used for protein sedimentation. The best simultaneous extraction efficiency was identified using acetone and 1-octanal as dispersive and extraction solvents, respectively. For DLLME, central composite design resulted in the optimised values of microextraction parameters as follows: 475 µL of dispersive and 60 µL of extraction solvents, 2 g NaCl at pH 2.5. Under optimum conditions, the calibration curve was linear over the range 0.1-50 µg mL(-1) and the square of correlation coefficient (R(2)) was 0.9992 for sorbic acid and 0.9994 for benzoic acid. Relative standard deviation (RSD %) was 6.1% and 3.1% (n = 5) for sorbic and benzoic acids, respectively. Limits of detection were 150 ng g(-1) for sorbic acid and 140 ng g(-1) for benzoic acid and recoveries were 88% and 103.7% respectively. Good reproducibility (RSD %), short extraction time and no matrix interference were advantages of the proposed method which was successfully applied to the determination of sorbic and benzoic acids in milk products.

Effect of different cooking methods on minerals, vitamins and nutritional quality indices of kutum roach (Rutilus frisii kutum).

In this study, the influence of four cooking methods (baking, boiling, microwaving and frying) was evaluated on the nutritional value of kutum roach. Proximate, fatty acid composition, vitamin and mineral contents and also nutritional quality indices (NQI) of kutum roach were investigated before and after cooking treatment. All treated samples showed increase in protein, ash and lipid contents and decrease in the content of total omega-3 fatty acids (n-3) in comparison to raw fish fillets (control group). Cooking methods had no significant effect on omega-6 fatty acids (n-6) except for frying that increased it. Nonetheless, all of the cooking methods reduced vitamin B1, A and D contents. Boiling significantly decreased mineral contents including Na, K, P and Zn. Considering the overall nutritional quality indices, vitamin and mineral contents, baking is the best cooking method among other applied methods.

Development of new active packaging film made from a soluble soybean polysaccharide incorporated Zataria multiflora Boiss and Mentha pulegium essential oils.

An active edible film from soluble soybean polysaccharide (SSPS) incorporated with different concentrations of Zataria multiflora Boiss (ZEO) and Mentha pulegium (MEO) essential oils was developed, and the film's optical, wettability, thermal, total phenol and antioxidant characteristics were investigated, along with their antimicrobial effectiveness against Staphylococcus aureus, Bacillus cereus, Escherichia coli O157:H7, Pseudomonas aeruginosa and Salmonella typhimurium. The film's colour became darker and more yellowish and had a lower gloss as the levels of ZEO or MEO were increased. Antioxidant activity of the films was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric-reducing antioxidant power assays. DPPH was reduced in the range of 19.84-74.12% depending on the essential oil type and concentration. Film incorporated with 3% (v/v) ZEO showed the highest DPPH radical scavenging activity and ferric reducing antioxidant power (IC50=4188.60±21.73mg/l and EC50=8.86±0.09mg/ml, respectively), compared with the control and MEO added film. Films containing ZEO were more effective against the tested bacteria than those containing MEO. S. aureus was found to be the most sensitive bacterium to both ZEO or MEO, followed by B. cereus and E. coli. A highest inhibition zone of 387.05mm(2) was observed for S. aureus around the films incorporated with 3% (v/v) ZEO. The total inhibitory zone of 3% (v/v) MEO formulated films was 21.98 for S. typhimurium and 10.15mm(2) for P. aeruginosa. Differential scanning calorimetry (DSC) analysis revealed a single glass transition temperature (Tg) between 16 and 31°C. The contact angle increased up to 175% and 38% as 3% (v/v) of ZEO or MEO used: it clearly shows that films with ZEO were more hydrophobic than those with MEO. The results showed that these two essential oils could be incorporated into SSPS films for food packaging.

Characterization of κ-carrageenan films incorporated plant essential oils with improved antimicrobial activity.

Antioxidant and antimicrobial kappa-carrageenan-based films containing different concentrations of Zataria multiflora Boiss (ZEO) and Mentha pulegium (MEO) essential oils were developed, and their water vapor permeability (WVP), optical, microstructure, antioxidant and antimicrobial properties were characterized. ZEO and MEO decreased the WVP of the emulsified films; for example, 3% ZEO reduced WVP by around 80%. Increasing the content of ZEO or MEO from 1% to 3% (v/v) increased values for elongation at break from 37.43% to 44.74% and from 36.09% to 41.25% respectively. Carrageenan-composite films were less resistant to breakage, more flexible and more opaque with lower gloss. These properties were related to the film's microstructure as analyzed by atomic force microscopy and scanning electron microscopy. ZEO affected the antioxidant properties of the films more markedly than MEO, e.g., ZEO containing films showed DPPH radical scavenging of 80.6% which were two-fold higher than those having MEO. The films' antimicrobial activities were increased by incorporating essential oils, particularly ZEO, which were more effective against the bacteria in the direct-contact method than a vapor phase. S. aureus was found to be the most sensitive bacterium to either ZEO or MEO, followed by B. cereus and E. coli. A highest inhibition zone of 544.05 mm(2) was observed for S. aureus around the films incorporated with 3% (v/v) ZEO. The total inhibitory zone of 3% (v/v) MEO formulated films was 20.43 for S. typhimurium and 10.15 mm(2) for P. aeruginosa. These results revealed that ZEO and MEO have good potential to be incorporated into κ-carrageenan to make antimicrobial and antioxidant edible films for food applications.

Incorporation of essential oil in alginate microparticles by multiple emulsion/ionic gelation process.

In this study, an o/w/o multiple emulsion/ionic gelation method was developed for production of alginate microparticles loaded with Satureja hortensis essential oil (SEO). It was found that the essential oil concentration has significant influence on encapsulation efficiency (EE), loading capacity (LC) and size of microparticles. The values of EE, LC and particle mean diameter were about 52-66%, 20-26%, and 47-117 µm, respectively, when the initial SEO content was 1-3% (v/v) .The essential oil-loaded microparticles were porous, as displayed by scanning electron micrograph. The presence of SEO in alginate microparticles was confirmed by Fourier transform-infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC) analyses. SEO-loaded microparticles showed good antioxidant (with DPPH radical scavenging activity of 40.7-73.5%) and antibacterial properties; this effect was greatly improved when the concentration of SEO was 3% (v/v). S. aureus was found to be the most sensitive bacterium to SEO and showed a highest inhibition zone of 304.37 mm(2) in the microparticles incorporated with 3% (v/v) SEO. In vitro release studies showed an initial burst release and followed by a slow release. In addition, the release of SEO from the microparticles followed Fickian diffusion with acceptable release.

Physical, mechanical and barrier properties of corn starch films incorporated with plant essential oils.

Corn starch-based films are inherently brittle and lack the necessary mechanical integrity for conventional packaging. However, the incorporation of additives can potentially improve the mechanical properties and processability of starch films. In this work two essential oils, Zataria multiflora Boiss (ZEO) or Mentha pulegium (MEO) at three levels (1%, 2% and 3% (v/v)), were incorporated into starch films using a solution casting method to improve the mechanical and water vapor permeability (WVP) properties and to impart antimicrobial activity. Increasing the content of ZEO or MEO from 2% to 3% (v/v) increased values for elongation at break from 94.38% to 162.45% and from 53.34% to 107.71% respectively, but did not significantly change tensile strength values of the films. The WVP properties of the films decreased from 7.79 to 3.37 or 3.19 g mm m(-2) d(-1) kPa(-1) after 3% (v/v) ZEO or MEO incorporation respectively. The oxygen barrier properties were unaffected at the 1% and 2% (v/v) oil concentration used but oxygen transmission increased with 3% (v/v) for both formulations. The films' color became slightly yellow as the levels of ZEO or MEO were increased although transparency was maintained. Both films demonstrated antimicrobial activity with films containing ZEO more effective against Escherichia coli and Staphylococcus aureus than those containing MEO. These results suggest that ZEO and MEO have the potential to be directly incorporated into corn starch to prepare antimicrobial biodegradable films for various food packaging applications.