Microbiological Profile of Meat from Pekin Ducks During Refrigerated Storage in Air and Vacuum

ABSTRACT This study investigates the dynamics of spoilage microflora in duck meat packed in vacuum and air during 9 days of storage. In total, 72 duck carcasses were used in the study. Samples of meat (breasts and thighs, with or without skin) were analysed on days 1, 3, 6 and 9 after packaging in two different atmospheres, at a storage temperature of 3°C ± 1°C. Enterobacteriaceae, coliform bacteria, and E. coli, Total Viable Count, psychrotrophic microorganisms, Lactic Acid Bacteria, Pseudomonas spp. counts, and Brochothrix thermosphacta were determined. As expected, the type of sample and storage length had the greatest influence on microbiological quality (p<0.001). Lower significance (p<0.01) was observed for the place of sampling factor - i.e. duck breast or thigh. As expected, better microbiological parameters were achieved with vacuum-packed samples. The pH value increased during storage, but the increase was minimal for the vacuum-packed samples. In all the microbiological parameters monitored, the best results at the end of storage were obtained for duck breast muscles packed in vacuum

The effects of selenium feed supplements on the oxidative stability indicators of egg yolk during the laying period

The aim of this study was to assess the effects of four types of selenium (Se) feed supplements on the indicators of the oxidative stability of egg yolk. A total of 1,740 Bovans Brown laying hens were divided into 4 experimental and 1 control group. The diets fed to the experimental groups were supplemented with 0.2 mg/kg of Se, provided as sodium selenite, Se-enriched yeast, synthetic L-selenomethionine and hydroxy-analogue of selenomethionine. The highest concentrations of MDA, an indicator of secondary lipid oxidation, were confirmed in the Control Group eggs (P &lt; 0.001). Egg yolks from the Control Group were found to have the highest lightness (P = 0.032), the lowest colour chroma and the lowest proportions of the red and yellow colours (P &lt; 0.001). The highest vitelline membrane strength was measured in eggs from groups fed diets supplemented with organic Se (P &lt; 0.001). No significant differences were found between groups in the total fatty acid content, the content of saturated and unsaturated fatty acids or the n-6/n-3 fatty acid ratios. Our study confirmed the effect of Se feed supplements on the concentration of MDA and the colour indicators of egg yolk and on the vitelline membrane strength

Bactericidal activity of caprylic acid entrapped in mesoporous silica nanoparticles

[EN] Development of nanotechnologies to improve the functionality of natural antimicrobials for food applications has received much attention in recent years. Mesoporous silica particles, such as MCM-41, have been recently proposed as smart delivery devices capable of loading and releasing large amounts of cargo. In this study, the antimicrobial activity of caprylic acid entrapped in MCM-41 nanoparticles against Escherichia coli, Salmonella enterica, Staphylococcus aureus and Listeria monocytogenes was tested and compared with the bactericidal effect of free caprylic acid using the macrodilution method. The minimum bactericidal concentration for free caprylic acid was established to be below 18.5 mM for S. aureus and L. monocytogenes and within the 18.5-20 mM range for E. coli and S. enterica. Moreover, caprylic acid loaded nanoparticles showed a total inhibition of the growth within the 18.5-20 mM range for the tested bacteria, and therefore the antimicrobial activity was preserved. Transmission electron microscopy images revealed that bacteria treatment with the caprylic acid-loaded nanoparticles generated disruption of cell envelope and leakage of cytoplasmic content, which resulted in cell death. We believe that caprylic acid encapsulation in nanoparticles MCM-41 can provide an effective system for potential applications in food safety in the food industry due to the possible controlled release of fatty acid and the masking of its unpleasant organoleptic properties. (C) 2015 Elsevier Ltd. All rights reservedRuiz Rico, M.; Fuentes López, C.; Pérez-Esteve, É.; Jiménez Belenguer, AI.; Quiles Chuliá, MD.; Marcos Martínez, MD.; Martínez-Máñez, R.... (2015). Bactericidal activity of caprylic acid entrapped in mesoporous silica nanoparticles. Food Control. 56:77-85. doi:10.1016/j.foodcont.2015.03.016S77855

The Influence of Liquid Medium Choice in Determination of Minimum Inhibitory Concentration of Essential Oils against Pathogenic Bacteria

So far there is no internationally accepted, standardized method for MIC determination of natural substances such as essential oils (EOs). The aim of this study was to elucidate how much the MIC values obtained from various studies using different culture media are comparable. The median MICs for cinnamon essential oil (EO) obtained by broth dilution were 517, 465 and 517 &micro;g/mL for Mueller&ndash;Hinton Broth (MHB), Tryptone Soya Broth (TSB) and Brain Heart Infusion (BHI), respectively. The MIC values for oregano EO were significantly (p &lt; 0.001) lower in MHB than in highly nutritious media; the median MICs were 616 &micro;g/mL for MHB and 474 &micro;g/mL for TSB and BHI. This statistically significant difference was noted for all the pathogens studied (Salmonella Enteritidis, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus). In the presence of oregano EO lag phase was also much less prolonged in MHB (by 6&ndash;17%) than in the other media (by 92&ndash;189%). Some components of EOs may bind to starch in MHB; since the phenomenon seems to be selective and EO dependent, the use of MHB for comparison of antimicrobial properties of various EOs thus cannot be recommended

The Influence of Liquid Medium Choice in Determination of Minimum Inhibitory Concentration of Essential Oils against Pathogenic Bacteria

So far there is no internationally accepted, standardized method for MIC determination of natural substances such as essential oils (EOs). The aim of this study was to elucidate how much the MIC values obtained from various studies using different culture media are comparable. The median MICs for cinnamon essential oil (EO) obtained by broth dilution were 517, 465 and 517 µg/mL for Mueller–Hinton Broth (MHB), Tryptone Soya Broth (TSB) and Brain Heart Infusion (BHI), respectively. The MIC values for oregano EO were significantly (p &lt; 0.001) lower in MHB than in highly nutritious media; the median MICs were 616 µg/mL for MHB and 474 µg/mL for TSB and BHI. This statistically significant difference was noted for all the pathogens studied (Salmonella Enteritidis, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus). In the presence of oregano EO lag phase was also much less prolonged in MHB (by 6–17%) than in the other media (by 92–189%). Some components of EOs may bind to starch in MHB; since the phenomenon seems to be selective and EO dependent, the use of MHB for comparison of antimicrobial properties of various EOs thus cannot be recommended.</jats:p

Methods for Determination of Antimicrobial Activity of Essential Oils In Vitro&mdash;A Review

Essential oils (EOs) have been gaining popularity in the past decades among researchers due to their potential to replace conventional chemicals used in the fight against pests, pathogenic and spoilage microbes, and oxidation processes. EOs are complex mixtures with many chemical components, the content of which depends on many factors&mdash;not just the plant genus, species, or subspecies, but also chemotype, locality, climatic conditions, phase of vegetation, method of extraction, and others. Due to this fact, there is still much to study, with antimicrobial effect being one of the key properties of EOs. There are many methods that have been frequently used by researchers for in vitro evaluation; however, although the research has been going on for decades, an internationally accepted standard is still missing. Most of methods are based on time-proven standards used for the testing of antibiotics. Due to the specific properties of EOs and their components, such as volatility and hydrophobicity, many modifications of these standard procedures have been adopted. The aim of this review is to describe the most common methods and their modifications for the testing of antimicrobial properties of EOs and to point out the most controversial variables which can potentially affect results of the assays

Higher Resistance of Yersinia enterocolitica in Comparison to Yersinia pseudotuberculosis to Antibiotics and Cinnamon, Oregano and Thyme Essential Oils

Yersiniosis is an important zoonotic disease; however, data are scarce on the resistance of enteropathogenic yersiniae, especially that of Y. pseudotuberculosis. Minimum inhibitory concentrations (MIC) of 21 antibiotics and 3 essential oils (EOs) were determined by broth microdilution for Y. enterocolitica bioserotype 4/O:3 strains isolated from domestic swine (n = 132) and Y. pseudotuberculosis strains isolated from wild boars (n = 46). For 15 of 21 antibiotics, statistically significant differences were found between MIC values of Y. enterocolitica and Y. pseudotuberculosis. While Y. enterocolitica was more resistant to amoxiclav, ampicillin, cefotaxime, cefuroxime, gentamicin, imipenem, meropenem, tetracycline, tobramycin, and trimethoprim, Y. pseudotuberculosis was more resistant to cefepime, ceftazidime, colistin, erythromycin, and nitrofurantoin. Statistically significant differences were found between various essential oils (p &lt; 0.001) and species (p &lt; 0.001). The lowest MICs for multiresistant Y. enterocolitica (n = 12) and Y. pseudotuberculosis (n = 12) were obtained for cinnamon (median 414 and 207 &mu;g/mL, respectively) and oregano EOs (median 379 and 284 &mu;g/mL), whereas thyme EO showed significantly higher MIC values (median 738 and 553 &mu;g/mL; p &lt; 0.001). There was no difference between Y. enterocolitica strains of plant (1A) and animal (4/O:3) origin (p = 0.855). The results show that Y. enterocolitica is generally more resistant to antimicrobials than Y. pseudotuberculosis

The dependence of growth inhibition of Salmonella Typhimurium and Listeria monocytogenes by oregano or thyme essential oils on the chemical composition of minced pork

The dataset includes inhibition data used for modelling and full specification of essential oils used in this study