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Study of Microbiological Safety in the Food Chain

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Food Process Engineering".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 36341

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Guest Editor
Department of Hygiene, Technology and Food Safety, Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia
Interests: meat safety; foodborne pathogens; antimicrobials; food safety systems
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The complex agri-food chain in different cultures may be accompanied with specific and unknown microbial hazards and risk. Therefore, strict microbiological risk assessment of emerging and novel pathogens in animal–human–environment interactions is strongly needed today.

The microbiological safety of food relies on the effectiveness of specific hygienic procedures and technological processes. The concept of food safety has changed in recent years from a hazard- to a risk-based approach coupled with targeted preventive interventions along the food chain. The process from food production to consumption may be very challenging from a microbiological point of view. In that sense, this Special Issue on the “Study of Microbiological Safety in the Food Chain” will give a broad view to available tools and process interventions to combat traditional and potential microbiological hazards within the whole agri-food chain.

Potential topics include but are not limited to the following:

- Food safety assurance systems;

- Epidemiology of foodborne pathogens;

- Microbiological risk assessment in food safety;

- On-farm food safety;

- Emerging pathogens in food chain;

- Food processing hygiene and microbiological food safety;

- Effect of food processing methods on foodborne pathogens;

- Reduction of hazardous microbial metabolites in food;

- Thermal and non-thermal inactivation of microbes in food;

- Challenge tests;

- Bio-preservation and hurdle technology;

- Beneficial microbes in food;

- Antimicrobial capacity of natural compounds in food;

- Traditional and industrial food production: microbiological risk.

Dr. Nevijo Zdolec
Guest Editor

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Keywords

  • Food chain
  • Hygiene and technology
  • Emerging foodborne pathogens
  • Toxic microbial metabolites
  • Risk assessment
  • Food processing
  • Interventions
  • Microbial inactivation
  • Beneficial microbes
  • Natural compounds

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Published Papers (11 papers)

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Editorial

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3 pages, 175 KiB  
Editorial
Introduction to Special Issue: Study of Microbiological Safety in the Food Chain
by Nevijo Zdolec
Processes 2022, 10(1), 149; https://doi.org/10.3390/pr10010149 - 12 Jan 2022
Viewed by 1148
Abstract
Ensuring microbiological safety in the food (of animal origin) chain is a challenging task due to the complex interactions among animals, humans and the environment [...] Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)

Research

Jump to: Editorial, Review

10 pages, 259 KiB  
Article
Biogenic Amine Content in Retailed Cheese Varieties Produced with Commercial Bacterial or Mold Cultures
by Nevijo Zdolec, Tanja Bogdanović, Krešimir Severin, Vesna Dobranić, Snježana Kazazić, Jozo Grbavac, Jelka Pleadin, Sandra Petričević and Marta Kiš
Processes 2022, 10(1), 10; https://doi.org/10.3390/pr10010010 - 22 Dec 2021
Cited by 11 | Viewed by 3254
Abstract
Biogenic amines (BAs) are considered a potential microbiological toxicological hazard in aged cheese. Risk mitigation strategies include good hygiene practice measures, thermal treatment of milk and the use of competitive dairy cultures. The aim of this study was to evaluate the amount of [...] Read more.
Biogenic amines (BAs) are considered a potential microbiological toxicological hazard in aged cheese. Risk mitigation strategies include good hygiene practice measures, thermal treatment of milk and the use of competitive dairy cultures. The aim of this study was to evaluate the amount of BAs—tryptamine, β-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine—in the core and rind of cheeses ripened by bacteria (n = 61) and by mold cultures (n = 8). The microbial communities were counted, and the dominant lactic acid bacteria (LAB) were identified, corresponding to the BA concentrations. The total BA content was highest in the core of semi-hard cheeses (353.98 mg/kg), followed by mold cheeses (248.99 mg/kg) and lowest in hard cheeses (157.38 mg/kg). The highest amount of BAs was present in the rind of cheeses with mold (240.52 mg/kg), followed by semi-hard (174.99 mg/kg) and hard cheeses (107.21 mg/kg). Tyramine was the most abundant BA, represented by 75.4% in mold cheeses, 41.3% in hard cheese and 35% of total BAs in semi-hard cheeses. Histamine was present above the defined European maximum level (ML) of 100 mg/kg in only two semi-hard and three hard cheeses. High amount of BAs (above 600 mg/kg) in cheeses, mainly tyramine, were associated with the presence of Enterococcus durans, while negligible BA concentrations were found in cheeses ripened with Lacticaseibacillus rhamnosus, Lactococcus lactis or Lacticaseibacillus paracasei cultures. This study has shown that retailed cheese varieties produced with commercial bacterial or mold cultures have acceptable levels of biogenic amines with respect to consumers. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
15 pages, 1778 KiB  
Article
The Influence of Surface Mycobiota on Sensory Properties of “Istarski pršut” and “Dalmatinski pršut”
by Tina Lešić, Nada Vahčić, Ivica Kos, Manuela Zadravec, Dragan Milićević, Irena Perković, Eddy Listeš and Jelka Pleadin
Processes 2021, 9(12), 2287; https://doi.org/10.3390/pr9122287 - 20 Dec 2021
Cited by 4 | Viewed by 2246
Abstract
This study aimed to identify surface mould species overgrowing the Croatian protected meat products “Istarski pršut” and “Dalmatinski pršut” and their effect on sensory properties. Dry-cured hams were produced in 2018/2019 and obtained from annual fairs. The predominant surface species found on “Dalmatinski [...] Read more.
This study aimed to identify surface mould species overgrowing the Croatian protected meat products “Istarski pršut” and “Dalmatinski pršut” and their effect on sensory properties. Dry-cured hams were produced in 2018/2019 and obtained from annual fairs. The predominant surface species found on “Dalmatinski pršut” were Aspergillus chevalieri, Penicillium citrinum and Aspergillus cibarius, whereas those overgrowing “Istarski pršut” were Aspergillus proliferans, P. citrinum and Penicillium salamii. The results show species diversity, higher presence, and greater variety of Aspergillus species in “Dalmatinski pršut” in comparison to “Istarski pršut”, and significant variations in 9 of 20 sensory attributes. Principal component analysis revealed a clear distinction between the two, and a large contribution of P. salamii and Penicillium bialowienzense to one principal component. The texture traits, smoky odour, muscle and subcutaneous fatty tissue colour, and mould species found are valuable for product characterisation. The results also indicate that mould species may be responsible for some sensory traits, such as tenderness, juiciness, and lesser freshness. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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Figure 1
<p>Sensory characteristics of “Istarski pršut” and “Dalmatinski pršut” (appearance, odour, texture, taste, and aroma). * statistically significant difference; numerical scale of intensity of sensory properties: “0” indicates the absence of a given sensory property, and “9” indicates its strongest intensity.</p>
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<p>Score plot of the variables encompassed by the principal component analysis of sensory attributes and mould species of “Istarski pršut” and “Dalmatinski pršut”. CMT = colour of the muscle tissue; CAST = colour of the subcutaneous adipose tissue; CU = colour uniformity; MA = marbling; SH = surface humidity; TC = tyrosine crystals; FO = favourable odour; UO = unfavourable odour; SMO = smoky odour; TE = tenderness; JU = juiciness; SA = saltiness; SW = sweetness; SO = sourness; BI = bitterness; SPA = specific aroma; BP = biochemical properties; FMA = fresh meat aroma; MO = moulds.</p>
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<p>Score plot of the principal component analysis of the sensory attributes and mould species of “Istarski pršut” (I) and “Dalmatinski pršut” (D) samples.</p>
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8 pages, 1240 KiB  
Article
Identification of Microbial Flora in Dry Aged Beef to Evaluate the Rancidity during Dry Aging
by Sejeong Kim, Jong-Chan Kim, Sunhyun Park, Jinkwi Kim, Yohan Yoon and Heeyoung Lee
Processes 2021, 9(11), 2049; https://doi.org/10.3390/pr9112049 - 16 Nov 2021
Cited by 12 | Viewed by 3368
Abstract
Dry aging creates a unique taste and flavor in beef; however, the process also causes rancidity, which is harmful to humans. During dry aging, the microbial flora in beef changes continuously; thus, this change can be used as an indicator of rancidity. The [...] Read more.
Dry aging creates a unique taste and flavor in beef; however, the process also causes rancidity, which is harmful to humans. During dry aging, the microbial flora in beef changes continuously; thus, this change can be used as an indicator of rancidity. The objective of this study was to analyze the correlation between microbial flora in beef and rancidity during dry aging. The round of beef (2.5–3 kg) was dry aged under 1.5 ± 1 °C and 82 ± 5% moisture for 17 weeks. The microflora in the dry aged beef was analyzed by pyrosequencing. The volatile basic nitrogen (VBN) and thiobarbituric acid reactive substance (TBARS) values were also measured. Primers were designed to detect and quantify bacteria using real-time polymerase chain reaction (RT-PCR). The VBN and TBARS values in the dry aged beef depreciated from week 11 of aging. The levels of Streptococcus spp., Pantoea spp., and Pseudomonas spp. significantly changed at around week 11. Quantitative RT-PCR showed that the levels of Pantoea spp. and Streptococcus spp. could be used to identify rancidity during dry aging. Thus, among the microbial flora in dry aged beef, Pantoea spp. and Streptococcus spp. can be used to determine the rancidity of dry aged beef. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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<p>Changes in the (<b>A</b>) thiobarbituric acid reactive substance (TBARS), (<b>B</b>) volatile basic nitrogen (VBN), and (<b>C</b>) water holding capacity values in the dry aged beef during an aging time of 24 weeks. a–d: means with different letters are significantly different (<span class="html-italic">p</span> &lt; 0.05). The data were analyzed using Analysis of Variance (ANOVA).</p>
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<p>Metagenomic analysis of the microflora in the early (before the 11th week) or late stage (after the 11th week) of dry aging. (<b>A</b>) Diversity indices; and (<b>B</b>) microbial composition at the genus and species levels. * indicates that the two groups are significantly different (<span class="html-italic">p</span> &lt; 0.05). The data were analyzed using Wilcoxon rank-sum test.</p>
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<p>Bacterial levels in the early (before the 11th week) or late stage (after the 11th week) of dry aging observed using the 16S sequencing-based method. (<b>A</b>) <span class="html-italic">Pantoea</span> spp., (<b>B</b>) <span class="html-italic">Pseudomonas</span> spp., and (<b>C</b>) <span class="html-italic">Streptococcus</span> spp. * indicates that the two groups are significantly different (<span class="html-italic">p</span> &lt; 0.05). The data were analyzed using Wilcoxon rank-sum test.</p>
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<p>Levels of (<b>A</b>) <span class="html-italic">Pantoea</span> spp., (<b>B</b>) <span class="html-italic">Pseudomonas</span> spp., and (<b>C</b>) <span class="html-italic">Streptococcus</span> spp. measured using qRT-PCR during dry aging of beef. ** indicates that the points are significantly different from those in the previous week (<span class="html-italic">p</span> &lt; 0.05). The data were analyzed using Analysis of Variance (ANOVA).</p>
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8 pages, 1747 KiB  
Communication
Microbiome Associated with Slovak Traditional Ewe’s Milk Lump Cheese
by Andrea Lauková, Lenka Micenková, Monika Pogány Simonová, Valentína Focková, Jana Ščerbová, Martin Tomáška, Emília Dvorožňáková and Miroslav Kološta
Processes 2021, 9(9), 1603; https://doi.org/10.3390/pr9091603 - 7 Sep 2021
Cited by 6 | Viewed by 1806
Abstract
Worldwide consumers increasingly demand traditional/local products, to which those made from ewe’s milk belong. In Slovakia, dairy products made from ewe’s milk have a long tradition. A total of seventeen farmhouse fresh ewe’s milk lump cheeses from various local farm producers in central [...] Read more.
Worldwide consumers increasingly demand traditional/local products, to which those made from ewe’s milk belong. In Slovakia, dairy products made from ewe’s milk have a long tradition. A total of seventeen farmhouse fresh ewe’s milk lump cheeses from various local farm producers in central Slovakia were sampled at farms and then analyzed. Based on the sequencing data analysis, the phylum Firmicutes dominated (60.92%) in ewe’s lump cheeses, followed with the phylum Proteobacteria (38.23%), Actinobacteria (0.38%) and Bacteroidetes (0.35%). The phylum Firmicutes was represented by six genera, among which the highest amount possessed the genus Streptococcus (41.13%) followed with the genus Lactococcus (8.54%), Fructobacillus (3.91%), Enterococcus (3.18%), Staphylococcus (1.80%) and the genus Brochotrix (0.08%). The phylum Proteobacteria in ewe’s lump cheeses involved eight Gram-negative genera: Pseudomonas, Acinetobacter, Enterobacter, Ewingella, Escherichia-Shigella, Pantoea and Moraxella. The phylum Bacteroidetes involved three genera: Bacteroides, Sphingobacterium and Chrysobacterium. Results presented are original; the microbiome of Slovak ewe’s milk lump cheese has been not analyzed at those taxonomic levels up to now. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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<p>Detection of microbiota at the levels of phyla and genera (individual cheeses are also indicated in <a href="#sec2-processes-09-01603" class="html-sec">Section 2</a>).</p>
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<p>Phyla detected in Slovak ewe’s lump cheeses (in percentage).</p>
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<p>Gram-positive genera detected in Slovak ewe’s lump cheeses (in percentage).</p>
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<p>Gram-negative genera detected in Slovak ewe’s lump cheese (in percentage).</p>
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12 pages, 1763 KiB  
Article
Characterization of Bacillus Species from Market Foods in Beijing, China
by Qiao Hu, Yuwen Fang, Jiajia Zhu, Wenjiao Xu and Kui Zhu
Processes 2021, 9(5), 866; https://doi.org/10.3390/pr9050866 - 14 May 2021
Cited by 9 | Viewed by 3292
Abstract
Foodborne diseases have been witnessing a constant rising trend worldwide, mainly caused by pathogenic microorganisms, such as Bacillus spp., posing a direct threat to public health. The purpose of this study was to evaluate the biological risk of foodborne and probiotic Bacillus spp. [...] Read more.
Foodborne diseases have been witnessing a constant rising trend worldwide, mainly caused by pathogenic microorganisms, such as Bacillus spp., posing a direct threat to public health. The purpose of this study was to evaluate the biological risk of foodborne and probiotic Bacillus spp. in Beijing markets. A total of 55 Bacillus isolates, including 29 B. cereus, 9 B. licheniformis and 7 B. subtilis, mostly found in dairy products (32.7%), were recovered from 106 samples and identified by matrix-assisted laser desorption/ionization mass spectrometry and polymerase chain reaction methods. The susceptibility towards 16 antibiotics was determined using a broth microdilution method. Bacillus showed a high level of resistance to florfenicol (100%), lincomycin (100%), tiamulin (78.2%) and ampicillin (67.3%), while they were all susceptible or intermediate to vancomycin and rifampin. Additionally, we obtained the whole genome of 19 Bacillus strains using high-throughput sequencing, and the rates of resistance genes van, fosB, erm and tet were 57.9%, 57.9%, 21.1% and 26.3%, respectively. Moreover, 100%, 9.1%, 45.5% and 100% of these isolates carried virulence genes nhe, hbl, cytK and entFM, respectively. Lastly, 60% Bacillus strains were positive in hemolysis tests, and 3 B. licheniformis strains displayed an inhibitory activity on the growth of S. aureus ATCC 29213 using agar overlay technique. Our study outlines the characteristics of foodborne Bacillus spp. and provides information for the monitoring of food safety. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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<p>Proportion of different species of <span class="html-italic">Bacillus</span> isolates. <span class="html-italic">B. cereus</span>, <span class="html-italic">B. licheniformis</span>, <span class="html-italic">B. subtilis</span> and <span class="html-italic">B. pumilus</span> constitute 52.7%, 16.4%, 12.7% and 9.1% of the total number, respectively. Other species include <span class="html-italic">B. amyloliquefaciens</span> (3.6%), <span class="html-italic">B. taeanensis</span> (1.8%), <span class="html-italic">B. velezensis</span> (1.8%) and <span class="html-italic">Paenibacillus cookie</span> (1.8%).</p>
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<p>Phylogenetic tree of <span class="html-italic">Bacillus</span> isolates based on 16S rRNA sequences. The tree was constructed using maximum likelihood method, and genetic distances were generated using Kimura 2-parameter model. The numbers at the branches are bootstrap confidence percentages from 1000 bootstrapped trees.</p>
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<p>Compositions of <span class="html-italic">Bacillus</span> species in the samples from different sources. <span class="html-italic">B. cereus</span> is the dominant species in the isolates recovered from dairy products, Beijing specialty foods and rice products. <span class="html-italic">B. pumilus</span> and <span class="html-italic">B. licheniformis</span> are the most prevalent groups of fermented foods and probiotics-derived <span class="html-italic">Bacillus</span> strains, respectively.</p>
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<p>The proportions of susceptible, intermediate and resistant strains among 55 isolated <span class="html-italic">Bacillus</span> strains to 16 antibiotics. AMC: ampicillin, CRO: ceftriaxone, GEN: gentamicin, STR: streptomycin, KAN: kanamycin, ERY: erythromycin, TET: tetracycline, FFC: florfenicol, CIP: ciprofloxacin, VAN: vancomycin, RIF: rifampicin, LZD: linezolid, LIN: lincomycin, TIA: tiamulin, CHL: chloramphenicol, AMC: amoxicillin + clavulanate.</p>
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<p>Results of the hemolysis test and agar overlay technique. (<b>a</b>) proportion of hemolytic and non-hemolytic <span class="html-italic">Bacillus</span> strains; 60% of <span class="html-italic">Bacillus</span> strains were hemolytic on sheep blood. (<b>b</b>–<b>d</b>) are the inhibition zones of <span class="html-italic">B. licheniformis</span> CAU514, CAU495 and CAU511, respectively, with <span class="html-italic">S. aureus</span> ATCC 29213 added in the soft-agar overlay.</p>
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9 pages, 289 KiB  
Article
Enterococcal Species Associated with Slovak Raw Goat Milk, Their Safety and Susceptibility to Lantibiotics and Durancin ED26E/7
by Andrea Lauková, Valentína Focková and Monika Pogány Simonová
Processes 2021, 9(4), 681; https://doi.org/10.3390/pr9040681 - 13 Apr 2021
Cited by 6 | Viewed by 1693
Abstract
Goat milk has become a popular item of human consumption due to its originality. Enterococci are ubiquitous bacteria, and they can also be found in traditional dairy products. This study focuses on the safety of enterococci from Slovak raw goat milk and on [...] Read more.
Goat milk has become a popular item of human consumption due to its originality. Enterococci are ubiquitous bacteria, and they can also be found in traditional dairy products. This study focuses on the safety of enterococci from Slovak raw goat milk and on their susceptibility to lantibiotic bacteriocins and durancin ED26E/7, which has not previously been studied. Biofilm formation ability in enterococci, virulence factor genes, enzyme production and antibiotic profile were investigated. Samples of raw goat milk (53) were collected from 283 goats in Slovakia. MALDI-TOF mass spectrometry identified three enterococcal species: Enterococcus faecium, E. hirae and E. mundtii, with dominant occurrence of the species E. faecium. Low-grade biofilm formation ability (0.1 ≤ A570 < 1.0) was found in four strains of E. faecium. Gelatinase, hyaluronidase, aggregation substance and enterococcal surface protein genes were absent in these enterococci. Gene efaAfm (adhesin) was detected in five E. faecium strains. However, it was not detected in biofilm-forming strains. Enterococci detected in Slovak raw goat milk were found not to have pathogenic potential; four strains even produced high amounts of useful β-galactosidase. The strains were susceptible to lantibiotic bacteriocin treatment and to durancin ED26E/7 as well, which represents original information in dairy production. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
17 pages, 2233 KiB  
Article
Effect of Cladosporium cladosporioides on the Composition of Mycoflora and the Quality Parameters of Table Eggs during Storage
by Pavlina Jevinová, Monika Pipová, Ivana Regecová, Soňa Demjanová, Boris Semjon, Slavomír Marcinčák, Jozef Nagy and Ivona Kožárová
Processes 2021, 9(4), 613; https://doi.org/10.3390/pr9040613 - 31 Mar 2021
Cited by 5 | Viewed by 3022
Abstract
The eggshells of 120 experimental one-day-old table eggs were contaminated with the spore suspension of Cladosporium cladosporioides, divided into three groups (A–C) and stored at three different temperatures (3 °C, 11 °C and 20 °C) for 28 days. Visible growth of molds [...] Read more.
The eggshells of 120 experimental one-day-old table eggs were contaminated with the spore suspension of Cladosporium cladosporioides, divided into three groups (A–C) and stored at three different temperatures (3 °C, 11 °C and 20 °C) for 28 days. Visible growth of molds on/in experimental eggs was not observed within the entire storage period. No significant differences in the numbers of molds were found between particular groups of eggs. However, the composition of egg mycoflora was greatly influenced by storage conditions. Three mold genera were identified using the PCR method. The highest mold numbers were determined on Day 14 (Groups A and C) and Day 21 (Group B) when the maximum relative humidity and dew point temperature were recorded. On the same days, the dominance of Penicillium spp. and the minimum eggshell firmness were observed. Noticeable changes in egg quality were observed in eggs stored at 20 °C, and most of these eggs were downgraded at the end of storage period. The growth ability differed significantly among three mold genera. Penicillium spp. and Fusarium spp. showed better growth intensity at increased values (0.91–0.94) of water activity (aw) indicating a possible risk associated with the occurrence of mycotoxins in the egg contents. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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Figure 1
<p>Detection of individual mold genera by PCR: (<b>a</b>) <span class="html-italic">Cladosporium</span> spp. (87 bp; internal control 370 bp) Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">Cladosporium cladosporioides</span> CCM F-348; Lines 3 to 8: isolates of <span class="html-italic">Cladosporium</span> spp.; (<b>b</b>) <span class="html-italic">Penicillium</span> spp. (336 bp) Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">Penicillium chrysogenum</span> CCM F-362; Lines 3,5,6,7, and 8: isolates of <span class="html-italic">Penicillium</span> spp.; Line 4: non- <span class="html-italic">Penicillium</span> spp isolate; (<b>c</b>) <span class="html-italic">Fusarium</span> spp. (410 bp) Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">Fusarium graminearun CCM</span> F-683; Lines 3 to 8: isolates of <span class="html-italic">Fusarium</span> spp.</p>
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<p>Antifungal activity of mold species tested in this study: (<b>a</b>) <span class="html-italic">C. cladosporioides</span> CCM F-348 (1), <span class="html-italic">P. chrysogenum</span> CCM F-362 (2), <span class="html-italic">P. crustosum</span> CCM F-8322 (3), <span class="html-italic">P. griseofulvum</span> CCM F-8006 (4), <span class="html-italic">P. glabrum</span> CCM F-310 (5); (<b>b</b>) <span class="html-italic">C. cladosporioides</span> CCM F-348 (1), <span class="html-italic">P. griseofulvum</span> CCM F-8006 (4), <span class="html-italic">P. glabrum</span> CCM F-310 (5), <span class="html-italic">F. graminearum</span> CCM F-683 (6), <span class="html-italic">C. herbarum</span> CCM F-455 (7).</p>
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<p>Plot of individuals in the first and second extracted dimension under different storage conditions. A—table eggs stored at average temperature of (11.43 ± 0.20) °C, relative humidity of (79.00 ± 2.94)% and the dew point of (7.90 ± 0.47) °C. B—table eggs stored at average temperature of (3.33 ± 1.1) °C, relative humidity of (57.76 ± 5.30)% and the dew point of (−4.25 ± 1.96) °C. C—table eggs stored at average temperature of (20.60 ± 1.04) °C, relative humidity of (43.55 ± 5.93)% and the dew point of (7.60 ± 2.39) °C.</p>
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<p>Correlation plot of variables in the first and second extracted dimension under different storage conditions.</p>
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14 pages, 2393 KiB  
Article
Identification of Penicillium verrucosum, Penicillium commune, and Penicillium crustosum Isolated from Chicken Eggs
by Soňa Demjanová, Pavlina Jevinová, Monika Pipová and Ivana Regecová
Processes 2021, 9(1), 53; https://doi.org/10.3390/pr9010053 - 29 Dec 2020
Cited by 8 | Viewed by 8688
Abstract
Penicillium species belong to main causative agents of food spoilage leading to significant economic losses and potential health risk for consumers. These fungi have been isolated from various food matrices, including table eggs. In this study, both conventional Polymerase Chain Reaction (PCR) and [...] Read more.
Penicillium species belong to main causative agents of food spoilage leading to significant economic losses and potential health risk for consumers. These fungi have been isolated from various food matrices, including table eggs. In this study, both conventional Polymerase Chain Reaction (PCR) and Polymerase Chain Reaction-Internal Transcribed Spacer-Restriction Fragment Length Polymorphism (PCR-ITS-RFLP) methods were used for species identification of Penicillium (P.) spp. isolated from the eggshells of moldy chicken eggs. Seven restriction endonucleases (Bsp1286I, XmaI, HaeIII, HinfI, MseI, SfcI, Hpy188I) were applied to create ribosomal restriction patterns of amplified ITS regions. To identify P. verrucosum, P. commune, and P. crustosum with the help of conventional PCR assay, species-specific primer pairs VERF/VERR, COMF/COMR, and CRUF/CRUR were designed on the base of 5.8 subunit-Internal Transcribed Spacer (5.8S-ITS) region. Altogether, 121 strains of microscopic filamentous fungi were isolated by traditional culture mycological examination. After morphological evaluation of both macroscopic and microscopic features, 96 strains were classified in Penicillium spp. Two molecular methods used have confirmed eight isolates as P. verrucosum, 42 isolates as P. commune, and 19 isolates as P. crustosum. Both PCR-ITS-RFLP and conventional PCR assays appear to be suitable alternatives for rapid identification of the above mentioned Penicillium species. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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Figure 1

Figure 1
<p><span class="html-italic">Penicillium verrucosum</span>. Seven-day-old colonies on Malt Extract Agar (MEA) (<b>a</b>) obverse, (<b>d</b>) reverse, Czapek Yeast Autolysate agar (CYA) (<b>b</b>) obverse, (<b>e</b>) reverse, Yeast Extract Sucrose agar (YES) (<b>c</b>) obverse, (<b>f</b>) reverse, (<b>h</b>) Creatine Sucrose Agar (CREA)—no acid production, (<b>g</b>) conidiophores and conidia. Scale: black bar = 10 µm.</p>
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<p><span class="html-italic">Penicillium commune</span>. Seven-day-old colonies on Malt Extract Agar (MEA) (<b>a</b>) obverse, (<b>d</b>) reverse, Czapek Yeast Autolysate agar (CYA) (<b>b</b>) obverse, (<b>e</b>) reverse, Yeast Extract Sucrose agar (YES) (<b>c</b>) obverse, (<b>f</b>) reverse, (<b>h</b>) Creatine Sucrose Agar (CREA)—strong acid production, (<b>g</b>) conidiophores and conidia. Scale: black bar = 10 µm.</p>
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<p><span class="html-italic">Penicillium crustosum</span>. Seven-day-old colonies on Malt Extract Agar (MEA) (<b>a</b>) obverse, (<b>d</b>) reverse, Czapek Yeast Autolysate agar (CYA) (<b>b</b>) obverse, (<b>e</b>) reverse, Yeast Extract Sucrose agar (YES) (<b>c</b>) obverse, (<b>f</b>) reverse, (<b>h</b>) Creatine Sucrose Agar (CREA)—good acid production, (<b>g</b>) conidiophores and conidia. Scale: black bar = 10 µm.</p>
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<p>Restriction patterns presented by the reference strains and <span class="html-italic">Penicillium</span> (<span class="html-italic">P.</span>) isolates analyzed: (<b>a</b>) <span class="html-italic">P. verrucosum</span>. Line 1: 50 bp ladder standard; Lines 2 to 8: restriction fragments formed after digestion by endonucleases <span class="html-italic">Bsp1286</span>I, <span class="html-italic">Xma</span>I, <span class="html-italic">Hae</span>III, <span class="html-italic">Hinf</span>I, <span class="html-italic">Mse</span>I, <span class="html-italic">Sfc</span>I, and <span class="html-italic">Hpy188</span>I; (<b>b</b>) <span class="html-italic">P. commune</span>. Line 1: 50 bp ladder standard; Lines 2 to 8: restriction fragments formed after digestion by endonucleases <span class="html-italic">Bsp1286</span>I, <span class="html-italic">Xma</span>I, <span class="html-italic">Hae</span>III, <span class="html-italic">Hinf</span>I, <span class="html-italic">Mse</span>I, <span class="html-italic">Sfc</span>I, and <span class="html-italic">Hpy188</span>I; (<b>c</b>) <span class="html-italic">P. crustosum</span>. Line 1: 50 bp ladder standard; Lines 2 to 8: restriction fragments formed after digestion by endonucleases <span class="html-italic">Bsp1286</span>I, <span class="html-italic">Xma</span>I, <span class="html-italic">Hae</span>III, <span class="html-italic">Hinf</span>I, <span class="html-italic">Mse</span>I, <span class="html-italic">Sfc</span>I, and <span class="html-italic">Hpy188</span>I.</p>
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<p>The specificity of primer pairs used in conventional PCR. (<b>a</b>) DNA amplicons of <span class="html-italic">Penicillium</span> (<span class="html-italic">P.</span>) reference strains using the VERF/VERR primer pair. Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. verrucosum</span> (ATCC<sup>®</sup> 44407™); Line 3: negative control; Line 4 to 9: reference strains <span class="html-italic">P. commune</span> (CCM F-327), <span class="html-italic">P. crustosum</span> (CCM 8322), <span class="html-italic">P. chrysogenum</span> (CCM F-362), <span class="html-italic">P. brevicompactum</span> (CCM 8040), <span class="html-italic">P. glabrum</span> (CCM F-310), <span class="html-italic">P. expansum</span> (CCM F-576); (<b>b</b>) DNA amplicons of <span class="html-italic">Penicillium</span> reference strains using the COMF/COMR primer pair. Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. commune</span> (CCM F-327); Line 3: negative control; Line 4 to 9: reference strains <span class="html-italic">P. verrucosum</span> (ATCC<sup>®</sup> 44407™); <span class="html-italic">P. crustosum</span> (CCM 8322), <span class="html-italic">P. chrysogenum</span> (CCM F-362), <span class="html-italic">P. brevicompactum</span> (CCM 8040), <span class="html-italic">P. glabrum</span> (CCM F-310), <span class="html-italic">P. expansum</span> (CCM F-576); (<b>c</b>) DNA amplicons of <span class="html-italic">Penicillium</span> reference strains using the COMF/COMR primer pair. Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. crustosum</span> (CCM 8322); Line 3: negative control; Line 4 to 9: reference strains <span class="html-italic">P. verrucosum</span> (ATCC<sup>®</sup> 44407™); <span class="html-italic">P. commune</span> (CCM F-327), <span class="html-italic">P. chrysogenum</span> (CCM F-362), <span class="html-italic">P. brevicompactum</span> (CCM 8040), <span class="html-italic">P. glabrum</span> (CCM F-310), <span class="html-italic">P. expansum</span> (CCM F-576).</p>
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<p>Electrophoretic analysis of amplicons of <span class="html-italic">Penicillium</span> (<span class="html-italic">P.</span>) isolates from table eggs by conventional PCR. (<b>a</b>) <span class="html-italic">P. verrucosum</span>: Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. verrucosum</span> (ATCC<sup>®</sup> 44407™); Line 3: negative control; Lines 4 to 8: isolates of <span class="html-italic">P. verrucosum</span> (607 bp); Line 9: 18S rRNA internal control (99 bp); (<b>b</b>) <span class="html-italic">P. commune</span>: Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. commune</span> (CCM F-327); Line 3: negative control; Lines 4 to 8: isolates of <span class="html-italic">P. commune</span> (464 bp); Line 9: 18S rRNA internal control (99 bp); (<b>c</b>) <span class="html-italic">P. crustosum</span>: Line 1: 100 bp ladder standard; Line 2: <span class="html-italic">P. crustosum</span> (CCM 8322); Line 3: negative comtrol; Lines 4 to 8: isolates of <span class="html-italic">P. crustosum</span> (892 bp); Line 9: 18S rRNA internal control (99 bp).</p>
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13 pages, 1953 KiB  
Article
Antimicrobial Resistance of Lactobacillus johnsonii and Lactobacillus zeae in Raw Milk
by Jana Výrostková, Ivana Regecová, Mariana Kováčová, Slavomír Marcinčák, Eva Dudriková and Jana Maľová
Processes 2020, 8(12), 1627; https://doi.org/10.3390/pr8121627 - 10 Dec 2020
Cited by 7 | Viewed by 2985
Abstract
Lactobacillus johnsonii and Lactobacillus zeae are among the lactobacilli with probiotic properties, which occur in sour milk products, cheeses, and to a lesser extent in raw milk. Recently, resistant strains have been detected in various species of lactobacilli. The aim of the study [...] Read more.
Lactobacillus johnsonii and Lactobacillus zeae are among the lactobacilli with probiotic properties, which occur in sour milk products, cheeses, and to a lesser extent in raw milk. Recently, resistant strains have been detected in various species of lactobacilli. The aim of the study was to determine the incidence of resistant Lactobacillus johnsonii and Lactobacillus zeae strains in various types of raw milk. A total of 245 isolates were identified by matrix-assisted laser desorption/ionization mass spectrometry and polymerase chain reaction methods as Lactobacillus sp., of which 23 isolates of Lactobacillus johnsonii and 18 isolates of Lactobacillus zeae were confirmed. Determination of susceptibility to selected antibiotics was performed using the E-test and broth dilution method, where 7.3% of lactobacilli strains were evaluated as ampicillin-resistant, 14.7% of isolates as erythromycin-resistant, and 4.9% of isolates as clindamycin-resistant. The genus Lactobacillus johnsonii had the highest resistance to erythromycin (34.8%), similar to Lactobacillus zeae (33.3%). Of the 41 isolates, the presence of the gene was confirmed in five Lactobacillus johnsonii strains and in two strains of Lactobacillus zeae. The presence of resistant strains of Lactobacillus johnsonii and Lactobacillus zeae is a potential risk in terms of spreading antimicrobial resistance through the food chain. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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Figure 1

Figure 1
<p>Identification <b>of</b> genus <span class="html-italic">Lactobacillus</span> sp. L: 100 bp ladder standard; lines 1, 2, 3, and 4: isolates of <span class="html-italic">Lactobacillius</span> sp. (250 bp); line 5: <span class="html-italic">Lb. johnsonii</span> reference strain CCM 2935; line 6: <span class="html-italic">Lb. zeae</span> reference strain CCM 7069; line 7: <span class="html-italic">Lb. paracasei</span> reference strain CCM 4649.</p>
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<p>Identification of genus <span class="html-italic">Lb. johnsonii.</span> L: 100 bp ladder standard; lines 1, 2, 3, 4, and 5: <span class="html-italic">Lb. johnsonii</span> isolates (750 bp); line 6: <span class="html-italic">Lb. johnsonii</span> reference strain CCM 2935.</p>
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<p>Identification <b>of</b> genus <span class="html-italic">Lb. zeae.</span> L: 100 bp standard; line 1: <span class="html-italic">Lb. zeae</span> reference strain CCM 7069 (750 bp); lines 2, 3, 4, and 5: <span class="html-italic">Lb. zeae</span> isolates.</p>
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<p>Number of resistant strains in each type of milk.</p>
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<p>Identification of the <span class="html-italic">ermB</span> gene in <span class="html-italic">Lactobacillus</span> sp. L: 50 bp standard; line 1: <span class="html-italic">Staphylococcus aureus</span> reference strain CCM 4223 (639 bp); lines 2–3: isolates of <span class="html-italic">Lb. zeae</span> with <span class="html-italic">ermB</span> gene; lines 4-8: isolates of <span class="html-italic">Lb. johnsonii</span> with <span class="html-italic">ermB</span> gene.</p>
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Review

Jump to: Editorial, Research

13 pages, 270 KiB  
Review
Meat Safety from Farm to Slaughter—Risk-Based Control of Yersinia enterocolitica and Toxoplasma gondii
by Nevijo Zdolec and Marta Kiš
Processes 2021, 9(5), 815; https://doi.org/10.3390/pr9050815 - 7 May 2021
Cited by 17 | Viewed by 3573
Abstract
The implementation of the traditional meat safety control system has significantly contributed to increasing food safety and public health protection. However, several biological hazards have emerged in meat production, requiring a comprehensive approach to their control, as traditional methods of meat inspection at [...] Read more.
The implementation of the traditional meat safety control system has significantly contributed to increasing food safety and public health protection. However, several biological hazards have emerged in meat production, requiring a comprehensive approach to their control, as traditional methods of meat inspection at the slaughterhouse are not able to detect them. While national control programs exist for the most important meat-related hazards, similar data are still lacking for certain neglected threats, such as Yersinia enterocolitica or Toxoplasma gondii. The obstacle in controlling these hazards in the meat chain is their presence in latently infected, asymptomatic animals. Their effective control can only be achieved through systematic preventive measures, surveillance or monitoring, and antimicrobial interventions on farms and in slaughterhouses. To establish such a system, it is important to collect all relevant data on hazard-related epidemiological indicators from the meat chain, which should provide relevant guidance for interventions at the harvest and post-harvest stage. The proposed approach is expected to improve the existing system and provide many opportunities to improve food safety and public health. Full article
(This article belongs to the Special Issue Study of Microbiological Safety in the Food Chain)
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