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Open AccessFeature PaperArticle

The Effect of Ethanol Propolis Extracts on Inhibition of Growth of Fusarium solani on Hen Eggs

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Appl. Sci. 2023, 13(1), 315; https://doi.org/10.3390/app13010315 - 27 Dec 2022

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Abstract

The inhibition of growth of Fusarium solani mold on the shells of coated table hen eggs of a ethanol extract of propolis was investigated. Hen eggs were inoculated with F. solani spores and then coated with propolis extract at a concentration of 1, [...] Read more.

The inhibition of growth of Fusarium solani mold on the shells of coated table hen eggs of a ethanol extract of propolis was investigated. Hen eggs were inoculated with F. solani spores and then coated with propolis extract at a concentration of 1, 2, 3, 5 or 10% using the spray method. Hen eggs were stored at room temperature for 28 days. Weight loss and the color of coated hen eggs were checked during storage. The color of hen eggs was tested using the CIELab method. Propolis extract was found to inhibit the growth of F. solani on hen eggshells. A reduction of three log cycles in the number of molds was observed on hen eggs coated with 10% propolis extract. Coating hen eggs with propolis extract slowed down and limited weight loss. No statistically significant changes in color parameters or sensory characteristics were observed during storage of hen eggs. There was a slight smell of propolis on the shells of hen eggs. Spraying table hen eggs with propolis extract at a concentration of 10% can help to improve the microbiological safety of hen eggs in terms of anti-mold protection. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessArticle

Diversity and Safety Aspects of Coagulase-Negative Staphylococci in Ventricina del Vastese Italian Dry Fermented Sausage

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Appl. Sci. 2022, 12(24), 13042; https://doi.org/10.3390/app122413042 - 19 Dec 2022

Viewed by 721

Abstract

Ventricina del Vastese is a traditional dry fermented sausage from Central Italy not yet characterized for the occurrence, identity and safety of coagulase-negative staphylococci (CNS), a bacterial group technologically important for this kind of product. Therefore, in this study, 98 CNS isolates from [...] Read more.

Ventricina del Vastese is a traditional dry fermented sausage from Central Italy not yet characterized for the occurrence, identity and safety of coagulase-negative staphylococci (CNS), a bacterial group technologically important for this kind of product. Therefore, in this study, 98 CNS isolates from four manufacturers were differentiated using repetitive element palindromic PCR (Rep-PCR) and identified using 16S rRNA gene sequencing. These were examined for genes encoding biogenic amine (BA) production, resistance to aminoglycosides, β-lactams, tetracyclines and staphylococcal enterotoxins (SEs). Staphylococcus succinus (55%) predominated, followed by S. xylosus (30%), S. epidermidis (7.4%), S. equorum (3.1%), S. saprophyticus (3.1%) and S. warneri (1%). One S. succinus subsp. casei isolate was slightly β-hemolytic. SEs and the histidine decarboxylase gene hdcA were not detected, whereas the tyrosine decarboxylase gene tdcA was detected in four S. xylosus isolates. The blaZ beta-lactamase gene in an S. equorum isolate, tetracycline resistance genes tetK in six S. succinus isolates and tetA in one S. succinus isolate also bearing tetK were found. The product examined is characterized by a peculiar CNS species ratio and a low occurrence and diversity of AR transferable genes than found in other studies, as a probable consequence of production only with meat from animals raised in small farms with extensive rearing systems in which antibiotic usage is infrequent. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessFeature PaperArticle

Research on Thermal Imaging Usage as a Method for Detecting Bacillus subtilis Bacteria in Mortadella

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Edyta Lipińska

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Katarzyna Pobiega

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Kamil Piwowarek

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Elżbieta Hać-Szymańczuk

Appl. Sci. 2022, 12(21), 11252; https://doi.org/10.3390/app122111252 - 06 Nov 2022

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Abstract

Meat and meat products are important sources of valuable proteins and other nutrients, but they are also a conducive environment for microorganisms’ growth and can easily corrupt. In order to ensure the safety and quality of these products throughout its entire shelf-life, reliable [...] Read more.

Meat and meat products are important sources of valuable proteins and other nutrients, but they are also a conducive environment for microorganisms’ growth and can easily corrupt. In order to ensure the safety and quality of these products throughout its entire shelf-life, reliable microbial contamination assessment techniques must be used. Despite their effectiveness, traditional diagnostics methods are expensive and time consuming. Therefore, new timesaving, reliable techniques are searched for. Infrared thermography could be a good alternative method in this area. As a quick technique to detect microorganisms, it can overcome the limitations of traditional microbiological food-quality assessment methods. It has numerous advantages, such as the possibility of taking immediate temperature measurements and short processing times for obtaining a thermal image, non-contact and non-destructive measurements, and, unlike other methods, real-time measurement monitoring. Real-time monitoring is particularly important for modern production systems. The purpose of this research study is to develop a methodology for microbiological quality control of mortadella inoculated with Bacillus subtilis ATCC 6633 bacteria using a thermal imaging camera with an uncooled microbolometric detector. It was found that the thermal imaging measurements used in this research study enabled the distinction of contaminated samples (min. 10⁶ CFU/g) from sterile samples. The tests should only record the temperature of the samples during the first 25 s after previously performing activations at −18 °C ± 1 °C for 60 s. This is where differences between the samples are most pronounced. Estimating the trend line of the sample’s cooling process is advisable. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessArticle

Plant Extracts for the Control of Listeria monocytogenes in Meat Products

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Simona de Niederhäusern

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Appl. Sci. 2021, 11(22), 10820; https://doi.org/10.3390/app112210820 - 16 Nov 2021

Cited by 2 | Viewed by 1437

Abstract

The antimicrobial activity of garlic (Allium sativum L.) and onion (Allium cepa L.) plant active extracts was determined against Listeria monocytogenes in two meat products. Samples of sausages “cacciatore” and cooked ham in vacuum-packaged slices were artificially contaminated, and the presence [...] Read more.

The antimicrobial activity of garlic (Allium sativum L.) and onion (Allium cepa L.) plant active extracts was determined against Listeria monocytogenes in two meat products. Samples of sausages “cacciatore” and cooked ham in vacuum-packaged slices were artificially contaminated, and the presence of Listeria was evaluated during the sausages ripening and throughout the shelf-life of the cooked ham. The test carried out on sausages did not show differences among treated and untreated samples. The antagonistic activity of the plant extracts against the pathogen was probably hidden by the competition from the sausages microbial flora and the pH and the water activity (aw) decrease. On the other hand, the plant extracts determined an initial reduction of about 1.00 log cfu/g of the L. monocytogenes viable count in the cooked ham slices contaminated with 10³ cfu/g, but the best result was obtained with the contamination of 10² cfu/g of L. monocytogenes. In addition to the pathogen’s initial decrease, we observed an extension of the lag phase and a reduction of the Listeria growth rate. Considering that the presence of L. monocytogenes during the slicing phase of the cooked ham does not exceed 10 cfu/g, the use of plant extracts can lead to complete pathogen elimination. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessFeature PaperArticle

Ready-to-Eat Sandwiches as Source of Pathogens Endowed with Antibiotic Resistance and Other Virulence Factors

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Appl. Sci. 2021, 11(16), 7177; https://doi.org/10.3390/app11167177 - 04 Aug 2021

Cited by 2 | Viewed by 1375

Abstract

The aim of this study was to evaluate and characterize the bacterial load present in twenty-four Ready-To-Eat (RTE) sandwiches, purchased at refrigerated vending machines and supermarkets in the province of Modena (Italy). We isolated 54 bacterial strains, including pathogens of interest in food [...] Read more.

The aim of this study was to evaluate and characterize the bacterial load present in twenty-four Ready-To-Eat (RTE) sandwiches, purchased at refrigerated vending machines and supermarkets in the province of Modena (Italy). We isolated 54 bacterial strains, including pathogens of interest in food safety, such as Listeria, Staphylococcus, Enterococcus, Yersinia, Aeromonas and Acinetobacter spp. Phenotypic tests have been performed on these pathogens to detect the presence of virulence factors, such as gelatinase production and hemolytic capability. To test their antibiotic resistance features, the minimum inhibitory concentration (MIC) against eight commonly used antibiotics (Amikacin, Ciprofloxacin, Ampicillin, Oxacillin, Imipenem, Tetracycline, Erythromycin and Vancomycin) was also evaluated. The results showed that among the 54 isolates, fifty percent (50%) belonged to harmless microorganisms (Leuconostoc and Lactococcus), whereas the remaining fifty percent (50%) included pathogenic bacteria (Listeria ivanovii, Listeria monocytogenes, Staphylococcus aureus, Yersinia, and Citrobacter spp.), species responsible for pathologies often difficult to treat due to the presence of antibiotic resistance features. This study demonstrates the importance of thorough controls, both during the production and marketing of RTE food like sandwiches, to avoid reaching the infectious load and the onset of pathologies, particularly dangerous for old and immunocompromised patients. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessCommunication

Microbial Populations of Fresh and Cold Stored Donkey Milk by High-Throughput Sequencing Provide Indication for A Correct Management of This High-Value Product

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Appl. Sci. 2020, 10(7), 2314; https://doi.org/10.3390/app10072314 - 28 Mar 2020

Cited by 10 | Viewed by 1895

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Donkey milk is receiving increasing interest due to its attractive nutrient and functional properties (but also cosmetic), which make it a suitable food for sensitive consumers, such as infants with allergies, the immunocompromised, and elderly people. Our study aims to provide further information [...] Read more.

Donkey milk is receiving increasing interest due to its attractive nutrient and functional properties (but also cosmetic), which make it a suitable food for sensitive consumers, such as infants with allergies, the immunocompromised, and elderly people. Our study aims to provide further information on the microbial variability of donkey milk under cold storage conditions. Therefore, we analysed by high-throughput sequencing the bacterial communities in unpasteurized donkey milk just milked, and after three days of conservation at 4 °C, respectively. Results showed that fresh donkey milk was characterized by a high incidence of spoilage Gram-negative bacteria mainly belonging to Pseudomonas spp. A composition lower than 5% of lactic acid bacteria was found in fresh milk samples, with Lactococcus spp. being the most abundant. The occurrence of microbial species belonging to risk group 2 was found in fresh milk. After three days of cold storage, the bacterial biodiversity of donkey milk was strongly reduced, since about 93% of the bacterial communities were identified as different species of psychrotrophic Pseudomonas. In conclusion, we report a preliminary description of the microbial diversity of donkey milk by using a metagenomic approach and encouraging a correct exploitation of this high-value niche product. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Open AccessArticle

Damaging Effects of Pulsed Electric Field Process Parameters on Rhizoctonia solani Cells Using Response Surface Methodology

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Appl. Sci. 2019, 9(21), 4706; https://doi.org/10.3390/app9214706 - 04 Nov 2019

Cited by 3 | Viewed by 2161

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This work aimed to analyse the damaging effects of pulsed electric fields on Rhizoctonia solani. Design Expert software was used to design an orthogonal experiment. The cell membrane damage and cell wall damage were observed by scanning electron microscopy and quantitatively determined [...] Read more.

This work aimed to analyse the damaging effects of pulsed electric fields on Rhizoctonia solani. Design Expert software was used to design an orthogonal experiment. The cell membrane damage and cell wall damage were observed by scanning electron microscopy and quantitatively determined while using a conductivity metre and an ultraviolet spectrophotometer. The results showed that the cell membrane damage rate was correlated with the voltage amplitude and processing time (p < 0.01), while the effect of pulse duration was not significant (p > 0.05). Besides, the cell wall damage was related to electric field strength (voltage amplitude) (p < 0.01), while the pulse duration and processing time had no significant effect on that (p > 0.05). The optimal process parameters for this method were 25 kV/cm, 5 min., and a pulse duration of 60 µs. The optimised conditions were tested based on these results. When compared with Control Check (CK), the cell membrane damage rate was 48.72%, which was significantly higher than CK (p < 0.01). Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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Review

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Open AccessReview

Probiotics and Beneficial Microorganisms in Biopreservation of Plant-Based Foods and Beverages

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Srusti Udayakumar

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Dissanayake M. D. Rasika

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Hasitha Priyashantha

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Janak K. Vidanarachchi

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Chaminda Senaka Ranadheera

Appl. Sci. 2022, 12(22), 11737; https://doi.org/10.3390/app122211737 - 18 Nov 2022

Cited by 1 | Viewed by 1140

Abstract

Maintaining the overall quality and shelf life of plant-based food and beverages is particularly important yet challenging to the food industry. Demand for natural preservation techniques has increased with the rising concerns over food safety and consumer awareness, e.g., health consciousness and food [...] Read more.

Maintaining the overall quality and shelf life of plant-based food and beverages is particularly important yet challenging to the food industry. Demand for natural preservation techniques has increased with the rising concerns over food safety and consumer awareness, e.g., health consciousness and food trends such as veganism and the demand for clean, labelled foods. Thus, a technique such as biopreservation has the potential to enhance food safety while fostering the quality, originality and naturalness of food. The application of probiotic microorganisms to foods and beverages provides various health benefits in addition to improved shelf life, stability and microbial safety of the food. The provision of probiotics is known to deliver various health benefits for the host’s gut health. Therefore, this review aims to investigate the importance of biopreservation and the role of probiotics in the food industry. An attempt was made to explore the various possibilities of shelf-life enhancement through the use of probiotic microorganisms as biopreservatives. Noticeable improvements in the shelf life of plant-based foods and beverages were observed due to the antimicrobial effects exerted by probiotics and potential probiotic strains which make them useful alternatives to artificially synthesized chemical preservatives. Full article

(This article belongs to the Special Issue State-of-Art of Microbial Concerns in Food Safety)

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