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Microorganisms in Foods and Food Processing Environments

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Applied Microbiology".

Deadline for manuscript submissions: closed (20 March 2024) | Viewed by 15751

Special Issue Editors


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Guest Editor
Department of Nutrition and Food Quality Assessment, Institute of Food Sciences and Nutrition, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovakia
Interests: food microbiology; low-temperature plasma; microbial inactivation; food chemistry; nutrition

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Guest Editor
Department of Nutrition and Food Quality Assessment, Institute of Food Sciences and Nutrition, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovakia
Interests: food chemistry; antioxidants; phenolic compounds; flavonoids; antioxidant activity; extraction cereals; polyphenols

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Guest Editor
Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Mlynská Dolina F1, 842 48 Bratislava, Slovakia
Interests: low temperature plasma

Special Issue Information

Dear Colleagues,

Microorganisms are ubiquitous in the environment and play a significant role in food production and processing. On the other hand, some microorganisms can also be a source of contamination and spoilage. The presence of pathogenic microorganisms can pose a significant health risk to consumers. Moreover, spoilage bacteria and molds can also deteriorate food products, leading to decreased shelf life and product loss. Therefore, implementing appropriate preservation techniques is crucial for ensuring food safety and quality. Many currently used decontamination technologies have certain limitations and drawbacks, such as alterations of the aroma, odour and colour of food. In addition, the need to meet consumers' expectations for safe and high-quality food products has resulted in the development of novel non-thermal technologies that can decontaminate foods. In recent years, for the purpose of the microbial inactivation of foods, cold atmospheric pressure plasma is gaining attention as one of the most innovative technologies in the field.

This Special Issue will focus on the latest findings on the antimicrobial effect of cold atmospheric pressure plasma. In addition, the influence of cold plasma on the nutritional aspects and physiochemical characteristics of foods should be considered. The action of other non-thermal processing techniques, including low-energy electron beam or pulsed light etc., will also be discussed.

Dr. Silvia Mošovská
Dr. Anna Mikulajová
Dr. Anna Zahoranová
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • pathogenic microorganisms
  • microbial spoilage
  • food safety
  • food quality
  • inactivation
  • non-thermal technologies
  • cold atmospheric pressure plasma
  • predictive microbiology

Published Papers (10 papers)

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Research

16 pages, 2168 KiB  
Article
Nutritional Value and Microbiological Aspects of Dried Yellow Mealworm (Tenebrio molitor L.) Larvae Pretreated with a Pulsed Electric Field
by Radosław Bogusz, Katarzyna Pobiega, Przemysław Łukasz Kowalczewski, Anna Onopiuk, Karolina Szulc, Artur Wiktor, Katarzyna Rybak and Małgorzata Nowacka
Appl. Sci. 2024, 14(3), 968; https://doi.org/10.3390/app14030968 - 23 Jan 2024
Viewed by 1272
Abstract
Complete protein, which includes all the essential amino acids, and bioactive compounds needed in human nutrition, can be found in edible insects. Bioactive compounds play a crucial role in protecting cells from the damage caused by free radicals. Therefore, in this study, fat [...] Read more.
Complete protein, which includes all the essential amino acids, and bioactive compounds needed in human nutrition, can be found in edible insects. Bioactive compounds play a crucial role in protecting cells from the damage caused by free radicals. Therefore, in this study, fat extraction yield, protein content, amino acid profile, total polyphenol content, antioxidant properties, crustacean and mollusk content, and microbiological quality have been assessed to evaluate the influence of the drying method and pulsed electric field (PEF) pretreatment. To this end, the sample was processed by the PEF at varied specific energy intakes (5, 20, and 40 kJ/kg) and dried by means of two methods: convective (CD) and infrared-convective (IR-CD). A comparable protein content (47.5–48.7 g/100 g d.m.) was determined for most of the samples tested. A significantly higher lysine and methionine content was detected in the CD insects, especially for samples treated by the PEF at 40 kJ/kg. The IR-CD samples exhibited a significantly higher content of polyphenols as compared to those obtained by means of the CD method, whereas the PEF apparently had a significant impact to the extent of increasing their content. Taking into account allergenicity, the crustacean content was approximately 10 times higher than the mollusk content. The study has shown that the PEF treatment prior to infrared-convective drying resulted in the assurance of the microbiological quality of dried insects for food use. Furthermore, a dose of the PEF at 20 and 40 kJ/kg demonstrated the antimicrobial effect. The results have proven that, in this case, a high temperature during the CD method did not cause the undesirable changes that had been expected. Therefore, PEF-assisted convective drying may conceivably be considered to obtain highly nutritionally valuable insects; however, it is crucial to utilize appropriate parameters in the course of the PEF processing. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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18 pages, 2391 KiB  
Article
The Influence of Fermentation Vessels on Yeast Microbiota and Main Parameters of Sauerkraut
by Paweł Satora and Szymon Strnad
Appl. Sci. 2024, 14(1), 236; https://doi.org/10.3390/app14010236 - 27 Dec 2023
Cited by 1 | Viewed by 868
Abstract
The aim of this study was to compare the yeast microbiota occurring during cabbage fermentation, along with selected parameters important for the quality of sauerkraut, depending on the vessel used. For this purpose, glass jars were used, in which anaerobic conditions are quickly [...] Read more.
The aim of this study was to compare the yeast microbiota occurring during cabbage fermentation, along with selected parameters important for the quality of sauerkraut, depending on the vessel used. For this purpose, glass jars were used, in which anaerobic conditions are quickly created, and stoneware vessels, whose appearance and characteristics are similar to tanks used on an industrial scale. WL nutrient agar with chloramphenicol and 10% NaCl was used to enumerate yeast. Isolates were differentiated using RAPD-PCR and identified by sequencing of the 5.8S-ITS rRNA gene region and PCR-RFLP. Selected organic acids, sugars, and polyols were analyzed using UHPLC-UV-Vis and -RI. Sauerkraut obtained in stoneware vessels was characterized by the presence of a larger amount of yeast, including those considered spoilage, such as Rhodotorula and Wickerhamomyces. It also contained 50% less lactic acid and a few times more acetic acids than that obtained using glass jars. A pH around 3.8 and 1.5% lactic acid, which are parameters indicating the end of fermentation of sauerkraut, were obtained in glass jars on the tenth day of fermentation. The yeast Wickerhamomyces anomalus may be an indicator of the presence of oxygen during sauerkraut fermentation, while Clavispora lusitaniae may indicate anaerobic conditions. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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22 pages, 2625 KiB  
Article
A Photonic Label-Free Biosensor to Detect Salmonella spp. in Fresh Vegetables and Meat
by Ana Fernández Blanco, Manuel Hernández Pérez, Yolanda Moreno Trigos and Jorge García-Hernández
Appl. Sci. 2023, 13(24), 13103; https://doi.org/10.3390/app132413103 - 8 Dec 2023
Viewed by 1093
Abstract
This paper presents a method that can be used to detect and identify Salmonella spp. in fresh meat and vegetable samples using a photonic biosensor with specialized bioreceptors. Detection was based on photon transduction. Silicon-nitride-based resonant cavities were used to capture the change [...] Read more.
This paper presents a method that can be used to detect and identify Salmonella spp. in fresh meat and vegetable samples using a photonic biosensor with specialized bioreceptors. Detection was based on photon transduction. Silicon-nitride-based resonant cavities were used to capture the change in light response when there is specific binding of the immobilized antibody to the sensor surface against the target antigen. A control immobilization experiment was conducted to validate the immobilization process on the biosensor surface prior to biofunctionalization for Salmonella spp. detection. This experiment involved immobilization of pre-selected antibodies on silicon nitride surfaces. Two types of antibodies were suitable. The first was a specific polyclonal antibody with superior antigen-binding capacity across a wide range of concentrations. The second was a monoclonal antibody designed for effective binding at lower concentrations. Rigorous validation was performed. The outcomes were compared with those of the habitual method used to detect Salmonella spp. (reference method). Replicates from different batches of contaminated meat and vegetable samples were analyzed. This comprehensive approach provides a methodologically robust, highly sensitive, and accurate way of rapidly detecting Salmonella spp. in food samples. It has potential implications for improved food safety and quality control. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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12 pages, 4868 KiB  
Article
Fir (Abies alba Mill.) Honeydew Honey Inhibits Growth and Adhesion of Campylobacter jejuni In Vitro
by Dina Ramić, Ivana Gobin, Darinka Vučković, Ana Planinić, Irena Brčić Karačonji and Sonja Smole Možina
Appl. Sci. 2023, 13(23), 12735; https://doi.org/10.3390/app132312735 - 28 Nov 2023
Viewed by 843
Abstract
This study investigated the physicochemical properties of fir (Abies alba Mill.) honeydew honey (FHH) and its biological activity against the leading foodborne bacterium Campylobacter jejuni. Antibacterial activity, bacterial growth and anti-adhesion tests were performed in Mueller Hinton (MH) broth and cow’s milk [...] Read more.
This study investigated the physicochemical properties of fir (Abies alba Mill.) honeydew honey (FHH) and its biological activity against the leading foodborne bacterium Campylobacter jejuni. Antibacterial activity, bacterial growth and anti-adhesion tests were performed in Mueller Hinton (MH) broth and cow’s milk used as a food model. FHH from the mountainous region of Croatia showed antibacterial activity against C. jejuni in MH broth and milk, with the minimal inhibitory concentration (MIC) values ranging from 12.5 to 50 mg/mL. A transmission electron microscopy (TEM) analysis of C. jejuni cells showed severe cellular damage after exposure to the tested honeydew honey. FHH in concentrations of 3 and 5% (w/v) inhibited growth and prevented adhesion to the polystyrene surface at a concentration of 25 mg/mL or lower of the bacterium C. jejuni in MH broth and milk. The anti-adhesion effect was more pronounced in the milk than in the MH broth. These results suggest that FHH has potent antibacterial activity against C. jejuni due to its particular physicochemical properties. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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14 pages, 3621 KiB  
Article
Reducing Storage Losses of Organic Apples by Plasma Processed Air (PPA)
by Robert Wagner, Thomas Weihe, Hauke Winter, Christoph Weit, Jörg Ehlbeck and Uta Schnabel
Appl. Sci. 2023, 13(23), 12654; https://doi.org/10.3390/app132312654 - 24 Nov 2023
Viewed by 768
Abstract
The consumer demand for organic food including apples is increasing worldwide. Despite favorable environmental and health benefits, organic farming bears also disadvantages like high amounts of fruit losses due to storage rot. A novel treatment with plasma-processed air (PPA) to sanitize organic apples [...] Read more.
The consumer demand for organic food including apples is increasing worldwide. Despite favorable environmental and health benefits, organic farming bears also disadvantages like high amounts of fruit losses due to storage rot. A novel treatment with plasma-processed air (PPA) to sanitize organic apples is investigated. The plasma source for the generation of PPA was operated at a frequency of 2.45 GHz, a power output of 1.1 kW and a gas flow of 18 standard liters per minute. The antimicrobial efficiency of the PPA was tested on the natural load of organic apples (cultivar Natyra) with a load ranging from 104 to 106 CFU/mL in an experimental laboratory setup. A larger application was applied on artificially inoculated (Pseudomonas fluorescens~108 CFU/mL and Pezicula malicorticis~106 CFU/mL) organic apples to test the up-scalability of the PPA treatment. The apples were photographically documented and their texture was analyzed during the 26-day storage phase to investigate the influence of the PPA treatment on the appearance of the apples. The laboratory experiments resulted in a log10-reduction of one to two log10 levels compared to untreated and compressed-air-treated apples. For apples inoculated with P. fluorescens, the up-scaled procedure resulted in up to four levels of log10 reduction. In apples inoculated with P. malicorticis, the up-scaled procedure resulted in no reduction. This indicates that the application of PPA to organic apples can be effective for bacteria but needs to be optimized for fungi. Therefore, further testing is needed to validate the results. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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20 pages, 1980 KiB  
Article
The Effect of Ultrasound and Pulsed Electric Field on the Osmotic Dehydration Process of Strawberries
by Katarzyna Pobiega, Aleksandra Matys, Magdalena Trusinska, Katarzyna Rybak, Dorota Witrowa-Rajchert and Malgorzata Nowacka
Appl. Sci. 2023, 13(22), 12335; https://doi.org/10.3390/app132212335 - 15 Nov 2023
Viewed by 888
Abstract
Currently, the demands of consumers are growing, and they expect safe and natural products of higher quality compared to products processed using thermal methods. Thermal treatment influences the sensory as well as quality and nutritional value of processed plant material. This results in [...] Read more.
Currently, the demands of consumers are growing, and they expect safe and natural products of higher quality compared to products processed using thermal methods. Thermal treatment influences the sensory as well as quality and nutritional value of processed plant material. This results in the development of innovative, non-thermal methods of food preservation and processing. Hence, the study was conducted to examine how ultrasound (US) and pulsed electric field (PEF) affect the osmotic dehydration process of strawberries. An US treatment with a power of 400 W and a frequency of 24 kHz for 30 and 90 s and a PEF treatment were used, adopting the appropriate energy consumption of 1 and 2.5 kJ/kg. Then, strawberries after both processes were osmotically dehydrated in 0.5; 1, and 2 h at 30 °C. Dehydration was carried out in a 50% sucrose solution. Research findings have indicated that the pretreatment positively enhanced the efficiency of osmotic dehydration. An improvement in the dry weight gain rate was noted. Strawberries dehydrated with the use of pretreatment had similar or lower color values and the content of bioactive components compared to strawberries subjected to dehydration only. The material treated with the PEF turned out to be the softest. Significant differences in sugar content were noted in fruits after pretreatment. Sucrose levels increased, glucose levels decreased, and fructose remained at a comparable level. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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16 pages, 1861 KiB  
Article
Microencapsulation of Phenolic Compounds Extracted from Okra (Abelmoschus esculentus L.) Leaves, Fruits and Seeds
by Salma Guebebia, Adem Gharsallaoui, Emilie Dumas, Fatemeh Baghi, Lazhar Zourgui, Mehrez Romdhane, Géraldine Agusti and Sami Ghnimi
Appl. Sci. 2023, 13(22), 12273; https://doi.org/10.3390/app132212273 - 13 Nov 2023
Cited by 1 | Viewed by 4903
Abstract
Several plants rich in phenolic compounds have many uses in the food and pharmaceutical fields. However, after extraction, these active biomolecules are susceptible to degradation. Microencapsulation is a possible solution to prevent this rapid degradation. In this study, phenolic compounds from the okra [...] Read more.
Several plants rich in phenolic compounds have many uses in the food and pharmaceutical fields. However, after extraction, these active biomolecules are susceptible to degradation. Microencapsulation is a possible solution to prevent this rapid degradation. In this study, phenolic compounds from the okra Abelmoschus esculentus L’s leaves, fruits and seeds were extracted using microwave-assisted extraction and then microencapsulated via the spray drying technique using maltodextrin combined with pectin (in a ratio of 10:1) as an encapsulation material. The total phenolic content, DPPH scavenging and antimicrobial activities of okra extracts and encapsulated samples were evaluated to verify the encapsulation efficiency. Particle size distribution determination and scanning electron microscopy of the microcapsules were also carried-out. The ethanolic leaf extract showed higher significant levels of total phenolic compounds (162.46 ± 4.48 mg GAE/g DW), and anti-oxidant (75.65%) and antibacterial activities compared to those of other aqueous and ethanolic extracts from fruits and seeds. Furthermore, the spray-dried ethanolic leaf extract had the highest total phenolic content. However, the encapsulated ethanolic fruit extract had the highest percentage of DPPH scavenging activity (30.36% ± 1.49). In addition, antibacterial activity measurements showed that the addition of ethanolic and aqueous seed microcapsules provided a significant zone of inhibition against the bacterium Brochotrix thermosphacta (38 mm and 30 mm, respectively). Okra aqueous leaf microcapsules showed the smallest Sauter mean diameter values (7.98 ± 0.12 µm). These data are applicable for expanding the use of okra leaves, fruits and seeds as food additives and/or preservatives in the food industry. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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11 pages, 290 KiB  
Article
The Bacteriocin-like Inhibitory Substance Producing Lacticaseibacillus paracasei LPa 12/1 from Raw Goat Milk, a Potential Additive in Dairy Products
by Andrea Lauková, Emília Dvorožňáková, Miroslava Vargová, Jana Ščerbová, Valentína Focková, Iveta Plachá and Monika Pogány Simonová
Appl. Sci. 2023, 13(22), 12223; https://doi.org/10.3390/app132212223 - 10 Nov 2023
Viewed by 590
Abstract
Goat milk is gradually becoming the preferred milk by consumers worldwide, including Slovakia. It is also demanded as a functional and/or nutraceutical drink as it is rich in bioactive components. However, another new development is the research into the beneficial autochthonous strains used [...] Read more.
Goat milk is gradually becoming the preferred milk by consumers worldwide, including Slovakia. It is also demanded as a functional and/or nutraceutical drink as it is rich in bioactive components. However, another new development is the research into the beneficial autochthonous strains used to enrich goat dairy products. Among individual species, representatives in raw goat milk are also involved in lacticaseibacilli. Bacteriocin-like inhibitory substance-producing Lacticaseibacillus paracasei LPa 12/1 was isolated from raw goat milk. This study focuses on its potential as a new additive in dairy products. No mortality was found when checking the safety of the LPa 12/1 strain using Balb/c mice. The strain reached higher counts in ewe–goat milk yoghurt (up to 6.1 cfu/g log 10) than in cow milk yoghurt (almost 5.0 cfu/g log 10). Cow milk yoghurts remained in more stable consistency after LPa 12/1 supplementation compared with ewe–goat milk yoghurts, although specific organoleptic tests were not performed. However, LPa 12/1 has survived sufficiently in both types of yoghurts. This bacteriocin-like inhibitory substance-producing strain LPa 12/1 in its encapsulated form applied in yoghurts seems suitable to supplement dairy products. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
16 pages, 3484 KiB  
Article
Economic Analysis of the Production Process of Probiotics Based on the Biological and Physiological Parameters of the Cells
by Jakub Kiepś, Anna Olejnik, Wojciech Juzwa and Radosław Dembczyński
Appl. Sci. 2023, 13(20), 11541; https://doi.org/10.3390/app132011541 - 21 Oct 2023
Cited by 1 | Viewed by 1219
Abstract
Probiotic bacteria confer a range of health benefits and are a focus of a growing number of studies. One of the main issues is their stability during drying and storage, which is why techniques, such as fluid bed drying and coating or treatment [...] Read more.
Probiotic bacteria confer a range of health benefits and are a focus of a growing number of studies. One of the main issues is their stability during drying and storage, which is why techniques, such as fluid bed drying and coating or treatment with stress factors during culturing, are utilized. The methods of the evaluation of probiotic viability and quality are, however, lacking and we need a way of distinguishing between different subpopulations of probiotic bacteria. To address this issue, imaging flow cytometry (IFC) has been utilized to assess cells after simulated in vitro digestion of dried and coated preparations treated with pH stress and heat shock. Samples were analyzed fresh and after 12 months of storage using RedoxSensor green and propidium iodide dyes to assess metabolic activity and cell membrane integrity of the cells. The results were then used to design a drying process on an industrial scale and evaluate the economic factors in the SuperPro Designer v13 software. Based on the number of biologically active and beneficial cells obtained utilizing tested methods, the coating process and treatment with heat shock and pH stress have been the most effective and up to 10 times cheaper to produce than only by drying. Additionally, samples after 12 months of storage have shown an increase in the proportion of cells with intermediate metabolic activity and small amounts of cell membrane damage, which are still viable in probiotic products. This subpopulation of bacteria can still be considered live in probiotic products but is not necessarily effectively detected by pour plate counts. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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21 pages, 716 KiB  
Article
The Use of Effective Microorganisms as a Sustainable Alternative to Improve the Quality of Potatoes in Food Processing
by Piotr Pszczółkowski, Barbara Sawicka, Piotr Barbaś, Dominika Skiba and Barbara Krochmal-Marczak
Appl. Sci. 2023, 13(12), 7062; https://doi.org/10.3390/app13127062 - 12 Jun 2023
Cited by 1 | Viewed by 2396
Abstract
Background: The ecological approach to agriculture causes the desire to eliminate pesticides. Work is underway to replace them with natural agents. Aim: The aim of the research was to introduce an innovative factor and non-invasively increase the yield of dry matter and starch [...] Read more.
Background: The ecological approach to agriculture causes the desire to eliminate pesticides. Work is underway to replace them with natural agents. Aim: The aim of the research was to introduce an innovative factor and non-invasively increase the yield of dry matter and starch and thus improve the quality of the raw material for the production of potato-enriched products. Material and methods: The field experiment was carried out in central-eastern Poland, using the randomized sub-block method, in a dependent split-split-plot design in three repetitions. The superior factor of the first order was pre-planting treatments by treating seed potatoes with a microbiological preparation for (a) 10 min, (b) 15 min, and (c) untreated seed potatoes (untreated control). The second-order factor was 14 potato cultivars of all groups of earliness. Qualitative research was carried out under laboratory conditions. Results: Pre-planting treatments with the use of a microbiological preparation had a positive effect on the yield of dry matter and starch compared to the control while modifying the characteristics related to the quality of potato chips. The tested cultivars determined both the quantitative and qualitative characteristics of the chips to the greatest extent. Conclusions: Alternative solutions will allow the effective replacement of pesticides in potato production and processing. Full article
(This article belongs to the Special Issue Microorganisms in Foods and Food Processing Environments)
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