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17 pages, 2008 KiB

Open AccessArticle

Key Factors Determining the Behavior of Pathogens in Dry-Cured Ham after High Pressure Processing

by Cristina Serra-Castelló, Noémie Desriac, Anna Jofré, Nicoletta Belletti, Louis Coroller and Sara Bover-Cid

Appl. Sci. 2022, 12(24), 12732; https://doi.org/10.3390/app122412732 - 12 Dec 2022

Cited by 2 | Viewed by 1115

Abstract

High pressure processing (HPP) inactivates pathogens and increases the safety of ready-to-eat meat products. The high-pressure lethality and the behavior of the surviving cells after HPP depends on process parameters (pressure and time), microorganism and matrix characteristics. The aim of the present study [...] Read more.

High pressure processing (HPP) inactivates pathogens and increases the safety of ready-to-eat meat products. The high-pressure lethality and the behavior of the surviving cells after HPP depends on process parameters (pressure and time), microorganism and matrix characteristics. The aim of the present study was to quantify the impact of pressure level, water activity (a_w), and fat content on the behavior of Salmonella spp. and Listeria monocytogenes during refrigerated storage of dry-cured ham after high-pressure processing. Salmonella enterica serotype London CTC1003 and L. monocytogenes CTC1034 were inoculated at ca. 7 log cfu/g in dry-cured ham of different a_w (0.87–0.98), vacuum packaged, pressurized from 300 to 852 MPa for 5 min, and stored at 7 °C for up to 2 months. Salmonella and L. monocytogenes populations were monitored by plate count during the storage of the hams. The gamma concept was used to quantify the individual effects of a_w and storage temperature on the pathogen growth/no-growth behavior in pressurized dry-cured ham. The Weibull (inactivation) or Logistic (growth) primary models were fitted to the log change of pathogen levels during storage of dry-cured ham after pressurization. According to the gamma approach, the refrigeration temperature and a_w were the main factors limiting the growth of Salmonella and L. monocytogenes, respectively, in dry-cured ham. Under conditions not allowing growth, the effect of increasing pressures on the microbial inactivation depended on the a_w of dry-cured ham and the pathogen; dry-cured ham with high fat content with an a_w ≥ 0.95 enhanced the inactivation of Salmonella whereas it reduced that of L. monocytogenes. Under conditions allowing growth of L. monocytogenes, the increase in a_w from 0.96 to 0.98 reduced the lag time with no apparent impact on the growth rate. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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13 pages, 1927 KiB

Open AccessArticle

Rapid Identification of Foodborne Pathogens in Limited Resources Settings Using a Handheld Raman Spectroscopy Device

by Cid Ramon Gonzalez-Gonzalez, Mark Hansen and Alexandros Ch. Stratakos

Appl. Sci. 2022, 12(19), 9909; https://doi.org/10.3390/app12199909 - 1 Oct 2022

Cited by 5 | Viewed by 1776

Abstract

Rapid and precise methods to detect pathogens are paramount in ensuring food safety and selecting appropriate disinfection treatments. Raman spectrometry is a promising technology being investigated for detecting pathogens and achieving rapid, culture-free, and label-free methods. Nonetheless, previous Raman techniques require additional steps, [...] Read more.

Rapid and precise methods to detect pathogens are paramount in ensuring food safety and selecting appropriate disinfection treatments. Raman spectrometry is a promising technology being investigated for detecting pathogens and achieving rapid, culture-free, and label-free methods. Nonetheless, previous Raman techniques require additional steps, including the preparation of slides that could introduce significant variability. In this study, we investigated the capability of a Raman handheld device for rapid identification of monocultures of Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli O157:H7, and Staphylococcus aureus, and the combination of co-cultures in BHI broth suspension by utilising principal component analysis (PCA) and support vector machine (SVM) classification of Raman spectra. The detection method accurately identified monocultures (0.93 ± 0.20), achieving good discrimination after 24 h of bacterial growth. However, the PCA–SVM system was less accurate for classifying co-cultures (0.67 ± 0.35). These results show that this method requires an isolation step followed by biomass enrichment (>8 log₁₀ CFU/mL) for accurate identification. The advantage of this technology is its simplicity and low-cost preparation, achieving high accuracy in monocultures in a shorter time than conventional culture-dependent methods. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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17 pages, 3751 KiB

Open AccessArticle

Physicochemical and Morphological Study of the Saccharomyces cerevisiae Cell-Based Microcapsules with Novel Cold-Pressed Oil Blends

by Wojciech Cichocki, Adrian Czerniak, Krzysztof Smarzyński, Paweł Jeżowski, Dominik Kmiecik, Hanna Maria Baranowska, Katarzyna Walkowiak, Ewa Ostrowska-Ligęza, Maria Barbara Różańska, Mariusz Lesiecki and Przemysław Łukasz Kowalczewski

Appl. Sci. 2022, 12(13), 6577; https://doi.org/10.3390/app12136577 - 29 Jun 2022

Cited by 9 | Viewed by 2090

Abstract

Vegetable oils rich in polyunsaturated fatty acids are a valuable component of the human diet. Properly composed oil blends are characterized by a 5:1 ratio of ω6/ω3 fatty acids, which is favorable from a nutritional point of view. Unfortunately, their [...] Read more.

Vegetable oils rich in polyunsaturated fatty acids are a valuable component of the human diet. Properly composed oil blends are characterized by a 5:1 ratio of ω6/ω3 fatty acids, which is favorable from a nutritional point of view. Unfortunately, their composition makes them difficult to use in food production, as they are susceptible to oxidation and are often characterized by a strong smell. Encapsulation in yeast cells is a possible solution to these problems. This paper is a report on the use of native and autolyzed yeast in the encapsulation of oils. The fatty acid profile, encapsulation efficiency, morphology of the capsules obtained, and thermal behavior were assessed. Fourier transform infrared analysis and low-field nuclear magnetic resonance relaxation time measurements were also performed. The process of yeast autolysis changed the structure of the yeast cell membranes and improved the loading capacity. Lower encapsulation yield was recorded for capsules made from native yeast; the autolysis process significantly increased the value of this parameter. It was observed that NY-based YBMCs are characterized by a high degree of aggregation, which may adversely affect their stability. The average size of the AY capsules for each of the three oil blends was two times smaller than the NY-based capsules. The encapsulation of oils in yeast cells, especially those subjected to the autolysis process, ensured better oxidative stability, as determined by DSC, compared to fresh blends of vegetable oils. From LF NMR analysis of the relaxation times, it was shown that the encapsulation process affects both spin-lattice T₁ and spin-spin T₂* relaxation times. The T₁ time values of the YBMCs decreased relative to the yeast empty cells, and the T₂* time was significantly extended. On the basis of the obtained results, it has been proven that highly unsaturated oils can be used as an ingredient in the preparation of functional food via protection through yeast cell encapsulation. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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17 pages, 331 KiB

Open AccessFeature PaperArticle

How Does the Addition of Biostimulants Affect the Growth, Yield, and Quality Parameters of the Snap Bean (Phaseolus vulgaris L.)? How Is This Reflected in Its Nutritional Value?

by Aly Farag El Sheikha, Ayman Younes Allam, Mohamed Taha and Theodoros Varzakas

Appl. Sci. 2022, 12(2), 776; https://doi.org/10.3390/app12020776 - 13 Jan 2022

Cited by 13 | Viewed by 2695

Abstract

Recently, the use of biostimulants as natural and eco-friendly fertilizers has received increasing attention because of their efficiency in terms of improving crops’ qualitative and quantitative parameters, i.e., growth, yield, and chemical composition. We studied the effect of four biostimulants—humic acid (20 g/L), [...] Read more.

Recently, the use of biostimulants as natural and eco-friendly fertilizers has received increasing attention because of their efficiency in terms of improving crops’ qualitative and quantitative parameters, i.e., growth, yield, and chemical composition. We studied the effect of four biostimulants—humic acid (20 g/L), vermicompost tea (15 mL/L), moringa leaf extract (1:30 v/v), and yeast extract (5 g/L), with tap water as a control treatment—on the qualitative and quantitative characteristics of snap beans. The experiment was designed using a complete randomized block with triplicates. The results showed a significant improvement in treated plant performance (growth and yield), chlorophyll, and chemical composition compared to untreated plants. Using moringa leaf extract increased the plant height, number of leaves and branches/plant, and fresh and dry weight. Additionally, the diameter of the treated plant stems and the quality of the crop and pods were also significantly higher than those of plants treated with vermicompost or humic acid extract. It is also noted that the profile of amino acids was improved using all tested biostimulants. This leads to the conclusion that the addition of moringa leaf extract and vermicompost tea not only positively affects the qualitative and quantitative properties of snap bean but is also reflected in its nutritional value as a plant-based food. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

17 pages, 3609 KiB

Open AccessArticle

Design of a Low-Power Radio Frequency Unit and Its Application for Bacterial Inactivation under Laboratory Conditions

by Dmytro S. Kozak, Maria Tonti, Patricia Cuba, Julian Espitia, Vladimir S. Tsepelev, Davy Verheyen, Simen Akkermans and Jan F. M. Van Impe

Appl. Sci. 2021, 11(23), 11117; https://doi.org/10.3390/app112311117 - 23 Nov 2021

Cited by 4 | Viewed by 2200

Abstract

A lab-scale low-power free-running radio frequency (RF) oscillator operating at a frequency of 27.12 ± 0.50 MHz was developed to be suitable for fundamental microbiological research topics. Calibration and validation were conducted for two common foodborne pathogens in relevant microbiological growth media, i.e., [...] Read more.

A lab-scale low-power free-running radio frequency (RF) oscillator operating at a frequency of 27.12 ± 0.50 MHz was developed to be suitable for fundamental microbiological research topics. Calibration and validation were conducted for two common foodborne pathogens in relevant microbiological growth media, i.e., Salmonella Typhimurium and Listeria monocytogenes in Tryptic Soy Broth and Brain–Heart Infusion broth, respectively. The evolution of temperature, frequency, and power consumption was monitored during treatments, both with and without bacterial cells. The setup operated within the predefined frequency range, reaching temperatures of 71–76 °C after 15 min. The average power consumption ranged between 12 and 14 W. The presence of bacteria did not significantly influence the operational parameters. The inactivation potential of the RF setup was validated, demonstrating the absence of viable cells after 8 and 10 min of treatment, for S. Typhimurium and L. monocytogenes, respectively. In future studies, the setup can be used to conduct fundamental microbiological studies on RF inactivation. The setup can provide added value to the scientific field, since (i) no consensus has been reached on the inactivation mechanisms of RF inactivation of pathogens in foods and (ii) most commercial RF setups are unsuitable to adopt for fundamental studies. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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Review

Jump to: Research

10 pages, 270 KiB

Open AccessReview

Molecular Hydrogen: The Postharvest Use in Fruits, Vegetables and the Floriculture Industry

by John T. Hancock, Grace Russell and Alexandros Ch. Stratakos

Appl. Sci. 2022, 12(20), 10448; https://doi.org/10.3390/app122010448 - 17 Oct 2022

Cited by 8 | Viewed by 1955

Abstract

Molecular hydrogen (H₂) has been found to have significant effects in a range of organisms, from plants to humans. In the biomedical arena it has been found to have positive effects for neurodegenerative disease and even for treatment of COVID-19. In [...] Read more.

Molecular hydrogen (H₂) has been found to have significant effects in a range of organisms, from plants to humans. In the biomedical arena it has been found to have positive effects for neurodegenerative disease and even for treatment of COVID-19. In plants H₂ has been found to improve seed germination, foliar growth, and crops: effects being most pronounced under stress conditions. It has also been found that treatment with H₂ can improve the postharvest preservation of fruits, vegetables and flowers. Therefore, H₂-based treatments may be useful for the storage and transport of food products. H₂ can be delivered in a range of manners, from the use of the gas to creating H₂-enriched solutions, such as hydrogen-rich water (HRW) or hydrogen nanobubble water (HNW). The exact action of H₂ at a biochemical level has yet to be established. Despite this, H₂ appears to be safe. Treatments of food with H₂ would leave no harmful residues, and H₂ itself is safe to use, as exemplified by its biomedical use. With H₂ production and transport being developed for other industries, H₂ is likely to become cheaper and its use for postharvest maintenance of food may be beneficial to explore further. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

40 pages, 2543 KiB

Open AccessFeature PaperReview

Advances, Applications, and Comparison of Thermal (Pasteurization, Sterilization, and Aseptic Packaging) against Non-Thermal (Ultrasounds, UV Radiation, Ozonation, High Hydrostatic Pressure) Technologies in Food Processing

by Viola Chiozzi, Sofia Agriopoulou and Theodoros Varzakas

Appl. Sci. 2022, 12(4), 2202; https://doi.org/10.3390/app12042202 - 20 Feb 2022

Cited by 54 | Viewed by 17811

Abstract

Nowadays, food treatment technologies are constantly evolving due to an increasing demand for healthier and tastier food with longer shelf lives. In this review, our aim is to highlight the advantages and disadvantages of some of the most exploited industrial techniques for food [...] Read more.

Nowadays, food treatment technologies are constantly evolving due to an increasing demand for healthier and tastier food with longer shelf lives. In this review, our aim is to highlight the advantages and disadvantages of some of the most exploited industrial techniques for food processing and microorganism deactivation, dividing them into those that exploit high temperatures (pasteurization, sterilization, aseptic packaging) and those that operate thanks to their inherent chemical–physical principles (ultrasound, ultraviolet radiation, ozonation, high hydrostatic pressure). The traditional thermal methods can reduce the number of pathogenic microorganisms to safe levels, but non-thermal technologies can also reduce or remove the adverse effects that occur using high temperatures. In the case of ultrasound, which inactivates pathogens, recent advances in food treatment are reported. Throughout the text, novel discoveries of the last decade are presented, and non-thermal methods have been demonstrated to be more attractive for processing a huge variety of foods. Preserving the quality and nutritional values of the product itself and at the same time reducing bacteria and extending shelf life are the primary targets of conscious producers, and with non-thermal technologies, they are increasingly possible. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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26 pages, 2838 KiB

Open AccessReview

Polyphenoloxidase (PPO): Effect, Current Determination and Inhibition Treatments in Fresh-Cut Produce

by Sergio Nogales-Delgado

Appl. Sci. 2021, 11(17), 7813; https://doi.org/10.3390/app11177813 - 25 Aug 2021

Cited by 15 | Viewed by 6727

Abstract

Fresh-cut produce are quite popular among consumers due to their eating ease, high quality and functional content. However, some of the processing steps taking place during minimal processing (such as cutting, peeling, draining, etc.) might speed up decay, e.g., microbial growth, dehydration or [...] Read more.

Fresh-cut produce are quite popular among consumers due to their eating ease, high quality and functional content. However, some of the processing steps taking place during minimal processing (such as cutting, peeling, draining, etc.) might speed up decay, e.g., microbial growth, dehydration or browning. When it comes to the latter, polyphenol oxidase (PPO) plays an important role, being the center of many works focused on the understanding of its reaction mechanism and the application of conservative techniques. The aim of this review study was to compare recent research about the effect of PPO on minimally processed fruits and vegetables, trying to understand the way it acts, the measurement of its activity and current treatments, such as modified atmosphere packaging, washing treatments or edible coatings, among others. In conclusion, the combination of conservation techniques (that is, hurdle technology) is vital to guarantee global quality in minimally processed fruits and vegetables, including synergistic effects which will allow the use of mild treatment conditions to decrease PPO activity. However, further research is required to clearly understand PPO inhibition in trendy techniques such as irradiation. Full article

(This article belongs to the Special Issue Modern Food Production: New Approaches in Detection, Processing and Packaging Methods)

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