Evaluation of a sanitizing washing step with different chemical disinfectants for the strawberry processing industry

Strawberries are often consumed fresh or only receive minimal processing, inducing a significant health risk to the consumer if contamination occurs anywhere from farm to fork. Outbreaks of foodborne illness associated with strawberries often involve a broad range of microbiological agents, from viruses (human norovirus) to bacteria (Salmonella spp. and Listeria monocytogenes). The addition of sanitizers to water washes is one of the most commonly studied strategies to remove or inactivate pathogens on berries as well as avoid cross contamination due to reuse of process wash water. The risk posed with the safety issues of by-products from chlorine disinfection in the fruit industry has led to a search for alternative sanitizers. We evaluated the applicability of different chemical sanitizers (peracetic acid (PA), hydrogen peroxide (H2O2), citric acid (CA), lactic acid (LA) and acetic acid (AA)) for the inactivation of S. enterica, L. monocytogenes and murine norovirus (MNV-1) on strawberries. A control treatment with chlorine (NaClO) (100 ppm) was included. For each sanitizer, different doses (40, 80 and 120 ppm for PA and 1, 2.5 and 5% for H2O2, LA, AA and CA) and time (2 and 5 min) were studied in order to optimize the decontamination washing step. The best concentrations were 80 ppm for PA, 5% for H2O2 and 2.5% for organic acids (LA, AA and CA) after 2 min treatment. Results indicate that the sanitizers selected may be a feasible alternative to chlorine (100 ppm) for removing selected pathogenic microorganisms (P > 0.05), with reductions about ≥2 log for bacterial strains and ≥ 1.7 log for MNV-1. As the washing water may also increase the microbial counts by cross-contamination, we observed that no pathogenic bacteria were found in wash water after 5% H2O2 and 80 ppm PA after 2 min treatment. On the other hand, we also reported reductions about total aerobic mesophyll (TAM) (0.0–1.4 log CFU/g) and molds and yeasts (M&Y) (0.3–1.8 log CFU/g) with all alternative sanitizers tested. Strawberries treated did not shown significant differences about physio-chemical parameters compared to the untreated samples (initial). For this study, the optimal sanitizer selected was PA, due to the low concentration and cost needed and its microbiocidal effect in wash water and fruit. Notwithstanding the results obtained, the effect of PA in combination with other non-thermal technologies such as water-assisted ultraviolet (UV-C) light should be studied in future research to improve the disinfection of strawberries.info:eu-repo/semantics/acceptedVersio

Evaluation of a sanitizing washing step with different chemical disinfectants for the strawberry processing industry

Strawberries are often consumed fresh or only receive minimal processing, inducing a significant health risk to the consumer if contamination occurs anywhere from farm to fork. Outbreaks of foodborne illness associated with strawberries often involve a broad range of microbiological agents, from viruses (human norovirus) to bacteria (Salmonella spp. and Listeria monocytogenes). The addition of sanitizers to water washes is one of the most commonly studied strategies to remove or inactivate pathogens on berries as well as avoid cross contamination due to reuse of process wash water. The risk posed with the safety issues of by-products from chlorine disinfection in the fruit industry has led to a search for alternative sanitizers. We evaluated the applicability of different chemical sanitizers (peracetic acid (PA), hydrogen peroxide (H2O2), citric acid (CA), lactic acid (LA) and acetic acid (AA)) for the inactivation of S. enterica, L. monocytogenes and murine norovirus (MNV-1) on strawberries. A control treatment with chlorine (NaClO) (100 ppm) was included. For each sanitizer, different doses (40, 80 and 120 ppm for PA and 1, 2.5 and 5% for H2O2, LA, AA and CA) and time (2 and 5 min) were studied in order to optimize the decontamination washing step. The best concentrations were 80 ppm for PA, 5% for H2O2 and 2.5% for organic acids (LA, AA and CA) after 2 min treatment. Results indicate that the sanitizers selected may be a feasible alternative to chlorine (100 ppm) for removing selected pathogenic microorganisms (P > 0.05), with reductions about ≥2 log for bacterial strains and ≥ 1.7 log for MNV-1. As the washing water may also increase the microbial counts by cross-contamination, we observed that no pathogenic bacteria were found in wash water after 5% H2O2 and 80 ppm PA after 2 min treatment. On the other hand, we also reported reductions about total aerobic mesophyll (TAM) (0.0–1.4 log CFU/g) and molds and yeasts (M&Y) (0.3–1.8 log CFU/g) with all alternative sanitizers tested. Strawberries treated did not shown significant differences about physio-chemical parameters compared to the untreated samples (initial). For this study, the optimal sanitizer selected was PA, due to the low concentration and cost needed and its microbiocidal effect in wash water and fruit. Notwithstanding the results obtained, the effect of PA in combination with other non-thermal technologies such as water-assisted ultraviolet (UV-C) light should be studied in future research to improve the disinfection of strawberries.info:eu-repo/semantics/acceptedVersio

Effectiveness of a pomegranate peel extract (PGE) in reducing Listeria monocytogenes in vitro and on fresh-cut pear, apple and melon

Pomegranate peel extract (PGE) is a new promising natural alternative control substance with large spectrum of activity against wide range of pathogenic microorganisms. In the present study, PGE was firstly investigated as natural antimicrobial against Listeria monocytogenes both in vitro and on fresh-cut fruits. The in vitro results showed quick and strong bactericidal and bacteriostatic activity against five different strains which were almost completely inhibited by the extract. Furthermore, it significantly decreased growth rate and maximum growth of all tested strains. In vivo trials, confirmed a strong antibacterial activity of the extract that significantly reduced the bacterial load on fresh-cut apple, melon and pear and maintained the population at low levels throughout the storage period (7 days). PGE at 12 g/l reduced L. monocytogenes by 1.24, 1.89, and 0.91 log units soon after treatment and by 3.81, 1.53, and 2.99 log units, after 7 days of storage on apple, pear and melon, respectively. This high antibacterial activity could be mainly related to the high content of polyphenols (ellagitannins) in the extract. Overall, results of this study suggest a potential industrial application of PGE to reduce the growth of the pathogenic microorganisms in fresh-cut fruit and ensure a microbial safety in case of contamination.info:eu-repo/semantics/acceptedVersio

Composition, Structure and Tribotechnical Properties of TiN, MoN Single-Layer and TiN/MoN Multilayer Coatings

Results of comprehensive investigations of nanostructed TiN and MoN single layer coatings as well as multilayer coatings consisting of TiN/MoN alternating layers have beenconsidered. The coatings have been deposited by a promising modern method of cathode-arc evaporation (vacuum-arc method). The elemental and phase compositions of coatings, their tribological and physico mechanical properties: friction coefficient, wear, adhesion, hardness, and elastic modulus have been studied and the mechanisms of the coatings fracture have been discussedyesBelgorod State Universit

In situ stress evolution during growth of transition metal nitride films and nanocomposites

The issue of stress evolution during growth of hard transition metal nitride (TMN) based coatings is of vital importance to understand origin of intrinsic stress development and to control stress level in order to avoid mechanical failure of coated components and devices. By using in situ and real-time wafer curvature measurements based on a multiple- beam optical stress sensor (MOSS), basic insights on the atomistic mechanisms at the origin of stress development and stress relaxation can be obtained. In the present paper, a review of recent advances on stress development during reactive magnetron sputter-deposition of binary TMN films (TiN, ZrN, TaN) as wells as ternary systems (TiZrN, TiTaN) will be presented. The influence of growth energetics on the build-up of compressive stress will be addressed. A correlation between stress, texture and film morphology is demonstrated. Finally, illustration will be given for quaternary TiZrAlN nanocomposites. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2074

Conductive nitrides: growth principles, optical and electronic properties, and their perspectives in photonics and plasmonics

The nitrides of most of the group IVb-Vb-VIb transition metals (TiN, ZrN, HfN, VN, NbN, TaN, MoN, WN) constitute the unique category of conductive ceramics. Having substantial electronic conductivity, exceptionally high melting points and covering a wide range of work function values, they were considered for a variety of electronic applications, which include diffusion barriers in metallizations of integrated circuits, Ohmic contacts on compound semiconductors, and thin film resistors, since early eighties. Among them, TiN and ZrN are recently emerging as significant candidates for plasmonic applications. So the possible plasmonic activity of the rest of transition metal nitrides (TMN) emerges as an important open question. In this work, we exhaustively review the experimental and computational (mostly ab initio) works in the literature dealing with the optical properties and electronic structure of TMN spanning over three decades of time and employing all the available growth techniques. We critically evaluate the optical properties of all TMN and we model their predicted plasmonic response. Hence, we provide a solid understanding of the intrinsic (e.g. the valence electron configuration of the constituent metal) and extrinsic (e.g. point defects and microstructure) factors that dictate the plasmonic performance. Based on the reported optical spectra, we evaluate the quality factors for surface plasmon polariton and localized surface plasmon for various TMN and critically compare them to each other. We demonstrate that, indeed TiN and ZrN along with HfN are the most well-performing plasmonic materials in the visible range, while VN and NbN may be viable alternatives for plasmonic devices in the blue, violet and near UV ranges, albeit in expense of increased electronic loss. Furthermore, we consider the alloyed ternary TMN and by critical evaluation and comparison of the reported experimental and computational works, we identify the emerging optimal tunable plasmonic conductors among the immense number of alloying combinations

Влияние параметров осаждения нитридов высокоэнтро¬пийных сплавов (TiZrHfVNb)N на их структуру, состав, механические и трибологические свойства

Методами растровой электронной и атомно-силовой микроскопии, энергодисперсионного анализа, анализа Резерфордовского обратного рассеяния ионов, рентгено-дифракционного анализа, измерениями микротвердости и трибологическими испытаниями исследованы нитриды высокоэнтропийных сплавов (TiZrHfVNb)N, полученные при помощи вакуумно-дугового испарения катода. Обнаружено влияние параметров осаждения на структуру, морфологию поверхности, распределение элементов, механические и трибологические свойства исследуемых покрытий.Методами растрової електронної та атомно-силової мікроскопії, енергодисперсійного аналізу, аналізу Резерфордівського оберненого розсіювання іонів, рентгено-дифракційного аналізу, вимірюванням мікротвердості та трибологічними випробуванями досліджено нітриди високоентропійних сплавів (TiZrHfVNb)N, отримані за допомогою вакуумно-дугового випарування катоду. Виявлено вплив параметрів осадження на структуру, морфологію поверхні, розподіл елементів, механічні та трибологічні властивості досліджуваних покриттів.Nitrides of high-entropy alloys (TiZrHfVNb)N, which were obtained by cathode vacuum-arc evaporation, were investigated using methods of scanning electronic and atomic force microscopy, energy-dispersive analysis, analysis of Rutherford ions backscattering, X-ray diffraction analysis, by measuring of microhardness and tribological tests. Influence of deposition parameters on structure, surface morphology, elements distribution, mechanical and tribological properties of investigated coatings was found

Biopreservation of fresh-cut pear using Lactobacillus rhamnosus GG and effect on quality and volatile compounds

In recent years, the consumption of minimally processed fruit has increased. However, unfortunately, these products could be an appropriate vehicle for the transmission of foodborne pathogens. In this study, the antagonistic capacity of the probiotic strain Lactobacillus rhamnosus GG against a cocktail of 5 serovars of Salmonella and 5 serovars of Listeria monocytogenes on fresh-cut pear at conditions simulating commercial application was assessed. Moreover, its effect on fruit quality, particularly on the volatile profile, was determined, during 9 days of storage at 5 C. L. monocytogenes population was reduced by approximately 1.8 log-units when co-inoculated with L. rhamnosus GG. However, no effect was observed in Salmonella. Fruit quality (soluble solids content and titratable acidity) did not change when the probiotic was present. A total of 48 volatile compounds were identified using gas chromatography. Twelve of the compounds allowed to discriminate L. rhamnosus GG-treated and untreated pears. Considering their odour descriptors, their increases could be positive in the flavour perception of L. rhamnosus GG-treated pear. The probiotic was able to control L. monocytogenes population on fresh-cut pear, which could be a vehicle of probiotic microorganisms as quality of fruit was not affected when the probiotic was presentinfo:eu-repo/semantics/acceptedVersio

Structure and properties of nanostructured NbN and Nb-Si-N films depending on the conditions of deposition: Experiment and theory

The first results of studying the phase–structural state, properties, sizes of nanograins, hardness, and microstresses in nanocomposite NbN and Nb–Si–N films are given. The investigated films were obtained by the method of the magnetron sputtering of Nb and Si targets onto silicon substrates at different negative potentials at the substrate (from 0 to –70 V), nitrogen pressures PN, and discharge powers at the targets. To determine the thermal stability of the films, they were annealed at 600, 800, and 1000°C in a vacuum.It was revealed for the first time that the NbN films have a twophase nanocomposite structure, which consists of δNbN (NaCl structure type) and α'NbN. The δNbN phase is also formed in Nb–Si–N films, where it is enveloped by an amorphous Si3N4 phase The hardness of the Nb–Si–N films reaches 46 GPa, which cor responds to the level of superhardness, while the hardness of the NbN nanocomposites is somewhat lower, but also very high (34 GPa). The experimental results for the Nb–Si–N films were explained based on the data obtained from the firstprinciples calculations of the NbN/SixNy heterostructures by the molecular dynamics method