Effect of plasma activated water (PAW) on rocket leaves decontamination and nutritional value

Plasma Activated Water (PAW) obtained by exposing water to cold atmospheric pressure plasma, has recently emerged as a promising alternative for food decontamination, compared to the use of traditional chemical sanitizers. The aim of the study was to evaluate the efficacy of PAW treatments for rocket salad decontamination. Washing with PAW for 2, 5, 10 and 20 min was assessed against different endogenous spoilage microorganisms and compared to untreated water and hypochlorite solution. The chemical composition of PAW as a function of treatment and delay time was characterized and the effect on product quality and nutritional parameters was evaluated.Results showed that PAW allowed an average reduction of 1.7–3 Log CFU/g for total mesophilic and psychrotrophic bacteria and Enterobacteriaceae following 2–5 min washing with minimal variation of qualitative and nutritional parameters. Overall, experimental results highlighted the potentiality of PAW treatments as a promising alternative to chlorine having the advantage of a minor adverse impact on environment and consumers' health.Industrial relevanceTo meet consumers demand, the minimally processed fruit and vegetable industry needs to find sustainable solutions as alternative to the use of traditional chemical sanitizers that allow to increase product shelf-life and preserve safety, qualitative and nutritional characteristics.Plasma activated water represents a promising strategy for food decontamination, but its effects on foods have been only limitedly investigated. The present research is the first study on the use of plasma activated water on fresh rocket leaves, providing new and important information on microbial inactivation and quality of the fresh cut product.     

Efficacy of cold atmospheric plasma for inactivation of viruses on raspberries

In this study, the effectiveness of cold atmospheric plasma (CAP) in inactivating murine norovirus (MNV/human norovirus surrogate) and hepatitis A virus (HAV) on aerosol-inoculated dark red Willamette raspberries was explored. Pulsed positive corona discharge system fed by synthetic air was used for the production of CAP. Raspberries were treated for 1, 3, 5, 7, and 10 min at 25 W. Application of CAP enabled a 4 log₁₀ infectivity reduction in <5 min for MNV and approximately 10 min for HAV (from starting level of 6.91 and 7.84 log₁₀ PFU/mL, respectively). Viral genome copies reduction of 3.18 log₁₀ for MNV and 4.32 for HAV were found from starting level of 5.76 and 6.47 log₁₀ gc/μL, respectively. CAP treatment did not result in significant degradation of fruit color, an important quality attribute. The study demonstrated CAP as an efficient post-harvest decontamination method to reduce viral load in raspberries without significantly affecting its quality parameters.Industrial relevanceDue to the fast-processing paces required in the raspberry industry, it is difficult to assure the complete microbiological safety of this fruit. Cold atmospheric plasma is a practical, environmentally-friendly, non-thermal tool for the effective reduction of microbial pathogens. The model developed in this study demonstrated that CAP treatment of fresh raspberries not only inactivated hazardous enteric viruses in a short time (10 min) but also unaffected fruit color stability. The simplicity of described CAP design and low-cost inputs (air and electricity) enable the commercial application of inexpensive plasma chambers for continuous surface decontamination of large volumes of raspberries without bringing processing to a standstill.     

Evaluation of pulsed electric field and minimal heat treatments for inactivation of pseudomonads and enhancement of milk shelf-life

Pulsed Electric Field (PEF) treatment of milk provides the opportunity to increase the shelf-life of fresh milk for distribution to distant markets. PEF treatments were evaluated in sterile (UHT) milk to determine the inactivation of added spoilage Pseudomonas isolates and the subsequent gains in microbial shelf-life (time taken to reach 10⁷ CFU mL^− 1). Little inactivation of Pseudomonas was achieved at 15 or 40 °C compared with 50 or 55 °C. The greatest inactivation (> 5 logs) was achieved by processing at 55 °C with 31 kV cm^− 1 (139.4 kJ L^− 1). Heat treatment at the application temperature without PEF treatment caused minimal inactivation of Pseudomonas (only 0.2 logs), demonstrating that the inactivation of the Pseudomonas was due to the PEF treatment rather than the heat applied to the milk. At added Pseudomonas levels of 10³ and 10⁵ CFU mL^− 1, the microbial shelf-life of PEF-treated milk was extended by at least 8 days at 4 °C compared with untreated milk. The total microbial shelf-life of the PEF-treated milk was 13 and 11 days for inoculation levels of 10³ and 10⁵ CFU mL^− 1 respectively. The results indicate that PEF treatment is useful for the reduction of pseudomonads, the major spoilage bacteria of milk.Industrial relevancePseudomonads are the major psychrotrophic spoilage microflora of refrigerated, stored HTST pasteurised milk. Long-life (UHT) products are an important component of milk sales in South-East Asia, but in recent years there has been an increasing demand for less processed milk products with extended shelf-life. The recent practice of shipping fresh bulk milk from Australia to South-East Asian countries has necessitated additional heat treatment prior to export and on arrival, to achieve the required shelf-life. Pulsed electric field treatment of HTST milk, applied alone or in combination with mild heat under optimised conditions, offers the opportunity of shelf-life extension, while limiting the reduction in quality attributes of milk associated with more severe additional heat treatments.     

Commercial application of high-pressure processing for increasing starter-free fresh cheese shelf-life

Different non-thermal technologies have been proposed to extend the shelf-life of solid food products, high-pressure processing (HPP) being one of the emerging technologies which has been most extensively studied. In this study, one of the first commercial industrial-scale applications of HPP on a starter-free fresh cheese, with the aim of increasing its shelf-life, is presented. The effect of 500 MPa (5 min, 16 °C) on physico-chemical, microbial, colour, microstructure, texture and sensorial characteristics of starter-free fresh cheeses during cold storage of 21 days was studied. The results showed that pressurised cheeses presented a shelf-life of about 19–21 days when stored at 4 °C, whereas control cheese became unsuitable for consumption on day 7–8. On the other hand, cheese treated at 500 MPa was firmer and more yellow than the untreated one. However, these changes, which were detected by instrumental and sensory analysis, did not affect the preference for pressurised cheese. These results may lead to practical applications of HPP in the food industry to produce microbiologically safe cheese with extended shelf-life and sensory quality.     

Bacterial contamination of ready-to-eat foods and fresh products in retail shops and food factories.

Raw vegetables cut for salad, cooked salad, cooked rice, boiled noodles, bean curd, and cooked Japanese foods were purchased in 27 retail shops in Tokyo. Intact vegetables before being processed and ready-to-eat fresh salad products were obtained from two food factories located in the suburbs of Tokyo. Two hundred thirty-eight retail samples, 137 samples of intact vegetables, and 159 samples of fresh products were examined for aerobic plate count (APC), coliforms, Escherichia coli, Listeria spp., Staphylococcus aureus, and Bacillus cereus. The APC of retail foods were 2.1 to 5.7 log CFU/g, and the range for the coliforms was 0.1 to 2.3 log CFU/g. The APC and coliform values showed that the raw vegetables cut for salad were the most heavily contaminated among the six kinds of ready-to-eat foods examined. Although L. monocytogenes was not detected, two samples of raw vegetables and five kinds of cooked foods yielded Listeria spp. S. aureus was detected in one sample of Japanese cooked food. The APC of the intact vegetables were 2.9 to 7.3 log CFU/g upon arrival and 2.2 to 7.2 log CFU/g after 3 days storage at 10 degrees C. The APC of the fresh products were 3.4 to 7.6 log CFU/g upon arrival and 4.7 to 8.7 log CFU/g after 3 days storage at 10 degrees C. The isolation rates for coliforms were 6.1 to 50% for intact vegetables and 50 to 66.7% for fresh products. E. coli was detected only in the fresh products. B. cereus was isolated from 20.1% (17 of 81) of the intact vegetables and 9.2% (8 of 87) of the fresh products.     

Magnetic field hydrocooling system: Effect of field intensities on the cooling characteristics of three different leavy vegetables

The physiological changes occurring during postharvest of leafy vegetables affect quality. To address this, several cooling technologies that utilize physical fields like magnetic fields (MFs) have been proposed. The application of MFs in the cooling of leafy vegetables however remains a substantial controversy among the food engineers. Therefore, the effectiveness should be clarified by experiments. In the current study, the effect of MFs (at 534.1 mT, 458.0 mT, and 396.8 mT) on hydrocooling process of three different leafy vegetables including jute mallow, fluted pumpkin, and bitter leaf was investigated by using a specially designed hydrocooling system facilitated with magnetic field (also known as magnetic field hydrocooling; MFHC) generated from a Neodymium permanent magnet. The investigation included the comparison of the cooling curves, physiological loss in weight (PLW), microbial loads, and observation of microstructures. Based on the results of the experiment, it was observed that the weak magnetic fields provided significant improvement on the hydrocooling technique as well as the quality of hydrocooled vegetables. The MFHC assisted by Neodymium magnet (at 396.8 mT) provided higher cooling rate (at P ≤ 0.05) when compared with conventional room cooling, reduced microbial loads significantly from 8.40 × 10⁵ to 5.86 × 10⁵ CFU/ml, 7.03 × 10⁵ to 5.89 × 10⁵ CFU/ml and 6.00 × 10⁵ to 4.0 × 10⁵ CFU/ml (at P ≤ 0.05) for jute mallow, fluted pumpkin and bitter leaf respectively. In addition, hydrocooling-assisted by magnetic field (at 396.8 mT) is more effective in the preservation of the microstructures. The study indicates that the MFHC technology enhances cooling process and preserves the leafy vegetables, thus pose great potential in the food industry.Practical applicationsLeafy vegetables deteriorate faster after harvest; hence, there is a need to cool them in order to extend their shelf-life. MFHC technique has great potentials in preservation of leaves, with the advantage of minimum quality loss due to reduction in cooling time and microbial activities. Currently, innovative studies have been carried out on the use of MFHC technique to improve the cooling process and achieve better quality preservation. However, the findings presented in this work can provide detail insights on the quality of some leafy vegetables that were cooled by MFHC, and give some guidance for further developments of MFHC technology.     

Active packaging solution to prolong the shelf life of rocket salad

The best packaging conditions for rocket salad were assessed by subsequent experimental trials. In the first step, a preliminary screening of different packaging materials was performed and two micro‐perforated oriented polypropylene films with different micro‐hole diameters (90 and 110 μm) were selected as best packaging solutions. In the subsequent experimental step, modified headspace conditions were applied without any improvement on product quality. In the last step, the effects of an ethylene adsorbent were analysed. Rocket salad packaged in both films with the ethylene adsorbent recorded a shelf life of about 16 days, compared to the control samples that remained acceptable for 13 days. During storage, the microbial quality (mesophilic and psychrotrophic bacteria, pseudomonadaceae, lactic acid bacteria, yeasts, total coliforms and enterobacteriacae), the pH, the colour changes and the main sensory parameters were also monitored.     

Growth potential of Listeria monocytogenes strains in mixed ready-to-eat salads

In this study, a microbiological challenge test in three artificially contaminated retail mixed mayonnaise-based ready-to-eat salads stored at refrigerator temperatures (3 °C and 7 °C) for 48 h was carried out. Shrimp-tomato salad, smoked ham salad and garlic cheese salad were separately contaminated by a suspension of particular Listeria monocytogenes strains. The number of L. monocytogenes, Enterobacteriaceae, staphylococci and total plate count (CFU/g) was determined. Listeria monocytogenes growth potential in the salads was calculated and evaluated.A significant increase in total plate count and L. monocytogenes count throughout storage of all three investigated salads was found. Enterobacteriaceae levels were high at the beginning in all salads but significantly (p < 0.05) decreased throughout the experiment depending on the temperature.All investigated L. monocytogenes strains demonstrated growth at both temperatures but expressed different growth potential. Especially garlic cheese salad and smoked ham salad were able to support the growth of Listeria. Shrimp-tomato salad supported growth the least. The growth potential increased with the increasing temperature and exceeded 0.5 log₁₀ CFU/g in many cases. If the potential for growth is > 0.5 log₁₀ CFU/g, food products can potentially endanger human health. Reference strain (ATCC 7644) showed the least growth potential almost in all cases in comparison with strains isolated from frozen pollock loins and from thermally treated specialty sausage containing preservatives. To eliminate the occurrence of microbiological risks, the shelf-life of the studied salads was estimated.     

Impact of different temperature abuse scenarios on sensory quality and off-odour formation in ready-to-eat salad leaves

Packages of ready-to-eat (RTE) wild rocket and lettuce baby leaves were subjected during 8 days of cold storage to a chronic temperature abuse (CTA) at sub-optimal storage temperature (10 °C) or to a short-term (6 h) abuse at ambient temperature (STA) to evaluate the impact of two temperature abuse scenarios on gas composition within the packages, leaf sensory quality and volatile organic compounds (VOCs). In both species, the CTA scenario had a markedly higher impact on gas composition, sensory quality and off-odour formation than the STA, and the limit of sensory acceptability was reached in the CTA scenario 4 days or more earlier than in the STA. Sulphur compounds were the main responsible for off-odour perception in both leafy salads. Results from the present study may be useful in the assessment of critical points in the cold chain of RTE fresh produce and in prioritising actions towards improved cold-chain management.     

Combined effect of ozonated water and chitosan on the shelf-life of Pacific oyster (Crassostrea gigas)

Effects of ozonated water and chitosan treatment on the shelf-life extension of Pacific oysters (Crassostrea gigas) stored at 5 ± 1 °C were studied. Results indicated that ozonated water treatment reduced the total microbial load of fresh oysters by about 10-fold (from 3.2 × 10³ CFU/g to 1.8 × 10² CFU/g) before storage and the microbial flora was different with that of raw samples. The wide-spectrum antibacterial property of chitosan against bacteria isolated from oysters was confirmed, and chitosan concentration of 5.0 g/l was eventually determined for application in oyster preservation. Based on microbiological analysis, biochemical indices determination and sensory evaluation, shelf-lives of 8–9 days for control, 10–12 days for ozonated water treated samples, 14–15 days for chitosan treated samples and 20–21 days for samples with combined treatment were observed, indicating that ozonated water and chitosan have a great potential for oyster preservation.Industrial relevanceAs seafood, Pacific oysters have a short shelf-life. Improvements in the shelf-life of oysters can have an important economic impact by reducing losses and by allowing the products to reach distant and new markets.In this work, Shelf-life of oysters with combined treatment of ozonated water and chitosan doubled, which has great practical meaning, and the process could be fully adopted by the food industry.We also did some research about the changes in microbial flora after ozonated water treatment. This work could help in preservation of oysters when ozone or ozonated water concerned.We discovered Wide-spectrum antibacterial property of chitosan against the strains isolated from raw oysters. The potential for using chitosan as a natural preservative in oysters was approved.     

Effect of cold atmospheric plasma and pulsed electromagnetic fields on strawberry quality and shelf-life

The effect of cold atmospheric plasma (CAP) and pulsed electromagnetic fields (PEMF) on the metabolic process, microbiological, enzymatic and quality parameters of fresh strawberries, after processing and during storage at 1 and 6 °C, was studied. CAP was more effective on microorganisms, reducing the total viable count by ~0.9 logCFU/g. Phenolic compounds and antioxidant activity were increased after CAP processing by ~20.9 and 16.5%, respectively. PEMF strawberries were firmless by ~16% compared to control. Both treatments did not significantly affect the weight loss, color, anthocyanins content and pH-value. B-glucosidase activity was higher for PEMF strawberries by at least 35 and 20%, compared to control and CAP respectively, explaining PEMF enhancing aromatic-profile. Ascorbic acid was decreased during storage, nevertheless, nonthermal treated samples showed higher values by at least 10%, compared to control samples. The shelf-life at 1 °C for control, CAP and PEMF strawberries was estimated as 13, 17 and 15 days, respectively.     

Quality attributes of shredded carrot (Daucus carota L. cv. Nantes) as affected by alternative decontamination processes to chlorine

The effects of alternative decontamination processes to chlorine: ozonated-water (1 ppm/5 min), hot water (100 °C/45 s) and ultrasonication (45 kHz/1 min), applied pre- or post-cut in the technological diagram of minimal processing of carrots were tested. Ultrasonication in chlorinated-water and thermo-ultrasonication as combined processes applied just in pre-cut carrot were also tested. The initial microbial load reduction, soluble solids content, pH and sensorial attributes of shredded carrot just after processing were evaluated. Decontamination processes applied on pre-cut carrot provided maintenance of fresh-like sensorial quality, regardless the type of treatment, due to diminished leaching phenomena which is critical for shredded carrot. Chlorination, ozonization and ultrasonication achieved ca. 1 Log₁₀ reduction of initial microbial load. No additional decontamination effect in combined processes was observed. The use of heat in pre-cut carrot proved to be the most efficient process regarding microbial reduction (3 Log₁₀ units) providing, as well, an acceptable fresh-like quality product.Industrial relevanceThe major constraint for marketability of minimally processed shredded carrot is its limited shelf-life due to rapid microbial growth and colour loss (decrease of orange intensity and/or whitening of the shreds). These questions arise from the practical experience of a fresh-cut industry directly involved in the R&D research project which supported this study. Chlorine solutions have been widely used to sanitize fruit and vegetables in the fresh-cut industry. However, reduced microbiological efficiency allied to the eventual formation of carcinogenic chlorinated compounds pointed out the need for alternative methodologies. The present work aimed the evaluation of clean alternative decontamination processes applied both to pre- and post-cut carrot for the production of shredded carrot, operating under conditions of industrial practice at pilot-plant scale.     

Shelf-life extension of herring (Clupea harengus) using in-package atmospheric plasma technology

Atmospheric cold plasma is a green and emerging technology, highly interesting to the food industry for its application. Dielectric Barrier Discharges (DBD) can generate atmospheric cold plasma inside sealed packages filled with air through the use of high voltages. This study investigated the use of a large gap DBD design to generate a plasma discharge within the headspace of packaged herring fillets, and its effects on microbiological and quality markers of the fish stored for 11 days at 4 °C. DBD plasma treatment conditions were 70 kV or 80 kV for 5 min treatment time.Results showed that the microbial load (total aerobic mesophilic, total aerobic psychrotrophics, Pseudomonas, lactic acid bacteria and Enterobacteriaceae) were significantly (p < 0.05) lower in the treated samples compared to the control samples. However, samples exposed to the lowest applied voltage better retained key quality factors (lower oxidation and less colour modification). DBD-treatment caused a reduction in trapped water in the myofibrillar network (T21), identified using low-field nuclear magnetic resonance of protons (¹H LF NMR).The results indicate that in-package plasma treatment could be employed as an effective treatment for reducing spoilage bacteria in fish.Industrial relevanceDielectric Barrier Discharge (DBD) was evaluated as a treatment for highly perishable fish products. DBD's is a safety and lower costs alternative for processing industry. DBD has been scarcely tested on fish; this work showed results on quality and shelf-life of a highly perishable fish species, which might serve as reference for processing optimisation of fish products minimally processed by DBD.     

A microbiological perspective of raw milk preserved at room temperature using hyperbaric storage compared to refrigerated storage

The effects of hyperbaric storage (HS, 50–100 MPa) at room temperature (RT) on endogenous and inoculated pathogenic surrogate vegetative bacteria (Escherichia coli, Listeria innocua), pathogenic Salmonella enterica and bacterial spores (Bacillus subtilis) were assessed and compared with conventional refrigeration at atmospheric pressure for 60 days. Milk stored at atmospheric pressure and refrigeration quickly surpassed the acceptable microbiological limit within 7 days of storage, regarding endogenous microbiota, yet 50 MPa/RT slowed down microbial growth, resulting in raw milk spoilage after 28 days, while a significant microbial inactivation occurred under 75–100 MPa (around 4 log units), to counts below 1 log CFU/mL throughout storage, similar to what was observed for B. subtilis endospores. While inoculated microorganisms had a gradually counts reduction in all HS conditions. Results indicate that HS can not only result in the extension of milk shelf-life but is also able to enhance its safety and subsequent quality.Industrial relevanceThis new preservation methodology could be implemented in the dairy farm storage tanks, or during milk transportation for further processing, allowing a better microbial control, than refrigeration. This methodology is very promising, and can improve food products shelf-life with a considerable lower carbon foot-print than refrigeration.     

Physiological basis of sensitivity to enzymatic browning in ‘lettuce’, ‘escarole’ and ‘rocket salad’ when stored as fresh-cut products

In fresh-cut leafy vegetables, the operation of cutting may stimulate enzymatic browning, with important commercial consequences. In this work, a number of physiological and biochemical parameters, including the activities of key enzymes involved in the metabolism of phenols (such as PAL, PPO, and PODs) and ascorbic acid (ASA), were measured in three species: lettuce (Lactuca sativa var. capitata L.), escarole (Cichorium indivia var. latifolium) and rocket salad (Eruca sativa), upon cold storage as fresh cuts. The first two species are quite sensitive to leaf browning, which does not affect rocket salad.     

Enhancing gallic acid antimicrobial activity against Escherichia coli by ultraviolet-C light irradiation

This study aimed to evaluate the UV-C light effect on enhancing the antimicrobial activity of gallic acid (GA) against Escherichia coli at different initial microbial loads. The highest microbial reduction (3.08 ± 0.09 log) was attained at low microbial load after 10-min contact with irradiated GA (IGA). Increasing the initial microbial load (6–7 × 10⁷ CFU/mL) reduces the IGA effect. Application of the IGA (0.015 M) in combination with UV-C light (15 min) caused lethal injury in E. coli at a low microbial load. Furthermore, at a low microbial load, a contact time of 5 min and 0.15 M was enough to reach >5-log reductions, whereas, at high microbial concentrations, the maximum GA concentration (0.25 M) was necessary to achieve the same inactivation. Increasing GA concentration, irreversible microbial damage was observed, with no microbial growth in samples treated for 10 min with IGA at 0.10–0.25 stored at 22 °C.Industrial relevanceGA is a phenolic compound with limited antimicrobial activity. However, the UV-C light treatment enhances its antimicrobial activity, increasing its application as a disinfectant of surfaces, instruments, and fresh food products, among other applications currently demanded by the consumers and food industry. In this sense, IGA can be used as a disinfectant agent for fruit and vegetables, in combination with novel or traditional technologies as a combined methodology to reduce the microbial load, or even as a preservative to maintain the microbial load during storage.     

Pasteurization of carrot juice by combining UV-C and mild heat: Impact on shelf-life and quality compared to conventional thermal treatment

The combination of UV-C radiation and mild heat (UV-H) treatment is a promising strategy for synergistically increasing microbial inactivation in low UV-transmitting juices. In this research, we explored the suitability of UV-H treatment in carrot juice pasteurization and its impact on juice quality during shelf-life compared to that of thermal pasteurization. UV-H treatment at 60 °C (3.92 J/mL, 3.6 min) enabled reductions of over 5 log₁₀ cycles in the reference pathogens and a significant reduction in spoilage yeasts, bacteria, and bacterial spores. The activity of pectin methylesterase and polyphenol oxidase was reduced by UV-H treatment to levels close to those of low-temperature pasteurization (60 °C/18.1 min). The native population of total aerobic bacteria, lactic acid bacteria, and yeasts and molds of UV-H-treated juice remained undetectable during 29 days of cold storage. Furthermore, viscosity, cloud stability, and the color of fresh juice were better preserved by UV-H treatment than by thermal pasteurization throughout storage.Industrial relevanceThis study demonstrates that UV-H treatment is a beneficial alternative to conventional thermal processing in carrot juice pasteurization, since appropriate inactivation levels of pathogenic and spoilage microorganisms can be reached while better preserving the quality attributes of fresh juice throughout its shelf-life.     

Chemical composition,cooking quality,texture and consumer acceptance of pasta with Eruca vesicaria leaves

In this study, pasta with dried Eruca vesicaria leaves commonly known as Rocket salad and spinach leaves flours were prepared. Samples were evaluated for its chemical composition, cooking quality, textural, colour and consumer acceptance. Results showed that pasta with Eruca vesicaria had the highest dietary fibre content (5.30–9.50 g/100 g) and the lowest fat content (2.13–2.80 g/100 g). The optimally cooked pasta with 5% of leaves (stored 30 days) and pasta with 10% of leaves (stored 14 days) have good cooking quality with cooking loss ≤8%. The green colour and textural characteristics of pastas were stable during all period at 4 °C. Textural characteristics of pasta with rocket and spinach were similar. Pasta with 10% of rocket leaves has presented the highest overall acceptability score.     

A comparative study on the antifungal efficacy of cold atmospheric plasma at low and high surface density on Aspergillus chevalieri and mechanisms of action

Cold atmospheric plasma (CAP) is a promising innovative technology for microbial inactivation on food surfaces. In this study, we evaluated the potential of CAP at low (CAP-O₃) and high (CAP-NO_x) power using Aspergillus chevalieri as a fungal model, one of the most xerophilic and xerotolerant molds causing food spoilage, We observed a strong reduction in mycelial growth (60%) and conidial germination (90%) after 30 min of CAP-NO_x, while CAP-O₃ was less effective showing no reduction in mycelia growth and only 36% of spore germination reduction. Furthermore, cell death was accompanied by a loss of cellular and mitochondrial potential membrane, a significant (p < 0.05) increase in intracellular ROS, RNS, calcium, and DNA damage. For the first time, we reported that trehalose, glycerol, chitin and glucan accumulation are some adaptive mechanisms of A. chevalieri to counteract CAP stress, with CAP-NO_x treatments inducing a major accumulation of these two osmolites. Our results suggested that Cold atmospheric plasma-induced cell death can be explained by oxidative stress-dependent through a cascade of reactions initiated by membrane depolarization.     

Microbiological study of ready-to-eat salad vegetables from retail establishments uncovers a national outbreak of salmonellosis

The increasing availability of bagged prepared salad vegetables reflects consumer demand for fresh, healthy, convenient, and additive-free foods that are safe and nutritious. During May and June 2001 a study of retail bagged prepared ready-to-eat salad vegetables was undertaken to determine the microbiological quality of these vegetables. Examination of the salad vegetables revealed that the vast majority (3,826 of 3,852 samples; 99.3%) were of satisfactory or acceptable microbiological quality according to Public Health Laboratory Service microbiological guidelines, while 20 (0.5%) samples were of unsatisfactory microbiological quality. Unsatisfactory quality was due to Escherichia coli and Listeria spp. (not Listeria monocytogenes) levels in excess of 10(2) CFU/g. However, six (0.2%) samples were of unacceptable microbiological quality because of the presence of Salmonella (Salmonella Newport PT33 [one sample], Salmonella Umbilo [three samples], and Salmonella Durban [one sample]) or because of a L. monocytogenes level of 660 CFU/g, which indicates a health risk. In each case, the retailer involved and the UK Food Standards Agency were immediately informed, and full investigations were undertaken. Nineteen cases of Salmonella Newport PT33 infection were subsequently identified throughout England and Wales. The outbreak strain of Salmonella Newport PT33 isolated from the salad and from humans had a unique plasmid profile. Campylobacter spp. and E. coli O157 were not detected in any of the samples examined. The presence of Salmonella, as well as high levels of L. monocytogenes, is unacceptable. However, minimally processed cut and packaged salad is exposed to a range of conditions during growth, harvest, preparation, and distribution, and it is possible that these conditions may increase the potential for microbial contamination, highlighting the necessity for the implementation of good hygiene practices from farm to fork to prevent contamination and/or bacterial growth in these salad products.