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Intense Light Pulse treatment as alternative method for mould spores destruction on paper polyethylene packaging material
Abstract
Intense light pulse (ILP) is one of the emerging non-thermal techniques investigated as an alternative to traditional thermal treatment because it has been proven to be effective for microbial inactivation on food surfaces and food packages. The aim of this study was to evaluate the possibility of using pulsed light treatment for the effective killing of moulds on paper–polyethylene packaging material. Coupons of 20 × 20 mm paper–polyethylene were artificially contaminated with Cladosporium herbarum, Aspergillus niger, Aspergillus repens and Aspergillus cinnamomeus than subjected to different light energetic densities (from 0.244 to 0.977 J/cm2) for different durations (from 10 × 10-3 to 30 × 10-3 s). The results showed that there is a significant reduction of population along with an increase of light fluence and ILP treatment duration. The highest level of inactivation achieved in this study was about a 2.7-log reduction, which is more than
enough for a normal contaminated packaging material. It is estimated that pulse light treatment could lead to an effective reduction of moulds, being also possible to obtain a sterile surface of the packaging material. Blastospores as those produced by C. herbarum are easier destroyed (z = 0.795 J/cm2) than fialospores as those produced by aspergilli (z = 0.81–0.927 J/cm2). Spore colour seems to play some role in spore resistance to light pulses: green fialospores, as those produced by A. repens, has higher z values (0.927 J/cm2) than the black or brown ones as those produced by A. niger (z = 0.81 J/cm2), and A. cinnamomeus (z = 0.875 J/cm2) respectively.
... Pulsed light (PL) is a traditionally considered non-thermal technique that is used to reduce or kill microorganisms by using broad spectral wavelengths (100 to 1100 nm) (Gόmez-Lόpez et al., 2007;Turtoi and Nicolau, 2007;Takeshita et al., 2003). Pulsed light, a relatively new technique, has been studied through different applications, such as mycotoxins degradation (Moreau et al., 2013), food allergen reduction , and enzyme inactivation (Janve et al., 2014). ...
... Pulsed light is a non-thermal technique that is used to reduce or kill microorganisms by using broad spectral wavelengths (100 to 1100 nm) (Gόmez-Lόpez et al., 2007;Turtoi and Nicolau, 2007;Takeshita et al., 2003)). PL is a relatively new technique, has been studied through different applications, such as mycotoxins degradation (Moreau et al., 2013), food allergen reduction , and enzyme inactivation (Janve et al., 2014). ...
... Pulsed light (PL) is a non-thermal technique that is used to reduce or kill microorganisms by using broad spectral wavelengths (100 nm to 1100 nm) (Gόmez-Lόpez et al., 2007;Turtoi and Nicolau, 2007;Takeshita et al., 2003). Pulsed light contains approximately 54% UV-C, 25% visible, and 20% infrared light . ...
Soybean (Glycine max) is a legume that has the highest protein content (40%) compared with all legumes, and the second highest content of oil (20%). Soymilk products are suggested to be as alternative of dairy product because of their nutritional value, but the biggest hindrance is that soymilk has an undesireable beany flavor. The main source of beany flavor of soymilk is lipoxygenase (LOX) catalyzed peroxidation of polyunsaturated fatty acids (PUFAs) when LOX reacts with the substrate during milling. If LOX can be inactivated in whole soybean, the peroxidation from LOX can be prevented. Pulsed light (PL) has been demonstrated to inactivate LOX in buffer solution non-thermally. Therefore, the first part of this study investigated the effect of PL on LOX inactivation in a real food system (soymilk), and determined the effect of PL with controlling the soymilk temperature. The second part of this study was the exploration of the ability of PL to inactivate LOX in whole soybean. Determining the sensory effect of PL on soymilk produced from soybeans treated and not treated with PL was another part of this study; in addition to the investigation of the flavor compounds of producing soymilk. The final part of this study was determining the effect of PL on the LOX inactivation in solution, and the effect of PL on the degradation of other proteins by electrophoresis. The results showed that PL inactivated whole LOX in soymilk and soybean almost exclusively thermally by using different distances from the PL strobe and samples with different times. Lipoxygenase was degraded by PL non-thermally with lower LOX concentrations by photo-chemical effect, and also different low concentration protein bands was reduced by PL. The effect of PL was little with high protein concentration. This research provides evidence that PL treatment can fully degrade LOX in soymilk and whole soybean, with the photo-thermal effect being the main factor. With low LOX concentration, the was evidence that the photo-chemical effect of PL occurred.
... The ability of microorganisms' inactivation has been demonstrated in many studies: Bacillus sp. on wheat flour and black pepper [8], Botrytis cinerea and Monilia fructigena on strawberries [9], E. coli and Listeria innocua on fresh-cut mushrooms [10], Listeria monocytogenes on ready-to-eat (RTE) sausages [11], infant foods [12], and RTE cooked meat products [13], native microbiota of fresh-cut mushrooms [14], Salmonella enteritidis on shell eggs [15][16][17][18], L. monocytogenes and E. coli on meat slicing knife [19], L. innocua on stainless-steel surfaces [20][21], Aspergillus niger, A. cinnamomeus and Cladosporium herbarum on paper-polyethylene packaging material [22]. ...
... The decrease in microbial concentration has been explained in several mathematical models, linear or non-linear. Thus, linear models related the surviving microorganisms or the microbial survival fraction, which is defined as the ratio of the living cells before and after treatment (N/No) with time [22] or with the main characteristic of the applied treatment, e.g. electric field strength [23,24] for pulsed electric field (PEF) or energetic density of light [22,25]. ...
... Thus, linear models related the surviving microorganisms or the microbial survival fraction, which is defined as the ratio of the living cells before and after treatment (N/No) with time [22] or with the main characteristic of the applied treatment, e.g. electric field strength [23,24] for pulsed electric field (PEF) or energetic density of light [22,25]. ...
Experimental tests were performed to evaluate the effect of intense pulsed light (IPL) treatment on
microbial inactivation of yeast cell suspensions of Saccharomyces cerevisiae CBS 493.94 and Candida
utilis MIUG 3.5. Regression analysis of microbial inactivation with IPL was then investigated. The aim of
this study was to apply the response surface methodology (RSM) to define the relationship between the
reduction of yeast cells and the process parameters, namely energetic density of light and duration of IPL
treatment. Moreover, RSM was used to verify the predicted models and to adapt them on particular
conditions of yeast cells inactivation by IPL treatment. The final model shows the dependency of the
yeast cells reduction by independent variables (energetic density of light and duration of IPL treatment)
and certain binary interactions of the IPL process parameters. The response surface follows the reduction
of yeast cells and reaches the lowest level for N/No = 0. This level represents the optimal area of the
response surface, which is ideal for any microbial inactivation treatment.
... The fialospores produced by storage moulds such as Aspergillus and Penicillium are more difficult to destroy than porospores, blastospores and sporangiospores produced by field moulds such as Alternaria, Cladosporium and Mucor, respectively. 23 Having in mind that the Romanian wheat contained storage moulds and that field moulds were predominant in the Spanish wheat, this can explain why higher inactivation levels were reached for Spanish wheat samples. Previous studies in different food products have demonstrated the efficiency of PL to inactivate bacteria and moulds, but information on the fungal decontamination of stored grain using PL technology is not available. ...
... Having in view that normal mould loads of cereals range from 10 2 to 10 4 CFU g −1 , 25 and the number of surviving moulds decreased with an increase in pulse number, it is possible to set a PL treatment in which mould decontamination of wheat grain is attained almost completely. Our results, together with those published by other researchers demonstrating the ability of PL treatments to inactivate bacterial and fungal spores, 16,23 allow anticipating PL treatments as a feasible alternative to thermal and chemical decontamination methods applied to cereals in food safety programmes. ...
... 29 All of the mechanisms suggested for explaining the effect of PL treatment are based on the photochemical and/or photothermal effect of the UV spectrum. 12,14,23,30,31 Both mechanisms may coexist and the importance of each one depends on the fluence and the type of microorganism. As in the case of bacteria, UV-C light influences the inactivation of moulds. ...
Pulsed light (PL) is emerging as a non-thermal technology with excellent prospects for the decontamination of foods and food contact surfaces. Its application for mould inactivation on cereal grains would allow a reduction of storage losses as well as the prevention of mycotoxin contamination at a post-harvest level. The potential of PL for the decontamination of naturally occurring moulds on wheat grain was investigated in this study.
Treatments of up to 40 flashes of a fluence of 0.4 J·cm(-2) ·pulse(-1) were applied to both sides of the grain, with an overall energy release ranging from 6.4 to 51.2 J·g(-1) . The most powerful treatment applied to wheat in this study (51.2 J·g(-1) ) resulted into a mould reduction of approximately 4 log cycles on samples displaying an initial mould contamination level of 2.2·10(5) CFU·g(-1) . At the same time, the seed germination percentage was only slightly affected. For PL treatments causing an inactivation of 3-4 log cycles, only 14-15% of the germination power of the wheat seeds was lost.
The PL treatments attained greater microbial reductions for higher treatment times and lower initial mould loads. The absence of the UV portion of the radiation spectrum was found to significantly reduce the treatment effectiveness.
... The main effects of pulsed light on microorganisms is said to be due to the photochemical action of (mainly the UV-C region of) the pulsed light, with about 54% of the emitted energy coming from the ultraviolet range [7]. Basically, the germicidal effects of pulsed light on microbial organisms are attributed mainly to DNA mutations induced from the absorption of UV portion of the pulsed light by the DNA molecules of the organism [1,7,10,20]. This is referred to as photochemical effects. ...
... The use of pulsed light for bacterial and other microbial inactivation tend to gain higher acceptance in the medical pathology and food preservation industries over the use of chemicals or thermal technology for some reasons. First is that generally, the use of light has less damaging effects on treated samples and reduces after -treatment effects such as corrosion, odour, protein denaturation, altered chemical composition, etc, which are often associated with chemical or thermal treatment [20]. In water treatment, the use of chlorine as a major disinfectant has generated some concerns because of the formation of additional potentially toxic disinfection by-products [2]. ...
The use of pulse light to inactivate microbes has recently attracted interest of many researchers. Consequently, there are various reports on the efficacy and advantages of pulsed light in microbial inactivation; and also the potentiality of pulsed light systems being adopted for industrial use in this regards. Here, we review some of the works done in relation to microbial inactivation with pulse light, with emphasis on the role played by pulse light parameters such as fluence, spectral range, pulse power, pulse width, pulse frequency, etc. We focussed in particular on factors that make pulsed light systems more effective than their continuous wave counterpart and also proffer suggestions on possible areas for improvement in future study. The use of pulsed lasers in inactivating microbes was briefly appraised. Also, prospects and challenges in the use of pulsed light for inactivation were highlighted.
... Inactivation by PL is commonly attributed to DNA damage caused by UV irradiation. Turtoi and Nicolau (2007) also reported spore color seems to play some role in spore resistance to light pulses, the dark colored fialospores produced by A. niger (black) and A. cinnamomeus (brown) are easier destroyed than those of A. repens (green). The absorbance scan of pigment extracts from the fungus over the range 240-480 nm indicated that the pigments of A. niger absorb strongly in the UV range. ...
... In contrast, on surfaces with roughness values that are less than the micrometer range, such as low-density polyethylene (LDPE) and high-density polyethylene (HDPE), inactivation of Listeria innocua with 12 pulses of PL treatment at fluence of 0.67 J/cm 2 yielded 7.1 and 7.2 log reductions, respectively. Turtoi and Nicolau (2007) also demonstrate that intense light pulses treatment holds promise for destroying the microorganisms from paper-polyethylene packaging material. They found blastospores as those produced by Cladosporium herbarum are easier destroyed (z = 0.795 J/cm 2 ) than fialospores as those produced by aspergilli (z = 0.81-0.927 ...
... As regards susceptibility toward UV, gram-negative bacteria are most sensitive, followed by gram-positive, fungi, and bacterial spores. Pigmentation is also probably protective because of partial UV absorption [101, 104, 108, 109]. A fluence of approximately 50–200 J/m 2 is necessary for a 90% viable count reduction; inactivation follows first-order kinetics, with an additional sigmoid delay at low fluence levels because of a non-lethal injury phase [3, 110]. ...
... Inactivation was affected not only by roughness but also by surface hydrophobicity, bacteria distribution, and reflectivity. Packaging materials such as polyethylene (PE)-coated paper [109], aluminum foil, and high-density (HD) PE bottle caps [119] can also be disinfected by radiation with short UV-C pulses at dose rates up to 200 mW/cm 2 . The application of continuous UV light for sterilization of commercial titanium dental implants examined by Riley et al. [120] gave effects of several orders of magnitude because of nanostructured TiO 2 at the surface that produces radicals upon radiation. ...
Cleaning and disinfection are important operations in food processing because of the significant contributions to product
hygiene and food safety. The transfer of residues from surfaces into a product and the contamination with adhering microorganisms
must therefore be avoided with sufficient certainty. Traditional methods for the removal of adherents and inactivation of
microorganisms are based on thermal, mechanical, or chemical principles and are known to be time- and energy-consuming. This
has resulted in a search for alternative methods that show prospective potential for their use in food-processing plants.
This review gives an overview on such methods, which are based on physical principles. In dry-ice cleaning, for example, carbon
dioxide snow pellets are blasted onto a surface to remove adherents through a combined action of thermal and mechanical effects,
followed by dissolution of these adherents. Ice-pigging is a procedure where an ice/water mixture is forced through pipes,
heat exchangers, or other equipment to carry off adhered substances. Another method for physical cleaning, mainly described
in context with membrane filtration, is to use vibration in the ultrasonic frequency domain to reduce fouling and to stabilize
permeate flux. Radiation from various sources (UV lamps, radionuclides, X-ray tubes) differs in its applicability and disinfection
efficiency because of differences in energy and penetration depth. Cold plasma treatment is another promising technology that
is currently under investigation for cleaning and disinfection of surfaces of inorganic and organic materials.
KeywordsCleaning–Disinfection–Surface–Physical methods–Dry-ice cleaning–Ultrasound–Radiation–Plasma
... Microorganisms are inactivated by short-time (10 26 to 10 23 s), UV-C-rich light pulses of high energy (with a peak power density that can exceed several thousand watts per square centimeter) (9). PL is able to inactivate a range of molds, viruses, and bacteria in solid foods, such as food powders, vegetables, or salmon (7,8,17), in water (11), in liquid foods, such as milk and fruit juices (21), and on the surface of material in contact with foods, such as packaging material (6,23). Up to several log reductions of microbiological populations have been obtained in many instances. ...
... Up to several log reductions of microbiological populations have been obtained in many instances. This demonstrates the possibilities of application of the technology (6,23). The objective of this work was to evaluate the efficiency of PL for the decontamination of sugar syrup. ...
The pulsed light produced by xenon flash lamps was applied to 65 to 67 °Brix sugar syrups artificially contaminated with suspensions of Saccharomyces cerevisiae and with spores of Bacillus subtilis, Geobacillus stearothermophilus, Alicyclobacillus acidoterrestris, and Aspergillus niger. The emitted pulsed light contained 18.5 % UV radiation. At least 3-log reductions of S. cerevisiae, B. subtilis, G. stearothermophilus, and A. acidoterrestris suspended in 3-mm-deep volumes of sugar syrup were obtained with a fluence of the incident pulsed light equal to or less than 1.8 J/cm(2), and the same results were obtained for B. subtilis and A. acidoterrestris suspended in 10-mm-deep volumes of sugar syrup. A. niger spores would require a more intense treatment; for instance, the maximal log reduction was close to 1 with a fluence of the incident pulsed light of 1.2 J/cm(2). A flowthrough reactor with a flow rate of 320 ml/min and a flow gap of 2.15 mm was designed for pulsed light treatment of sugar syrup. Using this device, a 3-log reduction of A. acidoterrestris spores was obtained with 3 to 4 pulses of incident pulsed light at 0.91 J/cm(2) per sugar syrup volume.
... In the entire process, packaging material can also get contaminated with pathogens. These pathogens get transferred to the produce in mean time and can spoil the food or cause serious health hazard (Turtoi and Nicolau, 2007). A salient feature of this non-thermal plasma technology is the ability to establish plasma inside a sealed package. ...
Plasma is the fourth state of matters which have a wide application in food processing and post harvest technology. Plasma when
applied over crops has tremendous effects in improvement in the quality and other post harvest attributes. Application of cold plasma
technology could effectively induce desirable changes in its overall quality and diverse physiology. The following review would discuss
the application of non-thermal plasma technology to disinfect and decontaminate processed food product and fresh horticultural
crops. Horticultural crops which are treated with plasma technology do not show any loss in nutrients. The packaging materials can
also be sterilized by using plasma technology. Similarly, the food packed inside a package can also be sterilized without harming the
package integrity. Beside that it can also be used to reduce the enzymatic activity of fresh fruits and vegetables and help to modify the
food properties. Cold plasma technology can penetrate fungal biofilm and destroy resting fungal spores. This technology can also be
harnessed to remove residual toxic pesticide from food products and fresh fruits and vegetables. However, the technology might
sound a bit expensive but have a long future in terms of utility.
... Previous studies have shown that inactivation effects may be reduced for darker samples due to their greater absorption of UV light [7,22]. The effects of pulsed light on color differences of bacteria and fungi and the pigments synthesized by them have also been examined [23][24][25]. Pseudomonas fluorescens, a Gram-negative strain, can synthesize the blue, fluorescent pigment called pyoverdin, which can absorb UV light and reduce the effects of pulsed light. Turtoi and Nicolau also confirmed that dark-colored phialospores produced by A. niger (black) and A. cinnamomeus (brown) were more easily destroyed than A. repens, which has a green color. ...
Controlling microbial problems when processing seeds and powdered foods is difficult due to their low water activity, irregular surfaces, and opaqueness. Moreover, existing thermal processing can readily cause various undesirable changes in sensory properties. Intense pulsed light (IPL) can be effective in nonthermal processing, and so two xenon lamps were attached to the sides of a self-designed cyclone type of pilot-scale IPL device. Each lamp was connected to its own power supply, and the following treatment conditions were applied to four sample types: lamp DC voltage of 1800–4200 V, pulse width of 0.5–1.0 ms, frequency of 2 Hz, and treatment time of 1–5 min. This device achieved reductions of 0.45, 0.66, and 0.88 log CFU/mL for ground black pepper, red pepper, and embryo buds of rice, respectively, under a total energy fluence of 12.31 J/cm2. Meanwhile, >3-log reductions were achieved for sesame seed samples under a total energy fluence of 11.26 J/cm2. In addition, analyses of color changes, water activity, and moisture content revealed no significant differences between the control and IPL-treated samples. These findings indicate that IPL treatment may be considered a feasible sterilization method for seeds and powdered foods.
... spores. Molds species such as A. niger, A. cinnamomeus, A. repens, and C. herbarum, that are prevalent on the food packaging surface, after PL treatment, were reduced significantly by 2.7 logs on a paper-polyethylene packaging surface [128]. Currently, the form fill seal type or aseptic packaging films materials are sterilized in packaging machine by either H2O2 and/or UV light. ...
Consumers of the 21st century tend to be more aware and demand safe as well as nutritionally balanced food. Unfortunately, conventional thermal processing makes food safe at the cost of hampering nutritional value. The food industry is trying to develop non-thermal processes for food preservation. Pulsed light (PL) is one such emerging non-thermal food processing method that can decontaminate food products or food contact surfaces using white light. Exposure to intense light pulses (in infrared, visible, and ultraviolet (UV) regions) causes the death of microbial cells, rendering the food safe at room temperature. PL technology is an excellent and rapid method of disinfection of product surfaces and is increasingly being used for food surfaces and packaging decontamination, enabling the minimal processing of food. This paper aims to give an overview of the latest trends in pulsed light research, discuss principles of pulse generation, and review applications of various PL systems for the inactivation of microorganisms invitro, in various food products, and on food contact surfaces. Effects of PL on food quality, challenges of the process, and its prospects are presented.
... The high energy content of short intense pulses amplifies the destruction mechanisms of individual wavelength contents. A few studies have also been reported on the photo thermal action of PL (Takeshita et al., 2003;Turtoi and Nicolau, 2007), though the effect depends on factors like the fluence of the irradiated light and absorption properties of the food matrices (Pataro et al., 2011). ...
In this study, the effect of pulsed light (PL) treatment on the shelf life extension of yellowfin tuna (Thunnus albacares) steaks was investigated. Tuna steaks of 1 cm thickness weighing 80 g packed in 300 gauge cast polypropylene pouches were subjected to PL treatment using Xenon pulse light machine RC-847. The samples were stored at 2±1OC and analysed at specific time intervals. Shelf life studies were carried out in terms of reduction of aerobic flora as inferred from the total plate count (TPC) and the psychrophilic count. The samples were also evaluated in terms of colour (L*, a* and b*), biochemical and sensory parameters. The initial reduction as well as lower rate of increase in the microbial count on the PL treated samples clearly highlighted the efficiency of PL technology as a novel non-thermal preservation technique. Low values of chemical indicators of spoilage and better values of sensory and colour values of PL treated samples also suggested the efficacy of PL treatment in microbial inactivation. An overall extension of 13 days of shelf life was achieved for PL treated samples whereas control samples were rejected on 13th day
... The efficiency of the continuous-wave pulsed UV-light was proved for water disinfection [28,29]. The advantages of Xe-lamps allow them to be widely used for disinfection purposes in different spheres: food production and storage [30,31], disinfection of surfaces [32], and packaging [33]. ...
... UV-C light has been used to decontaminate air and water as well as a wide variety of contact surfaces and materials (Haughton, Lyng, Cronin, et al., 2011;Koutchma, 2014). PL has also proven effective in the decontamination of a large number of surfaces (Ringus & Moraru, 2013;Woodling & Moraru, 2005), packaging materials (Haughton, Lyng, Morgan, et al., 2011;Turtoi & Nicolau, 2007) and even liquids (Birmpa, Vantarakis, Paparrodopoulos, Whyte, & Lyng, 2014). Both technologies have also demonstrated their efficacy for food surface decontamination (Fan, Huang, & Chen, 2017;Gómez-López, Ragaert, Debevere, & Devlieghere, 2007;Heinrich, Zunabovic, Bergmair, Kneifel, & Jäger, 2015). ...
The decontamination effect of two light-based technologies on salmon, polyethylene (PE) and stainless steel (SS) was evaluated. Optimization of treatment conditions for ultraviolet light (UV-C) and pulsed light (PL) was carried out on raw salmon, obtaining inactivation levels of 0.9 and 1.3 log CFU/g respectively. The effects of treatments on several microbial groups present in salmon were then evaluated. For both technologies, Pseudomonas spp. were found to be the most resistant group of microorganisms tested. Three different strains from within this group were isolated and speciated, including a P. fluorescens strain which was selected for subsequent studies. PE and SS surfaces were inoculated with a suspension of the P. fluorescens suspended in a ‘salmon juice’ solution, and treated with UV-C and PL at different doses (mJ/cm²). PE surfaces were effectively decontaminated a low doses for both technologies, with a reduction of >4 log cycles observed. Decontamination of SS was also effective when treated with PL, although at higher doses than for PE. When SS was treated with UV-C, the maximum reduction of P. fluorescens achieved was 2 log cycles, even at the highest dose.
... [16] Besides, the release of energy from the numerous penetrating flashes per second that upsurges the rapid energy intensity also contributes to microbial inactivation. [35] This was attested in the study with increasing exposure time resulting in a significant (p < 0.05) log reduction in microbial load of the juice ( Table 1). This could be due to a progressive increase in the lethal effect that might have caused microbial cells inactivation. ...
Lactic acid fermented mulberry juice (LFMJ) was subjected to pulsed light (PL) treatment at exposure time of 2, 4 and 8 s at high insensitive pulses of 14.0 J/cm². The effect of PL treatment on the microbial inactivation, physicochemical, phytochemical, volatile and sensory characteristics of LFMJ was evaluated. It was found that the PL was able to reduce the microbial load to acceptable levels (1.02 ± 0.04 log10 cfu/mL) with no significant impact on the physicochemical properties of LFMJ. It was also observed that the PL treatment caused a slight decrease in anthocyanin concentration at 8 s exposure time. The color difference (∆E) of the juice treated for 2 and 4 s fell below the slightly noticeable range 0.5<ΔE<1.5 while ∆E values for the 8 s (0.55 ± 0.02) and the thermal (0.50 ± 0.02) treated samples were slightly noticeable. The volatile profile and odor activity values were positively affected by increasing the exposure time. The results depict that under the present experimental conditions, the application of the PL resulted in a fermented juice with superior quality attributes as compared to the thermal treated juice.
... and Cladosporium spp. are the more involved (Suominen et al., 1997;Binderup et al., 2002;Turtoi and Nicolau, 2007;Patrignani et al., 2016). Nevertheless, the presence of pathogenic microorganisms in not well-sanitized packaging material is reported in literature (Patrignani et al., 2016). ...
The aim of this work was to study the interaction of corrugated and plastic materials with pathogenic and spoiling microorganisms frequently associated to fresh produce. The effect of the two packaging materials on the survival during the storage of microorganisms belonging to the species Escherichia coli, Listeria monocytogenes, Salmonella enteritidis, Saccharomyces cerevisiae, Lactobacillus plantarum, Pseudomonas fluorescens and Aspergillus flavus was studied through traditional plate counting and scanning electron microscopy (SEM). The results obtained showed that cardboard materials, if correctly stored, reduced the potential of packaging to cross-contaminate food due to a faster viability loss by spoilage and pathogenic microorganisms compared to the plastic ones. In fact, the cell loads of the pathogenic species considered decreased over time independently on the inoculation level and packaging material used. However, the superficial viability losses were significantly faster in cardboard compared to plastic materials. The same behavior was observed for the spoilage microorganisms considered. The SEM microphotographs indicate that the reduction of superficial contamination on cardboard surfaces was due to the entrapping of the microbial cells within the fibers and the pores of this material. In addition, SEM data showed that the entrapped cells were subjected to more or less rapid lyses, depending on the species, due to the absence of water and nutrients, with the exception of moulds. The latter spoilers were able to proliferate inside the cardboard fibers only when the absorption of water was not prevented during the storage. In conclusion, the findings of this work showed the reduction of cross-contamination potential of corrugated compared to plastic packaging materials used in fruit and vegetable sector. However, the findings outlined the importance of hygiene and low humidity during cardboard storage to prevent the mould growth on packaging.
... Pulsed light (PL) is traditionally known as a nonthermal technique used to reduce or kill microorganisms by using broad spectral wavelengths (100-1100 nm) [ [5][6][7]]. PL contains about 54 % UV-C, 25 % visible, and 20 % infrared light [8]. ...
The inactivation of lipoxygenase (LOX) in the whole soya bean prevents lipid oxidation that produces an off-flavour of soya food. The inactivation of lipoxygenase in the whole soya bean by pulsed light (PL) was examined with three distances (5, 7 and 9 cm) from the PL strobe and for different durations. Soya bean was treated with PL with and without ice surrounding the soya bean sample tray for limiting the rise in sample temperature. Results show that without ice surrounding the sample tray, the lowest LOX residual activity was 4.7%, 0.4% and 0.0% for 80-s duration at 5 cm distance from the PL strobe, 110 s at 7 cm from the strobe and 150 s at 9 cm from the strobe, respectively; the soya bean temperature after treatment was 109.6, 116.3 and 114.8 °C, respectively. The instantaneous temperatures of the soya bean core measured during PL operating were above 100 °C. The lipoxygenase band was disappeared after longest PL treatments of each distance compared with the LOX band control as assessed by electrophoresis. The pulsed light had no negative effect on peroxide value of produced soya milk. However, PL reduced significantly the total solid amount and changed the colour of the produced soya milk. The residual activity with sample cooling by ice during treatment was 79.0%, 98.8% and 95.7%, with sample temperatures of 81.7, 91.2 and 66.9 °C, respectively. This study indicates that PL illumination could fully inactivate LOX in whole soya beans, with the photo-thermal effect of PL as the main factor responsible for the inactivation of LOX.
... In fact, extracting the pigments contained in this layer and exposing the extract to a spectrum light in the range of 240À480 nm showed a strong absorbance, which was believed to protect the spores against the deleterious effects of pulsed light. However, it was stated that the presence of these dark pigments, as it is the case for example of A. niger (black) and Aspergillus cinnamomeus (brown), allowing the absorption of more energy than that having lighter pigments (e.g., Aspergillus repens (green)), leads to faster destruction by pulsed light (Turtoi & Nicolau, 2007). Combining pulsed light with thermal treatment (35À45 C for 3À15 min) was shown to be effective in inactivating the growth of fungi conidia (Marquenie, Geeraerd, et al., 2003). ...
... The colour of the spores affected their resistance to pulsed light. Different spores required different fluence for their inactivation [90]. ...
Non-thermal processes have gained importance in recent years due to the increasing demand for foods with high nutritional value and fresh characteristics, representing an alternative to conventional thermal treatments. The sensory attributes of food samples of various kinds treated with non-thermal processing methods are meant to be well preserved and of extended shelf life. Yogurt drinks, apple sauce, and salad dressing have also been shown to retain the freshness with extended shelf life after processing. Food preservation technologies are based on the prevention of microbial growth or on the microbial inactivation. In many cases, foods are preserved by inhibiting microbial activity through those factors that most effectively influence the growth and survival of microorganisms such as temperature, water activity, preservatives addition, pH and modified atmosphere. In all these cases, the microorganisms will not be destroyed and will still be metabolically active and viable if transferred to favorable conditions. As estimates of the infection dose of some pathogenic microorganisms are very low, growth of these microorganisms in foods is not necessary to cause infection.
Most novel non-thermal technologies are still in their early stages of development although some emerging non-thermal processes have now been implemented in industrial-scale systems for commercial and research applications [49,61,80]. Other than irradiation, however, it is safe to say that not one non-thermal process has been developed to a point where its use alone can guarantee the safety of low acid foods. Effective combinations of two or more preservation hurdles may be chosen once the modes of action and cellular targets of each treatment are known [56]. For the intelligent selection of non-thermal processing combinations, therefore, target elements within cell and the effects of treatments on those elements need to be determined. The treatment intensities required for cell inactivation need quantification and standardization also. The small number of scientific studies summarized in this review show that combining non-thermal treatments has great potential for improving the safety and quality of foods, retaining the freshness although many technological and regulatory barriers still need to be overcome before the food supply can receive these benefits.
... The few literature data show that spore-forming bacteria (belonging to the genera Bacillus, Geobacillus, Alicyclobacillus, and Clostridium) and molds (belonging mainly to the species Aspergillus niger, A. cinnamomeus, and Cladosporium herbarum) prevail on packaging microbiota. They are widespread microorganisms, resistant to adverse environmental conditions and endowed with high spoilage potential (Binderup et al., 2002;Turtoi and Nicolau, 2007). However, also yeast and other spoilage bacteria can be present on packaging materials. ...
Aim: Aim of this work was understanding the microbial transfer dynamics from packaging to packed peaches in relation to the packaging used.
Method and Results: A challenge test was performed, inoculating Escherichia coli, Pseudomonas spp. and Saccharomyces cerevisiae on cardboards and RPC (Reusable Plastic Containers), and monitoring their cell loads on fruits according to a probabilistic model and a Response Surface Methodology (RSM) in relation to several independent variables (number of fruit lesions, fruit temperature storage and commercialization time). The data recorded on packed peaches for Pseudomonas and S. cerevisiae were modeled to fit the second order model to study the main, interactive and quadratic effects of the independent variables on the cell loads of target microorganisms as well as on the shelf-life of the fruits in relation to packaging material used. The data collected for E. coli were codified as presence (1) or absence (0) and modeled with a logistic regression analysis to assess the probability of E. coli transferring from packaging to fruits in relation to the adopted variables. The data showed a higher contamination frequency of the fruits packed in plastic than in cardboard. Increasing the storage temperature and the number of lesions, the probability of transferring of E. coli from packaging materials to fruits increased, independently on commercialization time or packaging used. For Pseudomonas, the contamination levels detected on fruits packaged in plastic were significantly higher compared to those found on fruits packed in cardboard, independently on the considered variables. The polynomial equations showed the S. cerevisiae cell loads of fruits stored in plastic was positively affected by the quadratic term of temperature.
Conclusions: the use of cardboard, compared to plastic, can significantly reduce the potential of microbial transferring from packaging to fruits. The probabilistic and kinetic models used showed a higher microbiological qualities of peaches stored in cardboard boxes, independently on the independent variables considered. The best performances of cardboard, compared to plastic, was probably due to its capability to entrap microbial cells.
Significance and Impact: cardboard reduces fruit contamination and increases their shelf-life with positive fallouts on fruit shelf-life and all the logistic and distribution chain.
... The colour of the spores affected their resistance to pulsed light. Different spores required different fluences for their inactivation (Turtoi and Nicolau, 2007). ...
With the increase in consumer awareness, demand for minimally processed foods and eco-friendliness, various technologies were developed for food processing and preservation. The conventional thermal food preservation and processing techniques appears to have the shortcoming of adversely affecting the food quality, organoleptic properties and nutrients. However, many non-thermal food preservation technologies were developed to serve the purpose. Many of such technologies are active packaging, pulsed electric field processing, high pressure processing, ultraviolet light processing and pulsed light processing. Pulsed light technology appears to be one of the best alternatives to conventional thermal and chemical decontamination process. Pulsed light processing technique has been commercialized and there have been many reports on the wide spectrum application of this technology. The technology not only decontaminates the food or packaging but also maintains its texture, nutrients etc. The germicidal effect was found to be due to photochemical and photothermal effect. It also has many other applications apart from decontamination, one such being reducing the allergen potent of some naturally occurring foods. The following review article is a compilation of reports on the mechanism of action of the technology and recent application of pulsed light processing.
... High intensity light is a synonymous term with pulsed UV light, pulsed light, broad spectrum white light, pulsed white light, and near infrared light; and defines the range of light in which non-ionizing irradiation is emitted [98,99]. Intense light pulses is an alternative preservation technique to thermal treatment for killing micro-organisms using short-time high frequency pulses of an intense broad spectrum, rich in UV-C light [100][101][102][103], which is the portion of the electromagnetic spectrum corresponding to the band between 200 and 280 nm. Pulsed light is produced using technologies that multiply the power manyfold [99]. ...
IntroductionSeafood preservation techniquesConclusions
References
... Another type of UV radiation source used for decontamination is the pulsed UV lamp (PUV), which produces a broad radiation spectrum (100-1000 nm) by pulsing the discharge produced by xenon lamps (1). A great number of studies have shown high efficiency of these pulsed UV radiation systems for inactivation of vegetative bacteria (3)(4)(5)(6), endospores (3,7), yeasts (3,8,9) and molds (7,10,11). A more recent study by Schaefer et al. (12) described a different type of pulsed UV radiation systemsurface discharge (SD) lampused for water treatment. ...
Among different physical and chemical agents, the UV radiation appears to be an important route for inactivation of resistant microorganisms. The present study introduces a new mercury free Dielectric Barrier Discharge (DBD) flat lamp, where the biocide action comes from the UV emission produced by rare earth phosphor obtained by spray pyrolysis, following plasma excitation. In this study, the emission intensity of the prototype lamp is tuned by controlling gas pressure and electrical power, 500 mbar and 15 W, corresponding to optimal conditions. In order to characterize the prototype lamp, the energetic output, temperature increase following lamp ignition and ozone production of the source were measured. The bactericidal experiments carried out showed excellent results for several gram-positive and gram-negative bacterial strains, thus demonstrating the high decontamination efficiency of the DBD flat lamp. Finally, the study of the external morphology of the microorganisms after the exposure to the UV emission suggested that other mechanisms than the bacterial DNA damage could be involved in the inactivation process.This article is protected by copyright. All rights reserved.
... Another type of UV radiation source used for decontamination is the pulsed UV lamp (PUV), which produces a broad radiation spectrum (100-1000 nm) by pulsing the discharge produced by xenon lamps (1). A great number of studies have shown high efficiency of these pulsed UV radiation systems for inactivation of vegetative bacteria (3)(4)(5)(6), endospores (3,7), yeasts (3,8,9) and molds (7,10,11). A more recent study by Schaefer et al. (12) described a different type of pulsed UV radiation systemsurface discharge (SD) lampused for water treatment. ...
In this paper, we investigate the UVC light emission from phosphors under plasma excitation for anti-microbial testing on Escherichia coli (E-coli).
... Thus, pyocyanin and pyoverdine pigments protect P. aeruginosa against UV light (Burke et al. 1990;Farrell et al. 2010). However, this point should still be addressed because contradictory results have been found concerning the UV-protective role of pigmentation (Turtoi and Nicolau 2007;Khaneja et al. 2010). ...
The potential to commercialize nonthermal ultraviolet (UV) light technologies as new methods for preserving food products has caught the attention of a food industry that wishes to fulfill consumers' demands for fresh products. Numerous investigations have demonstrated UV light's ability to inactivate a wide range of microorganisms. However, the lack of UV sensitivity data from pathogenic and spoilage bacteria is evident. In addition, the main factors associated with UV light in terms of microbial lethality remain unclear. This review surveys critical factors (process, microbial, and environmental parameters) that determine UV microbial resistance and assess the effects of such factors on the inactivation mechanism and repair pathway efficiency. The effects of some of these factors, such as prior sublethal stresses and post-recovery conditions of UV treatments, may extensively improve the damage repair capacity and thus microbial survivability. Further research is needed to establish adequate control measures pre- and post-UV treatments. Furthermore, the possibility of combining UV light with conventional preservatives and other nonthermal technologies was assessed. The combination of UV light with mild heating or oxidant compounds could offer promising treatments to enhance the safety and stability of minimally processed foods.
... Among them, pulsed light (PL) process showed to be effective in inactivating a wide range of microorganisms (vegetative bacteria, moulds, bacterial, fungal spores.) involved in food products spoilage (Arrowood, Xie, Rieger, & Dunn, 1996;Gómez-López, Devlieghere, Bonduelle, & Debevere, 2005;Nicorescu et al., 2013;Rajkovic, Smigic, & Devlieghere, 2010;Turtoi & Nicolau, 2007). Indeed, recent studies have demonstrated the efficacy of PL to inactivate microorganisms on the surface of several food products, such as seafood (Dunn, Ott, & Clark, 1995), salmon filets (Ozer & Demirci, 2006), ready-to eat sausages (Uesugi & Moraru, 2009) and chicken breast (Keklik, Demirci, & Puri, 2010). ...
... The mode of action of the pulsed light process is attributed to the effect of the high peak power and the UV co mponent of the broad spectrum of the flash. Inactivation occurs by several mechanisms, including chemical modificat ion and cleavage of DNA, protein denaturation and other cellular materials alteration [14]. Studies in which the UV co mponent was filtered out showed marked reductions in process efficacy [12]. ...
... The mode of action of the pulsed light process is attributed to the effect of the high peak power and the UV co mponent of the broad spectrum of the flash. Inactivation occurs by several mechanisms, including chemical modificat ion and cleavage of DNA, protein denaturation and other cellular materials alteration [14]. Studies in which the UV co mponent was filtered out showed marked reductions in process efficacy [12]. ...
... Although the main effect of PL on microorganisms is due to the photochemical action of the UV-C (200–280 nm), approximately 54% of the emitted energy falls into the ultraviolet range (Pataro et al., 2011), which causes thymine dimerisation in the DNA chain preventing cell replication and ultimately leading to death (Gómez-López, Ragaert, Debevere, & Devlieghere, 2007 ). Its lethal effect may also be caused by localised heating of microbial cells (photothermal effect) and the release of energy as several intense flashes per second which increases the instantaneous energy intensity that contributes to microbial inactivation (Turtoi & Nicolau, 2007). The impact of each mechanism in microbial inactivation would depend then on various factors such as the fluence or food adsorption characteristics (Pataro et al., 2011). ...
Pulsed light (PL) and Thermosonication (TS) were applied alone or in combination using a continuous system to study their effect on Escherichia coli inactivation in apple juice. Selected quality attributes (pH, °Brix, colour (L, a, b, ΔE), non-enzymatic browning (NEBI) and antioxidant activity (TEAC)) were also evaluated pre-and post-processing. Two PL (360 μs, 3 Hz) treatments were selected and the juice exposed to energy dosages of 4.03 J/cm 2 ('low' (L)) and 5.1 J/cm 2 ('high' (H)) corresponding to 51.5 and 65.4 J/mL, respectively. The juice was also processed by TS (24 kHz, 100 μm) at 40 °C for 2.9 min (L) or 50 °C for 5 min (H), corresponding to 1456 and 2531 J/ml energy inputs, respectively. The effect of the resulting four energy levels and sequence (PL + TS and TS + PL) was studied. When the technologies were applied individually the maximum reduction achieved was 2.7 and 4.9 log CFU/mL (for TS (H) and PL (H) respectively), while most of the combined treat-ments achieved reductions in the vicinity of 6 log CFU/mL, showing an additive effect for both technologies when acting in combination, regardless of the sequence applied. All treatments significantly changed the col-our of apple juice and the sequence in which the technologies were applied affected colour significantly (P b 0.05). The energy level applied did not affect any of the measured quality attributes.
... The inactivation of pathogen microorganisms in the food industry was applied with pasteurization, high temperature pasteurization and UV light techniques, which are common methods. However, in the recent years, the studies have been concentrated on non-thermal technologies which prevent the degeneration of the feeding value of food, such as microwave [2], high pressure [3], pulsed electric field [4], pulsed light [5], oscillating magnetic fields [6], ultrasound [7], pulsed X-Rays [8] and AC electric field [9]. The studies about the use of these new inactivation methods aiming to inactivate pathogens in the waste water have just started. ...
The treatment of the sewage sludge produced in the biological treatment plants have increasingly become a serious problem. For this reason, when the reuse and the disposal of the sludge are taken into consideration, the pathogens that the sludge contains should be seriously reduced. In this study, as an alternative to traditional treatment methods for the purpose of pathogen inactivation in sewage sludge, AC electric field, which is a non-thermal technology, was used. The electric field energy designed for the inactivation of the microorganisms in the sewage sludge affects directly the pores in the cell wall in a physical manner. In order to evaluate the inactivation effect of the electric field, AC electric field (50 Hz, 0,6 -1,2kV cm-1) was applied to the sewage sludge containing Salmonella spp. and Salmonella typhimurium. It was observed that Salmonella spp. population reduced 1.4 log in 0.6 kVcm-1, 1.1 log in 1.2 kV cm-1and S. typhimurium reduced 0.5 log in pure culture. The results showed that the electric field treatment increased the transmittance of the cell wall and that caused destructions in the cell membranes.
... When not stored in proper conditions, packaging materials can get contaminated with microorganisms. These contaminants are transferred to food via packages, and their growth on food can result in economic losses because of spoilage [88]. In addition, they may cause public health concerns. ...
Non-thermal plasma (NTP) is electrically energized matter, composed of highly reactive species including gas molecules, charged particles in the form of positive ions, negative ions, free radicals, electrons and quanta of electromagnetic radiation (photons) at near-room temperature. NTP is an emerging nonthermal technology with potential applications for decontamination in the food industries. An upsurge in the research activities for plasma based inactivation of food borne pathogens is evident in the recent years. These studies have shown that NTP can be used for the surface decontamination of raw produce, dried nuts and the packaging materials etc. This paper reviews the action of plasma agents on the microbial classes and describes proven and potential applications in food processing. Novel developments in the technology and a future outlook for the application to foods are discussed.
... Traditional methods for juice packaging aim to reduce the exposure of the juice to oxygen through the use of high barrier materials such as glass or foil laminates in brick packs, with or without nitrogen flushing or improving gas barrier of PET by blending with aromatic polyamides (Hu et al., 2005). The use of oxygen scavengers with an appropriate packaging material can further reduce the presence of dissolved oxygen in the juice or present initially in the headspace (Ros-Chumillas, Belissario, Iguaz, & López, 2007;Zerdin, Rooney, & Vermuë, 2003). Unlike glass and PET, PE-HD and PE-LD bottles were not effective at retarding degradations of flavour compounds and vitamin C of PEF-treated orange juice during storage at 4 C for 112 days, which might be due to their relatively low barrier property of polyethylene to oxygen (Ayhan, Yeom, Zhang, & Min, 2001). ...
Food processing and preservation are generic terms that cover all aspects of extending the shelf life of foods. A number of novel thermal and non-thermal processing methods are actively undergoing research and development. A key step that needs addressing is finding the best packaging materials for commodities which preserve the benefits of improved product quality imparted by preservation technologies.
Modern packaging can be defined as a means of ensuring the safe delivery of a product to the consumer at the lowest overall cost. Packaging materials are designed to protect the product from various environmental factors, including microorganisms. Microbiological studies of packaging materials and packages in Russia are sporadic and not systematized. At the same time, abroad, this issue is paid close attention, which is associated not only with environmental issues, but also with the desire to take a more advanced position in the consumer market. In this regard, the purpose of this study was to assess the role of packaging materials in the cross microbiological contamination of packaged products. We investigated different types of packaging and packaging materials. It was found that they were mainly contaminated by mold fungi, of which 70% were Aspergillus and 30% Penicillium. Of these, Aspergillus flavus, Aspergillus niger, Aspergillus amstelodami, Penicillium brevicompactum were most often present. The contamination level ranged from 1.1×103 to 1.6×105 CFU/sm2. Fresh tomato and cucumber packages contained 29% of mold fungi (Penicillium, Alternaria, Paeolomices, Fusarium) and 71% of Enterobacteriace (Enterobacter agglomerans, Enterobacter cloace, Serratia marcescens). A significant number of bacteria, including Salmonella arizona and Staphylococcus aureus were detected on the surfaces in contact with food products during their production and sale.
Pulsed light (PL) is an emerging processing method that utilizes short duration, high intense pulses of polychromatic light to disinfect food, food contact surfaces and packaging materials, through photochemical, photothermal, and photophysical mechanisms. Moreover, PL can be used to enhance functionality and reduce allergenic power of food and food ingredients. These effects are predominately derived from the UV portion of the PL spectrum. However, although the first industrial commercial applications have been achieved, the technique possess some intrinsic limitations, which make it suitable especially for smooth surface and transparent drinks, that have impeded till now the widespread exploitation in food industry. In this chapter, the fundamentals principle of PL technology, the mechanism of action, as well as the role played by the main process and design parameters, product properties and microbial factors and their interactions on the inactivation mechanism and efficacy of PL is critically analyzed and discussed. The most critical aspects of PL equipment and the different technological solution that could be adopted to improve the efficiency of PL treatment are also presented. The chapter then describe the applications of PL in food sector, emphasizing the main advantages and shortcomings in terms of their impact on the safety, nutritional, and health properties of food products. Moreover, the general discussion also covers the analysis of the energy consumption and sustainability aspects associate to PL technology, and conclude with the recent advancements and future perspectives.
Food preservation in the present era seems to be driven by plasma processing due to its efficiency in controlling microorganism at very less temperatures. Legumes are mostly soaked before cooking. Peleg model fitting for six chickpea cultivars after plasma treatment was studied when these were soaked in distilled water at ambient temperature. The cold plasma treatment of 40, 50 and 60 watts each with an exposure time of 10, 15, 20 minutes was applied. The Cold plasma treatment shown an increase in the water absorption rate of chickpea cultivars with respect to changing plasma parameters, but there was no change in the water absorption capacity of the samples. K 1 (Peleg rate constant) decreased from 32.3 to 4.3 x 10 − 3 (h % ⁻¹ ) for all the six chickpea cultivars consistently as plasma power and treatment time increased, which shown the increase in water absorption rate. K 2 (Peleg capacity constant) ranged from 9.4 to 12 x 10 − 3 (h % ⁻¹ ) for all the six chickpea cultivars. It did not increase or decrease consistently as plasma power and treatment time increased which shown no effect of plasma treatment on water absorption capacity. Peleg model fitting was found successful to show the correlation of water absorption of chickpea cultivars. The model fit was in the range from R ² ≥ 0.9873 to 0.9981 for all the six chickpea cultivars with increasing soaking time and cold plasma treatment.
Non‐thermal technologies can maintain fruit and vegetable products quality better than traditional thermal processing. Pulsed light (PL) is a non‐thermal method for microbial inactivation (vegetative cells and spores) in fruits and vegetables. The PL treatment involves application of intense and short‐duration pulses of broad spectrum wavelengths ranging from UV to near‐infrared (100 to 1100 nm). This review summarized application of PL technology to control microbial contamination and increasing shelf‐life of some fruits and vegetables including apple, blueberries, grape, orange, strawberries, carrot, lettuce, spinach and tomato. The microbial inactivation in very short treatment times, low energy used by this system, flexibility for solid or liquid samples, few residual compounds and no synthetic chemicals that cause environmental pollution or harm humans, are benefits of PL technique. The efficiency of PL disinfection is closely associated with the input voltage, fluence (energy dose), composition of the emitted light spectrum, number of lamps, the distance between samples and light source, and frequency and number of applied pulses. The PL treatments control pathogenic and spoilage microorganisms, so it facilitating the growth and development of the starter microorganisms affecting product quality.
Pulsed Light (PL) is now recognized as a promising non-thermal food processing technology with a wide range of applications in disinfection, extending shelf life, and inhibiting allergic reactions from the consumption of certain foods. In recent years, the research in PL has developed rapidly, and the knowledge domain associated with this area has made significant progress. Interested scholars in this and allied areas need to keep up with the new tendency and critical developments. In this study, a progressively integrated network is derived from 475 archived articles on PL technology obtained from the Web of Science Core Collection (WoSCC) database in “Food Science Technology” between 2011 and 2020. These scientific documents were analyzed through HistCite and CiteSpace. The hot-spots and landmark references of PL technology were obtained by scientometric analysis. This review will guide scholars to track new trends and identify critical new applications of PL technology in the food industry.
La décontamination microbienne est sujet majeur de préoccupation du secteur agroalimentaire. Des nouvelles technologies physiques de décontamination, dites athermiques, sont d’un emploi croissant. La Lumière Pulsée, utilisée pour décontaminer les surfaces et les liquides clairs, en fait partie. Elle utilise des flashes de lumière blanche riches en UV, et délivrés en moins d'une milliseconde. La plupart des traitements par lumière pulsée sont définis dans la littérature par des paramètres spécifiques à l'équipement utilisé. Le but de cette étude a été dans un premier temps de caractériser le traitement par lumière pulsée par les grandeurs physiques appropriées (fluence, tension aux bornes de la lampe, etc…), en reliant une dose de lumière à niveau de décontamination microbienne. L'équipement pilote de la société CLARANOR a révélé des réduction logarithmiques allant jusqu'à plus de 5 unités sur des spores de B. subtilis, et de plusieurs autres espèces de bactéries sporulées, avec des fluences inférieures à 1,5 J/cm², appliquée en un seul flash La mise au point d'une méthode d'inoculation par spray à permis d'évaluer l'efficacité décontaminante de la lumière sur différentes surfaces, y compris des hydrophobes, par pulvérisation des microorganismes en couches formées d’une seule épaisseur de cellules. L'application de la technologie sur des surfaces inertes comme le polystyrène a montré une décontamination notamment sur des spores de B. subtilis, et d'A. niger, supérieures à 4 cycles logarithmiques en utilisant des fluences inférieures à 1 J/cm². L'influence des facteurs liés au système d'éclairage a montré une importance capitale des longueurs d'onde UV, mais ne permettent pas de réduire l'efficacité à la seule action de la dose UV-C. L'efficacité de la technologie a permis de réaliser une étude concernant la décontamination de sirop de sucre dans une optique d'application industrielle. Une réduction supérieure à 3 cycles logarithmiques de spores d'A. acidoterrestris dans du sirop de saccharose a été obtenue en flux continu, sur une épaisseur de 10 mm de liquide.
In this work the influence of modified atmosphere packaging on the quality characteristics of fresh–cut green bell pepper stored at 0 °C and 5 °C was studied. The experimental results revealed that MAP managed to retain the colour, texture and nutritional value of the produce close to the initial ones. The employed gas mixtures of 5% Ο2–10% CΟ2 and 5% Ο2–15% CΟ2 retained the overall produce appearance in both storage temperatures reducing considerably the discoloration of the cut area. From the two tested storage temperatures, 0 °C proved to be more efficient, retaining the organoleptic quality of the produce.
Σκοπός της εργασίας αυτής ήταν η μελέτη της επίδρασης της τροποποιημένης ατμόσφαιρας (MAP) στα ποιοτικά χαρακτηριστικά κομμένης πράσινης πιπεριάς που συντηρήθηκε στους 0 °C και 5 °C. Τα αποτελέσματα έδειξαν ότι η MAP διατήρησε το χρώμα, την υφή και τη θρεπτική αξία του προϊόντος στα αρχικά επίπεδα. Τα μίγματα 5% Ο2–10% CΟ2 και 5% Ο2–15% CΟ2 διατήρησαν καλύτερα τη συνολική εμφάνιση του προϊόντος και στις δύο θερμοκρασίες μειώνοντας αισθητά τον αποχρωματισμό της τομής. Από τις δύο θερμοκρασίες οι 0° C αποδείχθηκαν πιο αποτελεσματικοί στη διατήρηση της οργανοληπτικής ποιότητας του προϊόντος.
Inactivation of pure soybean lipoxygenase (LOX) by pulsed light (PL) technique was found to occur due to a photochemical effect, while inactivation of soybean LOX in a real food (soymilk) was due to the photothermal effect of PL. The effect of solution properties on the photochemical ability of PL to inactivate and degrade LOX was investigated. LOX was placed in different conditions and treated with PL at a 7 cm distance with different times. The result showed that LOX was less stable during PL operation at pH 9 compared with pH 6.8. Increasing LOX concentration, adding starch, and making a colored solution did reduce the photochemical ability of PL to inactivate LOX. PL and thermal treatment of partially purified LOX degraded the LOX band (measured by using SDS-PAGE) when no protease inhibitors were added. Controlling protease activity led to degradation of LOX by PL but not by thermal treatment.
Background Nowadays emerging technologies for food preservation is a topic of increasing importance because of the high efficiency of these techniques controlling pathogenic or spoilage microorganisms in foods. Most of these technologies also work at low temperature (cold pasteurization processes) improving nutritional or sensory quality. Scope and approach Grapes normally show a typical wild microorganism population of log 2–4 cfu/mL in yeasts and fungus, log 2 in bacteria, mainly LAB. The use of emerging technologies such as high hydrostatic pressure, ultrasounds, pulsed electric fields, pulsed light, UV irradiation, e-beam irradiation, ozone and electrolyzed water destroy or strongly minimize the initial wild microbiota allowing more hygienic winemaking processes. Frequently, these technologies increase the extraction of phenolic compounds and aromatic molecules improving sensory quality. Also facilitate dose reduction of some chemical additives widely used in oenology and with allergenic properties like sulphur dioxide. Moreover, new winemaking biotechnologies like the use of non-Saccharomyces yeasts or yeast-bacteria co-inoculations can be facilitated in either grape or must fermentations with low microbial loads. Key findings and conclusions This review highlights some useful novel strategies to improve the phenolic extraction during maceration-fermentation processes and to reduce natural microflora present in grape must allowing the better implantation and performance of selected yeast strains.
Tra le numerose funzioni assegnate ai materiali e ai sistemi di confezionamento, le più importanti sono certamente quelle relative alla protezione degli alimenti e alla prevenzione delle possibili alterazioni di natura microbica, i cui effetti possono essere deleted sia per la qualità sia per la sicurezza dei prodotti. Una conoscenza corretta e approfondita di questo fondamentale ruolo del packaging — e, soprattutto, la possibilità di poterlo stimare e quantificare in anticipo — è particolarmente utile nella scelta delle forme di confezionamento più idonee e nell’organizzazione e nella gestione della logistica distributiva.
Microbial decontamination is a major concern in the food industry. Non-thermal physical technologies are increasingly used. Pulsed Light used to decontaminate surfaces and clear liquids is one of these new technologies. Pulsed Light uses intense flashes of white light rich in UV, delivered in less than one millisecond. Most of treatments are characterised in the literature using parameters which are specific to the equipment. The aim of this study was firstly to characterise the PL treatment in expressing a log reduction as a function of the dose received by the microorganism. The pulsed light pilot of the CLARANOR company allowed a high decontamination of B. subtilis spores and other sporulating bacterial species, with more than 5 log reductions at fluences lower than 1.5 J/cm², obtained in only one flash. The development of a spray inoculation method was made to evaluate the decontamination efficiency on different surfaces, including hydrophobic surfaces, with a monolayer inoculation. The Pulsed light efficiency on inert surfaces such as polystyrene lead to high decontaminations including B. subtilis and A. niger spores, with more than 4 log reductions using fluences lower than 1 J/cm² in both cases. The influence of the physical factors of the light showed that UV wavelengths are essential for the decontamination, but the efficiency is not totally explained by the action of the UV-C dose. The efficiency of pulsed light allowed to study sugar syrup decontamination, in view of industrial application. Three log reductions of A. acidoterrestris spores were obtained in 10 mm thickness sugar syrup, using a flow-through system
Growing awareness and preference of the consumers towards the minimum
processed meat with natural sensory and nutritive characteristics leads to the introduction of
non thermal techniques for the decontamination of meat. The Pulse Light (PL) and the Pulse
Electric Field (PEF) are the latest non thermal techniques employed for decontamination of
meat without production of any harmful toxic compounds. These techniques retain the
natural freshness, colour and nutritive characteristics of meat in comparison to thermal and heat processing.
Inactivation of Listeria innocua on food packaging materials by Pulsed Light (PL) treatment was investigated. Coupons of low density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene-laminated ultra-metalized polyethylene terephthalate (MET), polyethylene-coated paperboard (TR), and polyethylene-coated aluminum foil paperboard laminate (EP) were inoculated with L. innocua cells in stationary growth phase. Inoculated coupons (∼8 CFU/coupon) were treated with Pulsed Light fluence of up to 8.0 J/cm2, and survivors were determined. Reductions up to 7.2 ± 0.29, 7.1 ± 0.06, 4.4 ± 0.85, 4.5 ± 1.32, and 3.5 ± 0.82 log CFU/coupon were obtained on LDPE, HDPE, MET, TR, and EP, respectively. Inactivation data were used to determine Weibull kinetic parameters and predict inactivation in a wide range of fluence. Increasing surface reflectivity and surface roughness appeared to induce lower inactivation. Minimal surface heating was observed for all materials except MET, on which significant heating occurred. These results demonstrate the potential of Pulsed Light as an effective method for decontaminating food packaging materials.
In recent years, plasma has proved to have great promise in the fields of chemistry, biology, physics, biotechnological and medical sciences. In this review, we discuss plasma versatility and applicability in various areas, such as interactions with biomolecules, biomedical treatments, chemical synthesis, removal of volatile organic compounds, electrochemical reactions, nanoscience, surface modifications, food engineering and water purification applications. Specially, we discuss how we can increase the utility of plasma in various phases of chemistry and biochemistry. We also shed light on the aspect that plasma can be a new source of green chemistry.
The impact of several pulsed light (PL) processing
parameters on microbial inactivation was evaluated in
buffered water systems using Listeria innocua as test microorganism.
Reduction in L. innocua population increased
directly with pulse energy, pulse fluence and the number of
light pulses, and inversely with the distance between samples
and a xenon lamp. Overall, the higher the amount of
light received by the target microorganism by both direct
and reflected light, the larger the loss of cell counts. Total
fluence striking on the samples per area unit was shown to
be the most relevant process factor affecting L. innocua
inactivation by PL. Microbial population decreased with
total fluence, obtaining more than 7 log reductions after
0.4 Jcm−2. The inactivation kinetics was clearly sigmoidal,
showing an initial shoulder in the inactivation curve. No
significant reduction (<1 log) in L. innocua counts was
induced at fluences lower than 0.04 Jcm−2. From this
threshold total fluence, L. innocua inactivation increased
exponentially to the maximum detectable level. Since total
fluence is the most relevant process factor affecting microbial
inactivation by PL, this parameter must be reported to
describe PL processing conditions.
Consumers demand high-quality processed foods with minimal changes in nutritional and sensory properties. Nonthermal methods
are considered to keep food quality attributes better than traditional thermal processing. Pulsed light (PL) is an emerging
nonthermal technology for decontamination of food surfaces and food packages, consisting of short time high-peak pulses of
broad spectrum white light. It is considered an alternative to continuous ultraviolet light treatments for solid and liquid
foods. This paper provides a general review of the principles, mechanisms of microbial inactivation, and applications of PL
treatments on foods. Critical process parameters that are needed to be optimized for a better efficiency of PL treatments
are also discussed. PL has considerable potential to be implemented in the food industry. However, technological problems
need to be solved in order to avoid food overheating as well as to achieve better penetration and treatment homogeneity. In
addition, a more extensive research is needed to understand how PL affects quality food attributes.
The main objective of this work was to explore the applicability of the Intense Light Pulses (ILP) for decontamination of a stainless steel meat contact surface, exemplified by a slicing knife, as a function of time between contamination and decontamination, number of light pulses applied, and the prior contact with different meat matrices. Listeria monocytogenes and Escherichia coli O157:H7 were chosen as the challenge microorganisms. The ILP system was a laboratory-scale four-lamp batch system generating 3 J/cm2 with an input voltage of 3000 V. The results obtained demonstrate successful application of ILP treatment for reduction of L. monocytogenes and E. coli O157:H7 on a surface of stainless steel slicing knife. The inactivation effectiveness depended on the type of meat product that was in the contact with the treated surface and on the time between the contamination and the ILP treatment. Statistical analysis showed the significant interaction between the time and type of meat product on the effectiveness of ILP treatment. The highest effectiveness of the ILP (the complete inactivation of 6.5 log CFU/side of knife) was obtained when the knife surface was in contact with the products containing lower fat and protein content and when it was treated with pulsed light as fast as possible after the contamination (within 60 s). The decontamination efficacy of ILP treatment could not be improved by multiple light pulses if lost due to the extended time between the moment of contamination and ILP treatment. Results showed that the suggested approach can be very effective as an intervention strategy along meat processing lines preventing cross-contamination between the equipment and the final product.
Pulsed light (PL) treatment has been proven effective for killing a wide variety of microorganisms on foods and food contact materials. However, there is concern regarding how shading may impact the effectiveness of PL when applied to imperfect surfaces. The main objective of this work was to examine how surface properties, particularly topography, influence the microbicidal effect of PL. Four types of stainless-steel surfaces were inoculated with Listeria innocua and treated with up to 12 pulses of light. The highest level of inactivation achieved was about a 4-log reduction. Initially, an increase in inactivation with increasing treatment intensity was observed, but the inactivation curves tailed off above 3 light pulses. The differences in inactivation levels among the 4 finishes at specific treatment levels were rather insignificant, but some interesting trends were observed. At low treatment levels, inactivation on the smoothest finish was slightly lower than for the other surfaces, due to clustering of the cells on the highly hydrophobic smooth surface and to its reflective nature. For the roughest surface, scanning electron microscopy (SEM) imaging confirmed the preferential location of the cells inside surface features, which also promoted a relatively uniform distribution of the cells across the surface. This counter balanced to some extent of the shading effects, and as a result inactivation on the roughest surface was comparable to inactivation on the smoother surfaces. These results demonstrate that PL can be effective on both smooth and rough surfaces, but also indicate a complex effect of various surface properties on inactivation.
The combined effects of water activity (aw), pH and temperature on the germination and growth of seven xerophilic fungi important in the spoilage of baked goods and confectionery were examined. Eurotium rubrum, E. repens, Wallemia sebi, Aspergillus penicillioides, Penicillium roqueforti, Chrysosporium xerophilum and Xeromyces bisporus were grown at 25, 30 and 37 degrees C on media with pH values of 4.5, 5.5, 6.5 and 7.5 and a range of water activities (aw) from 0.92 to 0.70. The aw of the media was controlled with a mixture of equal parts of glucose and fructose. Temperature affected the minimum aw for germination for most species. For example, P. roqueforti germinated at 0.82 aw at 25 degrees C, 0.86 aw at 30 degrees C and was unable to germinate at 37 degrees C. E. repens germinated at 0.70 aw at 30 degrees C, but at 25 and 37 degrees C, its minimum aw for germination was 0.74. C. xerophilum and X. bisporus germinated at 0.70 aw at all three temperatures. The optimum growth occurred at 25 degrees C for P. roqueforti and W. sebi, at 30 degrees C for Eurotium species, A. penicillioides and X. bisporus and at 37 degrees C for C. xerophilum. These fungi all grew faster under acidic than neutral pH conditions. The data presented here provide a matrix that will be used in the development of a mathematical model for the prediction of the shelf life of baked goods and confectionery.
Pulsed light is produced using engineering technology that multiply power many fold. Power is magnified by accumulating the electrical energy in an energy storage capacitor over relatively long times and releasing this stored energy to do work in much shorter times. The result is a very high power during the duty cycle, with expenditure of only modest average power consumption. For food and packaging applications, a new method uses the bacterial power of an intense pulsed light to extend the shelf life of foods and kill microorganisms on packaging materials. Baked goods, seafoods and meats, fruits and vegetables and many other foods show significant reductions in microbial burden, enhanced shelf life, added safety, and no change in nutritional properties after pulsed light treatment.
Numerous food products owe their production and characteristics to the activities of microorganisms. Many of these, including such foods as ripened cheeses, pickles, sauerkraut, and fermented sausages, are preserved products in that their shelf life is extended considerably over that of the raw materials from which they are made. In addition to being made more shelf stable, all fermented foods have aroma and flavor characteristics that result directly or indirectly from the fermenting organisms. In some instances, the vitamin content of the fermented food is increased along with an increased digestibility of the raw materials. The fermentation process reduces the toxicity of some foods (for example, gari and peujeum), while others may become extremely toxic during fermentation (as in the case of bongkrek). From all indications, no other single group or category of foods or food products is as important as these are and have been relative to nutritional well-being throughout the world. Included in this chapter along with the classical fermented foods are such products as coffee beans, wines, and distilled spirits, for these and similar products either result from or are improved by microbial fermentation activities.
The first and second editions of Fungi and Food Spoilage established a reputation as the foremost book on foodborne fungi. This completely revised and updated third edition is an invaluable reference for food microbiologists investigating fungal spoilage and sources of mycotoxin contamination in foods. The introductory chapters of the book deal with the ecology of food spoilage and give an overview of how food processing, packaging and storage affect fungal growth. Subsequent chapters cover the fundamentals of classifying and naming fungi and current methods for isolation and enumeration, including general and special purpose media, incubation conditions, etc. The major part of the book provides keys, descriptions and illustrations of all yeasts and moulds commonly encountered in foods. Characteristics of the species, including their ecology and potential for mycotoxin production, are also included. The broad and practical nature of the coverage will appeal to microbiologists, mycologists and biotechnologists in the food industry, academic, research and public health institutions. Dr John Pitt and Dr Ailsa Hocking are both Honorary Research Fellows at CSIRO Food Science Australia, North Ryde, NSW, Australia. © Springer Science+Business Media, LLC 2009. All rights reserved.
Scope of Deliverables: Processes designed for the bacterial inactivation of foods and packages with pulsed light are described here. Possible mechanisms of bacterial inactivation are also discussed as well as critical factors that influence the efficiency of the process. Also, the need for future research is addressed. Much of the information comes from industry sources; therefore, independently conducted research is needed to validate the effectiveness of pulsed light processes for food preservation.
Cells of Saccharomyces cerevisiae were inoculated on glass and subjected to intense light pulses (ILP) treatment for up to 0.715 J/cm2 energetic density and different time at a 7-cm distance from the flash lamp. Population reductions higher than 2 log10 colony-forming units per square centimetre (CFU/cm 2 ) were achieved. Calculation revealed a D-value ranging from 1.04×10-3 s to 5.12×10-3 s and a Z-value of 0.684 J/cm 2 . The study has demonstrated that ILP is a promising treatment for packaging material decontamination and/or sterilisation.
A lot of research in the field of food science has focused on new preservation technologies but very few of these methods have been implemented by the food industry until now. This article describes the most intensively investigated new preservation methods with their possibilities and especially their limitations, often hampering their implementation by the food industry. Many alternative [`]non-thermal' treatments have been proposed with high hydrostatic pressure and pulsed electrical fields being the most investigated ones. Both techniques allow killing of vegetative microorganisms but fail until now, when applied alone, to destroy spores. New packaging systems are introduced such as modified atmosphere packaging and active packaging systems. The latter systems have until now a limited application in practice due to incompatibility with legislation, limited effectivity and thermolability of active compounds. Natural compounds, such as essential oils, chitosan, nisin or lysozyme, are investigated to replace chemical preservatives and to obtain [`]green label' products. Their application is mainly hampered due to interaction of the natural compounds with food ingredients and due to changes in the organoleptical properties when introduced in a food. The application of protective cultures, able or unable to produce antimicrobial compounds such as bacteriocins are proposed to inhibit growth of unwanted microorganisms. The activity of bacteriocins is however often limited due to its narrow activity spectrum, its inactivation due to interaction with food ingredients or proteolytic action of the food, its limited diffusion in solid matrixes and the occurrence of loss of bacteriocinogenicity of the culture and of resistance of the target organisms. This overview nuances the application of the above mentioned preservation techniques and focuses on draw backs on their application by the food industry.
An enzyme-linked immunosorbent assay was developed for the detection of molds in dairy products. New Zealand White female rabbits were immunized with .45 mg of partially purified extracellular antigen from freeze-dried culture filtrates of Aspergillus versicolor, Cladosporium herbarum, Geotrichum candidum, Mucor circinelloides, and Penicillium chrysogenum. Blood was drawn at various intervals, and antibodies were separated and purified. Antibody-peroxidase conjugates were prepared with the following ratios being the optimum ones: A. versicolor 10:20; C. herbarum 5:10; G. candidum 1:10; M. circinelloides 5:5; and P. chrysogenum 10:10. The assays were sensitive within a range of 1 ng to 1 microgram/ml, depending on the mold used. Inhibition tests were done for each mold with concentrations of 0 to 5000 micrograms/ml of antigen. The enzyme-linked immunosorbent assay tests for Cladosporium, Geotrichum, and Mucor were only inhibited by antigens from other species of the same genus; whereas there was crossreaction between antibodies and antigens of species of Penicillium and of Aspergillus. Citrate buffer was best for extracting the mold from cheese and yogurt. The extract was adjusted to pH 7.2 and ELISA was performed. Results showed that these molds can be detected in Cheddar and cottage cheeses and yogurt within 2 d, which is before mold growth is visible in these products.
High-pressure processing, ionizing radiation, pulsed electric field and ultraviolet radiation are emerging preservation technologies designed to produce safe food, while maintaining its nutritional and sensory qualities. A sigmoid inactivation pattern is observed in most kinetic studies. Damage to cell membranes, enzymes or DNA is the most commonly cited cause of death of microorganisms by alternative preservation technologies. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
The death kinetics of Aspergillus niger spores under high-pressure carbonation were investigated with respect to the concentration of dissolved CO2 (dCO2) and treatment temperature. All of the inactivation followed first-order death kinetics. The D value (decimal reduction time, or the time required for a 1-log-cycle reduction in the microbial population) in the saline
carbonated at 10 MPa was 0.16 min at 52°C. The log D values were linearly related to the treatment temperature and the concentration of dCO2, but a significant interaction was observed between them.
Criterii microbiologice pentru hartii si cartoane destinate industriei alimentare
- T Florea
- M Zara
- A Nicolau
- C Stanciu
Florea, T., Zara, M., Nicolau, A., & Stanciu, C. (2003). Criterii microbi-ologice pentru hartii si cartoane destinate industriei alimentare. Raport pentru Programul Orizont 2001–2003 (Microbiological criteria for food paper and cardboard, Orizont Programme Report 2001–2003).
Methods for preservation of foodstuffs
- J Dunn
- R W Clark
- J F Asmus
- J S Pearlman
- K Boyer
- F Pairchaud
Dunn, J., Clark, R. W., Asmus, J. F., Pearlman, J. S., Boyer, K., Pairchaud, F., et al. (1991). Methods for preservation of foodstuffs. Maxwel Laboratories, Inc., US Patent No. 5034235.
Proceedings of the second sterilisation of packaged pharmaceutical solutions, packaging and surgical tools with pulsed UV light
- A Wekhof
Wekhof, A. (2003). Proceedings of the second sterilisation of packaged pharmaceutical solutions, packaging and surgical tools with pulsed UV light, July 9–11, Vienna, Austria.
Kinetics of microbial inactivation for alternative food processing technologies: Pulsed light technology. Center for Food Safety and Nutrition
- M Turtoi
- A Nicolau
- Fda Cfsan
M. Turtoi, A. Nicolau / Journal of Food Engineering 83 (2007) 47–53 FDA/CFSAN. (2000). Kinetics of microbial inactivation for alternative food processing technologies: Pulsed light technology. Center for Food Safety and Nutrition. http://www.cfsan.fda.gov. Accessed oct. 25, 2006.
Materiale de ambalaj s ßi ambalaje pentru produsele alimentare (Food packaging materials and packages)
- M Turtoi
Turtoi, M. (2000). Materiale de ambalaj s ßi ambalaje pentru produsele alimentare (Food packaging materials and packages). Galati: Acade-mica Publishing House.
Studii privind imbunatatirea operatiilor si a instalat-iilor din industria alimentara prin utilizarea impulsurilor ultrascurte de lumina de intensitate inaltaStudies concerning food operations and equipment improvement by using ILP treatment
- V Nederita
Nederita, V. (1995). Studii privind imbunatatirea operatiilor si a instalat-iilor din industria alimentara prin utilizarea impulsurilor ultrascurte de lumina de intensitate inalta. Teza de doctorat, Universitatea Dunarea de Jos Galati (Studies concerning food operations and equipment improvement by using ILP treatment, Ph.D thesis, Galati Dunarea de Jos University).
Assessing food safety of polymer packaging
- J M Vergnaud
- I D Rosca
Vergnaud, J. M., & Rosca, I. D. (2006). Assessing food safety of polymer packaging. Rapra Technology.
Studii privind imbunatatirea operatiilor si a instalatiilor din industria alimentara prin utilizarea impulsurilor ultrascurte de lumina de intensitate inalta
- V Nederita