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Scanning electron microscopy (SEM) images of clean stainless-steel surfaces at 2260× magnification: (a) electropolished finish; (b) mill finish; (c) bead blasted finish ; and (d) aluminum oxide treated finish
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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,...
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Citations
... In the present study, texturation was only performed on metallic samples, but further investigation on other materials is needed to understand if texturation may prevail on the material composition and in which cases. The surface reflectiveness has also been pointed out to play an important role in treatment efficiency [30]. ...
Disinfection in the hospital environment remains challenging, especially for wide and structurally complex objects such as beds or wheelchairs. Indeed, the regular disinfection of these objects with chemicals is manually carried out by healthcare workers and is fastidious and time-consuming. Alternative antibacterial techniques were thus proposed in the past decades, including the use of naturally antimicrobial UVC. Here, the antibacterial efficiency of a large UVC box built to accommodate wheelchairs was investigated through testing bacterial burden reductions on various parts of a wheelchair, with various support types and with several treatment durations. The results demonstrate a time-dependent antibacterial effect, with a strong burden reduction at only five minutes of treatment (>3-log median reduction in Escherichia coli and Staphylococcus epidermidis). The UVC flux and residual bacterial burden both significantly varied depending on the spatial location on the wheelchair. However, the nature of the support impacted the antibacterial efficiency even more, with residual bacterial burdens being the lowest on rigid materials (steel, plastics) and being the highest on tissue. On metallic samples, the nature of the alloy and surface treatment had various impacts on the antibacterial efficiency of the UVC. This study highlights the efficiency of the tested UVC box to efficiently and quickly decontaminate complex objects such as wheelchairs, but also gives rise to the warning to focus on rigid materials and avoid porous materials in the conception of objects, so as to ensure the efficiency of UVC decontamination.
... The authors found that porous surfaces pose greater challenges in terms of disinfection compared to their non-porous counterparts. A study investigated this by testing four types of stainless-steel surfaces: electropolished, mill nish, glass bead blast nish, and aluminum oxide treated 14 . Their ndings revealed an unexpected uniformity in microbial inactivation kinetics across both polished and non-polished surfaces, suggesting that the surface nish may not signi cantly in uence the microbial inactivation process as previously thought. ...
The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms like E. coli (C3040- Kanamycin resistant), Salmonella Enteritis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by double plating. With a low RMSE and high R ² values, the biphasic kinetic model demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm − 2 , glass surfaces showed the maximum microbial inactivation ( i.e. 2.80, 3.81, and 3.56 log CFU/mL for E. coli , Salmonella , and P. fragi , respectively). Stainless steel and silicon rubber showed significant microbial inactivation but were consistently lower than glass. Our research indicates that UV-C LEDs can disinfect bioaerosols on food contact surfaces effectively.
... Furthermore, the choice of the UV-C wavelength should be based on the target microorganisms and the food product [24]. The material of the product's container can affect UV-C treatment, with transparent materials allowing for better penetration; the depth of the liquid and flow rate through the UV-C system should be considered for uniform exposure [31,32]. At the same time, suspended solids can reduce the effectiveness of UV-C treatment [25,33]. ...
... The optical properties of surfaces refer to how they interact with light. These properties can include the reflection, absorption, transmission, and scattering of light [21,32]. When it comes to UV-C light, the optical properties of surfaces that host microorganisms can affect the effectiveness of UV-C light. ...
... When it comes to UV-C light, the optical properties of surfaces that host microorganisms can affect the effectiveness of UV-C light. For example, surfaces that are rough or uneven may scatter UV-C light, potentially reducing the intensity of UV-C radiation in a particular direction [32], and if they are porous, UV-C light can be absorbed. Reflective surfaces can also scatter and absorb UV-C light [22,37]. ...
A variety of bioactive substances present in fruits and vegetables processed products have health-promoting properties. Consumption of nutrient-rich plant-based products is essential to address undernutrition and micronutrient deficiencies. Preservation is paramount in manufacturing plant-based non-solid foods such as juices, purees, and sauces. Thermal processing has been widely used to preserve fruit and vegetable-based products by reducing enzymatic and microbial activities, thereby ensuring safety and prolonged shelf life. However, the nutritional value of products is compromised due to the deleterious effects of thermal treatments on essential nutrients and bioactive compounds. To prevent the loss of nutrients associated with thermal treatment, alternative technologies are being researched extensively. In studies conducted on non-solid food, UV-C treatment has been proven to preserve quality and minimize nutrient degradation. This review compiles information on the use of UV-C technology in preserving the nutritional attributes of non-solid foods derived from fruit and vegetables. Legislation, market potential, consumer acceptance, and limitations of UV-C are reviewed.
... Furthermore, the choice of the UV-C wavelength should be based on the target microorganisms and the food product [24]. The material of the product's container can affect UV-C treatment, with transparent materials allowing for better penetration; the depth of the liquid and flow rate through the UV-C system should be considered for uniform exposure [31,32]. At the same time, suspended solids can reduce the effectiveness of UV-C treatment [25,33]. ...
... The optical properties of surfaces refer to how they interact with light. These properties can include the reflection, absorption, transmission, and scattering of light [21,32]. When it comes to UV-C light, the optical properties of surfaces that host microorganisms can affect the effectiveness of UV-C light. ...
... When it comes to UV-C light, the optical properties of surfaces that host microorganisms can affect the effectiveness of UV-C light. For example, surfaces that are rough or uneven may scatter UV-C light, potentially reducing the intensity of UV-C radiation in a particular direction [32], and if they are porous, UV-C light can be absorbed. Reflective surfaces can also scatter and absorb UV-C light [22,37]. ...
A variety of bioactive substances present in fruit- and vegetable-processed products have health-promoting properties. The consumption of nutrient-rich plant-based products is essential to address undernutrition and micronutrient deficiencies. Preservation is paramount in manufacturing plant-based nonsolid foods such as juices, purees, and sauces. Thermal processing has been widely used to preserve fruit- and vegetable-based products by reducing enzymatic and microbial activities, thereby ensuring safety and prolonged shelf life. However, the nutritional value of products is compromised due to the deleterious effects of thermal treatments on essential nutrients and bioactive compounds. To prevent the loss of nutrients associated with thermal treatment, alternative technologies are being researched extensively. In studies conducted on nonsolid food, UV-C treatment has been proven to preserve quality and minimize nutrient degradation. This review compiles information on the use of UV-C technology in preserving the nutritional attributes of nonsolid foods derived from fruit and vegetables. The legislation, market potential, consumer acceptance, and limitations of UV-C are reviewed.
... The sterilization mechanism of pulsed intense light leads to a strong relationship between its sterilization effect and the characteristics of the object to which the microorganism is attached. In addition, surface reflectance and other variables can also affect the sterilization effect of IPL [25]. Chicken skin has a higher penetration rate of UV and visible light compared to chicken meat, and pulsed intense light is easier for overall sterilization, while chicken meat is almost completely impervious to light due to its poor light transmission and inevitably thicker artificially cut thickness than chicken skin, making the sample almost completely impervious to light, so intense pulsed light can only perform surface sterilization and cannot be completely sterilized. ...
... Different studies demonstrated the effectiveness of UV rays to control foodborne pathogens in fresh-cut vegetables, including lettuce [49,50]. In general, the role of surface topography on the effectiveness of UV treatment for bacterial inactivation was demonstrated by Woodling and Moraro in stainless-steel surfaces [51]. In our study, UV treatment resulted in less E. ...
Understanding the relation between the susceptibility of different leafy greens to human pathogen contamination and leaf traits can contribute to increase the food safety of the fresh vegetable industry. The aim of this research was to evaluate the susceptibility to E. coli ATCC 35218 attachment in 30 accessions of baby leaves, and to identify leaf traits potentially involved in the contamination. The accessions were surface inoculated with a bacterial suspension containing 1 × 107 cells/mL and the attachment was measured 1.5 h after inoculation. Significant differences in attachment were detected between the accessions for p ≤ 0.05. The three most and the three least susceptible accessions were selected and characterized for leaf micro-morphological traits (stomata density and size, surface roughness) and water content. Scanning electron microscopy was used to analyse the stomatal parameters. Roughness was measured by an innovative portable 3D digital microscope. No significant correlation between the attachment of E. coli ATCC 35218 and stomatal parameters was detected, while the attachment was positively correlated with roughness and water content. The E. coli ATCC 35218 population in surface-inoculated leaves was also measured after a UV treatment, which was found to be less effective in reducing bacterial contamination in the rougher leaves. This result suggested that roughness offers UV protection, further highlighting its impact on the microbiological safety of baby leafy greens.
... A study suggested that it is possible to achieve 4 log CFU/cm 2 reductions of Listeria innocua on SS surfaces with PL treatment, regardless of surface conditions (Woodling & Moraru, 2005). Similar results were also obtained for L. innocua on SS surfaces, with a fluence of 12 J/cm 2 (Uesugi et al., 2007). ...
Bacterial biofilm formation in low moisture food processing (LMF) plants is related to matters of food safety, production efficiency, economic loss, and reduced consumer trust. Dry surfaces may appear dry to the naked eye, however, it is common to find a coverage of thin liquid films and microdroplets, known as microscopic surface wetness (MSW). The MSW may favor dry surface biofilm (DSB) formation. DSB formation is similar in other industries, it occurs through the processes of adhesion, production of extracellular polymeric substances, development of microcolonies and maturation, it is mediated by a quorum sensing (QS) system and is followed by dispersal, leading to disaggregation. Species that survive on dry surfaces develop tolerance to different stresses. DSB are recalcitrant and contribute to higher resistance to sanitation, becoming potential sources of contamination, related to the spoilage of processed products and foodborne disease outbreaks. In LMF industries, sanitization is performed using physical methods without the presence of water. Although alternative dry sanitizing methods can be efficiently used, additional studies are still required to develop and assess the effect of emerging technologies, and to propose possible combinations with traditional methods to enhance their effects on the sanitization process. Overall, more information about the different technologies can help to find the most appropriate method/s, contributing to the development of new sanitization protocols. Thus, this review aimed to identify the main characteristics and challenges of biofilm management in low moisture food industries, and summarizes the mechanisms of action of different dry sanitizing methods (alcohol, hot air, UV-C light, pulsed light, gaseous ozone, and cold plasma) and their effects on microbial metabolism.
... The bacteria sublethally injured by the first treatment activate defense mechanisms to address the damage caused by that particular stress. However, with the immediate application of the second treatment, the bacterial defense mechanisms are overwhelmed and not promptly activated, leading to a much greater population reduction than achieved by the application of a single intervention (37). The response mechanisms of L. monocytogenes to these interventions differ; chemical sanitizers cause oxidative or acid stress conditions, activating bacterial cell wall repair genes, whereas UV light creates abnormal chemical bonds in the DNA, triggering the photo reactivation repair system (28,30,34,39). ...
... The response mechanisms of L. monocytogenes to these interventions differ; chemical sanitizers cause oxidative or acid stress conditions, activating bacterial cell wall repair genes, whereas UV light creates abnormal chemical bonds in the DNA, triggering the photo reactivation repair system (28,30,34,39). When bacterial cells encounter several stresses simultaneously, the defense mechanisms are overwhelmed, resulting in a much greater population reduction than achieved with the application of a single intervention (37). UV irradiation damages nucleic acids, and chemical sanitizers weaken the cell wall and membranes. ...
The ability of Listeria monocytogenes to adapt under different environments and form biofilms is a challenge for food safety. Mature biofilms are difficult to disrupt. Chemical sanitizers combined with nonthermal technologies might be an effective way to control L. monocytogenes biofilms. This study was conducted to investigate L.monocytogenes biofilm survival after treatments withchemical sanitizers and UV-C light alone or in combination. A Centers for Diseases Control and Preventionbiofilm reactor was used to grow 4-day-old multistrainL.monocytogenes biofilms on stainless steel. Biofilmsurvival was evaluated after 10 min of exposure tolactic acid (4%), peroxy acid (100 ppm), and quaternaryammonium (400 ppm) alone or in combination with 15 or30 min of exposure to UV-C light (254 nm). The sequential treatment effect was also evaluated. Reductions of2.6 to 3.6 log CFU/cm2 were observed with chemicalsanitizers, whereas a maximum of 1.8 log CFU/cm2reduction was recorded after UV-C treatment. Combinedtreatments had an enhanced effect, and the sequence ofantimicrobial treatments was significant for lactic acid and peroxy acid (P < 0.05). The results obtained in this research offer an initial understanding of the response of L.monocytogenes biofilm to chemical sanitizers and contribute to development of effective strategies to controlthis pathogen in the food processing environment.
... Whitehead et al. [69] also detected similar trends for bacterial species of different sizes. instead, bacteria are more likely to colonize smooth surfaces like electropolished stainless steel [70]. Therefore, surface roughness alone is not sufficient to predict bacterial adhesion and surface topography must be considered. ...
Infections arising from implanted medical devices cause considerable challenges for medicinal specialists and patients. These infections usually arise from the accumulation of biofilm on the device, which is difficult to eliminate and typically needs antibiotic treatment and removal of the device. In this regard, efforts have been made to design the devices or functional polymer coatings that have anti-fouling or antimicrobial properties to limit the formation of biofilm and following infection by preventing or killing bacteria near the device surface or by restricting the initial binding of proteins and bacteria. Herein, the extent of device-related infections, the biofilm formation mechanism, the role of biofilm construction in human pathogenesis, and the key strategies for the progress of antibiofilm coatings are discussed. The most promising antibiofilm coating approaches, comprising the surface topography modifications as well as the PEG, hydrogel, polyzwitterion, Benign bacterial biofilm, enzyme, cationic polymer, PTFE, and smart coatings, etc., were also summarized to avoid the biofilm formation and bacteria proliferation via controlling the antibiofilm mechanisms. .
... Several studies have elucidated that the surface properties of the sample could exert an effect on the inactivation efficacy of bactericidal treatment, such as vaporized hydrogen peroxide, chlorine dioxide, pulsed light treatment, etc (Eschlbeck, Seeburger, & Kulozik, 2020;Park & Kang, 2017;Woodling & Moraru, 2005). Previous studies showed that Table 1 The values of contact angle ( • ) for the surface of iceberg lettuce, strawberry, and tomato a . ...
Pectobacterium carotovorum subsp. carotovorum and Dickeya chrysanthemi have been reported to cause soft-rot diseases to fresh produces. The aim of this research was to investigate the inactivation efficacy of a 222 nm KrCl excimer lamp and 280 nm UVC-LED against P. carotovorum subsp. carotovorum and D. chrysanthemi on fresh produces. When samples were subjected to UVC treatment by a excimer lamp or UVC-LED at 450 mJ/cm², it was observed that soft-rot bacteria on the surface of iceberg lettuce, strawberry, and tomato were reduced by a maximum of 5, 3, and 5 log units, respectively. The surface properties of fresh products, such as hydrophobicity, roughness, and topographic image, were analyzed under the hypothesis that the characteristics of the sample surface affected the inactivation efficacy of the excimer lamp and UVC-LED. It was determined that there was an inverse correlation between the surface roughness and inactivation efficacy of UVC treatment. The texture properties of samples were not significantly different (P > 0.05) from those of untreated samples. The results of this research substantiate that the excimer lamp and UVC-LED can be applied to decontamination processes for inactivating soft-rot bacteria, thereby prolonging the shelf life of fresh produce and reducing economic losses.
