Microbial Inactivation Effect Research Articles

Pulsed electric field processing of edible insect slurries induces thermally-assisted microbial inactivation

Insect-based food ingredients are emerging as sustainable protein sources, but their production requires ensuring microbial safety and inactivation of endogenous enzymes to avoid undesirable proteolysis, without compromising protein structure. While traditional thermal processing affects the protein structure, the potential of pulsed electric field (PEF) technology to inactivate microorganisms in lesser mealworm and house cricket slurries at pH 3 while simultaneously retaining the native protein structure is yet unexplored.Lesser mealworm and house cricket slurries at pH 3 were subjected to continuous and batch PEF treatments with varying intensities (0-450 kJ/kg). Microbial inactivation (aerobes, anaerobes, yeasts, and moulds), temperature changes, protein solubility, protein structure (SDS-PAGE and FTIR), and endogenous protease activity were assessed.For both insect species, high-intensity PEF (>150 kJ/kg) achieved up to 5 log microbial reduction, but increased temperatures up to 75°C, altering protein structure. Low-intensity PEF did not affect protein conformation and protease activity, but was not effective in microbial inactivation (<1 log reduction).We conclude that while PEF can effectively inactivate microorganisms, it cannot be considered a non-thermal method for the present sample conditions due to the temperature increase at higher intensities. PEF could be well-suitable for incorporation in hurdle techniques, such as combinations with moderate heating. Future research should investigate synergistic effects of PEF, also for using alternative PEF set-ups, with other mild processing techniques for effective microbial inactivation while preserving native protein structure. Furthermore, optimal PEF intensities for enhanced protein solubility should be explored.

Interventional human ocular safety experiments for 222-nm far-ultraviolet-C lamp irradiation.

The study aimed to directly assess the ocular safety of 222-nm far-ultraviolet-C (UVC) irradiation in humans, given the limited clinical trials in this area. This wavelength offers the potential for safe and effective microbial inactivation in occupied spaces, but its safety profile for human eyes requires thorough investigation. This prospective, interventional study involved five subjects aged 29-47 years, who were exposed to 222-nm UVC at doses of 22, 50, and 75 mJ/cm2. The subjects were monitored using custom-made glasses with a UV-cut filter on one eye to serve as a control. UVC irradiation was conducted using a KrCl excimer lamp, and ocular examinations were performed prior to exposure, 24 h post-exposure, and at 1, 3, and 6 months. Parameters assessed included visual acuity, refractive error, corneal endothelial density, corneal erosion scores, and conjunctival hyperemia scores. The study found no clinically significant photokeratitis or long-term eye damage across the five subjects, even at the highest dose of 75 mJ/cm2. Temporary ocular discomfort, including sensations of dryness and epiphora, was reported, but these symptoms subsided within hours after irradiation. The findings indicate that 222-nm far-UVC irradiation up to 75 mJ/cm2 does not cause "clinically significant photokeratitis" or long-term ocular damage, though it may induce temporary discomfort. This supports the safe use of 222-nm UVC for germicidal applications in occupied environments, providing a basis for revised safety guidelines.

Effects of washing with boric acid solutions on residual boric acid content, microbiological load, and quality of fresh-cut spinach

Insufficient disinfection of fresh-cut spinach poses significant health risks, along with potential issues like odor, color changes, and softening during short-term storage. To address these challenges, boric acid solutions were explored as an alternative to chlorine washes, which are known to produce toxic compounds. Among various concentrations, 1 % boric acid exhibited the most effective microbial inactivation, leading to substantial reductions in total mesophilic aerobic bacteria, total yeast and mold, and Enterobacteriaceae counts, with reductions of 1.64, 1.38, and 1.77 logs, respectively. Additionally, washing spinach leaves with this solution for 1 min maintained quality parameters, with enhanced antioxidant activity (55.26 mg kg−1 Trolox equivalent), increased total phenolic content (1214.06 mg kg−1 gallic acid equivalent), retention of chlorophyll a (839.16 mg kg−1), chlorophyll b (539.61 mg kg−1) and ascorbic acid content (264.72 mg kg−1). Mechanical properties such as puncture strength (1.81 N) and puncture distance (52.78 mm) also showed favorable outcomes, alongside optimal moisture content at 89.81 %. Notably, residual boric acid content was lowest in spinach leaves (1252.49 mg kg−1) and highest in the wash water (53.88 mg kg−1) after treatment. Scanning electron microscopy images demonstrated maintained tissue integrity, while Hunter Lab readings indicated minimal color changes post-washing. Additionally, sensory evaluations and various physicochemical analyses further supported the efficacy of boric acid washing. Consequently, washing spinach leaves with a 1 % boric acid solution for 1 min yielded favorable results across multiple quality parameters. These findings suggest the potential of boric acid as a safe and effective alternative disinfectant in the fresh-cut produce industry, highlighting its practical implications for food safety and quality. Future research should focus on exploring long-term effects and optimizing washing protocols for broader applications.

High Hydrostatic Pressure: Influences on Allergenicity, Bioactivities, and Structural and Functional Properties of Proteins from Diverse Food Sources.

High hydrostatic pressure (HHP) has gained prominence in the food processing industry over the last decade. In addition to the effectiveness of microbial and enzymatic inactivation, HHP directly impacts protein structures and properties. Accordingly, this review article aims to consolidate relevant research findings elucidating the effects of HHP on protein structure, allergenicity, bioactivities, and functional properties across diverse protein sources. They encompass cereals, legumes, nuts, meat, poultry products, milk, eggs, seafood, algae, insects, seeds, and vegetables. This review provides insights into the consistent trends of HHP effects on each protein source. In conclusion, HHP induces alterations in non-covalent bonds within protein structures, leading to the unfolding of their interior regions and consequential changes in their properties. Remarkably, the allergenicity of cereals, legumes, and nuts decreases while their bioactivities and digestibility escalate. The disruption of non-covalent bonds during HHP results in the exposure of the interior hydrophobic regions to the surface microenvironment, thereby enhancing the surface hydrophobicity of proteins, particularly those derived from seeds and vegetables. HHP weakens the allergenicity and elevates the foaming properties of proteins from dairy products, including improving the gelling properties and antioxidant activities of egg proteins. Texture profiles of meat and poultry, particularly hardness, are enhanced. Furthermore, HHP demonstrates the potential to diminish the allergenicity of seafood proteins and augment insect protein bioactivities. Lastly, HHP enhances the extraction of algal bioactive components, improving their nutritional quality.

The impact of movement path of sesame seeds (Sesamum indicum L.) during treatment with intense pulsed light (IPL) using a continuous pilot-scale device on the reduction of indigenous microorganisms.

The objective of this study was to enhance the microbial inactivation efficacy of sesame seeds through the utilization of a pilot-scale IPL device, while also identifying the process variables that influence the microbial inactivation effect. Three different types of IPL processes were employed, each with a distinct arrangement, to treat sesame seeds. The total fluences applied ranged from 1.33 to 53.94J/cm2. Total aerobic bacteria and fungi exhibited a maximum reduction of 2.27 and 2.77 log, respectively. The curved pathway of the sample flow effectively extended the duration of exposure to the IPL emitted by the lamps. The arrangement of the IPL process using two lamps in parallel but at different locations proved the most efficient for microbial inactivation. The application of IPL was found to be effective in reducing the presence of indigenous microbes in sesame seeds while having no significant impact on the physicochemical properties of the seeds.

Effect of pin‐to‐plate atmospheric cold plasma on technological and nutritional functionality of horse gram (Macrotyloma uniflorum) flour

AbstractAtmospheric cold plasma (CP), an acclaimed nonthermal technology, has gained popularity for its effective microbial inactivation in food materials, concurrently improving functional and nutritional aspects. Despite the nutraceutical benefits, horse gram (Macrotyloma uniflorum) is underutilized in baking and confectionery due to presence of major antinutrients. Our aim is to leverage CP to enhance horse gram's properties, promoting its viability in these sectors. The present study investigates the effect of CP treatment with varying output voltage (10–30 kV) and exposure time (5–25 min) on horse gram flour's nutritional, functional, and antinutritional properties. Moreover, the molecular interactions, crystallinity, thermal stability, and morphological characteristics were analyzed. CP treatment doubled the nutritional properties of horse gram flour and amplified the functional attributes by 1.5 times as compared to untreated flour, but excessively higher voltage (30 kV) and time (15 and 25 min) declined them. Whereas the antinutritional components—tannin, saponin, and phytic acid—were reduced to 1.43 ± 0.01 μg TAE/g, 0.72 ± 0.01 mg diosgenin/g, and 5.26 ± 0.03 mg phytate/g, respectively, after CP treatment, enhancing digestibility of the flour up to 75%. Principal component analysis illuminated the intricate relationship between CP treatment and flour attributes. Both low voltage (10 kV) with moderate exposure (15 and 25 min) and high voltage (30 kV) with shorter duration (5 min) exhibited favorable correlations with physiochemical, bioactive, and functional properties. Conversely, high voltage with prolonged exposure displayed a notable negative correlation with antinutritional properties, structural, and thermal characteristics, revealing the nuanced impact of treatment conditions on the quality of flour. Overall, CP can be recognized as a potential novel technique for the techno‐functional reformation of underutilized food materials.Practical applicationsThe horse gram is one of the underutilized crops rather than being a huge source of health and nutritional benefits. On the other hand, cold plasma is a novel technique in food processing which can be used for improvement of structural and functional properties of food products. That is why the purpose of the study not only was to enlighten the nutritional composition of the horse gram flour but also to improvise its techno functional qualities using cold plasma. However, the presence of the antinutrients in the horse gram flour acts as constraints for digestibility. The application of cold plasma on horse gram flour reduced the antinutrients present in it as well as improved the physiochemical and nutritional characteristics significantly. Moreover, the structural characteristics of the flour were affected by cold plasma which increased its stability for longer shelf life. Furthermore, the functionality of the flour was enhanced which showed an opportunity the better dough characteristic, emulsifying properties. These findings would help the usage of the horse gram flour as food ingredients in various bakery and confectionary food applications.

Determination of the effect of milk fat on the inactivation of Listeria monocytogenes by ohmic heating

Research in recent years has focused on innovative technologies that provide pathogen inactivation without damaging the structural properties of foods. Ohmic heating (OH) is an innovative technology, that provides an effective microbial inactivation with massive and rapid heating. This study aims to determine the effects of milk fat on the inactivation of Listeria monocytogenes by OH with a low voltage gradient. L. monocytogenes (ATCC 13932) inoculated 3.1%, 1.5%, and 0.1% fat-milk samples were heated up to 62°C by OH and conventional heating (CH) process. OH treatment lead to the inactivation of L. monocytogenes in both 1.5% and 0.1% groups and led to approximately 5.30 log decrease, however, there was a 3.10 log decrease in the 3.1% group at 6 min. CH lead to a few reduction as 0.21, 0.29 and 0.39 log in 3.1%, 1.5% and 0.1% fat-milk respectively. In OH, the sublethal injury ratio was higher than CH in all milk groups. However, OH did not statistically change color and pH values at the 6th min of the process, had a significant effect on hydroxymethylfurfural value only in 3.1% fat-milk. In conclusion, the increased fat content may have important inhibitory effects on pathogen inactivation in OH. Thus, the OH conditions should be chosen carefully to sufficient inactivation of pathogens in milk with high-fat content.

Combined ultrafiltration and ozone processing of sugarcane juice: Quantitative assessment of polyphenols, investigation of storage effects by multivariate techniques and shelf life prediction

Sugarcane juice (SJ) is prone to rapid spoilage post-extraction that limits its storage and marketing. To address this problem, two non-thermal techniques, viz., ultrafiltration (UF) and ozone treatment (OZ) combinedly are attempted. Cumulative enzyme and microbial inactivation effects were obtained by combining the processes (UF-OZ) providing about 85% polyphenoloxidase, 91% peroxidase, 7 log bacteria and 5.2 log yeast and mold inactivation. The effects of processing on major phenolic acids, flavonoids and sensory properties were evaluated. From HPLC characterization, it was found that, caffeic acid (13.22 ppm) which was the most abundant accounting for 50.5% of the total evaluated phenolic acids reduced by 26.7% in processed SJ. Among flavonoids, vitexin and its derivatives (22.19 ppm) constituted the highest proportion (63.3%) of total evaluated flavones which did not decrease significantly (p>0.05) after processing. Principal component analysis (PCA) and hierarchical cluster analysis efficiently distinguished the stored samples and showed the dissimilarities in quality characteristics after 12 weeks of storage. PCA very well outlined the interrelationship status of quality parameters and spoilage indicators associated with browning and microbial degradation. The microbiological stability analysis using microbial growth (Gompertz) model confirmed that the ultrafiltered ozonised sugarcane juice could be safely stored up to 90 days under refrigeration.

Photothermal and selective microbial inactivation behaviors of gluconamide-coated IR780 nanoparticles

Photothermal therapy (PTT) is a promising alternative treatment for bacterial infection. In this study, a photothermal nanoparticle was prepared by encapsulating IR780 into N-octyl-D-gluconamide (GA). The photothermal nanoparticle (IR780-GA NP) was evenly suspended in water with an average particle size of 42.2 nm. After exposure to near-infrared light, the temperature of the IR780-GA NP suspension was increased by around 15 °C within 5 min. This leads to an obvious microbial inactivation effect when it is adsorbed to methicillin-resistant Staphylococcus aureus (MRSA, 2 orders of magnitude reduction of CFU concentration) and Escherichia coli (1.5 orders of magnitude reduction of CFU concentration). Interestingly, Salmonella typhimurium survived after the same treatment. Different strains also showed variations. The hemolysis test showed that IR780-GA NPs had good blood compatibility. In vivo experiments collaborated with the in vitro findings. The IR780-GA NP-triggered photothermal effects killed 63–100% of bacteria in the wound site of mice depending on the IR780-GA NP concentration. Overall, this study provided the fundamental basis of IR780-GA NPs in four aspects: fabrication, photothermal characterization, selective adsorption, and microbial inactivation (in vitro and in vivo). The findings of this study provide a practical approach for the development of mild photothermal therapy which targets specific bacterial strains and treats MRSA infection effectively.

Photodynamic inactivation of microorganisms in different water matrices: The effect of physicochemical parameters on the treatment outcome

Wastewater (WW) insufficiently treated for the disinfection of microorganisms, including pathogenic ones, is a source of concern and a possible generator of public health problems. Traditional disinfection methods to reduce pathogens concentration (e.g., chlorination, ozonation, UV) are expensive, unsafe, and/or sometimes ineffective, highlighting the need for new disinfection technologies. The promising results of photodynamic inactivation (PDI) treatment to eradicate microorganisms suggest the efficacy of this treatment to improve WW quality. This work aimed to assess if PDI can be successfully extended to real contexts for the microbial inactivation in WW. For the first time, PDI experiments with 9 different water matrices compositions were performed to inquire about the influence of some of their physicochemical parameters on the effectiveness of microbial inactivation. Bacterial photoinactivation was tested in freshwater, aquaculture water, and seawater samples, as well as in influents and effluents samples from domestic, industrial, and a mixture of industrial and domestic WW receiving wastewater treatment plants (WWTPs). Additionally, PDI assays were performed in phosphate-buffered saline isotonic solution (PBS), used as an aqueous comparative matrix. To relate the PDI disinfection efficiency with the physicochemical compositions of the different used water matrices, a series of statistical analysis were performed, in order to support our main conclusions.Overall, the results showed that PDI is an effective and promising alternative to traditionally used WW disinfection methods, with a bacterial reduction of >3.0 log CFU/mL in all the water matrices within the first hour of PDI treatment, but also that the physicochemical composition of the aqueous matrices to be PDI-disinfected must be taken into account since they seem to influence the PDI efficacy, namely the pH, with acidic pH conditions seeming to be associated to a better PDI performance in general.

Chestnut Lily Beverage (CLB) Processing Using Ultrasound-Assisted Nisin: Microbiota Inactivation and Product Quality.

We evaluated the effects of ultrasound (US) and ultrasound combined with nisin (NUS) treatments on the properties of chestnut lily beverages (CLB) using conventional thermal pasteurisation (TP) as a control. After CLB samples were treated with US and NUS for 20, 40, or 60 min, the polyphenol oxidase activity (PPO), microbial inactivation effect, colour, pH value, total phenolic content, and antioxidant capacity of the CLB were observed. It was found that the inactivation rate of PPO in CLB after NUS treatment was higher than that in the US, indicating that NUS treatment aggravated PPO inactivation. Treatment time was important in the inactivation of microorganisms by US and NUS; NUS had a lethal synergistic lethal effect on microorganisms in CLB and when compared with US, NUS reduced changes in the CLB colour value. Notably, the total phenolic content and antioxidant capacity of the US- and NUS-treated CLB significantly increased relative to the TP group. These results that suggest NUS has a potential application value in the development of CLB because it reduces the risk of microorganism contamination and helps improve the quality of CLB. This study provides technical support and a theoretical basis for the improved production of CLB.

Investigating the microbial inactivation effect of low temperature high pressure carbon dioxide and its application in frozen prawn (Penaeus vannamei).

During the pandemic of coronavirus disease 2019, the fact that frozen foods can carry the relevant virus raises concerns about the microbial safety of cold-chain foods. As a non-thermal processing technology, high pressure carbon dioxide (HPCD) is a potential method to reduce microbial load on cold-chain foods. In this study, we explored the microbial inactivation of low temperature (5-10 °C) HPCD (LT-HPCD) and evaluated its effect on the quality of prawn during freeze-chilled and frozen storage. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min could effectively inactivate E. coli (99.45%) and S. aureus (94.6%) suspended in 0.85% NaCl, SARS-CoV-2 Spike pseudovirus (>99%) and human coronavirus 229E (hCoV-229E) (>1-log virus tilter reduction) suspended in DMEM medium. The inactivation effect of LT-HPCD was weakened but still significant when the microorganisms were inoculated on the surface of food or package. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min achieved about 60% inactivation of total aerobic count while could maintain frozen state and quality of prawn. Moreover, LT-HPCD treated prawn exhibited significant slower microbial proliferation and no occurrence of melanosis compared with the untreated samples during chilled storage. A comprehensive quality investigation indicated that LT-HPCD treatment could maintain the color, texture and sensory of prawn during chilled or frozen storage. Consequently, LT-HPCD could improve the microbial safety of frozen prawn while maintaining its original quality, and could be a potential method for food industry to improve the microbial safety of cold-chain foods.

Employment of cold atmospheric plasma in chilled chicken breasts and the analysis of microbial diversity after the shelf-life storage

Cold atmospheric plasma, featured as a non-thermal food processing technology has gained prominent attention for its practical application. The demand for chilled chicken has increased rapidly due to its nutritious value. However, chilled chicken often suffers from a short shelf life due to its susceptibility to spoilage. In this study, air- and nitrogen plasma were applied to investigate microbial inactivation effects and shelf-life extension of chilled chicken. Meanwhile, the microbial diversity of chicken breasts after air and nitrogen-CAP treatment and at the end of shelf-life was analyzed. Results illustrated that the inactivation effects of air plasma were more potent than that of nitrogen plasma, while nitrogen plasma could better maintain the sensory properties. Also, further investigation illustrated that air- and nitrogen-CAP could change the microbial community significantly. Both treatment time and working gases were essential experimental parameters that affected the microbial community composition.

High Hydrostatic Pressure vs. Thermal Pasteurization: The Effect on the Bioactive Compound Profile of a Citrus Maqui Beverage.

The effects of high hydrostatic pressure (HHP) compared to thermal pasteurization (TP) were studied in healthy citrus-maqui beverages. The impact of the processing technologies on the microbiological and phytochemical profile was assessed by applying two HHP treatments at 450 and 600 MPa for 180 s and TP at 85 °C for 15 s. The shelf life under refrigeration (4 °C) and room temperature (20 °C) was monitored for 90 days. All treatments ensured microbiological stability at both storage temperatures. Aside from that, the physicochemical parameters were not significantly different after processing or throughout the storage period. Regarding color parameters, an increase in the reddish coloration was observed during storage for those beverages treated by HHP. In general, phenolic compounds were little affected by the processing technique, even when treatment under HHP was more stable than by TP during storage. On the other hand, vitamin C showed great degradation after processing under any condition. It can be concluded that HHP is an effective alternative to thermal treatments, achieving effective microbial inactivation and extending the shelf life of the juices by contributing to a better preservation of color and bioactive compounds.

Validation of process technologies for enhancing the safety of low-moisture foods: A review.

The outbreaks linked to foodborne illnesses in low-moisture foods are frequently reported due to the occurrence of pathogenic microorganisms such as Salmonella Spp. Bacillus cereus, Clostridium spp., Cronobacter sakazakii, Escherichia coli, and Staphylococcus aureus. The ability of the pathogens to withstand the dry conditions and to develop resistance to heat is regarded as the major concern for the food industry dealing with low-moisture foods. In this regard, the present review is aimed to discuss the importance and the use of novel thermal and nonthermal technologies such as radiofrequency, steam pasteurization, plasma, and gaseous technologies for decontamination of foodborne pathogens in low-moisture foods and their microbial inactivation mechanisms. The review also summarizes the various sources of contamination and the factors influencing the survival and thermal resistance of pathogenic microorganisms in low-moisture foods. The literature survey indicated that the nonthermal techniques such as CO2 , high-pressure processing, and so on, may not offer effective microbial inactivation in low-moisture foods due to their insufficient moisture content. On the other hand, gases can penetrate deep inside the commodities and pores due to their higher diffusion properties and are regarded to have an advantage over thermal and other nonthermal processes. Further research is required to evaluate newer intervention strategies and combination treatments to enhance the microbial inactivation in low-moisture foods without significantly altering their organoleptic and nutritional quality.

Determination of pepper microbial contamination for low energy e-beam irradiation

Electrons with energies of 300 keV or lower have the potential to decontaminate the surfaces of various types of food products with minimal loss of quality. The aim of the present work was to determine the thickness of the layer inhabited by microorganisms. The food samples tested were black and white pepper irradiated with 200 keV, 230 keV, 300 keV and 9 MeV beams of electron energy. To determine the depth from the surface which can be inhabited by microorganisms two approaches were tested. The methods used were based on the application of different microbiological recovery techniques and the microbial effectiveness of the irradiation process depending on the energy of the electron beam. It was observed that the layer which microorganisms may contaminate differed for the tested samples it was estimated as being below 100 μm thick for white pepper and about 200 μm for black pepper. The penetration ability was significant in experiments performed, and as a result the electron beam at the lowest levels tested (200 and 230 keV) was found to be insufficient to effectively decontaminate the black pepper samples. The beam of energy 300 keV was found to have a similar microbial inactivation effect as the high energy electron beam (9 MeV).

The effect of water activity and temperature on the inactivation of Enterococcus faecium in peanut butter during superheated steam sanitation treatment

The objective of this study was to investigate the inactivation kinetics of Enterococcus faecium in peanut butter under different water activities (aw) and superheated steam temperatures. Peanut butters were prepared at 4 different initial water activities (0.19, 0.40, 0.60, and 0.80) and E. faecium was inoculated into the peanut butter (7.4–8.7 log CFU/g). The inoculated peanut butter samples were exposed at 4 different superheated steam temperatures (125 °C, 175 °C, 225 °C, and 250 °C). Survivor data were modelled using Weibull and log-linear models to describe the inactivation kinetics of E. faecium. The decimal reduction times (D-value), temperature sensitivity (zT) and aw sensitivity (zaw) of the D-value were determined from a log-linear model, and inactivation parameters from the Weibull model were also evaluated. An increase in aw of peanut butter and superheated steam temperature decreased the D-value of E. faecium. The zaw-value and zT-value were determined to be 0.60 ± 0.09 and 194.66 ± 40.69 °C, respectively (R2 > 0.89). The inactivation kinetics of E. faecium on surfaces contaminated with peanut butter can provide comprehensive information to superheated steam sanitation treatment which may be applied to environmental surfaces for effective microbial inactivation without the introduction of water.

Influence of Thermo-sonication and Ascorbic Acid Treatment on Microbial Inactivation and Shelf-Life Extension of Soft Persimmon (Diospyros kaki T.) Juice

This study applied hurdle technology to achieve effective microbial inactivation, and concurrently improve the qualities of soft persimmon juice during storage. Hurdle technology applied was based on moderate temperature, ultrasonication, and pH adjustment (using ascorbic acid) as preservative factors. The inactivation effect of preservative factors and their varying combinations at different levels on Escherichia coli and Listeria monocytogenes was investigated via a stepwise approach to determine suitable inactivation conditions. The hurdle treatment for soft persimmon juice was determined based on the results of microbial inactivation and sensory test as the addition of 1% ascorbic acid combined with thermo-sonication at 50 °C for 30 min (AAUSHT). The effect of individual and hurdle treatment on juice storage quality was examined for 21 days at 4 °C. AAUSHT effectively inhibited both bacteria and fungi growth ( 4 log CFU/mL). Furthermore, AAUSHT effectively reduced non-enzymatic browning, color change, and maintained apparent viscosity of juice.

Studies on ultraviolet C (UVC) radiation intensity of the high performance UVC disinfector using a newly developed UVC radiation sensor

To evaluate the effect of the ultraviolet (UV) disinfection system on controlling microorganisms on the surface of medical devices, it is essential to measure the intensity of UV radiation intensity. However, a sensor that can easily measure it has not yet been developed. Thus, we developed a new sensor that can measure the UVC radiation dose, and conducted a study to clarify the detailed UV dose and effective microbial inactivation conditions by the UVC irradiation device that have been practically used. A UV irradiation sensor consisted of a zinc oxide photoconductive element and multi-logger acquisition software was developed in collaboration with a company. The UV irradiation sensors were installed at several locations in the model hospital room including frequently touched areas, environmental surfaces and blind spots. The UVC radiation intensity was measured simultaneously and continuously at multiple locations. Radiation intensity varied with distance and height even in the effective radiation range of the device, and attenuation was significant in blind spots such as upward direction and shadows. Our results indicated that the effectiveness of UV radiation varies depending on the radiation location.

Investigation of Pulsed UV Light Effects on Turkey Salami

Pulsed UV light application has been a method used frequently in ensuring food safety recently. UV treatment is used in many areas including the food industry through UV treatment and high inactivation power. Pulsed UV light, which is an effective microbial inactivation method that takes place in a shorter time in solid and liquid foods, as it is accepted as an alternative to continuous UV light application, is a promising alternative to both chemical and thermal decontamination methods in the food industry. In this study, pulsed UV light was applied on ready-to-consumption packaged turkey salami samples. In order to ensure food safety and reduce consumer anxiety, the effect of pulsed UV light application of different time and distance on turkey salami slices contaminated with Listeria monocytogenes in equal thickness in order to use UV light was investigated. The effect of pulsed UV application on the microbial inactivation efficiency of the salami surface and the quality of the salami were evaluated. In pulsed UV light system, 3 different distances of quartz glass to samples will be 5-8-13 cm and sliced salami in 3 different periods of 15-30-60 sec. The results of the study showed that pulsed UV light method could be used effectively in inactivation against L. monocytogenes on the salami surface as an alternative to thermal and chemical methods. It was determined that L. monocytogenes inactivation increased as the distance to the quartz lamp decreased and the application time and total energy dose increased. The highest inactivation was obtained after 5 cm 60 sec pulsed UV light treatment.