Atmospheric Cold Plasma Inactivation of Salmonella and Escherichia coli on the Surface of Golden Delicious Apples

The contamination of fruits with human pathogens is a reoccurring concern in the fresh produce industry. Atmospheric cold plasma (ACP) is a potential alternate to customary approaches for non-thermal decontamination of foods. In this study, the efficacy of a dielectric barrier discharge ACP system against Salmonella (Salmonella Typhimurium, ATCC 13311; Salmonella Choleraesuis, ATCC 10708) and Escherichia coli (ATCC 25922, ATCC 11775) was explored. For each bacteria, a two-strain mixture at 8 log10 CFU/ml was spot inoculated on the surface of Golden Delicious apples, air dried, and exposed to ACP at a fixed distance of 35 mm, input power of 200 W for 30, 60, 120, 180, and 240 s. Bacterial inactivation was achieved in all treatment times with highest reduction of 5.3 log10 CFU/cm2 for Salmonella and 5.5 log10 CFU/cm2 for E. coli. Our results showed that reductions were interrelated to exposure time and ranged from 1.3 to 5.3 and 0.6 to 5.5 log10 CFU/cm2 for Salmonella and E. coli, respectively. Salmonella and E. coli significantly decreased (\u3e5.0 log) at 180 and 240 s as compared to 30, 60, and 120 s exposure. Microbial inactivation data was modeled by using Weibull distribution. These findings demonstrate the potential of ACP as a postharvest technology to effectively reduce pathogens on apples, with reference to Salmonella and E. coli

UV-C treatment on the safety of skim milk: Effect on microbial inactivation and cytotoxicity evaluation

The efficacy of UV-C irradiation as a nonthermal processing method for skim milk (SM) was investigated. SM inoculated with two surrogate viruses (MS2 and T1UV), and three bacteria (Escherichia coli ATCC 25922, Salmonella enterica serovar Typhimurium ATCC 13311, and Listeria monocytogenes ATCC 19115) was treated with Deanflow UV-C irradiation, a spiral reactor with the fluid pumped around a central low-pressure mercury UV lamp (40 W) emitting at 254 nm wave-length. A series of known UV doses (0–168.33 mJ·cm2) were delivered to the samples. The microbial loads of MS2, T1UV, E. coli, Salmonella, and Listeria were reduced by more than 5 log10. The inactivation kinetics of all microorganisms were best described by log linear models with a low RMSE and higher coefficient of determination (R2 \u3e 0.95). This study demonstrated that high levels of inactivation of pathogenic particles can be achieved in SM. Practical applications This scientific study provides evidence based data on the advantages of UV-C light in achieving microbial reduction in skim milk. The irradiated skim milk did not show any toxicity on mice liver and intestinal cells. UV-C irradiation is an efficient food preservation technology and offers opportunities for dairy and food processing industries to meet the growing demand from consumers for safer foods. This exploration would provide methodological evidence for commercialization of UV-C processing of milk and dairy based beverages

Microbial inactivation and cytotoxicity evaluation of UV irradiated coconut water in a novel continuous flow spiral reactor

A continuous-flow UV reactor operating at 254 nm wave-length was used to investigate inactivation of microorganisms including bacteriophage in coconut water, a highly opaque liquid food. UV-C inactivation kinetics of two surrogate viruses (MS2, T1UV) and three bacteria (E. coli ATCC 25922, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115) in buffer and coconut water were investigated (D10 values ranging from 2.82 to 4.54 mJ·cm− 2). A series of known UV-C doses were delivered to the samples. Inactivation levels of all organisms were linearly proportional to UV-C dose (r2 \u3e 0.97). At the highest dose of 30 mJ·cm− 2, the three pathogenic organisms were inactivated by \u3e 5 log10 (p \u3c 0.05). Results clearly demonstrated that UV-C irradiation effectively inactivated bacteriophage and pathogenic microbes in coconut water. The inactivation kinetics of microorganisms were best described by log linear model with a low root mean square error (RMSE) and high coefficient of determination (r2 \u3e 0.97). Models for predicting log reduction as a function of UV-C irradiation dose were found to be significant (p \u3c 0.05) with low RMSE and high r2. The irradiated coconut water showed no cytotoxic effects on normal human intestinal cells and normal mouse liver cells. Overall, these results indicated that UV-C treatment did not generate cytotoxic compounds in the coconut water. This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in coconut water, and suggested potential method for UV-C treatment of other liquid foods. Industrial relevance This research paper provides scientific evidence of the potential benefits of UV-C irradiation in inactivating bacterial and viral surrogates at commercially relevant doses of 0–120 mJ·cm− 2. The irradiated coconut water showed no cytotoxic effects on normal intestinal and healthy mice liver cells. UV-C irradiation is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier and safe food products. This study would provide technical support for commercialization of UV-C treatment of beverages

Impact of UV-C irradiation on the quality, safety, and cytotoxicity of cranberry-flavored water using a novel continuous flow UV system

The influence of short wavelength UV-C irradiation at 254 nm on microbial inactivation, anthocyanins stability, ascorbic acid, and cytotoxicity of formulated cranberry flavored water was studied. Escherichia coli ATCC 25922 and Salmonella enterica serovar Typhimurium ATCC 13311 were inactivated by more than 5 log10 at UV-C fluence of 21 mJ cm−2. At UV-C fluence of 40 mJ cm−2 the content of ascorbic acid was 82% of that in the untreated beverage. The concentrations of the anthocyanins (Cy3Ar, Cy3Ga, Pe3Ar, and Pe3Ga) were not significantly affected at the same treatment level. Cytotoxicity evaluation of the irradiated beverage on normal colon (CCD-18Co), colon cancer (HCT-116), and healthy mice liver (AML-12) cells showed that UV-C irradiation had no cytotoxic effects on all three cell lines. This research study suggests that UV-C treatment of formulated cranberry flavored water can achieve high levels of microbial inactivation without significantly decreasing the concentration of anthocyanins, ascorbic acid content or generating cytotoxic effects. These results suggest that UV-C irradiation can be an alternative to thermal pasteurization in producing high quality beverages