Elimination microplastic particles in brine process water for ensuring the safety of brined cabbage.

Various studies have investigated the presence of microplastics (MPs) in food and their potential hazardous impact on human health. The frequency of human exposure to MPs, particularly through the consumption of manufactured food and drinking water, is increasing. However, data regarding MP contamination in brine and brined cabbage used for the production of kimchi are limited. Here, we quantified MPs in brine process water during the production of brined cabbage. Pretreatment of the brine process water by performing a filtration step resulted in an MP-removal efficiency of 98.7-100%; 3671 ± 174 MP particles were observed in brining process water that was not filtered. A glass filter, STS filter, and Si Filter showed significant MP-removal efficiency, decreasing the number of MP particles in brining process water to 2,361, 2,775, and 3,490, respectively (p < 0.05). Our results provide data on how filtering of brine can effectively safeguard kimchi from MP contamination and e can be produced. However, to overcome the limitations of our laboratory-scale study, additional technologies should be used in the future for large-scale filtration processes.

Comparison of inactivation kinetics of Yersinia enterocolitica in vegan and non-vegan kimchi during fermentation.

Yersinia enterocolitica is occasionally detected in kimchi, a traditional food prepared from fermented vegetables. Changes in growth properties of Y. enterocolitica during kimchi fermentation are largely unknown. We investigated the viability of Y. enterocolitica during the fermentation of vegan and non-vegan kimchi at different temperatures. Changes in Y. enterocolitica population, pH, and titratable acidity were measured for 24 days. In a suspension test with kimchi juice, populations of three Y. enterocolitica strains were above 3.30 log10 CFU/mL at pH > 5 for 7 days. Yersinia enterocolitica counts in vegan kimchi were considerably reduced at 0 °C and 6 °C. During fermentation at 6 °C, Y. enterocolitica populations in non-vegan kimchi and vegan kimchi were not detected starting from days 14 and 10, respectively. In kimchi samples stored at 0 °C and 6 °C, Y. enterocolitica survival correlated with pH changes during fermentation; in samples stored for up to 24 days, Y. enterocolitica was not detected. According to the k max values from the "log-linear with shoulder and tail" model, Y. enterocolitica was more sensitive to vegan kimchi fermentation than to non-vegan kimchi fermentation. Our findings provide an important basis for ensuring the safe production of kimchi without Y. enterocolitica contamination. Further research is necessary to elucidate the mechanism of Y. enterocolitica inactivation and the major bacterial and physicochemical factors involved in kimchi fermentation.

Nondestructive classification of soft rot disease in napa cabbage using hyperspectral imaging analysis.

Identification of soft rot disease in napa cabbage, an essential ingredient of kimchi, is challenging at the industrial scale. Therefore, nondestructive imaging techniques are necessary. Here, we investigated the potential of hyperspectral imaging (HSI) processing in the near-infrared region (900-1700 nm) for classifying napa cabbage quality using nondestructive measurements. We determined the microbiological and physicochemical qualitative properties of napa cabbage for intercomparison of HSI information, extracted HSI characteristics from hyperspectral images to predict and classify freshness, and established a novel approach for classifying healthy and rotten napa cabbage. The second derivative Savitzky-Golay method for data preprocessing was implemented, followed by wavelength selection using variable importance in projection scores. For multivariate data of the classification models, partial least square discriminant analysis (PLS-DA), support vector machine (SVM), and random forests were used for predicting cabbage conditions. The SVM model accurately distinguished the cabbage exhibiting soft rot disease symptoms from the healthy cabbage. This study presents the potential of HSI systems for separating soft rot disease-infected napa cabbages from healthy napa cabbages using the SVM model, especially under the most effective wavelengths (970, 980, 1180, 1070, 1120, and 978 nm), prior to processing. These results are applicable to industrial multispectral images.

Evaluation of Virucidal Efficacy of Human Norovirus Using Combined Sprayed Slightly Acidic Electrolyzed Water and Ultraviolet C-Light-Emitting Diode Irradiation Treatment Based on Optimized Capture Assay for Quantitative RT-qPCR.

Slightly acidic electrolyzed water (SAEW), an effective non-thermal virucidal treatment, is used widely to prevent infectious viral cross-contamination. Surface disinfection technologies using ultraviolet C-light-emitting diode (UVC-LED) irradiation have recently attracted considerable attention. The SAEW sprayer technique is an efficient approach to preventing the spread of infectious viral pathogens in the public healthcare sector. Therefore, we investigated a small-scale system comprising sprayed SAEW disinfection combined with UVC-LED irradiation to inactivate the human norovirus (HuNoV) in the environment. A stainless-steel surface was inoculated with a HuNoV genogroup II genotype 4 (GII.4) to achieve maximum reduction values of 3.21 log10 genomic copies. For optimal disinfection conditions, the response surface methodology based on the Box-Behnken design revealed that the specific treatment conditions for inactivation of HuNoV GII.4 were an SAEW droplet volume of 180 µL, 30 ppm available chlorine concentration of SAEW, and a UVC-LED exposure dose of 2 mJ/cm2. The results indicate that the combined disinfection treatment could efficiently prevent the spread of HuNoVs in environment. Furthermore, the quadratic polynomial equations of the 3-D response surface can be employed to predict the effects of combined disinfection treatment on HuNoV contamination on environmental surfaces. Therefore, sprayed SAEW disinfection combined with UVC-LED irradiation proposed in this study may offer insights for designing optimal control strategies and techniques to prevent the transmission of infectious diseases, particularly HuNoV.

Optimizing Operating Parameters of Electric Ultra-Low Volume Sprayer with Slightly Acidic Electrolyzed Solution for Efficient Virucidal Activity on Environmental Surfaces.

Recently, and considering the COVID-19 pandemic, there has been a growing consensus that the disinfection of surfaces contaminated with pathogenic viral particles is essential. Chemical disinfectant sprays are effective at preventing the spread of infectious human noroviruses (Hu-NoVs) in healthcare and public areas. We assessed the virucidal activity of slightly acidic electrolyzed water (SAEW) spray on fomite surfaces. A multivariate statistical assessment that combined a response surface methodology (RSM) and a Box-Behnken design (BBD) was performed to define the optimal parameters of, and correlations among, experimental conditions. Spraying SAEW disinfectant (oxidation-reduction potential: 1123 mV, pH range: 5.12, available chlorine concentration: 33.22 ppm) resulted in the successful decontamination of Hu-NoV, with a 4-log reduction in viral particles on polyvinyl chloride, stainless steel, ceramic tile, and glass surfaces. Our experimental data revealed optimized treatment conditions for decontaminating Hu-NoV GI.6 and GII.4, using the numerical multiple optimized method (spraying rate: 218 mL/min, spraying time: 4.9 s, spraying distance: 0.9 m). These findings offer significant insights for designing optimal strategic control practices to prevent infectious disease, particularly Hu-NoV, transmission.

Application of Response Surface Methodology Based on a Box-Behnken Design to Determine Optimal Parameters to Produce Brined Cabbage Used in Kimchi.

The factors of brine time, concentration, and temperature, affect the high-quality production of brined cabbage used in Kimchi. Although changes in Kimchi cabbage quality depending on brine time and concentration have been reported, changes in brine temperature have not been explored. Here, we optimized the brine process considering specific conditions of temperature (15-25 °C), concentration (10-14%), and osmosis duration (14-18 h) affecting the characteristics such as pH, titratable acidity, soluble solid content, glucose, fructose, and lactic acid bacteria and mass transport (salt gain, water loss, and weight reduction). The optimal parameters were determined using multivariate statistical analysis using the Box-Behnken design combined with response surface methodology. For each response as qualitative characteristics, second order polynomial models were developed using multiple regression analysis. Analysis of variance was performed to check the adequacy and accuracy of the fitted models. The brine temperature and concentration affected salt gain and water loss; the optimal brining temperature, concentration, and time were 19.17 °C, 10.53%, and 15.38 h, respectively. Statistical regression analysis indicated that standardized brined cabbage can be produced efficiently using a brining tank at controllable temperature.

Effect of ascorbic acid and citric acid on the quality of salted Chinese cabbage during storage.

Changes in color, browning indices, enzyme activity, and physical and chemical quality during the storage period were investigated to assess the effectiveness of storage period extension along with the addition of ascorbic acid (AA) and citric acid (CA) to salted Chinese cabbage. After 16 days of storage, the change in chromaticity value showed treatment with 0.5% CA showed the lowest change in the brown index during the storage period. The control showed the highest residual activity of polyphenol oxidase among control, AA, and CA-treated salted cabbage. AA and CA treatment effectively inhibited the initial populations of microorganisms including total aerobic bacteria, lactic acid bacteria, and yeast and molds in salted Chinese cabbage during storage. Further, the texture, i.e., hardness, chewability, and elasticity, tended to decrease with increasing storage. These results suggest that treatment with AA could help maintain the quality of salted Chinese cabbage during the storage period.

Volatile Metabolic Markers for Monitoring Pectobacterium carotovorum subsp. carotovorum Using Headspace Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

Identifying the extracellular metabolites of microorganisms in fresh vegetables is industrially useful for assessing the quality of processed foods. Pectobacterium carotovorum subsp. carotovorum (PCC) is a plant pathogenic bacterium that causes soft rot disease in cabbages. This microbial species in plant tissues can emit specific volatile molecules with odors that are characteristic of the host cell tissues and PCC species. In this study, we used headspace solid-phase microextraction followed by gas chromatography coupled with mass spectrometry (HS-SPME-GC-MS) to identify volatile compounds (VCs) in PCC-inoculated cabbage at different storage temperatures. HS-SPME-GC-MS allowed for recognition of extracellular metabolites in PCC-infected cabbages by identifying specific volatile metabolic markers. We identified 4-ethyl-5-methylthiazole and 3-butenyl isothiocyanate as markers of fresh cabbages, whereas 2,3-butanediol and ethyl acetate were identified as markers of soft rot in PCC-infected cabbages. These analytical results demonstrate a suitable approach for establishing non-destructive plant pathogen-diagnosis techniques as alternatives to standard methods, within the framework of developing rapid and efficient analytical techniques for monitoring plant-borne bacterial pathogens. Moreover, our techniques could have promising applications in managing the freshness and quality control of cabbages.

The Delay in Confirming COVID-19 Cases Linked to a Religious Group in Korea.

OBJECTIVES: As of March 3, 2020, the Shincheonji religious group accounted for the majority of Korean cases of coronavirus disease 2019 (COVID-19). Nonetheless, the most likely cause of the broad spread of COVID-19 among members of the Shincheonji religious group remains largely unknown. METHODS: We obtained data of laboratory-confirmed cases related to the Shincheonji religious group from press releases by Korean public health authorities and news reports. We measured the period from the date of illness onset to the date of COVID-19 confirmation. RESULTS: We analysed data from 59 cases (median age, 30 years). The estimated median period between the date of symptom onset and the date of COVID-19 confirmation was 4 days (95% confidence interval, 1-12). CONCLUSIONS: There was a delay in COVID-19 confirmation from the date of illness onset among the cases linked to the Shincheonji religious group. This delay likely contributed to the occurrence of many cases of COVID-19 in the group.

Quality change of apple slices coated with Aloe vera gel during storage.

Fresh-cut apples are easily susceptible to browning and microbial spoilage. In this study, an edible coating prepared from Aloe vera gel containing antibrowning solution was applied to preserve the quality of fresh-cut apples during storage. Fresh-cut apples were treated with both an Aloe vera gel and an Aloe vera gel containing 0.5% cysteine and then stored at 4 °C for 16 d. The color, firmness, weight loss, soluble solid content, titratable acidity, microbial analysis, and sensory evaluation were analyzed during storage. Fresh-cut apples coated with the Aloe vera gel showed delayed browning and reduced weight loss and softening compared to the control. The Aloe vera gel coating was also effective in reducing the populations of the total aerobic bacteria and yeast and molds. In particular, Aloe vera gel containing 0.5% cysteine was most effective in delaying browning and the reduction of microbial populations among the treatments. These results suggest that an Aloe vera gel coating can be used for maintaining the quality of fresh-cut apples.