•Initial accumulation of some BAs occurred mainly owing to fish sauce.•Putrescine and tyramine accumulated rapidly upon fermentation.•Addition of 8% red pepper powder reduced the total BA content ...during fermentation.
This study was aimed at evaluating the effect of basic ingredients (white radish, red pepper powder, garlic, ginger, Welsh onion, fish sauce, and sticky rice porridge) used for kimchi seasoning on the accumulation of biogenic amines (BAs) during kimchi fermentation. Initial accumulation of cadaverine, putrescine, histamine, 2-phenylethylamine, tyramine, and tryptamine occurred mainly owing to fish sauce. Putrescine and tyramine content increased rapidly, reaching 14–15-times the initial values after 7 days of fermentation. Total BA content of kimchi without fish sauce was 42–63% lower than that of kimchi with 5% fish sauce. Moreover, the total BA content of kimchi with 8% red pepper powder added was 25–44% lower than that of kimchi without it. These results show that addition of less fish sauce and more red pepper powder can effectively decrease the total BA content in kimchi.
The presence of Pectobacterium carotovorum subsp. carotovorum (P. carotovorum) in kimchi cabbage (Brassica rapa L. subsp. pekinensis) negatively influences kimchi quality. Accordingly, inactivation ...processes to effectively control spoilage caused by plant bacteria, including P. carotovorum, are crucial for extending the shelf life of kimchi. In this regard, ultraviolet C light-emitting diode (UVC-LED) technologies are increasingly attracting attention as non-thermal and non-contact sterilization technologies and are also considered as alternatives to chemical disinfectants. In this study, we investigated the efficacy of the inactivation of P. carotovorum planktonic and biofilm cells that cause cabbage soft rot disease using the UVC-LED treatment technology as a potential disinfection method for a safe kimchi manufacturing process. A biofilm was formed on the surface of a stainless-steel cutter knife using the recommended CDC biofilm reactor system and thereafter, exposed to a range of UVC-LED intensities. Our results indicated that P. carotovorum planktonic and biofilm cells to UVC-LED irradiation at 9.0 mJ/cm2 resulted in >5.0 and >2.0 log10 inactivation, respectively. Additionally, the P. carotovorum planktonic and biofilm cell inactivation kinetics fitted the non-linear reduction curve. The UVC-LED treatment was also found to be highly efficient in eliminating planktonic cells, showing consistency with the Weibull and Weibull tailing models for planktonic cells.
•UVC-LED inactivation of Pectobacterium carotovorum was investigated.•UVC-LED treatment efficiently eliminated P. carotovorum planktonic cells.•The treatment showed consistency with the Weibull and Weibull tailing models.
The presence of white colony-forming yeasts (WCFYs) in raw materials negatively affects the quality of kimchi. Accordingly, disinfection processes to effectively control spoilage yeasts, including ...WCFYs, are crucial for extending the shelf life of kimchi. However, conventional disinfection procedures could result in undesirable changes in the nutritional attributes or sensory characteristics of the food. Therefore, in this study, we investigated whether ultraviolet-C light-emitting diode (UVC-LED) treatment combined with an impeller system could inactivate Candida sake and Kazachstania servazzii cells without causing significant variations in the physicochemical characteristics of kimchi seasoning. UVC-LED at 1680 mJ/cm2 combined with the impeller system at 70 and 140 rotations per min (rpm) reduced the number of C. sake cells in kimchi seasoning by 2.29 and 2.79 log10 CFU/g, respectively, whereas the reduction in the number of K. servazzii cells was observed to be < 2 log10 CFU/g. After UVC-LED irradiation up to 1680 mJ/cm2, the changes in titratable acidity, pH, viscosity, and volatile compounds of the kimchi seasoning remained mostly constant (p > 0.05). We observed that the efficacy of UVC-LED treatment increased as the impeller rotation speed increased. K. servazzii was more resistant to UVC-LED irradiation than C. sake. These experimental results demonstrate that UVC-LED treatment may be a practical alternative to the limited disinfection approaches for high-quality kimchi production.
•UVC-LED combined with an impeller system was used to disinfect kimchi seasoning.•White colony-forming yeast formation was inhibited with UVC-LED/impeller treatment.•The physicochemical properties of kimchi seasoning were not significantly altered.•C. sake and K. servazzii in kimchi were inactivated with UVC-LED/impeller treatment.
Easily producible sensors for harmful industrial waste compounds are of significant interest for both human health and the environment. Three novel coordination polymers, Ag(μ-aca)(μ4-bztpy)1/2 ...(1), Ag(μ-bza)(μ-bpa) (2), and Ag2(μ-aca)2(μ-bpa)2·EtOH·2H2O (3), were assembled in this study by reactions using Ag+ as a node with the pyridyl ligand 1,2,4,5-tetrakis(4-pyridyl)benzene (bztpy) or 9,10-bis(4-pyridyl)anthracene (bpa) and an auxiliary chelating carboxylic ligand. Single-crystal X-ray structural analyses revealed that compound 1 has a 3D framework consisting of 1D Ag(aca)∞ chains and bztpy linkers, while 2 and 3 have 2D layered structures consisting of binuclear Ag–carboxylate units and bpa linkers, respectively. Topological studies revealed that 1 has a bbf topology, while 2 and 3 are 2D 4,4 rhombic grids. The compounds were further characterized by powder X-ray diffraction, IR, elemental analysis, thermogravimetric analysis, and a luminescence study. The solids of 1–3 exhibited intense photoluminescent emission with λem max at ca. 493, 472, and 500 nm, respectively. Remarkably, due to their excellent framework stability, 1 and 2 can act as multiresponsive luminescent sensors for nitrobenzene, Fe3+, and Cr2O7 2– with a high selectivity and sensitivity ascribed to their quenching effect.
•Glucosinolates (GLS) in Brassica species were quantified by HR-HPLC-Q-Orbitrap-MS.•GLS profiling was performed for eight Brassica species.•The highest total GLS content were observed in cabbage ...samples.•The content of minor GLS helped in categorization of Brassica species.
Glucosinolates (GLS) have been reported to have significant anti-oxidative, antimicrobial, and anti-cancer activities. The current study was aimed to develop an analytical method for glucosinolate quantitation in eight Brassica species from Gwangju, Republic of Korea. For this purpose the UHPLC-Q-Orbitrap-MS technique was used and validated for optimal extraction conditions, detection and quantitation limits, linearity, precision, and accuracy. According to the results of GLS profiling, the total GLS concentration decreased in the order of cabbage > broccoli > cauliflower > mustard > kimchi cabbage > young radish ∼ kale. All Brassica species contained glucoerucin (GER) and glucobrassicin (GBR) as major GLS with the high levels in cabbage (5.913 μM/g) and broccoli (1.723 μM/g), respectively. The contents of minor GLS were species-dependent, and could therefore be used for Brassica species classification.
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/cm
. 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.
Presently, pertinent information on the ultra-small microbiome (USM) in fermented vegetables is still lacking. This study analyzed the metatranscriptome and metataxonome for the USM of kimchi. ...Tangential flow filtration was used to obtain a USM with a size of 0.2 μm or less from kimchi. The microbial diversity in the USM was compared with that of the normal microbiome (NM). Alpha diversity was higher in the USM than in NM, and the diversity of bacterial members of the NM was higher than that of the USM. At the phylum level, both USM and NM were dominated by
Firmicutes.
At the genus level, the USM and NM were dominated by
Lactobacillus
,
Leuconostoc
, and
Weissella,
belonging to lactic acid bacteria. However, as alpha diversity is higher in the USM than in the NM, the genus
Akkermansia
, belonging to the phylum
Verrucomicrobia
, was detected only in the USM. Compared to the NM, the USM showed a relatively higher ratio of transcripts related to “protein metabolism,” and the USM was suspected to be involved with the viable-but-nonculturable (VBNC) state. When comparing the sub-transcripts related to the “cell wall and capsule” of USM and NM, USM showed a proportion of transcripts suspected of being VBNC. In addition, the RNA virome was also identified, and both the USM and NM were confirmed to be dominated by
pepper mild mottle virus
(PMMoV). Additionally, the correlation between metataxonome and metatranscriptome identified USM and NM was estimated, however, only limited correlations between metataxonome and metatranscriptome were estimated. This study provided insights into the relationship between the potential metabolic activities of the USM of kimchi and the NM.
Abstract
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.
To observe the effect of using hydrogen peroxide in periodic disinfection combining with continuous disinfection of dental unit waterlines and to provide references for the selection of waterway ...disinfection measures.
A total of 4 dental units in a hospital of stomatology were selected through convenience sampling. The dental unit waterlines received periodic disinfection once every 4 weeks in addition to continuous disinfection (When the dental units were not used for more than 3 days, an additional periodic disinfection would be performed.). Periodic disinfection referred to filling up the waterlines with a disinfectant solution (1.4% hydrogen peroxide) by using the waterline disinfection device that came with the dental unit, immersing for 24 hours, and then emptying out the disinfectant solution. Continuous disinfection referred to using hydrogen peroxide at a concentration of 0.014% as dental treatment water and using it to flush the waterlines for 2 minutes before any dental treatment in the morning and
In this study, a solar-driven photocatalyst La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) with
p
–
n
heterojunction structure was synthesized and characterized. The magnetic, photocatalytic properties, ...Fenton-like action and the synergistic effect of the photocatalysis and Fenton-like on methyl orange (MO) degradation of La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) were also investigated. Results show that
p
–
n
heterojunction was formed, and it has considerable photocatalytic properties under ultraviolet light and solar irradiation. More importantly, La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) also exhibits Fenton-like catalytic performance in the presence of H
2
O
2
and oxalic acid (OA). The main reactive radicals of the La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
–H
2
O
2
–OA–sunlight system are h
+
,
·
OH and
·
O
2
−
. The chemical oxygen demand removal rate of MO wastewater in La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%)–H
2
O
2
–oxalic acid–sunlight system reached 72.4%; the value was higher than that of the sum of single photocatalysis (34.5%) and Fenton-like-dark system (27.6%), indicating that there is a synergistic effect between the photocatalysis and Fenton-like on MO degradation. In addition, La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) displays approximately superparamagnetism and has higher saturated magnetization (
M
s
), low coercive force and residual magnetism. So it can be easily recovered by an external magnetic field and can be reused 6 times. It was anticipated that La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) with
p
–
n
heterojunction structure is a stable and reusable solar-light-driven magnetic photocatalyst and has great potential applications for wastewater treatment.
Graphical abstract
The magnetic La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) with
p
–
n
heterojunction structure was synthesized and characterized by different methods. The magnetic, photocatalytic properties, Fenton-like action and the synergistic effect of the photocatalysis and Fenton-like on methyl orange (MO) degradation of La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%) were also investigated. It is not only a solar-driven photocatalyst with high efficiency, but also shows excellent Fenton-like catalytic effect. And the photocatalysis and Fenton-like system exhibited synergetic catalytic effect on MO degradation by La
0.7
Sr
0.3
MnO
3
/α-Fe
2
O
3
(20%). Furthermore, near superparamagnetic characteristics of the catalyst make it easy to recycle by the external magnetic field and can be reused for 6 times, suggesting that it is a stable multifunctional catalyst.
