Ultrasensitive monoclonal antibodies specific to thermal stable-soluble proteins of buckwheat.

Buckwheat is considered a severe food allergen, and its adulteration and mislabeling cause serious health risks. For protecting consumers suffering from buckwheat allergy, a high-sensitivity detection method is necessary to accurately identify intentional or unintentional adulteration of buckwheat in processed foods. The study revealed that buckwheat contains a significant amount of thermally stable-soluble proteins (TSSPs), which keep antigenicity even after heat treatment. Therefore, we used TSSPs to produce three monoclonal antibodies (MAbs) specific to buckwheat. A MAbs cocktail solution was subjected to enhance the sensitivity of an indirect enzyme-linked immunosorbent assay (iELISA), and the LOD was 1 ng/mL. The MAbs cocktail solution based-iELISA can successfully detect buckwheat adulterated in processed foods. The results suggested that the TSSPs in buckwheat can be used as suitable immunogens, and MAbs produced can be used as bioreceptor to develop immunoassays and biosensors for detecting buckwheat in food facilities and processed foods.

Antibiofilm efficacy of Leuconostoc mesenteroides J.27-derived postbiotic and food-grade essential oils against Vibrio parahaemolyticus, Pseudomonas aeruginosa, and Escherichia coli alone and in combination, and their application as a green preservative in the seafood industry.

Foodborne pathogen-mediated biofilms in food processing environments are severe threats to human lives. In the interest of human and environmental safety, natural substances with antimicrobial properties and generally regarded as safe (GRAS) status are the futuristic disinfectants of the food industry. In this study, the efficacy of bioactive, soluble products (metabolic by-products) from lactic acid bacteria (LAB) and plant-derived essential oils (EO) were investigated as biocidal agents. The postbiotic produced by kimchi-derived Leuconostoc mesenteroides J.27 isolate was analyzed for its metabolic components to reveal its antimicrobial potential against three pathogenic microorganisms (Vibrio parahaemolyticus, Pseudomonas aeruginosa, and Escherichia coli). Additionally, the efficacy of food-grade EO (eugenol and thymol, respectively) was also assessed in our study. Determination of the minimum inhibitory concentration (MIC) of postbiotic and EO against three tested pathogens revealed that the sub-MIC (0.5 MIC) of postbiotic and EO could efficiently inhibit the biofilm formation on both seafood (squid) and seafood-processing surfaces (rubber and low-density polyethylene plastic). Moreover, the polymerase chain reaction (PCR) analysis confirmed that the LAB J.27 isolate possesses bacteriocin- and enzyme-coding genes. The residual antibacterial activity of the produced postbiotic was maintained over a diverse pH range (pH 1-6) but was entirely abolished at neutral or higher pH values. However, the activity was unaffected by exposure to high temperatures (100 and 121 °C) and storage (30 days). Notably, the leakage of intracellular metabolites, damage to DNA, and the down-regulation of biofilm-associated gene expression in the pathogens increased significantly (p > 0.05) following the combination treatment of postbiotic with thymol compared to postbiotic with eugenol. Nonetheless, all in vitro results indicated the prospective use of combining Leu. mesenteroides J.27-derived postbiotic with both EO as a "green preservative" in the seafood industry to inhibit the formation of pathogenic microbial biofilms.

Quantitative analysis of lard in animal fat mixture using visible Raman spectroscopy.

Food adulteration is a serious issue that requires verification and strict management due to healthcare, morality, and social value problems. In the context of fat, food manufacturers blend lard with vegetable oils or animal fats for convenience and gaining economic benefits. Thus, we herein report the classification of 4 animal fats, e.g., beef tallow, pork lard, chicken fat, duck oil, using Raman spectroscopy combined with simple calculation of intensity ratios of Raman signal at vibrational modes corresponding to unsaturated fatty acids and total fatty acids. Various calculated values of the species were compared to find a feature that is able to classify each fats using Raman peak ratio. As a result, we suggested "Oil gauge (OG)" as a standard feature for classification of the fats in Raman analysis field. Furthermore, a quantification of the lard in other fat was accomplished with good linear correlation using the OG values.

Detection of ochratoxin A (OTA) in coffee using chemiluminescence resonance energy transfer (CRET) aptasensor.

We report a chemiluminescence resonance energy transfer (CRET) aptasensor for the detection of ochratoxin A (OTA) in roasted coffee beans. The aptamer sequences used in this study are 5'-DNAzyme-Linker-OTA aptamer-3'-dabcyl. Dabcyl at the end of the OTA aptamer region plays as a quencher in CRET aptasensor. When hemin and OTA are added, the dabcyl-labeled OTA aptamer approaches to the G-quadruplex-hemin complex by formation of the G-quadruplex-OTA complex. The G-quadruplex-hemin complexes possess horseradish peroxidase (HRP)-like activity, and therefore, the HRP-mimicking DNAzyme (HRPzyme) catalyzes peroxidation in the presence of luminol and H2O2. Resonance energy transfer between luminol (donor) and dabcyl (acceptor) enables quenching of chemiluminescence signals. The signal decreases with increasing the concentration of OTA within the range of 0.1-100ngmL(-1) (limit of detection 0.22ngmL(-1)), and the level of recovery of the respective 1ngmL(-1) and 10ngmL(-1) spiked coffee samples was 71.5% and 93.3%. These results demonstrated the potential of the proposed method for OTA analysis in diverse foods.

Occurrence of aflatoxins in herbal medicine distributed in South Korea.

The objective of this study was to investigate the occurrence of aflatoxins in herbal medicines distributed in South Korea. A total of 700 herbal medicine samples (10 samples each for 70 types of herbal medicine) were analyzed by an enzyme-linked immunosorbent assay (ELISA) for aflatoxin B(1) (AFB(1)), and levels of total aflatoxins were quantified and confirmed by liquid chromatography combined with tandem mass spectrometry (LC-MS/MS). The levels of recovery of the methods were 84.30 to 102.68% (ELISA for AFB(1)) and 72.17 to 90.92% (LC-MS/MS for total aflatoxins). Fifty-eight (8.29%) of 700 samples were AFB(1) positive by ELISA, and 17 (2.43%) of them were finally confirmed as positive for total aflatoxins by LC-MS/MS. Total aflatoxin levels in the herbal medicines were from 4.51 to 108.42 µg/kg. Among the 17 samples, the AFB(1) content of 6 samples (11.95 to 73.27 µg/kg) and the total aflatoxin content of 10 (12.12 to 108.42 µg/kg) samples exceeded the legal limits set by the Korea Food and Drug Administration for AFB(1) (10 µg/kg) and by the European Commission for total aflatoxins (10 µg/kg), respectively. These results demonstrate the risk to consumers of herbal medicine contamination by aflatoxins and encourage further studies to investigate the transfer rate of mycotoxins to decoction, which is the final product for consumption.

The in vitro and in vivo efficacy of hen IgY against Vibrio parahaemolyticus and Vibrio vulnificus.

The inhibitory effect of IgY against Vibrio parahaemolyticus and Vibrio vulnificus responsible for seafood-borne diseases was investigated in this study. Water-soluble fractions (WSF) of protein containing IgYs were isolated from the egg yolk of hens initially immunized with formalin inactivated V. parahaemolyticus or V. vulnificus. Protein, total and specific IgY contents of the WSF were determined. The inhibitory and protective effects of IgYs on the growth of V. parahaemolyticus and V. vulnificus were assayed in liquid medium and in mice. IgYs showed high affinity to their corresponding antigens with high titer from day 28 onwards. Protein contents and total IgY concentrations remained stable throughout the immunization period, whereas specific IgY concentrations increased steadily and reached a plateau at day 49. Specific IgY powder (150 mg/ml) significantly inhibited further multiplication of both V. parahaemolyticus and V. vulnificus in liquid medium as compared with the control IgY. The bacteria count in mice feces was lower in mice pretreated with specific IgYs than in those pretreated with PBS or control IgY. Higher survival of mice was observed in the experimental groups pretreated with either anti-V. parahaemolyticus (75% survival) or anti-V. vulnificus (87% survival) IgYs, compared with those in the control groups pretreated with PBS or nonspecific IgY. All mice in the control groups died within three days after bacteria inoculation; hence, the protective effect of specific IgYs against infection caused by V. parahaemolyticus and V. vulnificus was demonstrated.