RESUMEN
To assess the risk of food allergies in foods processed under the Japanese food labeling system, estimating exposure to hidden allergens is necessary. We assessed exposure to egg protein in foods processed according to the Japanese food labeling system. First, we estimated the concentration distribution of egg protein by Bayesian methods using data from the literature and the measurement of food products with precautional declarations in the labeling margin. We then estimated the food-intake portion-size distribution under two scenarios: soft drink consumption as an example of single, high-intake consumption, and confections, which are frequently consumed by children, as a realistic example of low-intake consumption. Finally, we estimated the distribution of unexpected intake of egg proteins in the form of single consumption. The mean exposure to egg protein under the high-intake scenario was estimated to be 0.0164 mg for 1-15-year-olds, 0.0171 mg for 4-15-year-olds, 0.0181 mg for 7-15-year-olds, and ≥0.0188 mg for 16-year-olds. The mean exposure to egg protein under the low-intake scenario was estimated to be 0.0018 mg for 1-15-year-olds, 0.0019 mg for 4-15-year-olds, 0.0020 mg for 7-15-year-olds, and ≥0.0022 mg for 16-year-olds. Compared to the reference dose of 2.0 mg proposed by the Joint the Food and Agriculture Organization (FAO)/World Health Organization (WHO) Expert Committee, the risk of onset of food allergies due to egg protein contamination from foods without egg labeling is considered to be extremely low under the current Japanese food labeling system.
RESUMEN
Sesame is a frequent cause of adverse food reactions in allergic patients. We developed a novel sandwich enzyme-linked immunosorbent assay (ELISA) using two monoclonal antibodies and a unique extraction buffer for the detection and quantification of sesame proteins in processed foods and in raw food ingredients to clarify the validity of sesame labeling and for precautionary allergen labeling. The developed sandwich ELISA method is highly specific for sesame proteins. The limit of detection (LOD) and limit of quantification (LOQ) are 0.013 µg/g and 0.025 µg/g, respectively. The recoveries for incurred food samples, such as dressing, breads, sauce and pudding, ranged from 67 % to 81 %, while the repeatability and reproducibility coefficients of variation were less than 4.7 % and 4.5 %, respectively. The developed method has applicability for food products and is a reliable tool for the detection of hidden sesame proteins in raw food ingredients and in processed foods.
RESUMEN
Only a few methods exist for simple, sensitive and rapid detection of alpha-toxin in clinical and biological samples. The aim of our study was to establish a procedure for the production of an antibody against a recombinant antigen with confirmed sequence identity. We applied a noble approach based on proteomics using a mass spectrometer for the conclusive identification of the recombinant alpha-toxin that was subsequently used as an antigen. The recombinant alpha-toxin was produced in Escherichia coli. A clinical isolate of Clostridium perfringens GAI 94074 was amplified by polymerase chain reaction (PCR) and subsequently, cloning was performed. Three different fragments were cloned using a pET100/D-TOPO vector. These fragments coded for a ribosome binding site, a signal peptide and the alpha-toxin gene, respectively. Recombinant pET100 plasmids were cloned into TOP 10 cells and the isolated plasmids were transferred into BL21 Star (DE3) cells. Their expression was then induced with isopropyl-beta-D-thiogalactopyranoside (IPTG). Recombinant E. coli transformed with a plasmid encoding the alpha-toxin gene alone produced a biologically inactive protein. On the other hand, E. coli carrying the plasmid encoding the toxin sequence and its native signal peptide sequence, or the toxin sequence along with the ribosome binding sequence and the signal peptide sequence secreted an active alpha-toxin with phospholipase activity. Accordingly, the C. perfringens gene encoding the alpha-toxin protein along with its signal peptide was successfully cloned, expressed, and secreted by E. coli. Furthermore, without consideration of its activity, we used mass spectrometry to confirm that the expressed protein was indeed the alpha-toxin. Thus, the identification of alpha-toxin protein using both the biological activity testing and the mass spectrometry analysis is expected to verify the significant production of C. perfringens antibody. The study for the analysis of recombinant alpha-toxin using ESI/MS has not been reported. In this study, we report the successful cloning, expression, secretion, identification and sequence determination of the C. perfringens alpha-toxin.