[Effect of Cooking and Processing on Quantitation of Soybean Proteins].

We examined the effects of cooking and processing on the quantitation of soy protein in various soy-based foods. For the phosphate-buffered saline (PBS) extraction, the total protein content was measured by bicinchoninic acid assay, and the buffer extraction containing sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (ME) was measured by the 2-D Quant Kit, and SDS-polyacrylamide gel electrophoresis analysis (SDS-PAGE) of each extraction was performed. Furthermore, measurements were performed by various ELISAs. During the tofu cooking process, the protein concentrations of soaked soybeans and Seigo (soybean homogenized with water) fluctuated- the change in protein solubility due to the amount of water during sample homogenization was considered to be a factor. It was thought that the decrease in protein concentration due to heating of Seigo during soymilk production was considered to indicate thermal denaturation of the protein, and that SDS and ME extraction in tofu may affect the measurement system. In cooking excluding roasted beans, proteins with a mass of 50 kDa or above and around 20 kDa were denatured, and in twice-fried tofu, proteins around 40 kDa were denatured, but the protein concentration excluding boiled soybeans did not decreased. Furthermore, the protein concentration from roasted beans, yuba, roasted okara and fried tofu increased with the cooking time, suggesting that the denaturation temperature of the protein shifted to a high temperature as the water content decreased. Both of the two types of ELISAs that comply with the official labeling system of foods containing allergenic substances were useful for detecting soybean protein by detecting proteins and peptides in processed soybean products, fermented foods excluding natto, and health foods.

Prevalence of and risk factors associated with faecal carriage of CTX-M ß-lactamase-producing Enterobacteriaceae in rural Thai communities.

OBJECTIVES: To determine the prevalence of CTX-M ß-lactamase-producing Enterobacteriaceae and to study the risk factors associated with faecal carriage in asymptomatic rural Thai people. METHODS: In all, 417 stool samples were obtained from rural Thai people and screened for extended-spectrum ß-lactamases (ESBLs) using MacConkey agar supplemented with 2 mg/L cefotaxime. Results were confirmed using cefotaxime and ceftazidime with and without clavulanic acid. The bla(CTX-M) genes were identified and genotyped using PCR with bacterial DNA samples. Multivariate analysis was performed to investigate risk factors associated with the faecal carriage of CTX-M producers. RESULTS: The prevalence of CTX-M-type ESBL-producing Enterobacteriaceae was 65.7%. The CTX-M-9 group (60.6%) was dominant, followed by the CTX-M-1 group (38.7%). Most of the bacteria were Escherichia coli (85.4%) and Klebsiella pneumoniae (4.7%). Of a total of 234 E. coli strains, 48.7% belonged to phylogenetic group A, 28.6% to group B1, 15.8% to group D and 6.8% to group B2. Most CTX-M producers were susceptible to carbapenems and amikacin, but resistant to tetracycline and gentamicin. In a multivariate logistic regression model, better education status (OR 2.245; 95% CI 1.297-3.884), history of hospitalization (OR 1.643; 95% CI 1.036-2.603) and the use of antibiotics within the last 3 months (OR 1.883; 95% CI 1.221-2.903) were independently associated with faecal carriage. CONCLUSIONS: Faecal carriage of CTX-M-type ESBL-producing Enterobacteriaceae among asymptomatic individuals in rural Thailand remains alarmingly high, and previous antibiotic use and a history of hospitalization may contribute to its dissemination.