Dietary exposure to acrylamide in a group of Japanese adults based on 24-hour duplicate diet samples

Acrylamide is a probable human carcinogen and known human neurotoxin that can be generated in food through heating. Using a mathematical modelling approach, our previous study estimated long-term average dietary exposure to acrylamide in the Japanese people; however, the validity of these estimates remained unknown. Here, we aimed to obtain a more accurate estimate of acrylamide exposure that would reflect the usual practice of heat processing and consumption of foods in the population. We collected duplicate diet samples and dietary records during 24 h from a group of Japanese adults. A total of 110 duplicate diet samples were analysed for acrylamide by LC-MS/MS. Data from individual dietary records were used to examine the association between dietary acrylamide exposure and consumption of selected food groups (e.g., coffee, tea, confectioneries, and vegetables prepared at high temperature [deep-frying, stir-frying, sautéing, and baking]). Of the 110 homogenised diet samples, 108 contained detectable levels of acrylamide. Dietary exposure to acrylamide ranged from 8 to 1582 ng/kg body weight (bw)/day, with the mean value of 215 ng/kg-bw/day and median value of 143 ng/kg-bw/day. This mean value was higher than the value we previously estimated for Japanese adults using a mathematical approach. Multiple linear regression analysis showed log dietary acrylamide exposure was significantly associated with consumption of coffee and vegetables prepared at high temperature during 24-hr of sampling (adj. R² = 0.250, p < 0.001). We revealed significant difference in dietary acrylamide exposure between participants who had coffee and vegetables prepared at high temperature (median, 169 ng/kg-bw/day; range, 35–1224 ng/kg-bw/day, n = 42) and those who had none of them (median, 75 ng/kg-bw/day; range, 8–311 ng/kg-bw/day, n = 15) (Steel-Dwass test, p < 0.05).     

Antibacterial action on pathogenic bacterial spore by green tea catechins

Antibacterial effects of catechins, the major green tea polyphenols, were studied using Clostridium and Bacillus spores. Incubation with crude catechins decreased the number of C botulinum and C butyricum spores but not B cereus spores. Furthermore, the effects of six catechin derivatives on spores were investigated. (−)‐Epicatechin gallate (ECg), (−)‐epigallocatechin (EGC), (−)‐epigallocatechin gallate (EGCg) and (+)‐gallocatechin gallate (GCg) were more effective in decreasing C botulinum and C butyricum spore numbers than (+)‐catechin (C) and (−)‐epicatechin (EC). The vegetative growth of C botulinum and B cereus was inhibited by crude extracts of the catechins. Specifically, purified GCg and EGCg inhibited the vegetative growth of C botulinum and B cereus. The inhibitory effect of ECg on B cereus was similar to that of GCg. However, toxin‐production by B cereus was not inhibited by catechin. Damage to the membrane of C butyricum spores by catechin derivatives was shown using fluorescent microscopy. This study shows that low concentrations of catechins, although requiring a long exposure time, inhibited the growth of bacterial spores. However, the effects of the purified derivatives of the catechins were not the same and GCg and EGCg were found to be the most potent. Spores that are generally resistant to many disinfectants were sensitive to catechins. Copyright © 2005 Society of Chemical Industry     

Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g^?1) than in the second (2.24 mg g^?1) or first crop season (1.79 mg g^?1). The amount of anthocyanins contained in the stem was high (1.61 mg g^?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g^?1, 0.52 mg g^?1, 0.40 mg g^?1, 0.22 mg g^?1, 0.14 mg g^?1, and 0.11 mg g^?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry     

Selective enumeration of viable Enterobacteriaceae and Pseudomonas spp. in milk within 7 h by multicolor fluorescence in situ hybridization following microcolony formation

Rapid and simultaneous enumeration of viable Enterobacteriaceae and viable Pseudomonas spp. in milk was achieved by using multicolor fluorescence in situ hybridization (FISH) with oligonucleotide probes based on 16S ribosomal RNA (rRNA) sequences in combination with a microcolony growth method (multicolor microcolony-FISH; MMC-FISH). The procedure of MMC-FISH method is rather simple; that is milk clearing, filtration of cells, incubation, hybridization and enumeration. Enumeration of targeted bacteria in logarithmic growth phase, stationary phase, or in a starved state in milk by MMC-FISH required 5-7 h, while it took 1-3 days to test for Escherichia coli and Pseudomonas putida by the conventional culture method. The numbers of E. coli and P. putida in each phase or in a starved state in milk determined by MMC-FISH were almost the same or greater than the number of colony forming units determined by the plate counting method. The MMC-FISH allows rapid examination of contamination in milk by viable Enterobacteriaceae and Pseudomonas spp. with growth potential.     

Polymerization of β-lactoglobulin and bovine serum albumin at oil-water interfaces in emulsions by transglutaminase

Polymerization of β-lactoglobulin and bovine serum albumin at the oil—water interfaces in n-tetradecane-in-water emulsions induced by the transglutaminase reaction was studied. The emulsions were incubated with transglutaminase for various times, and adsorbed and unadsorbed protein fractions at the oil—water interfaces were analyzed by sodium dodecyl sulfate—polyacrylamide gel electrophoresis. While only monomers were detected in the unadsorbed fractions, polymers were observed in the adsorbed fractions of the both proteins. The sizes and amounts of the polymers increased with incubation time. The incubation with transglutaminase caused much flocculation of the emulsion stabilized by β-lactoglobulin. An increase in viscosity was also observed with the flocculation. The flocculation was probably initiated by the formation of ε-(γ-glutamyl)-lysyl isopeptide bonds between β-lactoglobulin molecules adsorbed on different oil droplets. In the case of the emulsion stabilized by bovine serum albumin, however, the flocculation and the increase in viscosity occurred to only limited extents by the transglutaminase reaction. This suggests that ε-(γ-glutamyl)-lysyl isopeptide bonds induced by the transglutaminase reaction were formed only between neighboring molecules of bovine serum albumin on the same droplet.     

Antimicrobial activity of nutmeg against Escherichia coli O157

We examined the difference between Escherichia coli O157 and non-pathogenic E. coli in their tolerance to spices. Various spices (5 g each) were homogenized at 25 degrees C for 10 min with 5 ml of 70% ethyl alcohol, and the supernatant solutions obtained by centrifugation were used as spice extracts. When the E. coli strains were incubated with each spice extract at concentrations of 0.01% and 0.1%, a noteworthy difference was observed between the O157 and non-pathogenic strains in their tolerance to nutmeg. The populations of the non-pathogenic strains could not be reduced, but those of the O157 strains were remarkably reduced. Antibacterial activity by the nutmeg extract was also found against the enteropathogenic E. coli O111, but not against enterotoxigenic (O6 and O148) and enteroinvasive (O29 and O124) E. coli. When we examined the antibacterial effect of volatile oils in nutmeg on the O157 and non-pathogenic E. coli strains, all O157 strains tested were found to be more sensitive to beta-pinene than non-pathogenic E. coli strains.     

Characterization of mixing performance in a microreactor and its application to the synthesis of porous coordination polymer particles

Here we quantitatively evaluated the mixing performance of a tailor-made microreactor with central-collision type through the iodide/iodate chemical test reaction, and applied the microreactor to the synthesis of zeolitic imidazolate framework-8 (ZIF-8), which is a subclass of porous coordination polymers (PCPs) or metal organic frameworks (MOFs). The chemical test reaction demonstrated excellent mixing performance of the microreactor with a characteristic mixing time shorter than 1 ms, which is approximately 100 times faster than those of a batch reactor and a millimeter-sized Y-shaped mixer. Taking advantage of the rapid and uniform mixing, the microreactor successfully produced ZIF-8 particles with high reproducibility by simply mixing aqueous solutions of zinc nitrate and 2-methylimidazole. The synthesis at room temperature resulted in ZIF-8 particles with chamfered cube shape, while a lower temperature of 5 °C produced raspberry-type spherical particles. We confirmed that prepared ZIF-8 particles have BET surface area of ～1500 m²/g and exhibit the gate adsorption behavior caused by the structural transition of the ZIF-8 framework.     

Structure and Thermophysical Properties of Molten BaGe Using Electrostatic Levitation Technique

BaGe alloys with two compositions near their eutectic point form open framework structures called the clathrate structure. These BaGe compounds with the clathrate structure can be made by rapid solidification from their liquid state. However, the formation mechanism of the clathrate structure has not been clarified due to lack of information on their liquid-state structure and properties. Since BaGe alloy melts have very high reactivity, it is difficult to measure the thermophysical properties of them by ordinary methods using a container. Therefore, a containerless technique must be used to measure the thermophysical properties of BaGe melts. Using the electrostatic levitation (ESL) technique as a containerless technique, the thermophysical properties (density, surface tension, and viscosity) of BaGe melts around the eutectic composition were measured in order to clarify the formation mechanism of the clathrate structure, and also the structure of them was observed by using the high-energy X-ray diffraction method combined with ESL. From experimental results, it was observed that the short-range order based on the clathrate structure exists even in the liquid state at the clathrate-forming compositions.     

High Resolution Structure of the Mature Capsid of Ralstonia solanacearum Bacteriophage ϕRSA1 by Cryo-Electron Microscopy

The ϕRSA1 bacteriophage has been isolated from Ralstonia solanacearum, a gram negative bacteria having a significant economic impact on many important crops. We solved the three-dimensional structure of the ϕRSA1 mature capsid to 3.9 Å resolution by cryo-electron microscopy. The capsid shell, that contains the 39 kbp of dsDNA genome, has an icosahedral symmetry characterized by an unusual triangulation number of T = 7, dextro. The ϕRSA1 capsid is composed solely of the polymerization of the major capsid protein, gp8, which exhibits the typical “Johnson” fold first characterized in E. coli bacteriophage HK97. As opposed to the latter, the ϕRSA1 mature capsid is not stabilized by covalent crosslinking between its subunits, nor by the addition of a decoration protein. We further describe the molecular interactions occurring between the subunits of the ϕRSA1 capsid and their relationships with the other known bacteriophages.