Growth and toxin production by Clostridium botulinum in steamed rice aseptically packed under modified atmosphere

Sales and consumption of ready-to-eat aseptic steamed rice products have increased manyfold in Japan over the past 10 years. To determine the safety of steamed rice (water content 60%, pH 6.5) aseptically packaged under modified atmosphere, challenge studies were performed using a mixture of Clostridium botulinum proteolytic strains (five strains of type A and five strains of type B). Atmospheric conditions of 0 and 15% oxygen (with 5% CO2 and 5% N2 as the balance) were used. No neurotoxins were detected, and organoleptically acceptable conditions persisted for 24 weeks at 15% oxygen conditions. However, botulinum neurotoxin was found in one of three samples at 12 weeks and in one of two samples at 24 weeks at 0% oxygen and 30 degrees C. When samples were inoculated with C. botulinum with amylase (0% oxygen), neurotoxin and sample spoilage was detected after only 1 week of storage. Challenge studies using proteolytic strains of C. botulinum mixed with Bacillus subtilis (amylase formers) also were performed with atmosphere conditions of oxygen at 0, 5, 10, and 15% (with 5% CO2 and 5% N2 as the balance). Under 10 and 15% oxygen conditions, neurotoxin was not detected after 1 week of storage, but sample spoilage was detected after the same period. Under 0% oxygen conditions, neurotoxin was detected at 1 week, but the sample remained organoleptically acceptable even after 2 weeks of storage. Both neurotoxin and sample spoilage were detected at 1 week of storage under 5% oxygen conditions. Based on these results, cocontamination of amylase-producing Bacillus with C. botulinum would increase the risk of foodborne botulism when aseptic rice samples are packed under low-oxygen conditions (<5%). Therefore, to ensure the safety of these products, packing under atmospheric containing more than 10% oxygen is recommended.     

Improvement of Fish-sauce Odor by Treatment with Bacteria Isolated from the Fish-sauce Mush (Moromi) Made from Frigate Mackerel

ABSTRACT: A bacterium, which was isolated from fish-sauce mush (moromi) of frigate mackerel and identified as Staphylococcus xylosus , could change notes of an odor in fish sauce made in Thailand. Volatile compounds of the fish sauce after incubation at 32 °C for 24 d with the cultured bacterium were analyzed by gas chromatogra-phy. Although the contents of 2-ethylpyridine and dimethyl trisulfide were reduced during the incubation, 4 volatile compounds, including 2-methylpronal, 2-methylbutanal, 2-pentanone, and 3-(methylthio)propanal, showed no significant quantity changes. On the other hand, although 3-methyl-1-butanol and 2,6-dimethylpyrazine were markedly increased, 3-methylbutanoic acid was slightly increased. As a result of sensory evaluation, fishy, sweaty, fecal, and rancid notes of the fish sauce treated with the bacterium were all weaker than those of the nontreated fish sauce. No changes were found with respect to burnt, cheesy, meaty, and ammoniacal notes between fish sauce treated with the bacterium and that without treatment. Taken together, the odor of fish sauce was much improved by treatment with the isolated bacterium.     

Development of a novel microbial sensor with baker's yeast cells for monitoring temperature control during cold food chain

A novel microbial sensor containing a commercial baker's yeast with a high freeze tolerance was developed for visibly detecting inappropriate temperature control of food. When the yeast cells fermented glucose, the resulting gas production triggered the microbial sensor. The biosensor was a simple, small bag containing a solution of yeast cells, yeast extract, glucose, and glycerol sealed up with multilayer transparent film with barriers against oxygen and humidity. Fine adjustment of gas productivity in the biosensor at low temperatures was achieved by changing either or both concentrations of glucose and yeast cells. Moreover, the amount of time that food was exposed to inappropriate temperatures could be deduced by the amount of gas produced in the biosensor. The biosensor was stable without any functional loss for up to 1 week in frozen storage. The biosensor could offer a useful tool for securing food safety by maintaining low-temperature control in every stage from farm to fork, including during transportation, in the store, and at home.     

Microscopic evidences that bone marrow mononuclear cell treatment improves sciatic nerve regeneration after neurorrhaphy

Cell therapy constitutes a possibility for improving nerve regeneration, increasing the success of nerve repair. We evaluate the use of mononuclear cells in the regeneration of the sciatic nerve after axotomy followed by end‐to‐end neurorrhaphy. Forty adult male Wistar rats (250–300 g) were divided into four groups: (1) sham, (2) neurorrhaphy: the sciatic nerve was sectioned and repaired using epineural sutures, (3) culture medium: after the suture, received an injection of 10 μL of culture medium into the nerve, and (4) mononuclear cell: after the suture, a concentration of 3 × 10⁶ of mononuclear cell was injected in epineurium region. Mononuclear cells were obtained from the bone marrow aspirates and separated by Ficoll‐Hypaque method. The histological analyses were performed at the 4th postoperative day. The sciatic functional index, histological, and morphometric analyzes were used to evaluate nerve regeneration at the 6th postoperative week. Six rats were used for immunohistochemical analysis on the 4th postoperative day. In the group 4, on the fourth day, the histological analysis demonstrated a more accelerated degenerative process and an increase of the neurotrophic factors was observed. In the 6th week, all the morphometric results of the group 4 were statistically better compared with groups 2 and 3. There was a statistically significant improvement in the sciatic functional index for group 4 compared with groups 2 and 3. Mononuclear cells stimulated nerve regeneration, most probably by speeding up the Wallerian degeneration process as well as stimulating the synthesis of neurotrophic factors. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Expression of Aspergillus oryzae phytase gene in Aspergillus oryzae RIB40 niaD(-)

Aspergillus oryzae RIB40 niaD(-) was transformed using a plasmid constructed with the A. oryzae phytase gene and pNAN8142 vector. The culture broth of the transformant, which was grown in a medium containing starch as a carbon source and polyvinylpyrrolidone showed phytase activity of a maximum of 2.0 units ml(-1) at 37 degrees C, pH 5.5.     

Visualization of charges stored in the floating gate of flash memory by scanning nonlinear dielectric microscopy

By applying scanning nonlinear dielectric microscopy (SNDM), we succeeded in clarifying that electrons existed in the poly-Si layer of the floating gate of a flash memory. The charge accumulated in the floating gate can be detected by SNDM as a change in the capacitance of the poly-Si (floating gate) by scanning the surface of the SiO(2)-SiN(4)-SiO(2) (ONO) film covering the floating gate. There was a clear black contrast region in the SNDM image of the floating gate area, where electrons were injected. However, no clear contrast appeared in the floating gate where electrons were not injected. We confirmed that SNDM is one of the most useful methods of observing the charge accumulated in flash memory.     

Nanodomain manipulation for ultrahigh density ferroelectric data storage

Nanosized inverted domain dots in ferroelectric materials have potential application in ultrahigh density rewritable data storage systems. Herein, a data storage system is presented based on scanning non-linear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, we succeeded in forming our smallest artificial nanodomain single dot at 5.1?nm diameter and an artificial nanodomain dot array with a memory density of 10.1?Tbit?inch(-2) and a bit spacing of 8.0?nm, representing the highest memory density for rewritable data storage reported to date. Subnanosecond (500?ps) domain switching speed has also been achieved. Next, actual information storage with a low bit error and high memory density was performed. A bit error ratio of less than 1 × 10(-4) was achieved at an areal density of 258?Gbit?inch(-2). Moreover, actual information storage is demonstrated at a density of 1?Tbit?inch(-2).     

Operational stability enhancement of white OLEDs with single solution‐processed emitting layer fabricated by “self‐layered technique”

Abstract — We achieved operationally stable white OLEDs with a single solution processed EML fabricated using a self‐layered technique. An LT70 of 10 khr at an initial luminance of 1000 cd/m² was obtained by suppressing the exciplex formation between the EML and ETL, preventing Li diffusion into the EMLs, and using red dopants with shallow LUMO levels and stable host materials.     

Fine dispersion of carbon black in fluorene‐based resin

The dispersion ability of fluorene‐based epoxy resin (FBE), bisphenol A based epoxy resin (PBE), fluorene‐based polyester (FBP), and polycarbonate (PC) in carbon black (CB) was evaluated. CB/FBE composite had a lower L value (reflectance, blackness) than that of CB/PBE composite, for the same CB content. Aggregations of CB in CB/FBE composites were much smaller than those in CB/PBE composites. The strong interaction between fluorene with cardo structure and CB resulted in a fine dispersion of CB in FBE. FBP had much higher dispersion ability of CB than PC. CB (50 wt%) was dispersed into FBP compared with the 10 wt% of CB dispersed in PC by melt blending. The effect of CB on the mechanical properties of FBP was much higher than that on PC due to fine dispersion of CB in FBP. The effect of CB addition on the T_g of FBP was also higher than that of CB on the T_g of PC. Computational simulation indicates that most stable energy between fluorene with a cardo structure and graphite structure was smaller than the energy between bisphenol A and graphite. It was also shown that the minimum energy appeared when the fluorene structure was almost parallel to the graphite plane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

BAMO/NMMO Copolymer with Polyester Initiation

In order to improve of mechanical properties at low temperature region, 3,3-bis(azidomethyl)oxetan (BAMO), 3-nitratomethyl-3-methyloxetane (NMMO) and polyester (PE) copolymer were synthesized by using polyester initiator with boron trifluoride etherate. The molar ratio of each units in the BAMO/NMMO/PE copolymer was 7.4/2.6/0.39 according to the ¹H-NMR spectrum analysis and was almost exactly the same composition as the monomer fed (7/3/0.33). The relative composition of triad microstructures was same as theoretical value and they were randomly arranged. The PE, which was a replacement of 1,4-butanediol, acted as an excellent soft segment in the copolymer, and the glass transition point of the elastomer was 4.8 degrees lowered by the replacement. This effect was also verified in the mechanical properties of the composite propellant and the tensile elongation was increased from 15% to 40%percnt; at −40 °C.