Production of L-arabinose from corn hull arabinoxylan by Arthrobacter aurescens MK5 α-L-arabinofuranosidase

Arabinoxylans, which are comprised of a xylan backbone to which are attached glycosyl units that are primarily L-arabinofuranosyl units, are ubiquitous among plant species where it is a constituent of the cell wall. Arabinoxylan has attracted much attention as a potential biomass resource and L-arabinose has recently been reported to possess functional properties that are effective in the treatment of diabetes. Here, we report an α-L-arabinofuranohydrolase, isolated from the soil microbe Arthrobacter aurescens strain MK5, effective in releasing L-arabinose from corn hull arabinoxylan. When A. aurescens strain MK5 was grown in a liquid medium, corn hull arabinoxylan, which has a higher arabinose content (Ara/Xyl = 0.6) than oat spelts xylan (Ara/Xyl = 0.12), induced more efficient arabinoxylan hydrolase production. Analysis of enzyme activity in the culture broth revealed that arabinoxylan hydrolase activity was high, and α-L-arabinofuranosidase and β-xylosidase activities were low. The optimum pH of the MK5 arabinoxylan hydrolase at 40 °C was around 7 and enzyme activity was relatively stable at an alkaline pH up to 9.5. The optimum temperature at pH 7 was around 50 °C and enzyme activity was stable under 50 °C. During the hydrolysis of corn hull arabinoxylan, only L-arabinose was released and 45.1% maximum sugar recovery was achieved. The A. aurescens MK5 enzyme was a typical arabinoxylan α-L-arabinofuranohydrolase and was most effective at releasing L-arabinose from corn hull arabinoxylan, which has a high arabinose content. This enzyme may have important industrial applications.     

Comparison between old and new methods for detection of allergenic substances (egg and milk)

The old ELISA method for detection of allergenic substances (egg and milk) in Kanagawa prefecture from 2003 to 2007, employed before improvement of the food allergen labeling system, yielded detection rates of 20% for egg and 30% for milk. In 2005, after improvement of the labeling system, the detection rate using the new ELISA in solutions containing 1% SDS and 7% 2-mercaptoethanol increased by about 10% for egg, but decreased by half for milk. There were 4 positive samples (over 10 μg/g) for both egg and milk proteins, on account of contamination by ingredients at the manufacturing line and the lack of proper food labeling. In 2009, the contamination levels of egg and milk proteins in labeled commercial foods were low. In a comparison between the new and old methods with the same samples, both the new ELISA and Western-blot analyses showed an increase in the detection rate of egg protein. In relation to milk protein, the detection rates were decreased with the new ELISA, although the ELISA detection rate and consistency rates with Western-blot analysis were increased. On the other hand, in the case of a protein content below 5 μg/g, it was impossible to determine ovomucoid and casein by Western-blot analysis.     

Pt-Promoted Cu/SBA-15 Catalysts with Excellent Performance for Chemoselective Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

Cu/SBA-15 catalysts containing a small amount of Pt (Cu–Pt/SBA-15) were prepared by sequential adsorption–reduction method and examined for chemoselective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). The Cu–Pt/SBA-15 catalyst with an optimal Cu/Pt atomic ratio of 10 showed a DMO conversion close to 100 % with a 98 % selectivity to EG at a temperature as low as 463 K. The results showed that the best Cu–Pt/SBA-15 enhanced the space time yield of EG by about 1.47 times compared with Cu/SBA-15. The introduction of Pt with stronger ability for H₂ adsorption and activation substantially enhanced the reducibility of the Cu²⁺ species and further promoted the chemisorption capacity of H₂. After reduction, a portion of Cu was alloyed with Pt, which was beneficial for the generation and stabilization of a balanced Cu⁺/Cu⁰ ratio during the hydrogenation process.     

Direct analytical method for aromatic compounds in water by steam carrier gas chromatography

Conditions for direct analyses of various aromatic compounds in water by steam carrier gas chromatography (SCGC) were studied by using a hydrogen flame ionization detector and acid washed Chromosorb P modified with 3.5 ± 0.3 wt% of phosphoric acid as a stationary solid in 2 mm i.d. × 2 m glass column. A flowrate of approx. 60 ml min⁻¹ of carrier steam and a column temperature of 150–180°C were considered to be the optimum conditions for analyses of water samples containing several groups of aromatic compounds. Under constant conditions, aromatic compounds were generally eluted in order of their boiling points. The relationship between the retention time and the boiling point was obtained for two groups of substitutes of benzene and naphthalene. The retention time of a substitute of benzene or naphthalene can, therefore, be predicted from its boiling point, and conversely, the aromatic compounds in an unknown water sample can be characterized for identification from their retention times. By SCGC, various aromatic compounds in water at concentrations higher than approx. 30 μg l⁻¹ can be analysed directly without complicated pre-treatment.     

Visualization of Gluten,Starch, and Butter in Pie Pastry by Fluorescence Fingerprint Imaging

Food and Bioprocess Technology - The distribution of starches, proteins, and fat in baked foods determine their texture and palatability, and there is a great demand for techniques to visualize the...     

Ethanol production from ensiled rice straw and whole-crop silage by the simultaneous enzymatic saccharification and fermentation process

Silage production from rice straw and whole-plant forage paddy rice is increasing in Japan because of decrease in rice consumption. One potential use for this silage is bioethanol production. In this study, we analyzed the effectiveness of three different commercially available cellulases at saccharification of sun-dried rice straw, ensiled rice straw, and rice whole-crop silage (WCS). Furthermore, the ethanol productivity of the simultaneous saccharification and ethanol fermentation process (SSF) from the same plant substrates was analyzed. Among the three kinds of cellulases tested (Novozymes NS50013, Genencor GC220, and Acremonium cellulase), Acremonium cellulase showed the highest ethanol production for the three plant substrates, and the WCS produced the highest ethanol level. Analysis of the enzymatic degradation activity of the cellulases revealed that Acremonium cellulase contained remarkably high glucoamylase and pectinase side activities relative to the other cellulase preparations. The addition of glucoamylase and pectinase to the other two cellulases significantly increased ethanol productivity to levels observed for the Acremonium cellulase preparation, which showed little enhanced performance with the addition of the same enzymes. Finally, we tested whether milling and sterilization had an effect on ethanol production and found that sterilized silage produced higher ethanol levels but that the milling process had no significant effect. These results show that (i) silage made from whole-plant rice can be used for bioethanol production and (ii) the proper selection and combination of commercially available enzymes can make SSF more cost efficient by removing the need for a pre-treatment step.     

Inter-laboratory evaluation studies for establishment of notified ELISA methods for allergic substances (peanuts)

Inter-laboratory evaluation studies were conducted for ELISA methods for allergic substances (peanuts). Extracts of biscuit, sauce, chocolate and butter spiked with peanut standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of the ELISA methods using a Peanut Protein ELISA Kit (Peanut kit) and a FASTKIT Peanut ELISA kit (Peanut ELISA kit) were mostly below 10%. Mean recoveries of the peanut standard protein from the food extracts were over 40% in the two ELISA methods. Repeatability relative standard deviations of peanut standard protein in four food extracts were in the ranges of 15.2-49.7% and 3.0-28.3% for the Peanut kit and the Peanut ELISA kit, respectively. Reproducibility relative standard deviations of peanut standard protein in four food extracts were 23.5-44.4%, 9.6-28.4% for the Peanut kit and the Peanut ELISA kit, respectively. The detection limits of both ELISA methods were 2-2.5 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of peanut protein levels in extracts of biscuit, sauce, chocolate and butter.     

Ultrastructural analysis of buckwheat starch components using atomic force microscopy

Morphological and structural features of buckwheat starch granules and nanocrystals were examined using atomic force microscopy and dynamic light scattering. Partially digested starch granules revealed a clear pattern of growth rings with the central core revealing lamellar structure. Atomic force microscopy and dynamic light scattering experiments revealed that the buckwheat starch granules were polygonal in shape and were in the range of 2 to 19 μm in diameter. The optimized acid hydrolysis process produced nanocrystals with the shape of spherical structure with lengths ranging from 120 to 200 nm, and the diameter from 4 to 30 nm from aqueous suspensions of buckwheat starch solution. The sorption isotherms on buckwheat starch nanocrystal/glycerol composite exhibited a 3-stage transition of moisture in the blending. The biocompatible nature of buckwheat starch nanocrystals and their structural properties make them a promising green nanocomposite material. PRACTICAL APPLICATION: Buckwheat starches had never been studied on a nanoscale, but we have achieved new understanding of starch granule morphology and concentric growth rings using nanoscale imaging. Since buckwheat is an underutilized crop, we foresee the potential application of buckwheat starch, starch-based nanocrystals, and nanoparticles, to expand markets and encourage producers to expand their buckwheat acreage. The atomic force image analysis suggests that buckwheat starch could be used as a new biopolymer material in food industries.     

The relationship between intramembranous particles and aquaporin molecules in the plasma membranes of normal rat skeletal muscles: a fracture-label study

The plasma membrane of skeletal muscles contains water channels such as aquaporin 4 (AQP4), aquaporin 3 (AQP3) and aquaporin 7 (AQP7). In dehydrated mice, we have recently reported the altered distribution of the aggregations of intramembranous particles (IMPs), such as orthogonal array (a crystal-like structure) and IMP cluster (a rosette-like structure) on the freeze-fractured skeletal muscle plasma membranes. In this fracture-label study, we first tested whether the orthogonal arrays (OAs) were composed of AQP4 in skeletal muscles and further analyzed the relationship between IMPs including IMP clusters and AQP3 molecules. As a result, many of the gold particles indicating AQP4 was associated with OAs (79%) by our fracture-label technique. On the other hand, approximately 50% of gold particles indicating AQP3 were associated with IMP clusters. Thus we confirmed that the OAs are composed of AQP4 in skeletal muscles, and further demonstrated that some of the IMP clusters are composed of AQP3 and may participate in maintaining osmotic homeostasis in skeletal myofibers. The fracture-label method is useful in investigating the molecular identification of membrane proteins such as AQP3 and AQP4.