Inter-laboratory study for validation of a Japanese official analytical method for determination of patulin in apple juice

To validate a modified version of AOAC official method of analysis 995.10 as an official standard in Japan for determination of patulin in apple juice, an inter-laboratory study was performed in 11 laboratories using a non-contaminated sample, 2 naturally contaminated samples and 2 spiked samples of apple juice. For naturally contaminated apple juices, the relative standard deviations for repeatability and reproducibility were 3.2, 7.1% and 10.0, 21.7%, respectively. HORRAT values were 0.4, 0.9. The average recovery of patulin from spiked sample was 83.7%. The limit of quantification was calculated as 10 microg/kg. From these results, the method was thought to be suitable as an official standard for determination of patulin in apple juice in Japan.     

Increased riboflavin production from activated bleaching earth by a mutant strain of Ashbya gossypii

The production of riboflavin from vegetable oil was increased using a mutant strain of Ashbya gossypii. This mutant was generated by treating the wild-type strain with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Riboflavin production was 10-fold higher in the mutant compared to the wild-type strain. The specific intracellular catalase activity after 3 d of culture was 6-fold higher in the mutant than in the wild-type strain. For the mutant, riboflavin production in the presence of 40 mM hydrogen peroxide was 16% less than that in the absence of hydrogen peroxide, whereas it was 56% less for the wild-type strain. The isocitrate lyase (ICL) activity of the mutant was 0.26 mU/mg of protein during the active riboflavin production phase, which was 2.6-fold higher than the wild-type strain. These data indicate that the mutant utilizes the carbon flux from the TCA cycle to the glyoxylate cycle more efficiently than the wild-type strain, resulting in enhanced riboflavin production. This novel mutant has the potential to be of use for industrial-scale riboflavin production from waste-activated bleaching earth (ABE), thereby transforming a useless material into a valuable bioproduct.     

Phosphorylation of proteins by dry-heating in the presence of pyrophosphate and some characteristics of introduced phosphate groups

Various proteins and dextrin were phosphorylated by dry-heating in the presence of pyrophosphate, and phosphate bonds characterised. The basic proteins were more highly phosphorylated than acidic proteins by dry-heating in the presence of pyrophosphate. The phosphorylated poly-l-lysine hydrobromide (PP-PLy) and lysozyme (PP-Lz) were more highly dephosphorylated than phosphorylated dextrin and ovalbumin (PP-OVA) by phosphatases, and the dephosphorylation of PP-PLy was much higher than that of PP-Lz. The phosphate bonds in all phosphorylated samples were stable during heating at 120 °C. The ³¹P NMR spectral data suggested that different types of phosphate bonds were introduced, and the N–P bond was suggested in PP-PLy. Some phosphorylated tryptic peptides from PP-Lz and PP-OVA were detected by mass spectrometry analysis. Furthermore, the introduced phosphate linkages in peptides from PP-Lz and PP-OVA were identified.     

Multiresidue analysis of pesticides in agricultural products by GC/MS,GC-ECD and GC-FTD using acetonitrile extraction and clean-up with mini-columns

An analytical method was developed for determination of organochlorine, pyrethroid and nitrogen-containing pesticide residues in agricultural products by GC/MS, GC-ECD and GC-FTD. Pesticides were extracted with acetonitrile, and the organic layer was cleaned up on C18 and ENVI-Carb/LC-NH2 cartridges. Pesticides were determined by GC/MS, GC-ECD and GC-FTD. Detection limits of pesticides by GC/MS and GC were below 1-30 ng/g and 1-3 ng/g, respectively. Recoveries of 27 out of 53 pesticides determined by GC/MS and 47 out of 53 determined by GC were 70-120%. This method was useful for the multiresidue analysis of pesticides in agricultural products. Pesticide residues in 81 domestic crops were investigated from April 2001 to March 2002. Residues of 31 pesticides were detected from 21 crops.     

Phenolic Antioxidants in Some Vigna Species of Legumes and their Distinct Inhibitory Effects on α-Glucosidase and Pancreatic Lipase Activities

Phenolic extracts of 4 Vigna species of legumes (mung bean, moth bean, and black and red varieties of adzuki beans) were evaluated for phenolic contents, antioxidant activities, and inhibitory properties against α-glucosidase and pancreatic lipase. Results showed that adzuki bean varieties contain higher phenolic indexes than mung bean and moth beans. Adzuki bean (black) variety was found to be the most active 2,2′-diphenyl-1-picrylhydrazyl and superoxide anion scavenger. However, the hydrogen peroxide scavenging and metal chelating abilities were significantly higher in adzuki bean (red) variety. Mung bean exhibited least antioxidant activities in all the methods tested. Phenolic extracts from these legumes also showed distinct variations in the inhibition of enzymes associated with hyperglycemia and hyperlipidemia. Inhibitory activities of all the extracts against lipase were found to be more potent than α-glucosidase. Although, α-glucosidase inhibitory activity was superior in the black variety of adzuki bean (IC(50,) 26.28 mg/mL), both adzuki bean varieties (black and red) along with moth bean showed strong inhibitory activities on lipase with no significant difference in their IC(50) values (7.32 to 9.85 mg/mL). These results suggest that Vigna species of legumes are potential source of antioxidant phenolics and also great sources of strong natural inhibitors for α-glucosidase and lipase activities. This information may help for effective utilization of these legumes as functional food ingredients for promoting health. Practical Application: Vigna species of legumes are good sources of phenolic antioxidants and strong natural inhibitors of enzymes associated with diabetes and obesity. Therefore, utilization of these legumes in the development of functional foods with increased therapeutic value would be a significant step toward health promotion and wellness.     

Structural analyses of unknown red dyes detected in dried strawberry

We examined two unknown red dyes (designated as red dyes "A" and "B") from a dried strawberry package with a label that indicated the presence of food red No. 40 (R40). Red dye "A" was identified as trisodium 3-hydroxy-4-[(2'-methoxy-5'-methyl-4'-sulfonatophenyl)azo]-2,7-naphthalenedisulfonate (CSA-R) by HPLC, UV-VIS spectra and MS spectra. This compound is one of the four reported subsidiary colors of R40. Detailed analyses of red dye "B" by MS and NMR demonstrated that its structure was disodium 3-hydroxy-4-[(2'-methoxy-5'-methyl-4'-sulfonatophenyl)azo]-2-naphthalenesulfonate. Red dye "B" is a structural isomer of R40, that has not been reported previously. Our results suggest that the two minor red dyes were subsidiary colors contained in R40, which had been added to the dried strawberries.     

Fabrication of Sr0.5Ba0.5Nb2O6 Nanocrystallite‐Precipitated Transparent Phosphate Glass‐Ceramics

Transparent (Sr_0.5Ba_0.5)Nb₂O₆ (SBN50) nanocrystallite‐precipitated phosphate glass‐ceramics were prepared by a conventional glass‐ceramic process. x(SrO–BaO–2Nb₂O₅) ? (100–4x)P₂O₅ (xSBNP) glasses with a refractive index of 1.9–2.0 exhibited high water resistance owing to the presence of Q⁰ and Q¹ phosphate units. Both bulk and surface crystallization of the SBN50 phase were observed in 20SBNP and 21SBNP glass‐ceramics. Although the nominal content of SBN50 crystals in the 21SBNP glass was larger than that in the 20SBNP glass, the latter exhibited better crystallinity of SBN50 and a higher number density of precipitated SBN nanocrystallites. By tuning the two‐step heat‐treatment and the chemical composition, transparent SBN50‐precipitated glass‐ceramics were successfully obtained. Given that no remarkable increase of the relative dielectric constants was observed after crystallization of the SBN50 nanocrystallites, it is postulated that the relative dielectric constant of the bulk is mainly governed by the amorphous phosphate region, and that the contribution of precipitation of the SBN50 nanocrystallites to the dielectric constant is not very significant in this system.     

5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的碳化促进养护

采用碳化养护方法促进5%乙烯-醋酸乙烯共聚物复合低热水泥浆体的水化.通过X射线衍射定性及定量分析测定了养护后样品的组成及水泥中硅酸三钙(3CaO·SiO2,C3S)、硅酸二钙(2CaO·SiO2,C2S)的水化率;利用带固体样品测试装置的全有机碳素分析仪测定了样品所吸收的CO2量;采用水银压入法检测了样品的孔径分布.结果显示:碳化养护大大促进了低热水泥的水化,并有球霰石生成.样品中的总孔隙体积也明显减少,但有大量较大孔径的毛细孔隙存在.碳化养护前,对样品进行水中预养护可以减少这些毛细孔隙,但不利于水泥的水化并导致CO2吸收量及抗折强度显著降低.     

Chemical stability of γ-butyrolactone-based electrolytes for aluminum electrolytic capacitors

γ-Butyrolactone-based electrolytes have been used as the operating electrolytes for aluminum electrolytic capacitors. The chemical stability of these electrolytes at elevated temperatures has been examined by monitoring the decrease in their electrolytic conductivities. The deteriorated electrolytes were analyzed by gas and liquid chromatography and the conductivity decrease was directly correlated with the loss of acid components. In quaternary ammonium hydrogen maleate/γ-butyrolactone electrolytes, the maleate anion decomposed by decarboxylation resulting in a complex polymer containing polyester and polyacrylate structures. Quaternary ammonium benzoate/γ-butyrolactoneelectrolytes decomposed by SN2 reactions giving alkyi benzoates and trialkylamines. The deterioration of the carboxylate salt/γ-butyrolactone electrolytes was accelerated by electrolysis.     

Promotional Effect of Iron for the Nitridation of Niobium Oxide to Niobium Nitride

Supported NbN catalysts were prepared under a N₂–H₂ gas stream by the addition of Fe species to Nb/SiO₂. The nitriding process was monitored by in situ XAFS measurements. Fe K-edge XAFS and Nb K-edge in situ XAFS measurements revealed that Fe species in close proximity to niobium oxide can effectively induce nitridation of the niobium oxide with the nitriding rate being dependent upon the dispersion of Fe species. It was concluded that the dispersed Fe species close to niobium effectively assisted the nitridation of niobium oxide into NbN. The nitriding degree can be expressed by the coordination number of Nb–N.