The reactants produced by action of a purified unique dye-decolorizing peroxidase, DyP, on a commercial anthraquinone dye, Reactive Blue 5, were investigated using electrospray ionization mass spectrometry (ESI-MS), thin-layer chromatography (TLC), and (1)H- and (13)C- nuclear magnetic resonance (NMR). The results of ESI-MS analysis showed that phthalic acid, a Product 2 (molecular weight 472.5), and a Product 3 (molecular weight 301.5), were produced. Product 2 and Product 3 were generated by usual peroxidase reaction, whereas phthalic acid was generated by hydrolase- or oxygenase-catalyzed reaction. One potential associated product, o-aminobenzene sulfonic acid, was found to be converted to 2,2'-disulfonyl azobenzene by ESI-MS and NMR analyses. From these results, we propose, for the first time, the degradation pathway of an anthraquinone dye by the enzyme DyP.

The volatile components of both the peel and juice of three major Japanese sour citrus cultivars with pleasant flavour, Yuzu (Citrus junos Sieb. ex Tanaka), Sudachi (Citrus sudachi Hort. ex Shirai) and Kabosu (Citrus sphaerocarpa Hort. ex Tanaka) were investigated using the solvent assisted flavour evaporation technique after solvent extraction. Limonene was the most abundant monoterpene hydrocarbon in all the extracts, followed by γ‐terpinene and β‐phellandrene in Yuzu and Sudachi and by myrcene in Kabosu. Mintsulfide was newly identified in juice extracts from Yuzu and Kabosu. Among the oxygenated components of these extracts, linalool was the most abundant in both the peel and juice of Yuzu and the peel of Sudachi, while both the peel and juice of Kabosu revealed the presence of high quantity of saturated aliphatic aldehydes. Wine lactone and rose oxide were identified in all the extracts, which have not been previously reported to occur in these citrus cultivars. The odour‐active components of each oxygenated fraction were revealed by aroma extract dilution analysis. Linalool, trans‐4,5‐epoxy‐(2E)‐decenal and wine lactone showed relatively high flavour dilution factors in the peel and juice of these citrus cultivars. The enantiomeric distribution of linalool, cis‐rose oxide, β‐citronellol and wine lactone was determined using a multi‐dimensional chiral gas chromatography–mass spectrometry. With regard to linalool, the (R)‐enantiomer was predominant in Yuzu and the (S)‐enantiomer in Sudachi and Kabosu. Copyright © 2012 John Wiley & Sons, Ltd.

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The volatile components of both peel and juice of Japanese citrus, Kabosu (Citrus sphaerocarpa Hort. ex Tanaka) were investigated using SAFE (Solvent Assisted Flavor Evaporation) technique after solvent extraction. In this study, wine lactone, rose oxide, (2E)-4,5-epoxy-2decenal, mintsulfide, and indole were newly identified from Kabosu. AEDA (Aroma Extract Dilution Analysis) of the oxygenated fraction of the peel extract showed high FD (Flavor Dilution) factors for linalool, (2E)-4,5-epoxy-2-decenal, octanal, (4Z)-decenal, β-citronellol, geraniol, and wine lactone, while wine lactone, linalool, eugenol, geraniol, and (2E)-4,5-epoxy-2-decenal from the juice extract. The enantiomeric distribution of linalool, cis-rose oxide, β-citronellol, and wine lactone were also determined using a multidimensional chiral GC/MS.

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