Analytical methods were investigated for the discrimination of 'nori', the dried laver Porphyra spp. sheet products, which were organoleptically judged as excellent-grade for commercial distribution. Volatile compounds of nori were analyzed with an electronic nose and a gas chromatography-mass spectrometer (GC/MS) with headspace solid-phase micro-extraction. Each chopped dry nori sample was sealed in a vial and the headspace gas at 40 A degrees C was analyzed. Excellent-grade nori product of 'Akime', first autumn shoots, of one season could be discriminated from other products by using principal component analyses (PCA) for the electronic nose response. PCA using a peak area of 32 compounds detected in the GC/MS analysis clearly discriminated all excellent-grade samples from all other samples. Excellent-grade products were considered to be characterized by higher total contents of 6-methyl-5-hepten-2-one, octanal and trimethylamine, and by lower total volatile contents, especially 1-pentanol, 2-pentenal, (E)-2-hexenal, acetoin, 2-methyl-2-butenal, 3-methyl butanal and others. These findings revealed the possibility of analytical discrimination of excellent-grade nori products as a substitution for organoleptic testing
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