Studies on the flavor substances of "nori", the dried laver porphyra spp. - III Sugars, organic acids, and minerals of "nori", the dried laver Porphyra spp.

Abstract

Eight commercial samples of ‘nori’, or the dried laver porphyra spp. were extracted with 75% ethanol and the extracts were analyzed for free sugars and organic acids by gas chromatography and for minerals by atomic absorption spectrophotometry. Isofloridoside and folridoside were found to be the predominant free sugars, followed by glucose and galactose. A small amount of mannose, inositol, ribose, arabinose and xylose were also detected. The contents of these sugars were generally lower in nori products of good quality than in those of poor quality. Volatile and nonvolatile organic acids found in the extracts were formic, acetic, propionic, butyric, lactic, oxalic, malonic, fumaric, succinic, malic and citric acids, Among them, formic acid was found to vary greatly from sample to sample. The contents of these organic acids were generally lower in tasty nori samples. Major cations found were Na+ and K+, followed by Mg2+ and Ca2+, whereas major anions were Cl- and PO43- The nori produced from the indoor cultured laver showed a general pattern similar to nori samples of poor quality, as far as the above components are concerned.