Relationship between 4-hydroxy-2-hexenal contents and commercial grade by organoleptic judgement in Japanese dried laver Porphyra spp.

• Excellent laver contained higher of free amino acids and 5′-nucleotides.
• Excellent laver contained higher of lipids and lipophilic pigments.
• Excellent laver contained lower of 4-hydroxy-2-hexenal and propanal.
• The 4-hydroxy-2-hexenal content was correlated with propanal in laver.
• Organoleptic judgement was correlated with chemicals related to color and taste.

To evaluate the correlation between the commercial grade determined by organoleptic judgment panel and chemical substances in dried laver Porphyra spp., we analyzed the contents of free amino acids, 5′-nucleotides, total lipids, fatty acids, α-tocopherol, lipophilic pigments, and aldehydes in several grades of laver that had been classified by an organoleptic judgment panel. Compared with the lower-grade laver samples, the excellent-grade laver samples contained higher concentrations of free amino acids, 5′-nucleotides, total lipids, α-tocopherol, chlorophyll a, and β-carotene and lower concentrations of aldehydes such as 4-hydroxy-2-hexenal (HHE), propanal, butanal, and 1-hexanal, which are formed during lipid peroxidation of n-3 or n-6 polyunsaturated fatty acids. In addition, the HHE content was strongly correlated with the propanal content in the analyzed laver (r2 = 0.9123). These results showed that the commercial grade assigned by an organoleptic judgment panel was correlated with chemical substances associated with color, taste, and the prevention of lipid oxidation.