Temporal and spatial variations in the proximate composition, amino acid, and mineral content of Pyropia yezoensis

Temporal and spatial variations in the proximate composition, amino acid content, and mineral content of Pyropia yezoensis were evaluated at Jindo, Haenam, and Seochun on the southern and western coasts of Korea. The proximate composition of P. yezoensis showed a specific pattern where carbohydrate, lipid, and ash increased over time, while protein decreased over time from January to April. Amino acids from P. yezoensis, such as alanine, aspartic acid, glutamic acid, leucine, and glycine, as well as 14 different minerals, were identified. Among them, aspartic acid, alanine, and glutamic acid were present at the highest concentrations. The concentration of alanine ranged from 3.40 ± 0.22 to 0.97 ± 0.07 g (100 g)⁻¹ at all sites. Five macro minerals (Ca, K, Mg, Na, and P) and seven micro minerals (Mn, Co, Fe, Ni, Cu, Zn, and Cr) were measured at three different sites. The macro mineral K was present at the highest concentration, followed by P, Na, Ca, and Mg. The concentration of K showed spatial and temporal variations. P. yezoensis at Haenam contained 3249.39 ± 100.82 mg (100 g)⁻¹ in January, but decreased to 55.39 ± 209.95 and 426.00 ± 389.74 mg (100 g)⁻¹ in February and March, and then increased to 2120.42 ± 454.53 mg (100 g)⁻¹ in April. The micro mineral, Fe, was present at the highest concentrations, followed by Zn and Co. The concentration of Fe ranged from 42.71 ± 57.23 to 12.08 ± 1.55 mg (100 g)⁻¹ in March and April at Haenam. The concentration of Zn was highest in January and then gradually decreased from February to April, while Jindo and Haenam did not show spatial and temporal variations in Zn concentrations. In this study, temporal and spatial variations in the proximate composition, amino acid content, and mineral content of Pyropia were determined to analyze the protein, amino acid, lipid, carbohydrate, and mineral contents, which showed temporal and spatial variations during cultivation from October to April.