Dynamic variation of fucoxanthin in Saccharina japonica during harvesting and storage processes

Saccharina japonica is an edible seaweed in which fucoxanthin shows anti-oxidant, anti-tumour and anti-obesity activities. In the present study, three varieties of fresh S. japonica were used as material. The fucoxanthin content and the expression level of Lhc subunits in fresh S. japonica during harvesting were studied. The variation of fucoxanthin in S. japonica raw material and its extract under different conditions, including freezing, drying, various temperatures and light qualities were also measured. Results showed that during the harvesting period of S. japonica , the content of fucoxanthin maintained at a high level in April and then decreased to a steady level from May. The expression level of light-harvesting protein subunits Lhcf5 and Lhcf6 in XS-2 finally decreased to a steady level, whereas those in XS-BN and LJ-205 showed fluctuating trends. The content of fucoxanthin in fresh S. japonica remained stable at -20 °C. The variation of fucoxanthin in freeze-dried S. japonica conformed to first-order kinetic. Fucoxanthin in S. japonica extract showed high stability in the dark, the variation conformed to second-order kinetic, while it was sensitive under condition of illumination, the variation conformed to zero-order kinetic. These findings will provide technical support for comprehensive utilization and aquacultural condition optimization of S. japonica .