Abstract:To investigate the influences of different drying methods on the levels of fucoxanthin, a new RP-HPLC method was established to determine the fucoxanthin content in the fresh or dried kelp and sargassum samples. The samples were extracted by methanol and then treated by C18 column solid-phase extraction to remove the other liposoluble components. The separation column was ZORBAX SB-C18(4.6×150 mm, 5 μm), which was held at 35℃. The mobile phase was composed of the gradient changes of methanol and ultrapure water at a flow rate of 0.7 ml/min. The sample loading volume was 10 μl. UV detection was performed at 450 nm. The method showed a good linear relationship between peak area and concentration over the range from 0.11 to 50 mg/L (R2=0.9999). The recoveries of fucoxanthin in three replicates ranged from 92.66% to 109.06%. The limit of detection was 0.03 mg/L. The RSD of precision was 3.46% to 4.61%. This method is simple, high sensitive and accurate. The levels of fucoxanthin in the fresh kelp and sargassum samples were 559.2 mg/kg (dry weight) and 680.4 mg/kg (dry weight), respectively. The fucoxanthin levels of the dried brown seaweed samples were significantly lower than those of fresh samples. All drying methods destroyed fucoxanthin in the seaweed samples, while freeze drying method was found superior to the low-temperature drying (45℃) method and natural drying method. Therefore, the fresh and freeze-drying seaweeds should be ensured to achieve high yield during the large-scale preparation of fucoxanthin. This research would provide the theoretical guidance and technical support for the development and utilization of seaweed fucoxanthin resource in the future.
