Allometric Growth of Sargassum fusiforme (Ochrophyta, Fucales) Organs in the Maturation Period Based on Biomass Analysis of Samples from Gouqi Island

Sargassum fusiforme is a seaweed species that plays an important role in the diverse communities of the flora and fauna of coastal food webs. Assessments of its biomass and energy allocation in addition to allometric organ growth have important ecological value for understanding the community structure, carbon storage, and resource assessment of seaweed beds during periods in which they thrive. In this study, the morphology of Sargassum fusiforme and the biomass of organs and total organisms in the maturation period were studied, and the allometric relationships for different organs of Sargassum fusiforme were analyzed using the standardized major axis (SMA). In the maturation period of Sargassum fusiforme, branch number, height × stem diameter were the prior independent variables, and the optimum biomass was y = 0.002x1.107 (R2 = 0.923). The biomass allocation ratio of blades was the highest (38.33%), followed by stems (32.90%) and receptacles (28.77%). The growth rates of the various organs were found to differ, and the rate of biomass increase for the blades and stems tended to converge. The rate of receptacle biomass growth of Sargassum fusiforme was the highest in the maturation period, and the rate of organ biomass increase was Wb < Ws < Wt < Wr, which reflects the trade-off with energy allocation as a strategy used by Sargassum fusiforme.

Evaluation of protein digestibility and iodine bioavailability in raw and cooked Sargassum fusiforme (harvey) setchell using in vitro methods

PurposeSargassum fusiforme is a popular edible seaweed in coastal cities of China that contains diverse nutrients including iodine. Cooking is an effective way to improve food safety, but it can alter both the contents of elements along with speciation and bioavailability. Three common cooking methods, the soaking, steaming and boiling, were evaluated for their effects on the protein structures, protein digestibility, iodine content and iodine bioavailability of S. fusiforme.Design/methodology/approachFourier transform infrared spectroscopy was used to study the structural changes of protein, and an in vitro digestion/Caco-2 cell culture system was used to evaluate the digestibility of protein, bioaccessibility and bioavailability of iodine.FindingsBoiling and steaming altered the protein secondary structure demonstrated by increased a-helix and random coil and decreased β-sheet, which improved the in vitro protein digestibility. Iodine content was reduced by cooking, with the highest loss observed after boiling, followed by soaking and steaming, while it was found that both bioaccessibility and cellular uptake of iodine were significantly elevated by boiling and steaming using an in vitro digestion/Caco-2 cell culture system. The presence of ascorbic acid, citric acid or tyrosine was beneficial for the iodine absorption, while oxalic acid and phytic acid hindered the iodine bioavailability.Originality/valueThe present finding suggested that cooking was conducive to the digestion and absorption of iodine in S. fusiforme. In addition, different dietary factors could have a certain impact on the absorption of iodine. Results of the study are essential for improving the application value of S. fusiforme to ensure reasonable consumption of seaweeds.