Chemical and Nutritional Compositions and in vitro Digestibility of Brown and Green Seaweed in Southern Oman

Background and Objective: Seaweeds have over the last century been identified as a major source of nutritional and medicinal active agents. In this study, brown alga Nizamuddinia zanardinii and green alga Ulva fasciata were evaluated for their chemical compositions. Materials and Methods: Nizamuddinia zanardinii and Ulva fasciata were collected, washed vigorously and dried in shade (the temperature around 30°C) for 2-5 days. After that, chemical and nutritional compositions and in vitro digestibility were assessed. One-way ANOVA was used to compare the chemical composition, minerals and in vitro digestibility of the samples. Multiple comparisons among the samples were performed using a Tukey HSD post hoc test. Results: The 2 most dominant components in both seaweeds were total carbohydrates (51.31-65.05%, dry weight) and ash (16.34-24.22%, dry weight), however their crude lipid (0.08-0.24%, dry weight) and fibre (5.23-5.45%, dry weight) contents were low. Protein content (13.94%, dry weight) of Ulva fasciata was higher than that of N. zanardinii (3.86%, dry weight). Atomic spectrophotometry of the minerals has revealed that U. fasciata contained greater concentrations of macro-minerals (K, Na, Ca, Mg) but a lower amount of trace elements (Fe, Zn) than N. zanardinii. In vitro digestibility assays of total dry matter in these seaweeds showed high digestibility (98.37-99.05%, dry weight) whereas protein digestibility in U. fasciata (90.46%, dry weight) was higher than in N. zanardinii (85.30%, dry weight). Conclusion: The findings show that those seaweeds have a high nutritional benefit and should be used as ideal human and animal dietary supplements.