Abstract:
Sargassum is a genus of brown seaweed rich in bioactive compounds such as fucoidan which has various health-promoting properties including anti-cancer activity, anti-viral activity, and anti-inflammatory activity. This study examines the potential to develop herbal tea using Sargassum cristaefolium and Sargassum crassifolium Seaweeds were collected from the southern coastal area of Sri Lanka and identified using a morphological key. Each seaweed type was thoroughly cleaned, blanched and dehydrated either by oven-drying (40°C for 48h) or freeze-drying technique and ground to a coarse powder. Dried Sargassum powders were analyzed for moisture content, total phenolics (Folin-ciocalteu method), total flavonoids (Aluminum chloride method), radical scavenging activity (DPPH method), total carotenoids, and fucoidan content (spectrophotometric method). Freeze-dried Sargassum powders gave significantly higher total phenolic content (P<0.05) compared to the oven-dried Sargassum powder. Total phenolics content of S.crassifolium and S.cristaefolium were 0.7310.12 and 1.27±0.32 mg gallic acid equivalents/g dry weight, respectively. Total flavonoid contents were not significantly different among the two types of seaweed powder considering one drying method. Freeze-dried Sargassum powders gave significantly higher radical scavenging activity (P<0.05) than oven-dried Sargassum powder. Radical Scavenging activities of freeze-dried S.crassifolium and S.cristaefolium powders were 34.6%±1.87 and 46.8318.30%, respectively. Oven-dried Sargassum powders gave significantly higher total carotenoid content (P<0.05) than freeze-dried powders. For the S.crassifolium it was 1.8810.002 ii,g/g dry weight while it was 1.86±0.089 pg/g dry weight for S.cristaefolium: Freeze-dried Sargassum powder gave higher fucoidan content than oven-dried powder but there was no significant difference in the fucoidan content considering the four treatments and their tea liquors. Fucoidan content of the freeze-dried S.crassifolium seaweed powder was 30.7416.36 mg/200 mL, while that of S.cristaefolium was 30.014.09 mg/200 mL. Highest overall acceptability was taken from the oven-dried S.cristaefolium tea from the sensory evaluation. Results revealed that Sargassum powders can be successfully used as herbal tea with functional properties.
Keywords: Antioxidant activity, Freeze-drying, Fucoidan, Herbal tea, Sargassum
