Nutritional evaluation of some subtropical red and green seaweeds: Part I — proximate composition, amino acid profiles and some physico-chemical properties

The proximate composition, amino acid profile and some physico-chemical properties of two subtropical red seaweeds (Hypnea charoides and Hypnea japonica) and one green seaweed (Ulva lactuca) were investigated. The total dietary fiber [ranged from 50.3 to 55.4% dry weight (DW)] and ash (ranged from 21.3 to 22.8% DW) were the two most abundant components in these seaweeds but their crude lipid contents were very low (ranged from 1.42 to 1.64% DW). Although the crude protein content of the red seaweeds was significantly (p<0.05, ANOVA, Tukey-HSD) higher than that of the green, the three seaweed proteins contained all essential amino acids, the levels of which were comparable to those of the FAO/WHO requirement. Moreover, the swelling capacity (SWC), water-holding capacity (WHC) and oil-holding capacity (OHC) of the seaweeds had a high positive correlation (r=0.99–1.00) with their total amount of fiber and protein. Among the three seaweeds, the two red seaweeds exhibited significantly (p<0.05, ANOVA, Tukey-HSD) better physico-chemical properties, which were similar to some commercial fiber-rich food ingredients.