Studies on nutritional composition of three colour forms of Kappaphycus alvarezii (Doty) Doty

Biochemical composition of seaweeds is known to vary with species and environment. Kappaphycus alvarezii is an important commercial source of carrageenans (gel-forming and viscosifying polysaccharides). The nutritional and mineral composition of three (brown, green and pale yellow) colour forms of edible seaweed K. alvarezii is investigated in the current study. The brown colour form of this seaweed contained highest ash content of (25.99 +/- 0.22 %), crude fibre (21.0 +/- 0.68 %), and protein (8.92 +/- 0.41 %), while, the green form had highest carbohydrate (22.0 +/- 0.00 %) and sulphate (5.89 +/- 0.00 %) content. On the other hand, the pale yellow colour form had highest lipid content (0.72 +/- 0.00 %). Amongst the 17 minerals analyzed, highest total mineral macro-elements (viz. Na, K, Ca and Mg) were recorded in the brown form (18.8 +/- 0.71 g/100 g d wt) followed by the pale yellow (17.3 +/- 1.07 g/100 g d wt) and green colour form (11.9 +/- 1.22 g/100 g d wt). The micro-elements varied within the three colour forms; however, the brown colour form had maximum micro-element content (P, Cd, Pb, As, Hg, Cr, Zn, Cu, Fe, Mn, Co, Mo and Ni; 19.96 +/- 0.24mg/100 g d wt), followed by green (8.6 +/- 0.64 mg /100 g d wt) and pale yellow form (7.15 +/- 0.58mg /100 g d wt). On the basis of this study, it could be said that these three colour forms (i.e. brown, green and pale yellow) of Kappaphycus alvarezii could be utilized as a condiment in the omnivorous diet; however, a daily intake of 5.68 g d wt is recommended in case of the brown form, while in case of the green and pale yellow form a maximum daily intake of 9.55 and 10.5 g d wt, respectively is recommended. The study also reveals that the three colour-forms differed in their nutritional and mineral composition.