Nutritional value of Chlorella vulgaris : Implication of color

Microalgae such as Chlorella vulgaris has been consumed as food and food supplements for being rich in proteins and omega 3 polyunsaturated fatty acids (n-3 PUFAs). Different varieties of C. vulgaris with different colors are already promoted for these purposes. This paper aimed to explore the changes of nutritional value of commercial C. vulgaris according to their color with a focus on lipid composition. As microalgal color is strictly related to their photosynthetic process, though to chloroplast membrane, special attention was made on glycolipid components. Four commercials C. vulgaris samples whose colors were dark green, light green, yellow and white, resulting from their autotroph and heterotroph cultures, were studied. The photosynthesis process was found to have significant impacts on the lipid composition and nutritional values of C. vulgaris. The dark green C. vulgaris biomass contained the highest content of lipids (10.3 % dry weight, DW) as well as alpha-linolenic acid (ALA), 8.8 ± 0.2 µg/mg DW and n-3 PUFAs, 14.7 ± 0.4 µg/mg DW, principally under glycolipid forms. The light green and the yellow ones contained about one third of the quantity of ALA of the dark green one, i.e. 2.9 ± 0.1 µg/mg DW and about 2.5-2.6 times less of n-3 PUFAs compared to the dark green one. In contrast, the white one contained insignificant amounts of ALA and n-3 PUFAs, 0.2 ± 0.0 and 1.1 ± 0.1 µg/mg DW, respectively. The LA/ALA ratio of the dark green, light green and yellow C. vulgaris were nutritionally much more interesting than the white C. vulgaris, 1.0, 4.1 and 2.9 respectively compared to 28.5.