Algal products beyond lipids: comprehensive characterization of different products in direct saponification of green alga Chlorella sp.

Algae as a raw material are highly important, since algae have high growth rates and are rich in lipids, proteins, and carotenoids. Direct saponification of alga with an ethanolic solution of KOH or NaOH followed by extraction was investigated and the composition of different fractions was studied by several physico-chemical methods, such as gas- and liquid chromatography, Fourier transform infrared analysis, scanning and transmission electron microscopy, organic elemental analysis, and thermogravimetric analysis. Direct saponification of Chlorella sp. was demonstrated with detailed analysis of different products, such as lipids, proteins, carotenoids and carbohydrates. The yield of lipids and the unsaponifiable fraction was independent on the type and concentration of alkali in direct saponification of green alga Chlorella sp. Proteins were mainly in the solid residue remaining after saponification. Protein content in the solid residue decreased with increasing alkali concentration and the solid residue. The main fatty acids were oleic and linoleic acids. Lutein and β-carotene were the main carotenoids in Chlorella sp. Sugars and large part of proteins remained in the polar fraction after separation of lipid and carotenoids.