TITLE:
Quantification of Lipid Content and Identification of the Main Lipid Classes Present in Microalgae Extracts Scenedesmus sp. for Obtaining Fatty Compounds for Biofuel Production
AUTHORS:
Carolina Vieira Viegas, Leonardo Brantes Bacellar Mendes, Rafael Richard João, Gisel Chenard Díaz, Donato A. G. Aranda, Yordanka Reyes Cruz
KEYWORDS:
Microalgae, Lipids, Extraction, Saponifiable Compounds, Biofuels
JOURNAL NAME:
Energy and Power Engineering,
Vol.12 No.6,
June
12,
2020
ABSTRACT: Microalgae biomass has been reported in the literature as one of the most
promising sources for obtaining different products of industrial interest such
as lipids, fatty acids, carotenoids, proteins and fibers. The lipid fraction of
microalgae comprises neutral lipids, free fatty acids and polar lipids. It is
of great importance to estimate the composition of the lipid fraction to define
the potential for use, either as a raw material for the production of biofuels
or for use for nutraceuticals and/or food purposes. The microalgae Scenedesmus sp. cultivated in a
photobioreactor, the sky open raceway type, was
evaluated for lipid content, identification and quantification of lipid
components obtained from different extracts. In the quantification of the lipid
content, extraction methods were proposed without chemical treatment (use of
solvents only) such as chloroform:methanol (2:1 v/v)—Bligh & Dyer, Ethanol,
Ethyl acetate:Hexane (1:1 v/v) and others with chemical treatment such as
J-Schmid-Bondzynski-Ratzlaff (acid) and saponification (basic). For the
identification of the main lipid components present in the extracts, the Thin
layer chromatography (TLC) technique was used. This made it possible, using a
simple and inexpensive method, to identify the compounds extracted by different
extraction methods, that is, it was possible to verify the selectivity of the
different extraction methods. In addition, it has been shown that using these
methods, widely described in the literature as methods of extracting lipids in
practice, extracts a wide diversity of compounds. The levels of lipids obtained via solvent
extraction were up to 50% higher than those obtained with chemical treatment.
In lipid extracts, obtained via solvent extraction, the presence of polar
compounds, glycerides, carotenoids, pigments and sterols was identified, with
up to 53% being composed of an unsaponifiable fraction, thus,
presenting low selectivity for extracting fatty components. The acidic and
basic treatments applied to the biomass of Scenedesmus sp. showed greater selectivity for obtaining fat components of 71.47% and 94.99%,
respectively. The results showed that depending on the solvent/method used to
quantify the lipids, the selectivity for obtaining the grease fraction,
fundamental for conversion into biofuels, varies and the total lipid content
may be overestimated.