Supercritical fluid extraction of lipids from broccoli leaves

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Abstract

The supercritical fluid extraction (SFE) and fractionation of lipids from broccoli leaves is presented in this work. For this purpose the effect of the different variables on the extraction was studied, obtaining the best results at 60°C, 300 bar and 3 mL/min. Two different fractions were obtained: First, the samples were extracted with pure CO2, and afterward the residual material was extracted using CO2 modified with 15% of methanol. The total fatty acid content of the extracts was determined by GC-MS and compared with those results obtained by Soxhlet extraction with hexane and a chloroform/methanol (2:1) mixture. The SFE extracts presented a higher percentage of unsaturated fatty acids, especially the polyunsaturated 18:3 n − 3. The methodology was successfully applied to the analysis of the fatty acid composition of the leaves from five different cultivars of broccoli. In all the samples the main fatty acids were α-linolenic (18:3 n − 3), linoleic (18:2 n − 6), and palmitic (16:0). Among the different cultivars analyzed, Naxos variety presented the highest levels in fatty acids, while Parthenon and Viola the lowest.

Practical applications: The proposed method allows the fractionation of lipids from broccoli leaves using a small volume of organic solvent and mild conditions. This is advantageous compared to conventional methods where large volumes or organic solvents are used, and the cost and time for the removal of these solvents, along with the possibility of degradation and toxicity, are the major disadvantages. The results obtained contribute to a better compositional characterization and a possible revaluation of this by-product as a source of biologically active compounds.

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