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, 300bar and 3mL/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. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The authors thank the Junta de Castilla y León for financial support (project GIR127). J. B. would like to thank the Spanish MEC for his Juan de la Cierva contract and M. T. Martín thanks the Spanish MEC for the Ramon y Cajal contract.

Peer Reviewed