Optimisation of the Supercritical Fluid Extraction of Antioxidants from Broccoli Leaves
2016
Arnáiz, Esther | Bernal, José | Martín, María Teresa | Diego, Juan Carlos | Bernal, José Luis | Recio, Laura Toribio
This work presents the application of supercritical fluid extraction (SFE), an environmentally friendly methodology, to obtain broccoli leaves extracts with a high antioxidant activity. The following processing variables: pressure, temperature, percentage of ethanol and dynamic extraction time were optimised by means of a central composite design, combined with response surface methodology. The optimised conditions were applied to the extraction of broccoli leaves from different cultivars (Naxos, Nubia, Marathon, Parthenon and Viola). The optimal values of the extraction variables were 150 bars, 35 °C, 20 % ethanol and 10 min of dynamic extraction time. Percentage of ethanol and the combined effect of pressure and time were the factors that affected the extraction the most. The results obtained from different cultivars showed that the Naxos variety provided the extracts with the highest antioxidant activity and total phenolic content; moreover, DPPH (EC 50) values were higher than those previously reported for water extracts. The extracts were recovered in a small quantity of ethanol that could be easily eliminated, obtaining a residue free of contaminants.
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