Bioactive Compounds from Carrot Pomace as Natural Antioxidants to Enhance the Oxidative Stability of Linseed Oil Encapsulated by Particles from Gas Saturated Solutions Technique

Abstract

In this work, supercritical fluids were used to (1) extract bioactive compounds from carrot pomaces and (2) to use them as ingredient to test their antioxidant capacity to retard the oxidation of linseed oil produced by an innovative microencapsulation technique, called particles from gas saturated solutions (PGSS). Briefly, the extract was obtained from dried and milled carrot pomaces by supercritical CO₂ extraction. The extraction was run at 30 MPa and 60 °C with a CO₂ flow rate of 2 L/h for 120 min leading a yield ranging from 1 to 2 %. Then, the extracts were mixed with linseed oil and turned into powders by PGSS. This operation consisted of two steps. First, sunflower wax (~80 %), linseed oil (~20 %) and the extract from carrot pomace (from 0.01 to 0.3%) were mixed in a melting chamber saturated with CO₂, for 30 min at a constant pressure of 10, 20 or 30 MPa and 65 °C. Then, the melted mixture was sprayed into a cyclone chamber at ambient temperature and pressure. The depressurization cooled down the droplets and turned them into powder crystals. Interestingly, the lower pressures applied in the melting chamber, greatly increased the encapsulation efficiency, powder density (bulk and tapped) and powder flowability (Carr index). Finally, the oxidative stability of the powders was tested by isothermal calorimetry (at 40°C). The powders prepared at 10 MPa showed an oxidative stability 2 times longer than those prepared at 30 MPa. Also, the addition of carrot extracts (0.3 %) induced an improved oxidative stability to the powders 8 times longer than those prepared without carrot extracts. Overall, our findings highlighted the potential use of supercritical CO₂ to recover bioactive compounds from carrot pomaces and develop powder microcapsules with enhanced oxidative stability by PGSS technique.