Stability of canola oil encapsulated by co-extrusion technology: Effect of quercetin addition to alginate shell or oil core

This study examines the co-extrusion encapsulation of canola oil by alginate, with an antioxidant (quercetin) incorporated either in the oil core or alginate shell. Optical and environmental scanning electron microscopy revealed spherical beads of diameter similar to 350 mu m and wall thickness similar to 65 mu m. Bead appearance, size, wall thickness and surface characteristics did not change appreciably after treatments at pH 3 for 2 h, pH 6.5 for 2 h or pH 6.5 for 1 min then pH 3 for 2 h, although the amounts of phenolics released from beads differed depending on the conditions. The quercetin addition approach strongly influenced the stability of canola oil during storage at 20 and 38 degrees C. Quercetin in the core more effectively suppressed oil deterioration. Quercetin in shell caused a higher phenolic content after storage. FTIR and HPLC analyses were used to track changes in the chemical composition of the encapsulated oil beads during storage. (C) 2013 Elsevier Ltd. All rights reserved.