Cruciferin nanoparticles: Preparation, characterization and their potential application in delivery of bioactive compounds

Encapsulation of bioactive compounds is an emerging technique to provide protection against food processing and digestion as well as to increase their bioavailability. In this study, cruciferin, a major canola protein, was used to prepare calcium-induced nanoparticles by a cold gelation method. The particles were spherical in shape with similar to 200 nm diameter and polydispersity index (PDI) of 0.2-0.3. Alpha-helix structure was decreased while disordered structure and beta-sheet/turn were increased respectively for heated protein and calcium-induced particles based on circular dichroism, FTIR and fluorescence studies. Driving forces for the particles formation were hydrophobic and electrostatic interactions. The particles did not show toxicity to Caco-2 cells at concentrations of up to 2.5 mg/mL. The cell uptake of labelled nanoparticles was also observed using confocal microscopy after 6 h incubation with Caco-2 monolayer. Release studies showed that the particles were resistant to pepsin and low pH in simulated gastric fluid, but released the encapsulated compounds (brilliant blue and beta-carotene) in simulated intestinal conditions. Encapsulation also significantly increased the stability of beta-carotene in a heat treatment (75 degrees C and 30 min) compared to unencapsulated form. Our results suggested that cruciferin can be used for preparing particles and delivery of bioactive food components. (C) 2015 Elsevier Ltd. All rights reserved.