Goji berry chromoplasts as water-dispersible carotenoid vehicles: characterization and stability assessment under different storage conditions

Abstract

Chromoplasts are organelles found in plant cells that store carotenoids. Their naturally hydrophilic structure, which accommodates carotenoids, has garnered increasing interest in recent years. However, the structural characteristics of carotenoid-loaded chromoplasts are still not fully understood, and their impacts on the stability and antioxidant capacity of carotenoids remain unclear under different storage conditions. In this study, chromoplasts were isolated using sucrose density gradient centrifugation and evaluated by their stability and antioxidant capacity under different light and temperature conditions. Spherical to ellipsoidal structures (3.5-6 μm) were observed in isolated chromoplasts bounded by intact bilayer membranes and containing carotenoid-rich tubular substructures arranged in a nematic liquid crystalline state. The dispersions exhibited optimal color and carotenoid stability when stored at 4 °C in the dark, with minimal degradation over 15 days. Higher temperatures and UV exposure accelerated pigment instability, with heat driving structural destabilization and aggregation, and UV exposure triggering distinct photodegradation accompanied by yellow-green discoloration and profound pigment depletion. Collectively, these findings establish a characterization and stability assessment for chromoplast dispersions and reveal current limitations in photothermal sensitivity. Further stabilization strategies will therefore be required to improve tolerance to thermal and photochemical stresses encountered under typical storage and processing conditions.