Isolation of Carrot Chromoplasts and Assessment of Their Carotenoid Content and Bioaccessibility

Abstract

The bioaccessibility (fraction of compounds released from the food matrix and available for absorption) and carotenoid content of carrot chromoplasts obtained through high-speed centrifugation using sucrose gradients were assessed. Three chromoplast bands were isolated, corresponding to sucrose gradients between 15 and 30%, 30 and 40%, and 40 and 50%. Total carotenoid levels increased ~2.8-fold when comparing the fractions of the bands of the lowest and highest sucrose gradients. The carotenoid profiles of the bands were similar. Phytoene and phytofluene accounted for approximately 3 and 4%, respectively, while ζ-carotene made up about 3%. Provitamin A carotenoids comprised about 85% of the total carotenoids in the respective fractions. Lutein content varied among fractions, with 1.61% in the 15/30% band and 0.77% in the 40/50% sucrose band. Similar micellar carotenoid profiles were also observed across fractions. α-carotene and β-carotene accounted for 8% and 0.2% of the total carotenoid content, respectively, while ζ-carotene constituted 19%. Lutein content in micelles ranged from 0.5% in the highest sucrose content fractions to 3.2% in the lowest. Phytoene and phytofluene were the predominant carotenoids in micelles. They accounted for 41.7% and 28.4%, respectively, together representing 70% of all carotenoids, with no differences among fractions. Colourless carotenoids were more readily incorporated into micelles, followed by ζ-carotene, lutein, and provitamin A carotenoids.

Keywords

• colourless carotenoids
• phytoene
• phytofluene
• plastids
• provitamin A carotenoids