Influence of chromoplast morphology on carotenoid bioaccessibility of carrot, mango, papaya, and tomato.

Based on the observation of outstanding dissimilarities of the morphology of pigment-containing chromoplasts in nutritionally important carotenoid sources, the bioaccessibility (BA) of carotenoids from edible portions of carrot, mango, papaya, and tomato was compared using an in vitro digestion model. While carrot and tomato contained large carotenoid crystals clearly visible by light microscopy, mango and papaya contained different types of carotenoid-bearing structures. Particularly, β-carotene is deposited in globular and tubular elements in papaya and mango chromoplasts, where carotenoids accumulate in a lipid-dissolved and liquid-crystalline form, respectively. The highest BA of β-carotene was found for mango (10.1%), followed by papaya (5.3%), tomato (3.1%), and carrot (0.5%). In our digestion model, differences between total lycopene BA from papaya and tomato were insignificant, possibly since both pigments occur in a solid crystalline deposition form in both fruits. Furthermore, the BA of lutein, β-cryptoxanthin, and β-cryptoxanthin esters was shown to be superior to that of the carotenes from the respective food sources. The effect of lipid addition to the different food sources was studied. Although BA was enhanced for most carotenoids, the above-mentioned ranking of BAs of β-carotene remained unchanged after lipid addition. Consequently, the physical form of carotenoid deposition in plant chromoplasts is suggested to have major impact on their liberation efficiency from the food matrices.