With regard to its cost-effective cultivation and the composition of high-value nutrients, the diatom Phaeodactylum tricornutum (P. tricornutum) attracts interest for the use in human nutrition. Besides a number of important nutrients, it is rich in carotenoids. Therefore, this study aimed to investigate the potential of P. tricornutum as a carotenoid source for human nutrition. In photoautotrophically produced P. tricornutum biomass the carotenoid constitution, bioaccessibility (in vitro digestion model) and cellular uptake in differentiated Caco-2 cells (Transwell model system) was determined. Furthermore, the influence of sonication on these parameters was investigated. The results indicate that β-carotene, zeaxanthin and fucoxanthin were the main carotenoids found in P. tricornutum. Moreover, these carotenoids showed a good bioaccessibility (β-carotene: 25%, zeaxanthin: 27%, fucoxanthin: 57%), which is further improved by sonication for β-carotene and fucoxanthin. In line with the good bioaccessibility, fucoxanthin was the most abundant carotenoid in Caco-2 cells followed by zeaxanthin. In contrast, β-carotene could not be detected in the cells. The present study demonstrated that P. tricornutum represents a good source of carotenoids, particularly fucoxanthin. Thus, this diatom can contribute to the intake of bioaccessible carotenoids, even without processing. In addition, sonication might be a useful tool to improve the carotenoid bioaccessibility.
Keywords: Bioaccessibility; Caco-2 cells; Fucoxanthin; In vitro digestion; Phaeodactylum tricornutum; Zeaxanthin; β-Carotene.
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