Bioaccessibility, Bioavailability and Bioactivities of Carotenoids in Microalgae: A Review

In recent years, carotenoids, as photosynthetic pigments, have drawn increasing interest due to their health benefits. This is because carotenoids have possessed enormous potential in lowering the risk of cardiovascular, cataracts, macular degradation and malignant tumours. Although many carotenoids can be produced via chemical synthesis, the commonly used petroleum-derived extraction method can be problematic for the environment and potentially contaminate the isolated carotenoids. Therefore, in contrast to chemosynthesis, microalgae can be considered an excellent alternative natural source to synthetic ones. Varying in microalgal strains, a variety of different carotenoids can be produced, for instance, the beta-carotene from Dunaliella salina, the fucoxanthin from Undaria pinnatifida and the astaxanthin from Haematococcus pluvialis. Besides, the pharmacological action of carotenoids is highly associated with their bioaccessibility and bioavailability, which is one of the research directions and affecting factors of the carotenoid application in the food, pharmaceutical, nutraceutical and cosmeceutical industries. Despite there being numerous publications about carotenoids, a comprehensive review on the microalgal carotenoids and their triggered bioactivities is still lacking. Considering the significance of bioavailability, this review presents extensive information on microalgal carotenoids, including their classifications, bioaccessibilities, absorption process mechanisms, bioactivities and relevant health benefits.