Encapsulation of microalgal-based carotenoids: Recent advances in stability and food applications

Carotenoids are among the most important pigments found in nature, which are synthesized by various eukaryotic and prokaryotic organisms. With few knows exceptions they are not synthetized de novo by animals, however, they can be accumulated through food. In the food, supplement, and pharmaceutical industries, carotenoids are used for their coloring and nutraceutical properties. Microalgae are a unique source of these bioactive substances since some of these carotenoids (e.g., astaxanthin and fucoxanthin) are not synthetized by plants and most microorganisms. These carotenoids are also known to exhibit stronger antioxidant activities than other pigments. Most carotenoids undergo rapid degradation when exposed to light, oxygen, moisture, and heat during processing and storage, leading to color fading and reduction in bioactivity. This review presents recent advances in the encapsulation of microalgal carotenoids, as well as several scale-up technologies with potential for carotenoid-enriched foods development. It also discusses microalgal carotenoids digestibility in vivo and in vitro, highlighting the variability of encapsulated vs non-encapsulated pigments. Encapsulation technologies have been developed to increase the dispersibility, stability, and bioavailability of carotenoids by incorporating them into colloidal particles. These particles can be fabricated from a variety of food-grade materials, including alginate, carrageenan, chitosan, gelatin, starch, and other food proteins. Despite the increased microalgal carotenoids absorption associated to improved health benefits, encapsulation technologies remain very limited and there are no clear legislations regarding their commercial use and safety in most countries.