Insights on the intestinal absorption of chlorophyll series from microalgae.

The bioaccessibility and subsequent uptake by Caco-2 human intestinal cells of chlorophyll pigments from Scenedesmus obliquus were determined for the first time. In order to evaluate the impact of different types of the matrix on bioaccessibility of chlorophyll from microalgae, three different products were evaluated: isolated chlorophyll extract (ICE); wet ultrasonicated biomass (WUB); and whole dried biomass (WDB). The samples were submitted to in vitro digestion model according to the INFOGEST protocol, and Caco-2 cells determined the intestinal uptake. Chlorophyll pigments were determined by HPLC-PDA-MS/MS. A total of ten chlorophyll pigments (8,318.48 µg g-1) were separated in S. obliquus biomass, with chlorophyll a (3,507.76 µg g-1) and pheophytin a' (1,598.09 µg g-1) the major ones. After in vitro digestion, all tested products showed bioaccessible chlorophylls. However, the total bioaccessibility results were as follows: ICE (33.45%), WUB (2.65%), WDB (0.33%). Five compounds were bioaccessible in ICE, three in WUB, and one in WDB. The hydroxypheophytin a showed the highest bioaccessibility (212%) in ICE, while pheophytin a' in WUB (11%) and WDB (2%). As a result, bioavailability estimates of ICE using the Caco-2 cell showed hydroxypheophytin a (102.53%), followed by pheophytin a' (64.69%) as the chlorophyll pigments most abundant in intestinal cells. In summary, from a nutritional perspective, these three types of the matrix (WDB, WUB, and ICE) influence the promotion of chlorophyll bioaccessibility. In this way, the data suggest that chlorophylls bioaccessibility from ICE is greater than that in WDB and WUB. Therefore, ICE should be considered a product that provides bioavailable chlorophyll and could be the best choice, such as ingredients in the development of functional foods chlorophyll-based.

Carbon dioxide capture and use in photobioreactors: The role of the carbon dioxide loads in the carbon footprint.

This research evaluated the carbon dioxide capture and use by Scenedesmus obliquus in a photobioreactor under different CO2 loads. Performance indicators, carbon and energy balances, sustainability indicators, and carbon credits on the photobioreactor were assessed. The results expressed that the CO2 loads of 384.9 kg/m3/d (15% CO2) provide the best trade-off for the process. For this condition, maximum biomass productivities of 0.36 kg/m3/d, carbon dioxide conversion rates of 0.44 kgCO2/m3/d, and oxygen release rates of 0.33 kgO2/m3/d were observed, reaching maximum CO2 removal efficiencies of 30.76%. Volatile organic compounds were the major products generated (>80%). However, only <3% was fixed in biomass. From the environmental and economic point of view, the net energy ratio was 3.44, while the potential carbon credit was of 0.04 USD per m3 of culture. Finally, the use of adequate CO2 loads was also proven to be determinant to improve the global performance of the system.