Abstract
Microalgae are a promising source of polyunsaturated fatty acids as well as bioactive antioxidant compounds such as carotenoids, phenolics and tocopherols. However, the accumulation of these biomolecules is often promoted by conflicting growth conditions. In this study, a phased bioprocessing strategy was developed to simultaneously enhance the lipid and antioxidant amounts by tailoring nitrogen content in the cultivation medium and applying light stress. This approach increased the overall contents of total fatty acids, carotenoids, phenolics, and α-tocopherol in Chlorella vulgaris by 2.2-, 2.2-, 1.5-, and 2.1-fold, respectively. Additionally, the bioaccessibility of the lipids and bioactives from the obtained biomasses improved after pulsed electric field (5 μs, 20 kV cm−1, 31.8 kJ kg−1sus) treatment (up to +12%) and high-pressure homogenization (100 MPa, 5–6 passes) (+41–76%). This work represents a step towards the generation of more efficient algae biorefineries, thus expanding the alternative resources available for essential nutrients.
Highlights
The human population is estimated to increase up to 9.7 billion in dividuals by 2050 (United Nations, 2015), with an increasing number of people living in urban environments
The aims of this study were i) to develop a pulsed-feed process with a modulated media composition that allows the simulta neous enrichment of C. vulgaris biomass with polyunsaturated fatty acids (PUFAs) and antioxidants; ii) to evaluate whether a higher content of endogenous antioxidants could lead to better stability against lipid oxidation; iii) to assess the impacts of different environmental conditions on the bioaccessibility of lipids and bioactive compounds; and iv) to assess changes in nutrient bioaccessibility after different disruption treatments (HPH/pulsed electric field (PEF))
The results suggest that mixotrophic biomass is the preferred option if a nutritionally favourable fatty acid profile is being targeted, as the effects of stearic acid on the lipoprotein profile in the blood are less disadvantageous than those of palmitic acid (EFSA, 2016)
Summary
The human population is estimated to increase up to 9.7 billion in dividuals by 2050 (United Nations, 2015), with an increasing number of people living in urban environments. Algae can grow on non-arable land, and marine species do not need freshwater For these reasons, microalgae are gaining attention as alternative sources of PUFAs. Among microalgae, Chlorella vulgaris biomass, which contains α-linolenic acid, is already commercially available and in growing demand (Canelli et al, 2020b; Muys et al, 2018). When using whole algal biomass, antioxidant compounds, such as carotenoids, phenolics and tocopherols, naturally present in C. vulgaris can help stabilize PUFAs for food and nutraceutical applications (Gouveia et al, 1996; Safafar et al, 2015) These antioxidants have nutri tional and health benefits, such as the prevention of several cancers and cardiovascular diseases, eye health, and anti-inflammatory and antimi crobial activities (Matos et al, 2017)
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