Abstract
The use of microalgal starch has been studied in biorefinery frameworks to produce bioethanol or bioplastics, however, these products are currently not economically viable. Using starch-rich biomass as an ingredient in food applications is a novel way to create more value while expanding the product portfolio of the microalgal industry. Optimization of starch production in the food-approved species Chlorella vulgaris was the main objective of this study. High-throughput screening of biomass composition in response to multiple stressors was performed with FTIR spectroscopy. Nitrogen starvation was identified as an important factor for starch accumulation. Moreover, further studies were performed to assess the role of light distribution, investigating the role of photon supply rates in flat panel photobioreactors. Starch-rich biomass with up to 30% starch was achieved in cultures with low inoculation density (0.1 g L−1) and high irradiation (1800 µmol m−2 s−1). A final large-scale experiment was performed in 25 L tubular reactors, achieving a maximum of 44% starch in the biomass after 12 h in nitrogen starved conditions.
Highlights
Several microalgal species accumulate starch as a storage compound under suboptimal environmental conditions and this property has made them extensively studied within the fields of biofuels, bioplastics and biorefining in general [1,2,3,4,5]
There are additional benefits related to the health-promoting properties of algal biomass as algae are rich in antioxidants and unsaturated lipids, even during starch accumulation [15]
We used a traditional shake flask system combined with the high-throughput Fourier Transform Infrared (FTIR) spectroscopy to assess qualitatively how nutrient and light treatments affect the metabolism and composition of C. vulgaris biomass over time
Summary
Several microalgal species accumulate starch as a storage compound under suboptimal environmental conditions and this property has made them extensively studied within the fields of biofuels, bioplastics and biorefining in general [1,2,3,4,5]. For a microalgal industry to thrive it is necessary to target high-value compounds [8], and microalgal biotechnologists are starting just recently to valorise starch-rich biomass as a potential ingredient in the agri-food-tech sector, an important economical field that could make algal production economically viable [9] and implement a sustainable technology into novel industrial sectors. The use of microalgal starch in foods has huge potential in terms of sustainability since algae production has higher ground areal productivities, high CO2 fixation rates and does not compete with crops for arable land and fresh water. There are additional benefits related to the health-promoting properties of algal biomass as algae are rich in antioxidants and unsaturated lipids, even during starch accumulation [15]
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