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Study and optimization of the recycling process of the Chlorella vulgaris culture medium and its effects on the functional properties of biomass for food applications
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Abstract(s)
As microalgas são consideradas uma solução sustentável global que responderá às necessidades alimentares, humanas e animais, num futuro próximo. No entanto, o seu cultivo requer um uso considerável de água (doce ou salgada), ameaçando a sustentabilidade da sua produção. Produzida em modo biológico, Chlorella vulgaris é comercializada para fins alimentares como negócio principal da Allmicroalgae. De forma a reduzir a pegada hídrica do processo, o permeado, resultante da colheita de biomassa através do processo de filtração de fluxo tangencial, foi reutilizado e testado por 3 vezes consecutivas (R1, R2 e R3) para o cultivo autotrófico de C. vulgaris, às escalas laboratorial e piloto. O permeado foi suplementado com amónia e outros nutrientes e testado como meio de cultura reciclado (RCM) para ser reutilizado em três concentrações diferentes, 100% (reutilização total – P100), 70% e 50% (P70 e P50). Comparou-se o crescimento das culturas e as propriedades físico-químicas e funcionais da biomassa foram avaliadas. À escala laboratorial, não foram observadas diferenças significativas nas produtividades e taxa especifica de crescimento entre o controlo e as condições testadas. À escala piloto, foram realizadas 3 reutilizações consecutivas, nas quais Chlorella vulgaris cresceu com sucesso e não apresentou diferenças de crescimento entre MF e MCR. Observou-se uma exceção na terceira reutilização, no caso de 100% de permeado, onde a produtividade foi significativamente mais baixa do que no controlo. Após avaliar a composição de proteína, cinzas, pigmentos e as propriedades funcionais da biomassa, concluiu-se que apenas o conteúdo em clorofila no cultivo P100 foi afetado negativamente aquando da terceira reutilização de MCR (R3). Estes resultados mostram a possibilidade de reutilizar MCR 3 vezes, até, pelo menos, aos 70 % de permeado, sem reduzir a produtividade e qualidade da biomassa.
Microalgae are considered a sustainable solution to meet the high demand for food and feed worldwide in a near future. However, its cultivation requires considerable amount of water (fresh or marine), threatening the sustainability of its production. With a certified organic cultivation mode, Chlorella vulgaris is the core business of Allmicroalgae, being sold mainly for food applications. To reduce the water footprint of the process, the permeate resulting from the biomass harvesting, through tangential flow filtration membranes, was used and tested to regrow C. vulgaris autotrophically on a laboratory and pilot scale, for three consecutive reuses (R1, R2, and R3). The permeate was supplemented with ammonium and other nutrients and tested as a recycled culture medium (RCM) at three different concentrations, 100% (fully reused – P100), 70% and 50% (P70 and P50). Growth assessment was evaluated and the physicochemical and technofunctional properties of the obtained biomass were evaluated. At the laboratory scale, no significant differences were observed between the productivity and the specific growth rate of the control and the conditions tested. At the pilot scale, 3 consecutive reuses were performed and Chlorella vulgaris was successfully cultivated under RCM with no differences between FM and RCM. An exception was observed for the case of 100% permeate in the growth of C. vulgaris in the third reuse, where the productivity was significantly lower than the control. After evaluating the total protein content, ash, pigments and technofunctional properties of the biomass, it was found that only the chlorophyll content of the P100 cultivation was negatively affected by the third reuse of the RCM (R3). These results showed the possibility of reusing RCM 3 times up to 70% of permeate, at least, without reducing the productivity and quality of the biomass.
Microalgae are considered a sustainable solution to meet the high demand for food and feed worldwide in a near future. However, its cultivation requires considerable amount of water (fresh or marine), threatening the sustainability of its production. With a certified organic cultivation mode, Chlorella vulgaris is the core business of Allmicroalgae, being sold mainly for food applications. To reduce the water footprint of the process, the permeate resulting from the biomass harvesting, through tangential flow filtration membranes, was used and tested to regrow C. vulgaris autotrophically on a laboratory and pilot scale, for three consecutive reuses (R1, R2, and R3). The permeate was supplemented with ammonium and other nutrients and tested as a recycled culture medium (RCM) at three different concentrations, 100% (fully reused – P100), 70% and 50% (P70 and P50). Growth assessment was evaluated and the physicochemical and technofunctional properties of the obtained biomass were evaluated. At the laboratory scale, no significant differences were observed between the productivity and the specific growth rate of the control and the conditions tested. At the pilot scale, 3 consecutive reuses were performed and Chlorella vulgaris was successfully cultivated under RCM with no differences between FM and RCM. An exception was observed for the case of 100% permeate in the growth of C. vulgaris in the third reuse, where the productivity was significantly lower than the control. After evaluating the total protein content, ash, pigments and technofunctional properties of the biomass, it was found that only the chlorophyll content of the P100 cultivation was negatively affected by the third reuse of the RCM (R3). These results showed the possibility of reusing RCM 3 times up to 70% of permeate, at least, without reducing the productivity and quality of the biomass.
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Keywords
Chlorella vulgaris culture medium recycling pilot scale sustainability nutritional composition