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Microalgae processing towards biorefinery routes: Harvesting and spray-drying of Dunaliella sp.
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Resumo(s)
A produção de produtos de valor acrescentado a partir de biomassa de microalgas requer o cultivo e recuperação da biomassa, e consequente processamento downstream e extração do produto desejado. Um dos maiores obstáculos da aplicação de biomassa de microalgas à escala industrial envolve o processo de colheita, que engloba grande parte dos custos totais associados com o processamento de microalgas. As estratégias de biorrefinaria de Dunaliella sp. focam-se essencialmente na recuperação de carotenóides para suplementos alimentares, lípidos para biodiesel e biomassa residual para a produção de biogás. Devido ao seu alto teor em carotenóides, Dunaliella sp. são comumente produzidas industrialmente sob a forma de produto seco, em forma de pó. Para tal, técnicas como spray-drying são aplicadas, providenciando um produto final adequado para a incorporação em formulações alimentares e para a extração de compostos de valor acrescentado.
O objetivo deste trabalho consistiu em desenvolver um processamento de Dunaliella sp. com foco principal em métodos de colheita e posterior secagem por spray-drying, para obtenção de um produto rico em carotenóides.
À escala laboratorial, combinaram-se métodos de centrifugação e floculaçãpo com adição de quitosano e água desionizada. Foi possível obter valores de eficiência de separação de 95.5% e 91.4% com recuperações de carotenóides de 97.6% e 98.2%, respetivamente. Um ensaio à escala piloto seguindo o scale-up do processo estudado laboratorialmente compreendeu a adição de um passo de spray-drying aos passos anteriormente estudados. Neste foi possível obter um pó rico em carotenóides com uma eficiência de secagem de 43.4%. Ensaios posteriores sobre a avaliação de concentração de quitosano ótimo a adicionar e extração de uma fração de sólidos com limoneno foram avaliadas.
Os processos estudados demonstraram ser eficientes na obtenção de um produto final com um elevado teor de carotenóides (7.2 % carotenóides em termos de peso seco sem cinzas).
The production of value-added products from microalgae biomass requires the cultivation and recovery of biomass and subsequent downstream processing and extraction of the desired product. One of the biggest obstacles to the application of microalgae biomass on an industrial scale involves the harvesting process, which encompasses a large part of the total costs associated with the production and processing. Dunaliella sp. biorefinery strategies focus essentially on the recovery of carotenoids for food supplements, lipids for biodiesel and residual biomass for the production of biogas. Due to its high content of carotenoids, Dunaliella sp. are commonly produced industrially as a dry product. Therefore, techniques such as spray-drying are applied, providing a final product suitable for incorporation into food/feed formulations and for extracting value-added compounds. The objective of this work was to develop the processing of Dunaliella sp. with special focus on harvesting methods and subsequent drying by spray-drying, to obtain a product rich in carotenoids. At the laboratory scale, centrifugation and flocculation methods were combined with the addition of chitosan and deionized water. It was possible to obtain separation efficiency values of 95.5% and 91.4% with carotenoid recoveries of 97.6% and 98.2%, respectively. A pilot-scale trial following the scale-up of the laboratory studied processes comprised the addition of a spray-drying step to the previously studied steps. It was possible to obtain a powder rich in carotenoids with a drying efficiency of 43.4%. Further trials on the assessment of optimal chitosan concentration to add and extraction of a solids fraction with limonene were evaluated. The processes studied proved to be efficient in obtaining a final product with a high content of carotenoids (7.2 % carotenoids in terms of ash free dry weight).
The production of value-added products from microalgae biomass requires the cultivation and recovery of biomass and subsequent downstream processing and extraction of the desired product. One of the biggest obstacles to the application of microalgae biomass on an industrial scale involves the harvesting process, which encompasses a large part of the total costs associated with the production and processing. Dunaliella sp. biorefinery strategies focus essentially on the recovery of carotenoids for food supplements, lipids for biodiesel and residual biomass for the production of biogas. Due to its high content of carotenoids, Dunaliella sp. are commonly produced industrially as a dry product. Therefore, techniques such as spray-drying are applied, providing a final product suitable for incorporation into food/feed formulations and for extracting value-added compounds. The objective of this work was to develop the processing of Dunaliella sp. with special focus on harvesting methods and subsequent drying by spray-drying, to obtain a product rich in carotenoids. At the laboratory scale, centrifugation and flocculation methods were combined with the addition of chitosan and deionized water. It was possible to obtain separation efficiency values of 95.5% and 91.4% with carotenoid recoveries of 97.6% and 98.2%, respectively. A pilot-scale trial following the scale-up of the laboratory studied processes comprised the addition of a spray-drying step to the previously studied steps. It was possible to obtain a powder rich in carotenoids with a drying efficiency of 43.4%. Further trials on the assessment of optimal chitosan concentration to add and extraction of a solids fraction with limonene were evaluated. The processes studied proved to be efficient in obtaining a final product with a high content of carotenoids (7.2 % carotenoids in terms of ash free dry weight).
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Palavras-chave
Dunaliella sp. harvesting spray-drying chitosan carotenoids