Vol.:(0123456789) 1 3 Bioprocess and Biosystems Engineering (2020) 43:1231–1240 https://doi.org/10.1007/s00449-020-02318-4 RESEARCH PAPER Magnetic felds: biomass potential of Spirulina sp. for food supplement Mayara Copello Veiga 1  · Mariana Martins Fontoura 1  · Mariana Gonçalves de Oliveira 1  · Jorge Alberto Vieira Costa 2  · Lucielen Oliveira Santos 1 Received: 31 January 2020 / Accepted: 23 February 2020 / Published online: 6 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract This study evaluated the infuence of the magnetic feld on the chemical composition of Spirulina sp. LEB 18 and its digest- ibility and protein solubility. The highest protein digestibility of biomass was obtained at 30 °C and with 2.5 g L −1 NaNO 3 (78.4%) in the medium, and the highest solubility was found in the cultivated biomass exposed to 60 mT, 30 °C and 2.5 g L −1 NaNO 3 (89%, pH 6). MF application did not modify the protein concentration of biomass, but reduced the carbohydrate concentration by 69.1%, showing that the biomass obtained in the culture submitted to MF may be used as an ingredient in the development of protein supplements. Keyword Ferrite magnets · Microalgae · Protein digestibility · Protein solubility Introduction Population growth has been stimulated the search for new sources of food, especially protein-rich foods. The use of microalgae, such as Spirulina for the development of food supplements becomes interesting because of its high protein concentration and the GRAS (Generally Recognized as Safe) certifcation from the Food and Drug Administration [1]. Due to its composition, a portion of the market could be sup- plied with foods containing microalgae proteins and lipids, making it a sustainable and cost-efective alternative [2, 3]. It is possible to modify its metabolic pathways to obtain greater biomass production and to induce the synthesis of biomolecules of high commercial interest [4]. However, for this to happen, new technological approaches should be studied for microalgae cultivations. New technologies may be tested to increase protein concentration, digestibility and solubility of Spirulina biomass, among them, the use of magnetic felds (MF). MF may stimulate or inhibit growth in biological organ- isms and may infuence the metabolism of microorganisms by modifying the synthesis of carbohydrates, proteins and accumulation of essential amino acids [5, 6]. Although this area of study is promising and innovative, it is still an unexplored area. Studies of the efects on the growth rate, biomass composition and generated products may be found. However, there are no studies on the infuence of MF on digestibility and protein solubility of the biomass. Producing more high protein and high digestibility bio- mass may be an alternative for human feeding since this biomass has a better quantity and quality than conventional proteins. Food proteins are added to food products due to their functionality and easy digestion. In the food indus- try, soy and milk proteins are widely used because of their functional properties and nutritional value [3, 7]. Alternative sources of protein for human consumption need to be devel- oped to attend population demand. Microalga proteins stand out favorably with conventional sources in terms of quality * Lucielen Oliveira Santos santoslucielen@gmail.com Mayara Copello Veiga mayaracopello@hotmail.com Mariana Martins Fontoura marianamartins@furg.br Mariana Gonçalves de Oliveira marianaoliveira@furg.br Jorge Alberto Vieira Costa dqmjorge@furg.br 1 Laboratory of Biotechnology, School of Chemistry and Food, Federal University of Rio Grande, Rio Grande, RS 96203-900, Brazil 2 Laboratory of Biochemical Engineering, School of Chemistry and Food, Federal University of Rio Grande, Rio Grande, RS 96203-900, Brazil