Hydrolyzed Spirulina Biomass and Molasses as Substrate in Alcoholic Fermentation with Application of Magnetic Fields

New substrates and fermentation conditions have been drawing researchers’ attention to increase the bioethanol productivity. The aim of this study was to evaluate the acid hydrolysis of Spirulina biomass and its use in association with molasses in ethanol production with and without magnetic field (MF) application. Hydrothermal hydrolysis of Spirulina biomass hydrolysis was evaluated. The highest reducing sugar concentration (79% w w−1) was obtained with sulfuric acid 5% (v v−1), 121 °C, 30 min, and 500 g L−1 of biomass. This hydrolyzed biomass and molasses were used as substrates in the alcoholic fermentation with Saccharomyces cerevisiae by varying the biomass/molasses (B/M) ratio: 25, 50, and 75% (v v−1). The medium 25% B/M had higher ethanol yield at 78.9% and productivity of 0.72 g L−1 h−1. MF application did not increase the cell growth and ethanol production. This is the first study that integrates molasses and microalgal biomass substrates for ethanol production and presents some new information about magnetic fields application that is still little explored in the literature.