Improved extraction of bioactive compounds by cold storage of spirulina fermented by Kazachstnia servazzii

In this study, alcohol fermentation and cold storage were conducted to enhance the extraction of bioactive compounds in spirulina. After alcohol fermentation of 20% spirulina paste with 5% glucose and 1% yeast extract using Kazachstnia servazzii KM2017 for 2 days, the pH and acidity were 6.91 and 0.26%, respectively. Viable yeast cells increased from 1.21×10 ⁷ CFU/mL to 2.51×10 ⁸ CFU/mL. In addition, the protein content of spirulina doubled to 423.98 μg/mL Polyphenols and flavonoids were also increased to 350.12 μg/mL and 28.04 μg/mL, respectively. Notably, the inherent off-odor of spirulina paste was partially removed with production of 1.3% alcohol. After cold-storage of yeast fermented spirulina paste at 1℃ for 5 days, the extraction of bioactive compounds was further enhanced, resulting in 464.09 μg/mL protein, 420.21 μg/mL polyphenol and 34.41 μg/mL flavonoids. On the other hand, the viable yeast cell count decreased to 4.39×10 ⁶ CFU/mL, revealing partial disruption of the spirulina. Thus, it was concluded that the odor and extraction of biologically active substance were improved by both yeast fermentation and cold storage of spirulina.