Photobiological (LED light)-mediated fermentation of blueberry (Vaccinium corymbosum L.) fruit with probiotic bacteria to yield bioactive compounds

The aim of this study was to investigate if fermentation of blueberry fruit by Bacillus amyloliquefaciens and Lactobacillus brevis under green, red, blue, and white light emitting diode (LED) illumination or sunlight could yield functionalized products for biomedical applications. Fermentation by both bacterial species under white and green LED light and sunlight resulted in increased viable cell count of the bacteria as well as total phenol and flavonoid contents over 72 h of fermentation. Blue and red LED light fermentation and that in darkness resulted in fermented samples with moderate anti-bacterial activity based on minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) as well as antioxidant and cytotoxic assays compared to fermentations under other light sources. In addition, Fourier transform infrared spectroscopy (FT-IR) was performed to determine the functional groups in the non-fermented (control) and fermented products. Sunlight and white, red, and green LED light-fermented extracts contained alcohol, acid, and phenol groups, as well as aliphatic amines. The results of this study clearly indicate that fermentation of blueberries with probiotic bacteria under various LED light sources can yield compounds that can be used in cosmetic and value-added food products.