Photo-fermentation of purple sweet potato ( L.) using probiotic bacteria and LED lights to yield functionalized bioactive compounds.

The purpose of this study was to examine if fermentation of purple sweet potato ( L.) powder (PSP) by under green, red, blue, white light-emitting diode (LED) illumination or sunlight might yield functionalized products with good antibacterial, antioxidant activity, and/or cytotoxic activity. The Purple sweet potato (PSP) powder fermented with probiotic bacteria under white LED light (1.9 ± 1.80/1.6 ± 0.52), blue LED light (1.4 ± 1.32/1.8 ± 0.83), or sunlight (1.2 ± 1.26/1.5 ± 1.83) for and displayed good to moderate antibacterial activity based on minimum inhibitory concentration (MIC) red, blue, white LED lights and sunlight (80 µg/mL) for and , minimum bactericidal concentration red, blue LED lights and sunlight shows (46/48, 61/70, 50/48 µg/mL) for and . Antioxidant activity for dark, white, blue and green LED lights for ABTS and white, blue and green Led for DPPH assay resulted in lower activity. Fourier transform infrared spectroscopy was performed to determine the functional groups in the non-fermented (control) and fermented products of PSP powders obtained using different light sources. Sunlight, white, and blue 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 purple sweet potato with probiotic bacteria under various LED light sources can yield compounds that can be used in cosmetic and value-added food products.