Exploring the prebiotic potential of fermented glutinous rice filtrate: In vitro skin bacterial balance and biological activities

This study aimed to investigate the prebiotic potential of fermented glutinous rice filtrate (FRF) for the skin bacterial balance, evaluate its suitability for topical formulations, and gain insights into its prebiotic properties. The fermentation process was carried out using an inoculum of Saccharomycopsis fibuligera (S. fibuligera) under various conditions, including the amount of initial inoculum, inoculum strain, incubation time, and concentra-tion of the rice solution. The fermented glutinous rice filtrate was screened for prebiotic activity, and the selected FRF candidate functional ingredient was evaluated for its composition and bacterial growth. An in vitro skin bacterial balance assessment was conducted using a cell culture model to examine the interaction between beneficial bacteria (Staphylococcus epidermidis) and pathogenic bacteria (Staphylococcus aureus). The viable counts of St. epidermidis were significantly higher in FRF treated than in Phosphate Buffer Saline incubation. Decreasing the amount of St. aureus were occurred in FRF incubated on the 2D and 3D skin models. Additionally, the antioxidant assay and anti-inflammation test were used to evaluate biological activities related to cosmetic applications. The results demonstrated that the prepared FRF had significant prebiotic activity on the skin bacteria model, with a nontoxic profile, making it a potentially useful tool for topical application. The finding of the study unveiled the potential of the optimized fermented glutinous rice within the green practices.