Antioxidant and Anticollagenase Activities of Fermented Pomegranate (Punica granatum L.) Peel Juice

Skin aging is driven by intrinsic factors, such as the accumulation of reactive oxygen species, and extrinsic factors, including ultraviolet (UV) radiation, which accelerate oxidative stress and extracellular matrix degradation. Strategies to mitigate skin aging often focus on antioxidant and anticollagenase activities. Several studies have shown that Pomegranate (Punica granatum L.) peel is an underutilized by-product rich in ellagitannins, which can be hydrolyzed into ellagic acid, a compound with well-documented bioactivity. Therefore, this study aims to investigate the effect of microbial fermentation using Lactiplantibacillus plantarum and Saccharomyces cerevisiae on the physicochemical properties and bioactivity of pomegranate peel juice. Non-fermented juice (NFJ), L. plantarum-fermented juice (LFJ), and S. cerevisiae-fermented juice (SFJ) were used for comparative evaluation. The results showed that fermentation (LFJ and SFJ) led to decreased pH and sugar content, along with significant increases in ellagic acid concentration, antioxidant activity, and collagenase inhibition compared to NFJ. After 168 h, ellagic acid levels increased to 329.87 µg/mL in LFJ and 341.41 µg/mL in SFJ, compared to 263.86 µg/mL in NFJ. Antioxidant activity also increased to 73.82%, 83.25%, and 82.70% for NFJ, LFJ, and SFJ, respectively. Meanwhile, collagenase inhibition was 67.43%, 71.81%, and 73.66% for NFJ, LFJ, and SFJ, respectively. These results provide scientific evidence that microbial fermentation enhances the bioactivity of pomegranate peel juice, showing its potential as a sustainable source of natural ingredients for future cosmetic applications. Further studies on formulation, stability, and safety are needed to translate the results into practical skincare products.