Polyphenol oxidase inhibition by Saccharomyces cerevisiae extracts: A promising approach to prevent enzymatic browning

Polyphenol oxidase (PPO)-mediated browning can have adverse effects on foods' quality during processing. Therefore, it's important to find natural and efficient PPO-inhibitors. This study investigated the effect and mechanism of yeast (Saccharomyces cerevisiae) extract in preventing PPO-mediated browning. Firstly, 0.5 g·L−1 S. cerevisiae extracts [calculated based on reduced glutathione (GSH) concentration] significantly reduced the browning of fresh-cut vegetable and fresh juice. The browning degree decreased by the maximum of 51.92% and 102.20%, respectively. Standard validation suggested that GSH in S. cerevisiae extracts contributed significantly to the anti-browning effect. Secondly, S. cerevisiae extracts showed an IC50 of 0.077 g·L−1 against potato-derived PPO using pyrogallol as the optimal substrate. Additionally, GSH displayed non-competitive inhibitory and static quenching effect on PPO. Finally, molecular docking and dynamics simulation demonstrated that GSH in S. cerevisiae extracts could interact with non-active sites of PPO with a binding free energy of −28.53 ± 6.29 kcal/mol. The binding process was mainly driven by electrostatic interactions and Van der Waals forces. These interactions could lead to the generation of stable GSH-PPO-substrate complexes and affect PPO's activity. Therefore, this study revealed new application prospects and laid a theoretical foundation for S. cerevisiae extracts as a PPO inhibitor in the food industry.