Shiitake mushrooms are prized for their unique flavor, which comes from a compound called lenthionine. This study found that treating shiitake mushrooms with citric acid (a common ingredient in food) can significantly increase the amount of lenthionine produced. The research identified the specific genes and enzymes responsible for this effect and determined the best conditions for the treatment, which could help mushroom producers create higher-quality, better-tasting products at lower cost.