Common culinary mushrooms can function as powerful natural tenderizers, not just flavor add-ins. Adding 2–4% oyster (Pleurotus ostreatus) or shiitake (Lentinula edodes) powder to beef marinades, with 3% shiitake in particular, cut meat toughness by about 40% while keeping fat oxidation extremely low. At the same time, free amino acids like glutamate and alanine increased, meaning the mushrooms softened the muscle fibers, protected the fats from rancidity, and boosted taste, showing that simple mushroom powders can transform tougher cuts into juicier, more tender, and more flavorful meat.