Quinones are reactive organic compounds formed during the enzymatic browning process in fruits and vegetables, primarily through the action of polyphenol oxidase (PPO) on phenolic compounds.
Quinones are significant because they are the intermediates in the browning reaction that leads to the formation of brown pigments, known as melanins. This browning can impact the visual appeal and flavor of foods like apples, potatoes, and avocados.
While quinones themselves are not harmful, their formation is often undesirable in food preparation, leading chefs and food processors to use methods such as acidification, refrigeration, or the application of antioxidants like ascorbic acid (vitamin C) to inhibit the enzymatic activity that produces quinones, thereby preventing or slowing down the browning process.