Prevent Brinjals From Turning Brown. when cut fruits and vegetables are exposed to air, it causes the enzymes and polyphenols in them to react with oxygen. This process, called enzymatic browning, produces brown pigments on the exposed surface of the fruits and vegetables. To avoid this process in brinjals, you can immerse them in water as soon as they are cut, which limits oxygen supply. Or, you could apply some lemon juice on the cut surface, which denatures the enzyme responsible for browni