Learn the science behind why fresh coriander chutney turns black so quickly in the fridge. Discover the role of oxidation in this color change.
1 Answer
Coriander chutney turns black in the fridge primarily due to oxidation of chlorophyll and other pigments in the coriander leaves, accelerated by enzymes and exposure to air. Acidic ingredients like lemon juice can help slow this process.
Detailed Explanation:
Coriander chutney's vibrant green color comes from chlorophyll, the pigment responsible for photosynthesis in plants. When coriander leaves are exposed to air, enzymes within the leaves react with oxygen, causing the chlorophyll to degrade. This degradation process, known as oxidation, results in the formation of pheophytin, which has a brownish-olive hue. Other pigments in the coriander, such as carotenoids, also undergo changes that contribute to the darkening. The rate of oxidation is influenced by factors like temperature, light, and pH. Refrigeration slows down the enzymatic activity, but it doesn't completely stop it. Furthermore, any metal utensils or containers used during preparation or storage can catalyze the oxidation process, speeding up the discoloration. The presence of moisture also contributes to the enzymatic reactions.
Pro Tip:
To prevent your coriander chutney from turning black, add a squeeze of lemon or lime juice. The acidity helps to inhibit the enzymes responsible for oxidation and preserves the green color for a longer period. Also, store the chutney in an airtight container to minimize exposure to air.