Why does raw mango develop black patches during storage?

Question

Learn what causes black patches on raw mangoes during storage. Discover if it's a sign of spoilage or a natural part of the ripening process.

Answer 1

Raw mangoes develop black patches during storage primarily due to chilling injury, a physiological disorder caused by exposure to low, non-freezing temperatures. This disrupts cell structure and enzyme activity, leading to discoloration.

Detailed Explanation:

When raw mangoes are stored at temperatures that are too low (typically below 13°C or 55°F), they experience chilling injury. This isn't freezing, but it's cold enough to damage the fruit's cells. Here's a breakdown of what happens:

1. Cell Membrane Damage: Low temperatures disrupt the structure of cell membranes within the mango. These membranes are crucial for regulating the flow of substances in and out of the cells.

2. Enzyme Activity Disruption: Chilling temperatures interfere with the normal functioning of enzymes responsible for various metabolic processes within the fruit. This can lead to the accumulation of undesirable compounds.

3. Ethylene Production: Chilling injury can sometimes trigger an increase in ethylene production, a plant hormone that accelerates ripening and senescence (aging). This can contribute to the development of black patches.

4. Phenolic Oxidation: The damaged cells release phenolic compounds, which are then oxidized by enzymes like polyphenol oxidase (PPO). This oxidation process results in the formation of melanin pigments, which are responsible for the black or brown discoloration observed on the mango's surface and sometimes within the flesh.

5. Secondary Infections: The weakened state of the mango due to chilling injury makes it more susceptible to fungal or bacterial infections, which can further contribute to the development of black patches and decay.

The severity of chilling injury depends on factors such as the mango variety, the storage temperature, and the duration of exposure to low temperatures.

Pro Tip:

To prevent black patches, store raw mangoes at temperatures between 13°C and 15°C (55°F and 59°F) with good ventilation. Avoid storing them in the refrigerator for extended periods.

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