Leaving an unripe sliced mango out of the fridge until it ripens is generally not recommended. Once you slice a mango, the inner flesh is exposed, and it becomes more susceptible to bacterial growth and spoilage. The warmth and moisture present at room temperature create an environment conducive to the rapid growth of microorganisms.
If you want to ripen a mango, it's best to do so at room temperature but keep the whole, uncut fruit at room temperature, not the sliced one. Once the mango is fully ripe, you can then refrigerate it to extend its shelf life. However, if you have already sliced a mango and don't plan to consume it immediately, it's crucial to store the sliced pieces in the refrigerator.
To store sliced mango properly:
Place the sliced mango in an airtight container or wrap it tightly with plastic wrap.
Store the container or wrapped slices in the refrigerator at a temperature of around 35°F to 40°F (1.5°C to 4.4°C).
Consume the sliced mango within 2-3 days for the best quality and to avoid spoilage.
Remember that refrigeration slows down the ripening process, so if you have an unripe whole mango, it's better to leave it at room temperature until it ripens fully. Once it's ripe, you can then transfer the whole fruit to the refrigerator to extend its shelf life for a few more days.