Are black bananas safe to eat? (how to use)
In this article, we will discuss whether a black banana is safe to eat, when is a black banana not safe to eat, the reasons that cause a banana to turn black, and how can you safely consume a black banana.
Bananas turn black when they ripen, however, eating an overripe banana may be safe.
Are black bananas safe to eat?
Yes, black bananas may be safe to eat, unless they are spoiled. The black colour in the peel of the banana is a sign of ripeness and not of microbial spoilage (2). On the other hand, overripen bananas may also be contaminated by microorganisms (5).
Black bananas have different nutritional properties than green bananas. They are sweeter, softer and more aromatic. During the ripening process, there is a decrease in the concentration of insoluble fibres (resistant starch) and phenolic acids (1, 2).
On the other hand, overripen bananas are very sweet and can be used as a substitute for refined sugar in the production of jams, and cakes (1).
Are black bananas safe for diabetic patients?
Yes, black bananas are safe for diabetic patients. In a study, the blood glucose increase in diabetic patients was analysed after the ingestion of ripe bananas in different stages of ripeness.
Overripe bananas, that is, black bananas, were considered safe and caused a similar glycemic response when compared to ripe yellow bananas and this response was significantly lower than the one after the ingestion of pure sugar (8).
Are black bananas nutritious?
Yes, black bananas are nutritious. Black bananas are rich in sugars, fructooligosaccharides, potassium and antioxidants (7). According to studies, overripe bananas have a higher radical scavenging capacity than unripe bananas (6).
The radical scavenging capacity is related to the capacity of the food to neutralise oxidative compounds in the body. Oxidative compounds induce cell damage and inflammatory processes, leading to diseases (1).
While green bananas contain only a reduced amount of resistant starch (less than 2 %), ripe bananas are free from resistant starch, low in acidity, and rich in sugars and volatile compounds (3, 4, 7).
When is a black banana not safe to eat?
A black banana is not safe to eat when it has signs of spoilage. Ripe bananas are very perishable and susceptible to microbial deterioration. Fruit damage, handling and poor storage conditions can accelerate the deterioration of bananas (4, 5).
Spoilage in bananas can be identified by the presence of pink colonies of mould, which is related to the fungus Fusarium, the formation of spores and fungal bodies of other fungal species, such as Collectotricchum, unpleasant off-odours, such as soapy and fermented (4, 5).
What causes the banana to turn black?
The reasons that cause bananas to turn black are storage in cold, leading to cold injury, and overripening (2, 3, 4).
Bananas are climacteric fruits. Their ripening process continues after harvesting and is affected by environmental factors, including the presence of ethylene, a plant hormone produced by bananas and other plants.
During ripening, quercetin, chlorogenic acid and other phenolic compounds are oxidised by the enzyme polyphenol oxidase, generating brown and black pigments on the banana skin. The activity of this enzyme reduces with time (2).
How to prevent bananas from turning black from overripening: Buy bananas in a limited quantity to consume them within 4 days. Store bananas in a cool and ventilated place, away from other climacteric fruits, such as tomatoes and apples (4).
Cold storage is used to reduce the ripening velocity in bananas and increase their shelf life. However, storing bananas at a temperature below 14 °C or 57 °F (4) can cause damage to the fruit, whose flesh and skin turn brown and black.
Alterations in the texture and aroma of the bananas may also be a consequence of the chilling injury, however, these changes do not affect the safety of consuming bananas.
How to prevent bananas from turning black due to cold injury: Store bananas at temperatures above 14 °C (57 °F) in a cool and ventilated place.
How to consume black bananas safely?
To consume black bananas safely, you should use the bananas in cooked dishes, such as jams, purees, cakes, breads, cookies and sauces (1, 7).
To use the black bananas, carefully inspect the bananas to identify possible signs of spoilage. If the bananas contain mould, discard them. If not, just remove the damaged tissue parts and cook the bananas with citric acid and sugar.
Alternatively, mash the black bananas and mix them with flour, eggs, cinnamon and baking powder to make a sweet banana bread. It is not necessary to add sugar, as the bananas substitute the sugar.
In this article, we discussed whether it is safe to eat black bananas, when is it not safe to eat black bananas and how to consume black bananas safely.
Bananas turn black when they are overripen. However, black bananas are nutritious and flavourful and can be used in many dishes as a sugar substitute.
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