Unripe bananas are rich in resistant starch, which enhances gut health and slows the rise in blood sugar levels. However, as bananas ripen, this starch is converted into sugar by enzymes. Germany's Bavarian Health and Food Safety Authority reported that when a banana changes color from yellow to brown, alcohol is produced through natural fermentation. The longer the banana ripens, the higher its alcohol content. The authority noted that the highest measured value was 7.37 grams per kilogram, warning of the risk of alcohol poisoning from consuming very ripe bananas. Green bananas contain a large amount of resistant starch, which is not digested in the small intestine and acts as a dietary fiber. Therefore, yellow bananas are characterized by their sweet taste and provide quickly absorbable energy. Thus, at-risk groups, such as infants and young children, should avoid very ripe bananas. The authority also added that alcohol evaporates during baking and cooking, noting that very ripe bananas can be salvaged, for example, by using them in cakes and pastries. Green bananas are a rich source of dietary fiber due to their high starch content.
