Today I found a lovely bunch of bananas on the fridge, and now they’ve completely ripened. How does this happen? Have you ever realized that whenever you mix cut bananas with other fruits, an intermittent ripening cascade covers the ensemble of fruits in a short time? What is this sort of surprise?

The change of color in a banana is due to an enzyme present in most fruits and vegetables, the polyphenol-oxidase (PPO), which is produced while cutting fruits. In combination with the oxygen in the air, the PPO converts phenolic molecules present in different foods into long chains of quinones , from which black, brown, and red pigments are formed. These pigments are responsible for the dark color of black tea and chocolate¹.

At the same time, bananas (as well as other fruits) produce a gas known as ethene or ethylene, which stimulates their ripening by initiating a process of conversion of starches into sugars, which make ripen bananas sweeter and tender. Some fruits designed as climacteric increase their ethylene production while ripening, and this process can be accelerated after being exposed to external sources of ethylene, such as ripened bananas. Among these fruits are apples, avocado, peach, and of course, bananas. For Non-climacteric fruits (such as citrus and strawberries), ethylene production doesn’t increase during ripening².

You can let your climacteric fruits ripen on your counter, accelerating their ripening by grouping them together or slowing it down by separating them from each other. Non-climacteric fruits are unlikely to continue ripening, so choose them when they are ripe at the grocecy shop³!

Today we will prepare a sweet, ripened banana and raspberry bread, ideal for breakfast on these summer days. If you don’t have raspberries, any other type of berries, pear, or apples will make a perfect combination!

Ingredients
Serves 2 loafs
Cooking time: 15 min active, 50-60 min passive

• 3 to 4 mashed ripe bananas (3 medium or four small bananas)
• 1 cup raspberries
• 2 cups all-purpose flour
• 1/2 teaspoon baking soda
• One teaspoon baking powder
• 1/2 teaspoon salt
• 1/2 teaspoon apple cider vinegar
• 1/2 cup vegan milk (almond or soy)
• 1/2 cup vegetable oil (I’m using canola oil)
• 3/4-1 cup sugar
• 1/4 cup chocolate chips (optional)

Recipe

1. Preheat your oven to 350F and lightly oil a muffin or loaf baking pan (or whatever baking pan you prefer).

2. In a large bowl, mix the flour, baking soda, baking powder, and salt.

3. In a second bowl, pour the vegetable milk and vinegar and mix. Add the oil, sugar, and mashed banana and whisk until homogeneity.

4. Add the dry ingredients (first bowl) to the wet mix and fully incorporate. Once the mixture is evenly combined, add the raspberries and the chocolate chips.

5. Pour the batter into a muffin or loaf baking pan and bake for 50-60 minutes. Check the bread after 45 minutes, continue checking until it’s fully baked (until the bread turns golden brown color and a toothpick comes out mostly clean). To prevent the surface from baking faster than the inside, cover with aluminum foil (optional).

6. Allow the bread to cool down for 20-25 minutes, or until it reaches room temperature.

Now, how about your favorite music and a good cup of coffee to enjoy aside?

References

1. Moirangthem K and Tucker G (2018) How Do Fruits Ripen? Front. Young Minds. 6:16. doi: 10.3389/frym.2018.00016

2. Jennifer Scott. Why do bananas go brown and ripen other fruit? BBC News. 22 May 2017

3. Desbiens, Anne-Marie, 2019, Mieux conserver ses aliments pour moins gaspiller, Éditions La Presse

Frida Buitron

Frida is a bubbly and curious chemist who is passionate about science and culture. A lover of food and nature, she’s always concocting treats with whatever she finds in the back of the fridge. In her free time, she enjoys good books and music as well as spending time with friends.

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