FROM FRESH TO FRESHER: WHAT HAPPENS WHEN A FRUIT IS RIPENING?



When you bite into a juicy, sweet mango or a perfectly soft peach, you’re enjoying the result of a fascinating biological transformation. 

Fruit ripening. 

This natural process is not just about getting sweeter or softer, it’s a complex dance of chemistry, biology, and evolution that turns a hard, sour fruit into a delicious treat.

What Is Ripening?

Ripening is the final stage of fruit development, occurring after the fruit has grown to full size. During this phase, a fruit undergoes biochemical and physiological changes that make it more appealing to animals, who, in turn, help disperse the seeds.

Ripening can change:

- Color

- Texture

- Flavor

- Aroma

- Nutritional content

These changes are triggered and regulated by plant hormones, particularly ethylene.

Ethylene: The Ripening Hormone

Ethylene is a naturally occurring plant hormone in gaseous form. It acts like a signal that tells the fruit: “It’s time to ripen.” Once ethylene is released, it sets off a chain reaction of internal changes:

- Starch → Sugar: Enzymes break down starches into simpler sugars like glucose and fructose, making the fruit taste sweeter.

- Chlorophyll degrades: Green fades, and pigments like carotenoids (orange/yellow) and anthocyanins (red/purple) appear.

- Pectin breaks down: Pectin is what keeps fruit firm. As it breaks down, the fruit becomes softer.

- Aromatic compounds increase: These give fruit its distinctive smell when ripe.

Fun fact: Some fruits produce lots of ethylene as they ripen, which in turn speeds up the ripening of nearby fruits. That’s why putting an avocado in a bag with a ripe banana can help it ripen faster.

Evolutionary Purpose: A Sweet Deal for Seeds

Why do fruits even bother ripening? The short answer: seed dispersal.

Plants rely on animals to carry their seeds far and wide. A ripe fruit is an advertisement, being colorful, aromatic, and flavorful. When animals eat the fruit, they often move to a new location before excreting the seeds, giving the next generation a chance to grow somewhere new.

In evolutionary terms, ripening is a mutualistic strategy: the animal gets food, and the plant gets seed dispersal.

Behind the Scenes: Key Enzymes in Ripening

Here are some of the major enzymes at work during ripening:

Enzyme

Function

Amylase

Breaks down starches into sugars

Pectinase

Softens fruit by breaking pectin

Cellulase

Breaks down cell walls

Polygalacturonase

Further breaks pectin for soft texture

Chlorophyllase

Degrades green pigment (chlorophyll)

Each enzyme plays a role in altering the texture, taste, and color of the fruit, making it more attractive to eat.

Not All Fruits Ripen the Same Way

Fruits are classified into two major groups based on how they ripen:

Climacteric Fruits

- Continue to ripen after being harvested.

- Show a big spike in ethylene production.

- Examples: Bananas, avocados, apples, tomatoes, mangoes.

Non-Climacteric Fruits

- Do not ripen significantly after harvest.

- Little or no ethylene production.

- Examples: Grapes, strawberries, citrus fruits, cherries.

This difference has a huge impact on how fruits are harvested, stored, and sold. More on that in a future post!

Can Ripening Be Controlled?

Absolutely. In commercial agriculture and supermarkets, ripening is carefully controlled to ensure fruit reaches consumers in good condition.

- Ethylene exposure can be used to trigger ripening at the right time (e.g., in ripening rooms).

- Refrigeration slows down ripening by reducing enzyme activity and ethylene production.

- Modified atmosphere packaging adjusts oxygen and carbon dioxide to slow ripening.

While convenient, these methods can sometimes affect taste and texture compared to vine-ripened fruits.

Conclusion from the Biolab desk: Ripening Is More Than Just Sweetness

Fruit ripening is a beautifully orchestrated process rooted in evolutionary biology, but brought to life through chemistry. The next time you enjoy a ripe piece of fruit, you’re not just indulging your taste buds—you’re participating in a complex natural strategy honed over millions of years.

So whether it's a banana on your counter or a tomato in your salad, remember: that flavor, aroma, and softness are all signs of a fruit fulfilling its biological destiny.

What are some of your experiences when trying to get a fruit to ripen? Feel free to let us know in the comments 

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