Why Refrigerated Bananas Smell Different

A research group in China has identified two transcription factors involved in odorous compound synthesis that are downregulated in refrigerated bananas.

AsianScientist (Jul. 10, 2018) – Scientists in China have discovered that cold temperatures suppress the activity of proteins that play a key role in the formation of the banana’s distinct aromas. Their findings, published in the Journal of Agricultural and Food Chemistry, may allow the enhancement of the fruit’s fragrance and flavor.

Billions of bananas are devoured worldwide every year. A typical American eats about 11 pounds of bananas annually, according to the US Department of Agriculture. Most bananas are grown overseas, which means to reach US shores intact, they must be shipped in refrigerated containers.

Although chilling delays ripening, it also can damage the fruit and subdue its aroma. Previously, researchers found that proteins called transcription factors, which help regulate the activity of certain genes, are involved in fruit ripening. Building on this work, Professor Kuang Jian-fei and colleagues at the South China Agricultural University wanted to find out if a particular set of transcription factors plays a role in the dampening of aromas in chilled or refrigerated bananas.

The scientists stored freshly harvested green bananas either in the cold or at room temperature. Once removed from storage, the chilled bananas ripened more slowly than those that had been stored at room temperature, and their flavors were different.

In a series of experiments, the research team found that refrigeration decreased the activity of aroma-forming genes during ripening. When bananas were stored at seven degrees Celsius, a pair of transcription factors called MabZIP4 and MabZIP5 were downregulated compared to when the bananas were stored at 22 degrees Celsius. MabZIP4 and MabZIP5 control the expression of other enzymes and compounds that give bananas their distinct flavor, hence their suppression can alter the resultant taste and fragrance of bananas.

The researchers suggest that this knowledge may lead to strategies that make bananas smell and taste even better.

The article can be found at: Guo et al. (2018) Identification of Two Transcriptional Activators MabZIP4/5 in Controlling Aroma Biosynthetic Genes during Banana Ripening.


Source: American Chemical Society; Photo: Pexels.
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