Proteins play a key role in the formation of the distinct aroma of banana. But this aroma goes bad when bananas are kept in the refrigerator because cold temperatures suppress the activity of proteins.
Billions of bananas are devoured worldwide every year. A typical American eats about 11 pounds of this fruit annually, according to the U.S. Department of Agriculture. Most bananas are grown overseas, which means to reach U.S. shores intact, they must be shipped in refrigerated containers. Although chilling delays ripening, it also can damage the fruit and subdue its aroma.
‘The reason why the aroma of banana goes bad in the refrigerator may be because cold temperatures suppress the activity of proteins as proteins play a key role in the formation of the aroma of banana.’
Previously, researchers found that proteins called transcription factors (TFs), which help regulate the activity of certain genes, are involved in fruit ripening. Building on this work, Jian-fei Kuang and colleagues wanted to find out if a particular set of TFs play 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 they had an off-flavor.
In a series of experiments, the research team found that refrigeration decreased the activity of aroma-forming genes during ripening. Digging deeper, they detected a pair of TFs called MabZIP4 and MabZIP5 that appear to play an important role in activating these genes. The researchers conclude that a better understanding of this regulatory process could lead to strategies to make bananas smell even better.