For my last critique I chose "Characterization of chlorophyll degradation in banana and plantain during ripening at high temperature". Yang et. al. studied the differences in degreening of bananas and plantains at tropical temperatures. HPLC was used to analyze changes in contents of chlorophylls and determine changes in chlorophyllase (chlase) and Mg-activities in both the peels of bananas and plantains at two different temperatures, 20 °C and 30 °C.
Previous studies have shown that bananas fail to develop a fully yellow peel when ripening at temperatures above 24 °C because they retain high levels of chlorophylls in their peel. While plantains break down chlorophyll faster at higher temperatures, this allows for a complete ripening of the fruit which can be observed from their yellow peel color. Ten bags of ten bananas were used for each treatment. One banana from each bag was randomly chosen for evaluation of its peel color and peel tissue sampling on a daily base. A Color Spectrophotometer was used to measure the color scores of fruit peel, a*, b*, L*, C*, and Hue angle values for ten fruits at three different places for each individual. Two and a half grams of peel tissue were grinded to extract the pigments which were then separated by a C18 column.
HPLC chromatogram profiles were used to identify chlorophyllide (Chlide) a and b and pheophorbide (Pheide) a based on the retention time of standards. Uneven degreening of bananas at 30 °C is due to high retained chlorophyll content, high remaining levels of Chlide a and Pheide a as well as inhibition of Mg-dechelatase activity.
Based on the results obtained from this study the researchers suggested that PaO, pheophorbide oxyganase, a key enzyme in chlorophyll degradation plays an important role in the uneven degreening of bananas.
For future studies, it would be interesting to see how bananas and plantains harvested in tropical countries would behave at tropical temperatures to see if the terrain were the fruits are harvested plays a role in the results. Both bananas and plantains were stored for six days for this study. In future studies it would be appropriate to see if a change in the period of time that these fruits were stored for would have an effect on banana degreening.
This article can be found through ejournals in the Journal of Agricultural and Food Chemistry.
Title: Characterization of chlorophyll degradation in banana and plantain during ripening at high temperature
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1 comment:
It sounds like an interesting article. I really like bananas!
Do you have any idea why bananas seem to ripen faster in the refrigerator? It makes sense that the researchers would choose higher temperatures for studying ripening since bananas are probably more likely to be subjected to higher temperatures than lower ones. Was there any discussion as to why they chose 20 degrees and 30 degrees C and not lower temperatures?
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