Abstract:
The purpose of this study was to determine the proanthocyanidin
content of bananas at the green, the ripe,
and the overripe stages. Three bananas from each of three
hands at each stage of ripeness, making a total of 27
bananas, were freeze-dried. The ground tissue was dispersed
in methanol and the proanthocyanidin in the slurry
was converted to anthocyanidin by heating in 0.8 N
HCl-n-butanol containing iron (FeSO₄ . 7H₂0). The major
anthocyanidin was identified as delphinidin with a minor
pigment as cyanidin. Two sub-samples of each banana were
analyzed in triplicate and the absorbance of anthocyanidin
was read at a wavelength of 545 mμ.
The proanthocyanidin content, expressed as milligrams
of delphinidin chloride per gram of dried banana, averaged
19.7 for the green, 16.0 for the ripe, and 13.7 for the
overripe. Differences in the proanthocyanidin content of
the bananas due to ripeness were statistically significant. Moisture content averaged 71.3% for the green, 73.0% for
the ripe, and 74.9% for the overripe. Proanthocyanidin
content on a fresh weight basis, expressed as milligrams
of delphinidin chloride per gram of banana, averaged 5.63,
4.33, and 3.44 for the green, ripe and overripe, respectively.
The proanthocyanidin content of the bananas in this
study was considerably higher than values previously reported.
Analysis of the pulp rather than the extractable
proanthocyanidin and a more acidic developer and one which
contained iron were major factors contributing to the
higher values.
While the proanthocyanidin content decreased significantly
with ripeness of the bananas, two other groups of
workers reported decreases that were proportionately
greater. Their data was based on extractable proanthocyanidin
and polymerization of these compounds as the fruit
ripens could account for their lower values. Conversion
of unextractable polymers in the pulp to soluble anthocyanidin
could account for the higher values in the present
study.
A high proportion of the variance for treatment mean
was due to hand and relatively little due to banana on the
hand, suggesting that fewer bananas from more hands could
have been analyzed. A better method than skin color for
assessing ripeness is suggested.
