2.4.2.4. Determination of weight loss (%WL).Fruit weight was
measured at the beginning of storage time and then at the ripe
stage. Percent weight loss was calculated as a difference between
the original weight and weight at the ripe stage.
2.4.2.5. Measurement of total soluble solids (TSS).A 30 g banana
pulp (from middle and bottom portion of three ripe bananafingers
per replication) was blended in 90 mL sterile distilled water in a
homogenizer for 2 min. The juice was left for 10 min to settle and
total soluble solids were determined by putting 1 to 2 drops from
each sample on a prism of a hand refractometer (type Palm
Abbetm), scaled from 0 to 32
o
Brix. Undiluted TSS was calculated by
multiplying each reading by three, the dilution factor (Dadzie and
Orchard, 1997).
2.4.2.6. Measurement of pH value and titratable acidity (TA).
The pH value of the juice (it was prepared as described above) was
determined using a pH meter (model Jenway 3320). For titratable
acidity, an equal volume (25 mL) of the fruit juice (it was prepared
as described above) and 25 mL of sterile distilled water were
transferred into a 125 mL conical flask and 4 drops of phenolphthalein indicator was added. The solution was titrated with 0.1 N
sodium hydroxide (NaOH) until the indicator changed to pink
(Dadzie and Orchard, 1997). The titre volume was recorded and the
results were expressed as the percentage malic acid present. According toJosylin (1970), malic acid is the predominant acid in
banana, cooking banana and plantain. Percentage malic acid was
calculated using the following formula (Bhattarai and Gautam,
2006)