3.6. Chemical composition change in fruit
The chemical composition of the fruit pulp is an important
criteria needed for the evaluation of fruit quality. Normally,
biochemical changes of mangoes during ripening include a
reduction of titratable acidity (TA) and increase of pH, ascorbic
acid, and total soluble solids (TSS). The changes in the chemical
composition of mangoes after eight days of storage were studied
(Table 3). Titratable acidity decreased in all the mangoes, both
treated and untreated, and uncoated mangoes had the maximum
fall in acidity. pH increased from the initial value of 3.61 in the
uncoated mangoes (4.88). There was not a significantly different
change observed between control and coated fruit.
During ripening, TSS increased due to the degradation of
polysaccharides present in the fruit. In this study, there was no
significant difference between values of coated and uncoated
mangoes and reference values. However uncoated fruit showed a
maximum value of 14.8% TSS after eight days of storage. Initially,
fruit are rich in ascorbic acid but its level usually decreases during
maturation. After eight days of storage, ascorbic acid in uncoated
fruit fell significantly (5.84 mg/100 mL) compared to coated fruit
(23–26 mg/100 mL) (Table 3). Slowing maturation caused by the
coating of chitosan, thus reduced degradation of ascorbic acid.
An overall comparison between chitosan treatments showed
that there was no significant difference between chitosan
concentrations of 1% and 1.5%. Application of chitosan exhibited
a beneficial effect on the contents of TA, TSS, pH and ascorbic acid.
This could be due to low respiration of coated fruit. The presence of
the enzyme system did not influence chemical composition
changes in the fruit.