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.