*3.4. Changes in Soluble Solids Content, Titratable Acidity, Total Sugars, and Total Acids*

As expected, soluble solids content (SSC) and total sugar content increased over the period of storage for all the treatments, which reached the maximum value at the end of storage (Table 3 and Table S4). Nonetheless, the preharvest treatment of chitosan was associated with slower increasing rates of SSC during storage, as significantly lower (*p* ≤ 0.05) SSC at the end of storage were observed in preharvest chitosan-treated fruit (11.9% in 100 mg·L−<sup>1</sup> and 11.6% in 500 mg·L−1) compared with the control fruit (12.7%). In addition, preharvest chitosan-treated fruit displayed the lowest increase in total sugar content during the storage which resulted in a significantly lower (*p* ≤ 0.05) total sugar content at the end of storage. At harvest, the ratio of fructose + glucose/sucrose, a potential indicator of invertase activity [31], was lower (*<sup>p</sup>* ≤ 0.05) in 100 and 500 mg·L−<sup>1</sup> chitosantreated fruit. However, there was no difference in the fructose + glucose/sucrose ratio among treatments for the rest of the storage.

In regard to titratable acidity (TA) and total acid content, it was clear that both attributes displayed a decreasing trend over the storage time (Table 3 and Table S4). The preharvest chitosan-treated fruit had the greatest TA values (*p* ≤ 0.05) at harvest. The fruit treated with 100 mg·L−<sup>1</sup> chitosan displayed the positive effect on TA that preserved the greatest content (*<sup>p</sup>* ≤ 0.05) during storage time compared with the control and 500 mg·L−<sup>1</sup> chitosan-treated fruit. As for the total acid content, preharvest chitosan treatments resulted in higher (*p* ≤ 0.05) values at harvest time than the control. Throughout the whole storage, the application of 100 mg·L−<sup>1</sup> chitosan was most effective in preserving the greatest total acid content, followed by 500 mg·L−<sup>1</sup> chitosan when compared with the control. In addition, the application of preharvest chitosan with 100 and 500 mg·L−<sup>1</sup> caused the greatest (*p* ≤ 0.05) citric acid/quinic acid ratio at harvest; however, there was no significant difference in this ratio among treatments during the rest of storage.
