3.3.1. Changes of Contents of Soluble Solid and Soluble Sugars

At 25 and 0 ◦C, SSC showed the trend of increasing before decreasing, and separately reached the maximum value on the 10th and 30th day (Figure 4). As shown in Figure 5, the TSS, fructose and glucose contents of flesh increased significantly due to starch hydrolysis, while the sucrose content remained at a high level, with no significant change in the early stage of storage at 25 and 0 ◦C [44]. This was also consistent with the phenomenon that the fruit will turn sweet during the storage after harvest. After storage, SSC declined significantly (*p* < 0.05), from 13.85% to 11.26% at 25 ◦C and from 13.97% to 12.26% at 0 ◦C.

**Figure 4.** Soluble solid content (SSC) of Fuji apple flesh for six storage times at 25 ◦C (**a**) and 0 ◦C (**b**). Data at six storage time with different letters are significantly different with *p* < 0.05. The vertical bars denote standard deviations. d, day.

**Figure 5.** Soluble sugars contents of Fuji apple flesh for six storage times at 25 ◦C (**a**) and 0 ◦C (**b**). Columns with different letters for the same cultivar are significantly different with *p* < 0.05. Standard error is indicated. d, day.

Increasing with storage time, the contents of TSS, fructose, glucose and sucrose gradually declined, and reached the lowest value at the end of storage. At 25 ◦C, the contents of TSS, fructose and glucose reached the highest value on the 10th day. After 50 days storage, the contents of TSS, fructose and glucose were reduced to 50.72, 25.67 and 17.62 g kg<sup>−</sup>1, respectively. In addition, the content of sucrose decreased from 11.52 to 7.44 g kg<sup>−</sup>1. At 0 ◦C, the TSS, fructose and glucose contents reached the highest value at a slower rate than at 25 ◦C, and reached the peak on the 30th day, with levels of 60.34, 31.95 and 18.14 g kg−1, respectively. On the 150th day, the TSS, fructose and glucose contents were the lowest, 47.62, 26.66 and 13.09 g kg<sup>−</sup>1, respectively. The content of sucrose did not change significantly during 60-day storage and reached the minimum value of 7.86 g kg−<sup>1</sup> on the 150th day.
