## 3 Results
### Differences of Aroma Components  
Figure 5a manifests the total ion flow in all periods. A total of 48 aroma components were detected in 7 categories, and there were 23-33 aroma components during the period of each softening method. The total relative content of each period was effective >95%. In the comprehensive comparison, the aroma species and relative content were higher in the on-vine group than in the cold group (Figure 5b). The basic aroma components detected in kiwifruit under different softening methods are listed in Figure 6a. The substances that were found in different periods under different softening conditions included pentanal (0.39-1.98%), hexanal (1.48-15.19%), 2-hexanal (6.61-61.44%), d-limonene (1.34-13.11%), and nonanal (0.56-1.37%). A total of 3 alkanes were detected under both softening conditions, but their contents were low with <1% of the total amount. Only 2 alcohols were found, and their contents were also low. However, the expression of these 2 alcohols was higher in the on-vine group than in the cold group. A total of 11 aldehydes were detected, and their contents significantly and continuously decreased. The contents of aldehydes in the cold group decreased slowly after reaching a peak of 81.44% after 28 d, which was the highest value recorded in the entire experiment. Among these, 2-hexanal showed the highest content. The species and content of esters increased as the fruit ripened. The species and the overall content of esters were more in the on-vine group than in the cold group. The alkene and terpene contents were high in both groups. In the on-vine group, these contents elevated substantially as the fruit matured and reached their highest values after 14 d. The peak value of terpen reached 83.26% after 70 d. The substance with the highest content was 2-carene. The total content in the cold group exhibited a decreasing and increasing trend, but not to a large extent. A total of 5 ketones were detected, and their contents in the on-vine group enhanced continuously and reached the peak value of 1.15% after 70 d. However, their contents in the cold group firstly increased and then reduced, with a peak of 1.92% after 28 d. A total of 4 furans were found. Their contents were all low at the beginning and diminished at the end of the experiment. There were some differences in the types and contents of numerous aroma substances between both groups, and unique aroma substances were produced at 70 d.  
Figure 4: Changes of flesh firmness and cohesiveness. (**a**) Flesh firmness. (**b**) Flesh cohesiveness. (**c**) The TPA characteristic curve of the on-vine group. (**d**) The TPA characteristic curve of the cold group. Data are expressed as mean \(\pm\) standard deviation of three biological repetitions. Error bars represent standard deviations of means. Different capital letters or \"\" represent the difference between the two softening methods at the same harvest time. Different lowercase letters are significantly different at \(p<0.05\). Data were analyzed with one-way analysis of variance (ANOVA) and [PERSON]’s multiple range tests. The red line in (**c**,**d**) represents the calculated flesh firmness, and this value was the average of all biological and technical repetitions of different methods in each collection period. Only one characteristic curve was selected to represent the test result, and other characteristic curves had only slight errors. Figure 5: Quantitative analysis of aroma compounds. (**a**) Total ion current flow diagrammatic sketch of aroma substances. (**b**) Quantity of aroma substances under different softening methods in each period. Figure 6: Identification and analysis of aroma components. (**a**) The relative content of aroma components in ‘Ganlv-2’ of different softening methods. (**b**) Aroma compounds correlation/significance of on-vine and cold group. In the colored area, rectangles represent r values resulting from Pearson correlation coefficient computation (see correlation color key).