## 3 Results and Discussion  
### Banana Starch Content  
During the postharvest ripening period, banana flour samples from 16 cultivars across the three genome groups (ABB, AAB, and AAA) exhibited significant differences in BRS, NRS, and total starch contents between D1 and D7 (\(p<0.05\)) (Table 2). The BRS content of the 16 cultivars decreased gradually, ranging from 42.39 to 96.74 g/100 g, while the NRS content showed an increased range of 2.03-27.63 g/100 g. A decline in total starch content was also observed across the 16 banana cultivars during the ripening. These results show that the unripe banana cultivars have a high BRS content and total starch content at an early postharvest ripening period, which was then converted into soluble sugar content through an enzymatic breakdown during the postharvest ripening [20]. The BRS of Meishi 2 (AAB), Jinfen 1 (ABB), and Maiden (AAB) cultivars (96.74, 90.92, and 90.10 g/100 g, respectively) at D1 were significantly higher (\(p<0.05\)) than those of the remaining 13 cultivars. In contrast, unripe mango, another climacter fruit, had a lower resistant starch content of only 68.6% [21]. It was noteworthy that during the postharvest ripening, the mean decrease in the proportion of BRS in total starch was 56.06% in the ABB genome group and 55.62% in the AAB genome group, while in AAA genome bananas, the proportion of BRS in total starch was reduced by an average of 77.66%. The ratio of BRS in total starch reduced more slowly in ABB and AAB genome bananas than in AAA genome bananas, likely due to differences in the internal starch structure and the activity of amylases [22; 23]. A genotype-specific pattern in resistant starch degradation was observed among the 16 banana cultivars. Compared to AAB genome and ABB genome BRS, AAA genome BRS was more susceptible to enzyme digestion, resulting in degradation widely.  
The hierarchical cluster analysis based on the content of BRS at D1 and D7 was carried out to explore the differences and similarities among the banana cultivars with different genotypes (i.e., ABB, AAB, AAA) (Figure 1, Table 3). The 16 banana cultivars were divided into cluster 1 (C1), cluster 2 (C2) and cluster 3 (C3). C1 contained two banana cultivars including Meishi 2 (AAB) and Jinfen 1 (ABB) with a high BRS content at both D1 and D7. C2 was further divided into two subgroups, C2A and C2B. C2A contained Yuejiao 2 (AAA) and Maiden (AAB) with a moderately high BRS content at D1 and a moderately low BRS content at D7. Guangfen 1 (ABB) was divided into C2B with a moderately high BRS content at D1 and a high BRS content at D7. C3 had 11 banana cultivars with a low BRS content, from 48.79 g/100 g to 65.93 g/100 g, at D1 and almost no BRS content, from 0 g/100 g to 12.4 g/100 g, at D7; it then was divided into three subgroups according to the different BRS content at D1 and D7. We could find that cultivars with the same genotype, such as Jinfen 1 and Guangfen 1, were distributed into different groups, indicating that cultivars of the same genotype had different BRS contents. In addition, the majority of the AAA genome bananas, including Kazirakwe, Mpotogoma, Ingagara, GN 60A, and Zhongjiao 8, presented moderate to low BRS content. The results pointed out that though the impact of distinct genotypes on the starch content at D1 of the banana cultivars remains uncertain, it is possible that the AAA genotype promoted BRS degradation during the postharvest ripening.  
Figure 1: Results of hierarchical cluster analysis of BRS from 16 banana cultivars at D1 and D7. The lines of the same color in the figure represent that these banana cultivars are classified into the same cluster.