## 1 Introduction  
The banana is a perennial herb that includes several species within the _Musa_ genus under the Musaceae family. It is widely planted in both tropical and subtropical areas [1]. It has been estimated that nearly one-third of bananas are lost due to the public tendency to consume only ripened fruit [2]. Thus, using bananas at different ripening stages has gained interest over recent years. Unripe bananas contain a high level of starch, ranging from 61.00% to 77.12% in different cultivars, and in the pulp, the resistant starch accounts for more than 50% (dry base) [3, 4]. Resistant starch has been reported to exhibit similar metabolic health benefits as dietary fiber, including significant roles in weight management, regulation of blood glucose and lipid levels, and the modulation of gut health [5, 6]. Thus, the development of banana resistant starch (BRS) not only avoids a large waste of banana raw material but also has a large potential for commercial demand because of its dietary benefits.  
The characteristics of banana starch are influenced by several factors, including cultivar, genome group, ripening stage, and environmental conditions [7, 8, 9, 10]. There are about 300 kinds of banana cultivars worldwide and nearly 30 cultivars are grown in China, especially in Guangdong Province. Different cultivars may exhibit distinct genotypes, includingthe two naturally occurring diploid species (_M. acuminata_ and _M. balbisiana_) and their hybrids [7]. Most of the banana cultivars that are widely grown today are triploids, including AAA, ABB, and AAB. Banana cultivars with varying genotypes can lead to significant differences in both the content of total starch and resistant starch during the postharvest ripening [11]. At early postharvest ripening, ABB genome bananas were reported to have higher levels of amylose and resistant starch [3]. Amylases, starch phosphorylase, and starch debranching enzyme were reported to be specifically up-regulated in AAB genome bananas, resulting in a faster starch degradation rate during ripening [12]. Moreover, the starch derived from banana cultivars has been analyzed for its structural characteristics, physicochemical properties, and potential applications [8]. For instance, [PERSON] et al. [9] found significant differences in the pasting properties of banana starch among seven cultivars, while [PERSON] et al. [10] demonstrated that pasting properties, color, and texture were strongly cultivar-dependent in banana starch from the AAA, AAB, and ABB genome groups. Hence, investigating the starch properties across various banana cultivars is crucial for understanding the specific starch characteristics associated with each genotype. This helps identify cultivars with a higher BRS content and better functional qualities, which can be used to develop new health-boosting products.  
In this study, we selected 16 banana varieties from three different genome groups that are widely planted around the world. There are three cultivars from the ABB genome group, six from the AAB genome group, and seven from the AAA genome group. Previous research primarily focused on using banana flour to investigate the structural and physicochemical properties [3; 7; 8; 9; 10]. In contrast, this study directly extracted and analyzed the characteristics of resistant starch from the different banana cultivars. This approach allows for a more direct and targeted understanding of how various genotypes affect the characteristics of resistant starch. Changes in the starch content throughout the postharvest ripening were also assessed. This study could provide valuable insights for banana breeding and processing as well as the development of healthy food products based on BRS.