Kiwifruit (Actinidia chinensis), also known as Chinese gooseberry, belongs to the family Actinidiaceae and the genus Actinidia (Liu et al., 2026b). It is rich in vitamins, minerals, and organic acids, often earning the title “King of Fruits” (Lim et al., 2017). Its high nutritional value supports various health benefits, including immune enhancement, prevention of cardiovascular diseases, and regulation of blood glucose and lipid levels, which have greatly increased its popularity among consumers worldwide (Hu et al., 2014). China, a major global producer, has a long history of kiwifruit cultivation; however, the rapid expansion of cultivation areas and industrial-scale production has intensified challenges related to postharvest decay and storage losses, significantly impacting industry profitability.

Kiwifruit, as a typical climacteric fruit, is highly vulnerable to pathogen invasion and mechanical damage, which accelerates postharvest decay (Lim et al., 2017). Effective control of microbial growth responsible for these diseases is therefore essential to minimize losses during storage (Hu et al., 2014). The pathogens causing kiwifruit rot are diverse and contribute to complex disease dynamics. In particular, ‘Xuxiang’ kiwifruit, one of the most widely cultivated cultivars, requires targeted isolation and identification of causative pathogens to inform control strategies. Previous studies have identified Botryosphaeria dothidea and Phomopsis spp. as the primary pathogens responsible for kiwifruit soft rot (Tan et al., 2026). Additionally, Diaporthe spp. have been detected in kiwifruit varieties grown in Sichuan Province, China (Liu et al., 2026a). Pathogen virulence is influenced by multiple factors such as climatic conditions, cultivation environment, and kiwifruit cultivar differences, thereby complicating efficient disease management (Sui et al., 2025). Notably, in addition to the fungal pathogens, bacterial decay can also cause significant postharvest losses in kiwifruit. The target pathogen in this study, Gluconobacter cerinus, was isolated from ‘Xuxiang’ kiwifruit showing symptoms of rapid softening and fermentative decay, and its pathogenicity was confirmed by Koch's postulates. Although G. cerinus has been seldom specifically reported in kiwifruit diseases, strain G. cerinus CDF1 was shown to accelerate banana rot, further demonstrating its ability to compromise fruit integrity (He et al., 2017). Thus, exploring control strategies against such bacterial pathogens is of practical importance.

In recent years, the valorization of agricultural by-products has attracted growing attention in the food science community, especially for the extraction of bioactive compounds with applications in food preservation (Viaggi, 2022). Citrus (Citrus reticulata Blanco), a member of the Rutaceous family that includes mandarins, tangerines, oranges, pomelos, and lemons, stands as one of the world's most economically important crops (Liu et al., 2021). Citrus peel, a primary byproduct of citrus processing, is rich in phytochemicals and bioactive compounds such as flavonoids and essential oils, which exhibit notable antibacterial and antioxidant activities (Jiang et al., 2022). However, the burgeoning citrus processing industry generates massive quantities of peel waste, causing resource depletion and environmental pollution (Zema et al., 2018). Several previously reported studies also show that in most citrus fruits, the compounds responsible for antioxidant properties are mainly present in their peels rather than in their pulps (Morais et al., 2016). Harnessing citrus peel for the extraction of valuable bioactive compounds presents a sustainable approach to reducing waste and adding economic value. Previous studies have reported that citrus peel-derived constituents effectively inhibit various spoilage and pathogenic microorganisms, thus offering promising applications in food preservation (Saleem et al., 2023). For instance, essential oils (EOs) extracted from citrus peel have demonstrated inhibitory effects against Colletotrichum gloeosporioides, a fungal pathogen responsible for mango anthracnose (Duong et al., 2023). Preparing essential oils extracted from citrus into low-concentration nanoemulsions and applying them to chili peppers before harvest can effectively reduce chili browning and extend their storage period (Promwee and Matan, 2025). These findings suggest substantial potential for citrus peel extracts in controlling fruit postharvest diseases, advancing sustainable preservation strategies.

This study focused on the ‘Xuxiang’ kiwifruit variety to evaluate the antimicrobial effects of green citrus peel extract (GCPE) against G. cerinus CX2, a dominant pathogen isolated from decayed ‘Xuxiang’ kiwifruit. The inhibitory mechanism of GCPE against G. cerinus CX2 was systematically elucidated by evaluating its effects on bacterial growth, cellular macromolecules, membrane integrity, and surface morphology. Concurrently, the effectiveness of GCPE in prolonging the shelf life of ‘Xuxiang’ kiwifruit artificially inoculated with G. cerinus CX2 was assessed under controlled storage conditions. Overall, this research aimed to explore the potential of GCPE as a natural preservative for postharvest kiwifruit preservation.