Comparative analysis of physicochemical quality and metabolite profiles during fruit ripening in three banana cultivars using multivariate approaches

We investigated three banana cultivars: 'Fenjiao', 'Dajiao', and 'Gongjiao' at five ripening stages (i.e., all green, RS1; bright green, RS2; yellow with a small amount of green RS3; yellow with only pointed tail dots green, RS4; and all yellow, RS5) and compared the physicochemical quality indicators and metabolite profiles. These banana varieties exhibited distinct growth durations: 'Gongjiao' (short, 270–280 d), 'Fenjiao' (medium, 375–390 d) and 'Dajiao' (long, 415–430 d). We found that 'Gongjiao' was the earliest to ripe (RS5 stage) in 5 d, followed by 'Fenjiao' (9 d) and 'Dajiao' (11 d). The total soluble solids (TSS) of each variety increased from RS1 to RS4, peaking at a later stage, followed by a reduction at RS5. The banana cultivar 'Dajiao' had the highest titratable acidity (TA), particularly during advanced ripening stages, whereas 'Gongjiao' had the lowest TA at RS5. Moreover, in 'Dajiao' and 'Fenjiao', the organic acid content of the fruit was higher during the early ripening stages (RS1-RS2), whereas in 'Gongjiao', it peaked at the full ripening stage (RS5). The levels of fruit amino acids and related compounds exhibited great variation among the three cultivars at different ripening stages, with more amino acids found in 'Fenjiao' and 'Gongjiao' at RS5 and 'Dajiao' at RS4. In summary, significant differences were observed among cultivars in terms of carbohydrates, sugars, vitamin C, and protein at the early and fully ripe stages. A total of 14 volatile compounds with odor activity values (OAVs) higher than 10 were identified as aroma-active markers in all banana varieties. Overall, fruit pulp hardness, TSS, and TA were closely linked to peel color changes, and the results of redundancy analysis (RDA) showed discrete associations between key ripening traits, such as peel color change parameters, TSS, TA, ethylene production (EP), respiration rate (RR), ACO, α-amylase, and β-amylase, and banana cultivars. Lastly, hierarchical cluster analysis (HCA) of the quality characteristics of banana cultivars revealed that 'Fenjiao' and 'Gongjiao' shared a more synchronized ripening pattern than 'Dajiao'. These findings have practical applications in monitoring and managing fruit ripening during postharvest handling and quality control of various banana varieties. • Stage-specific distinct changes provide theoretical basis for banana cultivar selection and quality control. • Only 'Gongjiao' fully ripened within five days (RS5 stage). • Volatile profiles among the three cultivars varied significantly and 14 aroma-active compounds were identified. • Both 'Fenjiao' and 'Gongjiao' exhibited more synchronized ripening characteristics