Changes in taste and volatile compounds and ethylene production determined the eating window of ‘Xuxiang’ and ‘Cuixiang’ kiwifruit cultivars

Edible kiwifruit has an attractive taste and a unique aroma. In the present study, changes in taste and volatile compounds, as well as ethylene production, in two kiwifruit cultivars (Actinidia deliciosa cv. ‘Xuxiang’ and ‘Cuixiang’) in six different firmness stages in late ripening were investigated to determine the eating window. Titratable acidity (TA), soluble solids content (SSC), and sugar content (fructose, glucose, and sucrose) changed slightly in kiwifruit throughout different firmness stages. In contrast, concentration and diversity of esters increased significantly in both ‘Xuxiang’ and ‘Cuixiang’ kiwifruit in the late ripening phases. Interestingly, a high correlation was found between increased content of volatile esters and ethylene production in kiwifruit. Moreover, the composition and concentration of volatile aroma compounds differed in both kiwifruit cultivars, and observed differences may have contributed to confer a unique aroma profile to each kiwifruit cultivars. Electronic tongue (E-tongue) and electronic nose (E-nose) data revealed that the overall taste and aroma profiles in both ‘Xuxiang’ and ‘Cuixiang’ kiwifruit cultivars differed in late ripening. Principal component analysis (PCA) of data of taste and volatile compounds as well as of ethylene production enabled determining the eating window of the two kiwifruit cultivars: 3–7 N for ‘Xuxiang’ kiwifruit and 3–9 N for ‘Cuixiang’ kiwifruit. The present study demonstrated changes in kiwifruit fruit quality in the late ripening phase, thus providing useful information for kiwifruit fruit quality assessment and eating window determination.