Assessment of fluorescence fingerprint in Hayward and Ruby-Red kiwi fruit as a potential approach to monitor quality changes during storage

The research identified time-series fluorescence characteristics from various parts of the kiwi fruit in two varieties over storage. EEM fluorescence was taken in the fruit area over a 14-day storage period at 4 °C. In the flesh of Hayward kiwifruit, a moderate to strong regression was observed between firmness and the B channel (R2_cal = 0.75, R2_pred = 0.70, RMSE_train = 1.28, RMSE_test = 1.41). While, in the skin part, the relationship was slightly higher (R2_cal = 0.80, R2_pred = 0.76). The fluorescence peak at 370/493 nm has a strong regression with B channel values in the skin (R2_cal = 0.89, R2_pred = 0.92). Additionally, the relationship between firmness and B channel intensity in the flesh of Ruby Red kiwifruit demonstrated a high predictive accuracy (R2_pred = 0.92) and RMSE values (1 and 0.9 for train and test, respectively).