Analysis of the volatile profiles of kiwifruits experiencing soft rot using E-nose and HS-SPME/GC–MS

Soft rot is a postharvest storage disease occurring in kiwifruit that can cause substantial losses and is difficult to detect. In this study, the internal quality of kiwifruits was measured. In addition, the volatile profiles of kiwifruits were analysed by electronic nose (E-nose) and headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS–SPME/GC–MS). The results showed that the firmness, titratable acidity (TA) and ascorbic acid (AA) decreased as the rot worsened, while malondialdehyde increased. A principal component analysis (PCA) of the E-nose data showed a clear distinction between the intact and diseased fruits. A loading analysis (LOA) of the E-nose data showed that the sensor response appeared to significantly vary between the intact and diseased fruits. Nine differential metabolites for the intact and diseased kiwifruits were acquired by HS–SPME/GC–MS, including isobutyl butyrate, ethyl 2-furoate, ethyl valerianate, propyl butyrate, ethyl hexanoate, 4-terpene alcohols, benzyl alcohol, oxime-methoxy-phenyl and 4-isopropyl toluene. There was a significant correlation (p < 0.05) between the physicochemical indices and volatile profiles obtained by E-nose and HS-SPME/GC–MS. This study proved that the combination of E-nose and GC–MS could potentially be used for detecting kiwifruits experiencing soft rot.