Volatile components in papaya fruits are the non-invasive biomarkers to monitor the ripening stage and the nutritional value

Abstract

Papaya fruits have great nutritional and economical values. The ripening stage of papaya fruits at the time of harvesting massively impacts the quality and shelf-life of fruits. Volatile organic compounds (VOCs) emitting from the papaya fruits during the ripening process could be used as a real-time non-invasive biomarker to characterize the ripening stage. This paper reports identification of VOCs as non-invasive ripening biomarkers of papaya fruits based on solid-phase micro-extraction coupled with gas chromatography–mass spectrometry (GC–MS) analysis of VOCs emitted from the papaya fruit cv. ‘Red Lady’. Three ripening stages were studied, viz., green unripe (UR), yellowish-green intermediate ripe (IR), and yellow full ripe (FR). GC–MS analyses and the subsequent statistical studies identified a total of 35 VOCs. Partial Least Squares Discriminant Analysis (PLS-DA) of VOCs from the three ripening stages identified six biomarker VOCs, which can efficiently distinguish between ripening stages. Among the six ripening biomarkers, three VOCs (methyl hexanoate, 3-carene and longifolene) showed a remarkable correlation with the ripening-associated changes in the fruit nutritional profile. The biomarkers reported here could be used as a viable technology for non-invasive monitoring of ripening stages and the nutritional value of papaya fruits.