Application of Electronic Nose to Monitor the Quality and Ripening Stages of Papaya During Postharvest Storage

Electronic noses (EN) are recently being explored for their application in postharvest quality monitoring. In this study, EN was used to assess different papaya ripening stages (days 1, 3, and 5 postharvest) through odor profile changes. Case-Based Reasoning classification analyzed EN sensor responses, showing 84.25% similarity between days 1 and 3, 82.81% between days 1 and 5, and 94.19% between days 3 and 5, all below 98%, indicating significant differences in volatile profiles. Gas chromatography–mass spectrometry identified specific volatile compounds for each day, such as vinyl butyrate and allyl propionate (day 1), acetone, tridecane (day 3), and cyclobutanol, oxalic acid (day 5). The sensor values showed strong correlations with physiochemical changes during ripening (r2 = 0.845 for weight, 0.943 for titratable acidity, 0.883 for total soluble solids, and −0.943 for chromaticity). These findings demonstrate EN’s promising potential as a reliable, nondestructive tool for distinguishing papaya ripeness levels during postharvest storage.