Impact of Low Humidity on Suppressing Stem-End Rot in Avocado During Ripening

Abstract

Avocados are susceptible to fungal fruit rot, particularly stem-end rot, resulting in significant quality loss during postharvest ripening processes. Here, we examined the effect of low humidity conditions on slowing down fungal growth in “Hass” avocados during ripening using non-destructive X-ray imaging. Stem ends of unripe avocados were artificially infected by inoculating them with a spore suspension of Nectria pseudotrichia and then stored at 20 °C and 25 °C with 20%, 50%, 70%, and 90% relative humidity (RH) until they fully ripened. Internal rot development was monitored daily via X-ray imaging, and the presence of stem-end rot was verified on the last day of ripening. The sensory attributes and weight loss were assessed to evaluate fruit quality. The results showed that lower humidity and temperature significantly suppressed the occurrence and severity of fungal fruit rot. Although 20% RH significantly suppressed fungal growth at both 20 °C and 25 °C, weight loss exceeded the market acceptable limit of 10%. Furthermore, a sensory evaluation involving 57 untrained panelists revealed that all sensory attributes of avocado flesh, including appearance, aroma, sweetness, texture, taste, firmness, and overall preference, remained consistent across different humidity conditions. Consequently, among the ripening conditions investigated in this study, a ripening environment of 20 °C and 50% RH is recommended for balancing stem-end rot prevention, acceptable weight loss, and sensory attributes.