AbstractMangosteen (Garcinia mangostana L.) is a tropical fruit that is grown commercially in many ASEAN (Association of Southeast Asian Nations) countries. The fruit, with its attractive shape, unusual color, and unique taste, is becoming increasingly popular with consumers. The fruit has a thick pericarp that can protect the internal aril against improper postharvest handling, such as that from drops, abrasion, vibration, impact, and compression. However, such physical forces applied to any point on the surface of mangosteen fruit will induce rapid hardening of the affected regions of the pericarp. Mangosteen fruits that have hardening of the pericarp have lower overall postharvest fruit quality. The degree to which the pericarp is hardened after impact depends on maturity stage, impact severity, and oxygen availability. Lignin content of the impacted pericarp has been shown to increase rapidly concomitantly with a decrease in the total phenolic content. Pericarp hardening, therefore, is associated with lignin biosynthesis that involves the metabolism of specific phenolic compounds, key enzyme activities, and the related expression of regulatory genes.