สำนักราชบัณฑิตยสภา

«“√ “√ √“™∫— ≥±‘ µ¬ ∂“π ªï ∑’Ë Û ©∫— ∫∑’Ë Û °.§.-°.¬. ÚıÙ¯ 639 “¬™≈ ‡°µÿ …“ Abstract Pericarp Hardening of Mangosteen Fruit after Impact Saichol Ketsa Associate Fellow of the Academy of Science, The Royal Institute, Thailand Mangosteen (Garcinia mangostana L. ) is a tropical fruit crop which is one of the most important economic fruit crops of Thailand. The pericarp of mangosteen fruits serves as an excellent packing material to protect the soft aril during postharvest handling. Mangosteen pericarp hardens rapidly as a result of impact. Even though pericarp hardening does not affect the eating quality of mangosteen fruits but consumers are prone to reject mangosteen fruits with pericarp hardening. It has been reported that pericarp hardening rapidly increased concomitant with an increase in lignin content and a decrease in total phenolics in damaged pericarp of mangosteen fruits after impact. Many enzymes involved in lignin synthesis such as phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, peroxidase, etc. have been found in damaged pericarp to rapidly increase and reach a maximum with 10-20 minutes after impact. Intermediates in lignin biosynthetic pathway such as p -coumaric acid and sinapic acid have been also found increasingly in damaged pericarp of mangosteen fruits after impact. Pericarp hardening of mangosteen fruits depends on many factors such as maturity, impact height, oxygen, etc. Lignin synthesis of damaged pericarp is a self-defense mechanism of plants against intruders. Key words : mangosteen, pericarp, hardening, impact, lignin Bunsiri, A., S. Ketsa and R.E. Paull. 2003. Phenolic metabolism and lignin synthe- sis in damaged pericarp of mangosteen fruit after impact. Postharvest Biol. Technol. 29 : 61-71. Bunsiri, A., R.E. Paull and S. Ketsa. 2003. Lignin accumulation in relation to in- creased firmness of damaged pericarp of mangosteen fruit after impact. Thai J. Agric. Sci. 37 : 373-381. Campbell, M.M. and R.R. Sederoff. 1996. Variation in lignin content and compo- sition : mechanism of control and im- plications for the genetic improvement of plants. Plant Physiol. 110 : 3-13. Iiyama, K., T.B.T. Lan and B.A. Stone. 1994. Covalent cross-links in the cell wall. Plant Physiol. 104 : 315-320. Keller, B., N. Saner and C.J. Lan. 1988. Glycine-rich protein in bean : gene structure and association of the protein with the vascular system. EMBO J. 7 : 3625-3634. Ketsa, S. and S. Atantee. 1998. Phenolics, lignin, peroxidase activity and increased firmness of damaged pericarp of mango- steen fruit after impact. Postharvest Biol. Technol. 14 : 117-124. Ketsa, S. and M. Koolpheksee. 1993. Some physical and biochemical characteristics of damaged pericarp of mangosteen fruit after impact. Postharvest Biol. Technol. 2 : 209-215. Vance, C.P., T.K. Kirk and T.K. Sherwood. 1980. Lignification as a mechanism of disease resistance. Ann. Rev. Phyto- pathol. 18 : 259-288. Whetten, R.W., J.J. MacKay and R.R. Sederoff. 1998. Recent advances in understanding lignin biosynthesis. Ann. Rev. Plant Physiol. Plant Mol. Biol. 49 : 585-609. Whitmore, F.W. 1978. Lignin-carbohydrate complex formed in isolated cell walls of callus. Photochem. 17 : 421-425.