Influence of ethylene and 1-methylcyclopropene on softening, ripening, and cell wall matrix polysaccharides of avocado fruit
J. Jeong , D.J. Huber and S.A. Sargent
Proceedings of 26th International Horticultural Congress. Volume of Abstract . Toronto, Canada, 11-17 August, 2002. p.241.
2002
บทคัดย่อ
Pre-ripe avocado (Persea americana) fruit were treated with 0.09 *L*L-1 per L 1-methylcyclopropene (1-MCP) for 12 hours at 20 0C. After 19 d storage in air at 130C, half of the 1-MCP-treated fruit were treated with 100 uL.L-1 per ethylene for 12 hours and then transferred to 20 0C. 1-MCP significantly delayed softening , and delayed the onset of the ethylene climacteric by 112 days. Fruit treated with 1-MCP retained more green color than air-treated fruit at the ripe stage (firmness 10-20 N). The delay in avocado ripening in response to 1-MCP was not influenced by the treatment with exogenous ethylene. 1-MCP affected the activities of polygalacturonase, pectimethylesterase, alpha- and beta-galactosiddase, and cellulase and completely suppressed the appearance of polygalacturonase activity for up to 24 days, at which time fruit firmness had declined to 35.1 +- 5.5 N. The activities of PG and cellulase increased and beta-galactosidase decreased in 1-MCP-treated fruit in response to exogenous ethylene treatment. 1-MCP treatment significantly delayed the solubillization and degradation of water- and CDTA –soluble polyuronides, apprently due to reduced PG activity. The molmass downshifts of polyuronides were accompanied by changes in neutral sugar composition. At the full-ripe stage, neutral sugar composition. At the full-ripe stage sugar levels of CDTA-soluble polyuronides were similar among all treatments. In contrast, galactose levels of water-soluble polyuronides decreased significantly in control fruit (40.6%) and decreased slightly (17.1%) in 1-MCP treated fruit. 1-MCP or ethylene treatment did not affect the sugar composition of hemicelluloses.