Effect of ethylene on ripening of kiwifruit stored under controlled or modified atmosphere packaging and treated with 1 methylcyclopropene.
BACKGROUND: Kiwifruit (Actinidia deliciosa (A. Chev. C.F. Liang et A.R. Ferguson cv. 'Hayward' is usually harvested firm, unripe, and with a high starch content, and thus fruit do not always achieve a suitable soluble solid concentration (SSC) and soft texture when ripe. A high dry matter concentration at harvest can be used to predict fruit sweetness at ripening. However, fruit softening capacity is difficult to predict because of the interaction between postharvest practices and biochemical processes that occur at 0*C. OBJECTIVE: To understand the effect of ethylene on restoring the lost softening capacity of kiwifruit treated with 1 methylcyclopropene (1 MCP) alone or in combination with modified atmosphere packaging (MAP) or controlled atmosphere storage (CA) METHODS: The effect of ethylene (100 l l 1 for 12 h at 20*C) on kiwifruit harvested at commercial maturity (6.2% SSC) and treated with 1 MCP (1 l l 1, 24 h) and packed in perforated bags (PB) or MAP for 60, 90 or 120 days at 0*C and ripened at 20*C for 17 days was determined. The effect of ethylene applied at 100 l l 1 for 24, 48 or 72 h was also evaluated on fruit treated with 1 MCP (1 l l 1, 24 h) subjected to 108 days of CA (2% O2 and 5% CO2) and a further 30 days in PB at 0*C. RESULTS: Both 1 MCP and MAP reduced fruit softening after 60 and 90 days at 0*C, and delayed fruit ripening at 20*C. A synergistic effect of 1 MCP and MAP extended those results to 120 days at 0*C. Ethylene treatment restored the ripening of MA fruit but not the 1 MCP treated fruit stored for 60 days at 0*C or when it was packed in MA bags for 90 days at 0*C. Ethylene for 48 h prevented the 'hard core' texture observed in CA with 1 MCP treated fruit. CONCLUSIONS: Kiwifruit treated with 1 MCP and/or packed with MA requires a minimum time at 0*C before to induce ripening by ethylene treatment (100 l l 1 for 12 h at 20*C) Ethylene treatment avoids 'hard core' development on 1 MCP treated fruit stored in CA. Keyword: 1 methylcyclopropene, hard core, fruit quality, ripening protocol *Corresponding author: Juan Pablo Zoffoli, Departamento de Fruticultura y Enologia, Facultad de Agronomia e Ingenieria Forestal, Pontificia Universidad Catolica de Chile, Chile. Tel. +562 26864159; Fax: +562 25534130; E mail: zoffolij@uc.cl. 1878 5093/16/$35.00 (c) 2016 IOS Press and the authors. All rights reserved 382 J.P. Zoffoli et al. Effect of ethylene on ripening of kiwifruit stored under controlled or modified