'Hayward' kiwifruit responses to ethylene in controlled atmosphere and storage performance in modified atmosphere packaging : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University, Palmerston North, New Zealand
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Date
2021
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Massey University
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Abstract
The relatively short storage life of some recently developed kiwifruit cultivars is the key limitation for sea freight. Modified atmosphere packaging (MAP) is a promising approach to maintain kiwifruit quality through the supply chain with high flexibility and relatively low cost, whereas there is a potential risk of ethylene accumulation in MAP that may accelerate kiwifruit softening. Meanwhile, controlled atmosphere (CA) can be used in research as a tool to investigate various atmospheric conditions. Hence, the objectives of this study were to investigate the influence of ethylene on kiwifruit quality in an optimal atmosphere, to evaluate the performance of kiwifruit in MAP during storage at low temperature and subsequent shelf-life at room temperature, and to decide whether an ethylene scavenger can reduce the damaging effects of ethylene in MAP. Kiwifruit (Actinidia chinensis var. deliciosa ‘Hayward’) were stored in a flow-through system of air and optimal CA (5% CO₂ + 2% O₂) at 0 °C 95% RH for 13 weeks, and ethylene at the concentration of <1, 10, 100, 1000 nL·L-¹ was added to the system after 3 weeks. The result has indicated that the responses of kiwifruit to ethylene were dose-dependent in both air and CA, but kiwifruit sensitivity to ethylene was lower in CA compared to that in air. Kiwifruit was packed in commercial sourced MAP film and stored at 1 °C for 5 weeks before being repacked into a retail pack and kept at 20 °C for 10 days. The equilibrium gas compositions of 3-4% CO₂ + 12-15% O₂ and 12-16% O₂ + 7-10% CO₂ were created at 1 °C and 20 °C, respectively. No detectable ethylene was observed in MAP with sound fruit, but up to 5600 nL·L-¹ ethylene was detected in MAP with rotten fruit. The quality assessment has shown that MAP retained kiwifruit firmness during coolstorage, but MAP at room temperature did not provide extra benefit. Applying potassium permanganate (KMnO₄) based ethylene scavenger sachet during the post-storage period did not improve kiwifruit quality. This study has indicated that ethylene impact on kiwifruit quality is relatively low during short term storage in MAP, but assessment on longer storage is required in the future to determine the effect of MAP on maintaining kiwifruit quality at the post-storage stage.
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Figures 2.1 & 2.2 are re-used with the publishers' permission.