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Abstract
Differences were found in the extent of freeze injury among ‘Fuerte’, ‘Hass’ and ‘Nabal’ avocados (Persea americana Mill.). Large ‘Fuerte’ fruit suffered more than small ones. Relatively high rates of ethylene production and of respiration were found in heavily injured fruit as soon as 1 day after harvest. Keeping quality of freeze-damaged fruit was reduced. It is concluded that the major processes involved in ripening, such as softening, respiration, ethylene production, and the activity of pectic enzymes, are enhanced in freeze-injured fruit.
Abstract
‘Fuerte’ avocado fruits at all development stages show a similar climacteric pattern; however, with development, the postharvest pre-climacteric becomes progressively shorter. The respiration rate of seeds is higher in young than in mature fruits when determined separately from that of the whole fruit. It is concluded that the contribution of seed respiration to whole fruit respiration decreases with development over the growth season.
Abstract
Continuous ethylene treatment (100 ppm) of avocado fruit stored at 6°C, for 13 days, caused acceleration in respiration rate for the duration of the treatment. At the end of the low temperature treatment and, also, after transfer of the fruit to 20°C, polygalacturonase activity and softening of the fruit were enhanced by ethylene treatment in comparisons with non-treated fruit. Endogenous ethylene production of ethylene-treated fruit was suppressed markedly after transfer to 20°C. Fruit treated 24 hours with ethylene at 6°C at the beginning of the storage period, ripened similarly to untreated control fruits.
For avocado we suggest that in cold storage (6°C) the presence of ethylene should be avoided so that the shelf-life period of the fruit will not be reduced.
Abstract
The response of fruits of avocado (Persea americana Mill.) to various temperatures was found to differ in the range 0° to 25°C. This temperature range was divided into 3 groups: 1) between 10° and 25°, the fruit softened at a rate which increases with increasing temperature; 2) between 5° and 8°C, fruit softening was inhibited and the fruit softened only after transfer to a higher temperature; and 3) between 0° and 4° storage life without the occurrence of chilling injury was limited.
Abstract
Response of ‘Ettinger’, ‘Fuerte’, and ‘Nabal’ avocados (Persea avocado Mill.) to 0, 2, 4 and 6°C at various stages of ripeness was tested. No damage appeared during cold storage and shelf-life when firm avocado fruit was stored at 0, 2, 4 and 6° for 1, 2, 3, 4 and 6 weeks, respectively. Fruit placed in cold storage when semi-firm or soft was more tolerant to low temperature than firm fruit There was no relation between the duration of cold storage at 0, 2, 4° and subsequent length of self-life at 14°; on the other hand, the longer the storage at 6°, the shorter the shelf-life. Chilling injury, although initiated during cold storage, did not become apparent until during the post-storage shelf-life period. ‘Nabal’ was more tolerant to low temperature than ‘Ettinger’ and ‘Fuerte’.