The ripening of bananas is a process that needs to take place in accurately controlled conditions to ensure synchronization of all the metabolic processes that are involved with ripening so that the best quality product can be made available to the consumer. Optimal ripening requires the correct ambient room temperature and relative humidity, adequate ventilation and ethylene treatment. Banana ripening occurs at temperatures between 16º-18ºC, with 95% humidity and constant ventilation. Ripening is triggered when the bananas are exposed to ethylene for 24 hours. Fruit that ripens in ideal circumstances has a bright yellow colour, firm soft pulp and strong peel, are sweet tasting and have a pungent aroma. The conditions in the store and ripening rooms, especially temperature, are not always regulated to the optimum and subtropical fruits such as bananas are injured at temperatures below 12ºC. Phase transitions in the membranes, from a liquid-crystalline to a solid gel-like phase, are responsible for chilling injury. Chilling injury delays ripening, but does not noticeably influence the eating quality of the fruit. The bananas are still sweet with a firm soft pulp and strong peel. The aroma production is however reduced by the cold and undesirable colour changes occur. The chilling injured bananas are dull greyyellow in colour with brown or black spots on the peel. The peel sometimes becomes completely brown or black. The quality of the bananas is potentially influenced by this colour change since the consumer judges the fruit on visual appearance. Controlled atmosphere storage and modified atmosphere packaging reduce chilling injury and extends the life of the fruit due to delayed ripening. Chilling injured fruit consequently has less brown or black spots and sometimes even an improved yellow colour. A better quality product can be supplied to the consumer and the temperature control in the storeroom does not need to be 100% accurate. The advantages of these techniques are attributed to the modified atmospheres, namely reduced oxygen and increased carbon dioxide concentrations which influence respiration, ethylene synthesis and action. / Prof. C.S. Whitehead
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:8238 |
| Date | 17 April 2008 |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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