Researchers have investigated some chemical and physical treatments of fruit, as a cheaper way of extending storage life. The main methods investigated so far are
Chemical coating of fruit. There is commercial interest in the use of chemical fruit coatings, such as Prolong and Semperfresh, to delay ripening. These formulations are based on sucrose esters and carboxymethyl cellulose, and they are water dispersable. They provide a microfilm coating on the fruit surface. This film has no effect on water movement, but it may restrict the rate of gas movement through the skin of the fruit, slowing down respiration.
Studies have shown that Prolong and Semperfresh delay the ripening of plantains by 8-10 days at 30 °C and low humidity. Hence, chemical coatings have potential use where temperature and humidity cannot be controlled.
However, fruit coating has not been accepted in the banana trade, mainly because of high costs. Also, the subsequent ripening of the coated fruit is unpredictable, and uneven.
Treatment with gibberellic acid. Dipping of fruit into gibberellic acid was shown to delay ripening of bananas at high humidity, but not at low humidity. This method has not been adopted commercially.
Radiation. Studies in the USA and India have reported that storage life can be extended by irradiating bananas after harvest. Doses of 200-400 Gy increased storage life by 4-8 days at 24-28 °C. However, some types of plantain might be damaged by these doses. Also, the technology is not widely available, and is expensive; and despite acceptance by the USA Food Council, radiation is still unacceptable to consumers in many countries because of negative associations.
|Objectives, Study materials, Practicals|
|1||Storing plantain and banana|
|2||Improving storage life|
|3||Temperature, humidity and ventilation|
|5||Treatment of fruit|
|6||Improving postharvest handling|
|8||Suggestions for trainers|