Improving southern Africa’s export of fruits

An inexpensive, renewable raw material, sorghum bran, from southern Africa' s indigenous sorghum cereal industry was be used to extract the protein kafirin, which is water insoluble, non-allergenic, and has good gas barrier and mechanical properties, i.e. kafirin makes excellent edible barrier coatings. Extraction and coating procedures were developed as well as a thermoplastic processing, sensory evaluation of coated fruits and peanuts and controlled release of preservatives from coatings to products, all through a multi-disciplinary approach in co-operation with the fruit export industry.

Some of the direct results are:

• coatings doubled the shelf life of exported pears and reduce hydrolytic rancidity in coated cashew nuts
• the coating is highly functional, yet hardly detectable by eye, and was found sensorically acceptable even by test panels from southern Africa used to fresh fruits and nuts
• the coatings actively reduce microbial spoilage
• transparent protein films as well as coated paper for packaging and bags could be produced by commercial film blowing and extrusion techniques