The ENVIROPAK project improves southern Africa's export of fruits and nuts through the improvement of product quality and extension of shelf-life by application of edible coatings with suitable barrier properties. The coatings are manufactured from the waste products of sorghum processing.
In a joint effort of European scientists and research groups in southern Africa, world-class expertise in the science and technology of edible, biodegradable, plant-based protein coatings and films has been developed. The project has developed extraction and coating procedures and modifications of the protein, thermoplastic processing, sensory evaluation of coated fruits and cashew nuts and controlled release of preservatives from coatings to products, all through a multi-disciplinary approach in co-operation with the fruit export industry.
The protein kafirin was extracted on a laboratory scale from a variety of bran fractions from different sorghum varieties and the resulting kafirin in grades from transparent to yellow and red, was characterized regarding chemical and film forming properties. The extraction was scaled up to pilot scale producing batches of pure kafirin. Various coating formulations of kafirin, pure and modified, and additives were developed to suit the requirements of selected food models, pears, litchi and cashew nuts. The formulation development was based on a complete characterization of the fruit respiration, nut oxidation and the barrier and mechanical properties of kafirin films. Packaging films produced by thermoplastic processing were developed in parallel and it’s properties characterized. The coated fruits and nuts were studied regarding shelf-life as well as consumer acceptance and were finally studied under export conditions.
Kafirin coatings and films have during the project been proven to be very efficient in preserving the quality of fruits and nuts. Some of the more direct results are:
- coatings double 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 can be produced by commercial film blowing and extrusion techniques
A well attended dissemination workshop for technology transfer from the project was held in Cape Town, South Africa, in November 2004. The attending fruit industry has shown an extensive interest in the results and continued application of the project results and commercialisation of the results continues in cooperation with industry.
The project was is a part of the European Commission programme INCO.
SIK - The Swedish Institute for Food and Biotechnology
IMCB-CNR Institute of Composite Materials Technology, Italy
IFR - Institute of Food Research, UK
CSIR - Division of Food, Biological and Chemical Technologies, South Africa
University of Pretoria, South Africa
University Eduardo Mondlane, Mozambique
University of Mauritius