Many of the technical problems appeared inter-related and programmes were initiated into researching these areas. During processing kiwifruit loses its green colour and changes to a dull, olive-brown coloration. DSIR developed a successful approach to the maintenance of green colour in dehydrated kiwifruit and this is currently the matter of a patent application. However, the creation of a green, heat-treated kiwifruit juice evades solution. Pasteurisation or sterilisation of this recombined juice results in conversion of chlorophyll to olive-brown pheophytin and other brown chlorophyll derivatives, as there is still no protection offered to the exposed chlorophyll.
Initial results are extremely encouraging.
Five synthetic model concentrates were studied in order to explore the contributions of different nonenzymic browning reactions to colour changes in stored kiwifruit concentrate. Reactions involving ascorbic acid were found to contribute more to overall browning than did Maillard browning. Kiwifruit juice concentrate produced under conditions of reduced oxidation leads to less conversion of ascorbic acid to dehydroascorbic acid and other reaction products which are capable of further reactions forming brown pigments. Flavour Changes Aroma. The natural flavour of fresh, ripe kiwifruit is very complex and subtle.