The main objectives are as follows :
* To produce strains of Kluyveromyces marxianus that over-express the endopolygalacturonase (endo-PG) gene.
* To study and optimise cocoa fermentations using these strains.
* To produce the enzyme endo-PG from these strains.
* To study and optimise processing qualities of indigenous Latin American fruits using the endo-PG enzyme.
* To isolate yeasts from indigenous fruits with superior enzyme and fermentation characteristics.
The work carried out should enable existing cocoa fermentations to be optimised which will lead to the production of chocolate of more reliable and improved quality. Some under-exploited Latin American fruits will be developed and be brought to market initially as fruit juices. An enhanced range of microbiological strains will be both created and characterised for use in these and other fruit fermentation industries. A new and independent source of pectinase will be developed for food use on Latin American fruits.
The key activities envisaged are :
* Create endo-PG overproducer strains of K. marxianus by conventional means. Use these yeast strains to produce stable, dried yeast for use in cocoa fermentations on the farm. Clone and sequence the endo-PG gene and then overproduce the enzyme using genetic modification techniques for large-scale production purposes.
* Use both wet and dried modified yeast strains to study altered cocoa fermentations both in laboratory-scale experimental fermenters and in small-scale field trials and determine the physiological parameters to optimise the fermentation.
* Develop a production protocol that integrates, in one step, fermentation and purification using the genetically modified K. marxianus yeast strains for bulk enzyme production. Scale-up to produce food-grade, partially purified and concentrated endo-PG.
* Analyse the biochemical and organoleptic characteristics of eighteen indigenous Latin American fruits. Choose those with pectinaceous pulp and other desirable characteristics and determine their suitability for producing fruit juice (which will be tested in local consumer trials) as well as juice concentrate and fruit nectars.
* Investigate these fruits for their suitability for producing a fermented alcoholic beverage using natural microflora which will be isolated from these fruits and characterised.
Funding SchemeCSC - Cost-sharing contracts
40 Rionegro - Antioquia
37200 000 Lavras