Studies of occurence of purple beans in cocoa produced in Ghana

Abstract

The study investigated the occurrence of high purple beans counts of cocoa produced in Ghana. The investigation consisted of a questionnaire survey of nineteen randomly selected districts in the six cocoa growing regions in Ghana and laboratory studies at the Cocoa Research Institute of Ghana. The studies were carried out from August 2005 to October 2006. Fennentation of cocoa beans for six or seven days did not guarantee the complete removal of anthocyanins and purpleness from the cocoa beans. It was observed that good quality dry cocoa beans had a Fennentation Index of one and above; 2.0mg/kg and below residual anthocyanins and pH of 5.4-5.5. Cocoa beans of partly brown/partly purple and pale purple colour were observed to have the same residual anthocyanins contents of the brown coloured cocoa beans considered to be of good quality. The residual anthocyanins contents of the fifteen cocoa cultivars after six days of fermentation varied considerably. Anthocyanins contents of the cultivars tested after six days fermentation, shows that only T85/799 x Amelonado and T60/887 x Amelonado contained 2.0mg/kg. However, cultivars with anthocyanins contents more than 2.0mg/kg reduced significantly below 2.0mg/kg after seven days fermentation except for T60/887 x IMC 60 and T60/887 x Be 8. The percentage purpleness of Criollo, Amelonado, Amazonia and all T85/799 crosses were found to be less than 20% while all the T60/887 crosses had purple beans of more than 20% except for T60/887 x IMC 60.