Comparative Study of Graded Cocoa Bean Quality

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Cocoa product quality has been argued to be dependent on the bean size both from the marketers and some processors who attribute some processing difficulties to this observation, though some still disagree. This study was aimed to determine the yield and quality of fat as a basis for standardization of the gradation of cocoa bean. Specifically, the project sought to determine the butter characteristics of the graded beans with regards to fat yield and other biochemical properties. Five different categories of cocoa originating from the three take-over centres of Cocoa Marketing Company within the same crop year (2014/2015) were processed into liquor. The cocoa butter extracted from these categories were evaluated for their iodine value (IV), peroxide value (PV), saponification value (SV), unsaponification value, slip melting point value, free fatty acid (FFA), tempering cooling curves, refractive index, colour and yield fat levels. The outcome of the experiment was that cocoa bean quality was in decreasing order of; super main crop > main crop > super light crop > light crop > small beans in terms of many of the attributes that were studied. Yield-fat decreased respectively in this order 55.24%, 54.71%, 53.01%, 52.67% and 52.21% while FFA increased along the same order as 0.89%, 0.90%, 1.05%, 1.06% and 1.23%. Again the larger Q-factor values explains a good crystallization behavior for cocoa butter from the cooling curves evaluated in the Shukoff tempering studies presented similar order as 0.16, 0.14, 0.12, 0.11and 0.12. All the other parameters studied showed similar trends. The IV, PV, SV and unsaponification values were significantly (p<0.05) lower as compared to codex standards. Thus, it appears the marketers are indeed within their rights if cocoa beans are graded and marketed based on their sizes.
A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management.