Effect of pulp preconditioning on acidification, proteolysis, sugars and free fatty acids concentration during fermentation of cocoa (Theobroma cacao) beans EMMANUEL OHENE AFOAKWA 1 , JENNIFER QUAO 1 , AGNES SIMPSON BUDU 1 , JEMMY TAKRAMA 2 , & FIRIBU KWESI SAALIA 1 1 Department of Nutrition and Food Science, University of Ghana, P.O. Box LG 134, Legon-Accra, Ghana, and 2 Cocoa Research Institute of Ghana, P.O.Box 8, New Tafo-Akim, Eastern Region, Ghana ( Received 10 March 2011; revised 11 April 2011; accepted 12 April 2011 ) Abstract Changes in acidification, proteolysis, sugars and free fatty acids (FFAs) concentrations of Ghanaian cocoa beans as affected by pulp preconditioning (pod storage or PS) and fermentation were investigated. Non-volatile acidity, pH, proteolysis, sugars (total, reducing and non-reducing) and FFAs concentrations were analysed using standard methods. Increasing PS consistently decreased the non-volatile acidity with concomitant increase in pH during fermentation of the beans. Fermentation decreased the pH of the unstored beans from 6.7 to 4.9 within the first 4 days and then increased slightly again to 5.3 by the sixth day. Protein, total sugars and non-reducing sugars decreased significantly ( p , 0.05) during fermentation, whereas reducing sugars and FFA increased. PS increased the FFA levels, reduced the protein content but did not have any effect on the sugars. The rate of total and non-reducing sugars degeneration with concomitant generation of reducing sugars in the cocoa beans was largely affected by fermentation than by PS. Keywords: Theobroma cacao, Forastero, pod storage, pulp preconditioning, fermentation, acidification Introduction The quality and flavour of cocoa beans depend on complex chemical and biochemical changes which occur in the beans during fermentation and drying. Currently, three broad cultivars of cocoa are com- monly recognized and grown for commercial pur- poses: Forastero, Criollo and Trinitario. These cultivars exhibit differences in the appearance of pods, yields of beans, resistance to pests and disease, acidification/ souring concentrations as well as flavour character- istics and intensity (Wood and Lass 1985; Asiedu 1989; Afoakwa et al. 2007, 2008; Afoakwa 2010). During fermentation, microorganisms grow in the pulp and produce a diversity of metabolites, along with substantial heat. The metabolites and heat diffuse into the cocoa seeds, killing them and disrupting their cellular integrity (Biehl et al. 1990; Voigt et al. 1994a). Cellular disruption and seed death initiate various enzymatic and non-enzymatic reactions between seed components. These reactions develop a range of flavour precursors (peptides, amino acids, reducing sugars and polyphenols) and also affect the colour of the beans (Schwan et al. 1995; Adeyeye et al. 2010). During roasting, these precursors undergo further transformations to form the final chocolate flavour compounds (Lopez and Dimick 1991; Beckett 2008). Bean death is a critical event during cocoa fermentation which allows the biochemical reactions responsible for flavour development to occur within the cocoa bean. The disruption of their cellular integrity and subsequent death of the bean lead to the ISSN 0963-7486 print/ISSN 1465-3478 online q 2011 Informa UK, Ltd. DOI: 10.3109/09637486.2011.581224 Correspondence: E. O. Afoakwa, Department of Nutrition and Food Science, University of Ghana, P.O. BoxLG 134, Legon-Accra, Ghana. Tel: þ 233 (0) 244 685893. Fax: þ 233-302500381. E-mail: e_afoakwa@yahoo.com; eafoakwa@ug.edu.gh International Journal of Food Sciences and Nutrition, November 2011; 62(7): 755–764 Int J Food Sci Nutr Downloaded from informahealthcare.com by University of Gent on 01/17/12 For personal use only.