Fermented Cocoa Beans

With the death of the bean, cellular structure is lost, allowing the mixing of water-soluble components that normally would not come into contact with each other. The complex chemistry that occurs during fermentation is not fully understood, but certain cocoa enzymes such as glycosidase, protease, and polyphenol oxidase are active. In general, proteins are hydrolyzed to smaller proteins and amino acids, complex glycosides are split, polyphenols are partially transformed, sugars are hydrolyzed, volatile acids are formed, and purine alkaloids diffuse into the bean shell. The chemical composition of both unfermented and fermented cocoa beans is compared in Table 1. 

KI Tomlins, DM Baker, IJ McDowell. HPLC method for the analysis of organic acids, sugars, and alcohol in extracts of fermenting cocoa beans. Chromatographia 29(11/12) 557-561, 1990. 

Cleaning and sizing of the fermented cocoa bean with a water content of 6-8% are the first step. Any extraneous matter and broken beans are removed and selected sizing of whole beans is performed by specialized equipment. Sizing of the beans is important in order to later achieve uniform roasting. 

De Vuyst L, Camu N, De Winter T, Vandemeulebioecke K, Van de Perre V, Vancanneyt M, De Vos P, Cleenwerck I. Validation of the (GTG)j-rep-PCR fingerprinting technique for rapid classification and identification of acetic acid bacteria, with a focus on isolates from Ghanaian fermented cocoa beans. Int J Food Mierobiol. 2008 125(l) 79-90. doi 10.1016/j.ijfoodmi-cro. 2007.02.030. 

Jinap Selamat M, Bakar J, Saari N (2002) Oxidation of polyphenols in unfermented and partly fermented cocoa beans by cocoa polyphenol oxidase and tyrosinase. J Sci Food Agric 82 559-566... 

Biehl B, Brunner E, Passem D, Quesnel VC, Adomako D (1985) Acidification, proteolysis and flavour potential in fermenting cocoa beans. J Sci Food Agric 36 583-598... 

AT-phenylpropenoyl amino acids (2-17) have been identified as the key contributors to the astringent taste of non-fermented cocoa beans and cocoa products. Besides the already known (E) -N- [ 3, 4 -dihydroxycinnamoyl-3-hydroxy-L-tyrosine (known as clovamide), (E)-Ar-(4Chydroxycinnamoyl)-L-tyrosine (deoxy-clovamide) and (E)-AT-(3, 4 -dihydroxycinnamoyl)-L-tyrosine, seven additional amides derived from cinnamic, 4-coumaric, caffeic and feruHc acids, namely, (- -)-(E)-N-(cinnamoyl)-L-aspartic acid, (-f)-( )-N-(4 -hydroxycinnamoyl)-L-aspartic add, (- -)-( )-iV-(3, 4 -dihydroxydnnamoyl)-L-aspartic add, (-l-)-(E)-N-(4 -hydroxy-3 methoxydnnamoyl)-L-aspartic acid, (-)-( )- /-(4 -hydroxydnnamoyl)-L-glutamic add, (-)-( )-N-(3, 4 -di-hydroxycinnamoyl)-L-glutamic add and (-)-( )-N-(4 -hydr-oxycinnamoyl)-3-hydroxy-L-tyrosine, were recently identified. 

Fig. 3.1 Cocoa bean box fermentation is a commonly used method for fermentation of the cocoa pulp-bean mass. A cascade of three boxes of about 1 m each is an optimal setup for this fermentation process. In a box fermentation process, fermentation of the cocoa pulp-bean mass starts in the upper box every 24 h, the fermenting cocoa pulp-bean mass is transferred to a lower box. At the end of the fermentation process, the fermented cocoa beans are collected...

Daniel et al. 2009 Papalexandratou and De Vuyst 2011 Papalexandratou et al. 201 Ic, 2013 Pereira et al. 2012 Crafack et al. 2013). As the variation of yeast species is much larger than that of bacterial species, the presence of the former may have profound effects on the fermentation efficiency and fermented cocoa bean quality, either directly or indirectly (Meersman et al. 2013). 

K. marxianus, as pectinase producer, and the naturally vigorous yeast, 5. cerevisiae, as ethanol producer, might he a better yeast choice for future defined inocula. Moreover, inoculation of fresh cocoa pulp-hean mass with a K. marxianus hybrid yeast strain with increased pectinolytic activity has shown that it affects the microbial community structure during fermentation, increases by one third the volume of sweatings (and hence naturally increasing aeration), stimulates faster and improved cocoa bean protein degradation, results in reduced cocoa bean cotyledon acidity, and hence positively influences the fermented cocoa bean quality as well as the sensory quality of the chocolates produced thereof (Leal et al. 2008). The enhanced pectinolytic activity of K. marxianus has been confirmed during cocoa bean tray fermentation processes inoculated with a culture of this yeast species (Crafack et al. 2013). 

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