Analytical study of cocoa beans and characterization of chocolates of different cocoa hybrids during the spontaneous and inoculated fermentation processes

Abstract

Cocoa beans from different genetic materials present different fermentation dynamics, consequently an unstable chocolate quality. The cocoa fermentation process is spontaneous and uncontrolled, thus, the use of starter cultures may influence the standardization and flavor of final product. The aim of this study was to investigate the volatile compounds and protein profile (semi-qualitative) during the fermentation of four cocoa hybrids (CEPEC2004, PH15, PS1319 and SJ02) grown in southern Bahia, and sensory characterization of the chocolates produced from these clonal varieties. A second aspect evaluated was the use of Saccharomyces cerevisiae and Pichia kluyveri as starter cultures on fermentation of two cocoa hybrids (CEPEC2002 and FA13). According to results, different volatile compounds were identified in fermented beans and chocolates samples. The most relevant volatile compounds groups identified were: acids, alcohols, aldehydes, ketones and esters. Chocolate from CEPEC2004 was the most accepted by judges and correlated with sweet and bitter taste, this result can explained by the presence of desired compounds, such as 2,3-butanediol and 2-Methyl-1-butanol in chocolate samples from this hybrid. A higher presence of acids, considered as undesirable compounds, such as valeric acid, was observed in chocolates samples from PS1319 hybrid, which may have generated the low acceptance by judges. MALDI-TOF analysis showed that during fermentation the protein profile was different among the hybrids. A total of 80 volatile compounds were identified by HS-SPME GC-MS in the fermentation and chocolate samples during spontaneous and inoculated processes of the CEPEC2002 and FA13 hybrids. Chocolate FA13 inoculated with S. cerevisiae contained all the acids identified, and was considered more sour than chocolate produced from FA13 spontaneous fermentation. CEPEC2002 inoculated with S. cerevisiae in co-culture with P. Kluyveri generated a chocolate less sour and sweeter chocolate than spontaneous fermentation. Both chocolates from inoculated assays were more accepted by judges. MALDI-TOF analysis proved that protein profiles changed during fermentation and also were influenced by the inoculation process. In future studies, the identification of the different peptides will help unraveling which peptides and free amino acids contribute for formation of cocoa-specific flavor.