ABSTRACT
Roasted cocoa is one of the most aromatic foods, having a rather complex chemical constitution. Nearly 400 volatile compounds have been identified to date, including pyrazines, thiazoles, oxazoles, pyrrol derivatives, pyridines, and furans (Ziegleder and Biehl 1988; Bonvehí 2005). It is still very difficult to assess which compounds are really important and which are not. Key flavor compounds have been identified in milk and dark chocolates (Cerny and Grosch 1994; Cerny and Fay 1995; Schnermann and Schieberle 1997; Counet et al. 2002, 2004; Taylor 2002; Taylor and Roberts 2004; Reineccius 2006). Cocoa-and chocolate-specific flavor compounds have been detected in dark but not in milk chocolates (Counet et al. 2002; Afoakwa et al. 2008). Cocoa and chocolate flavor development is influenced by the genetic constitution of the seed (Theobroma cacao), postharvest processing (fermentation and drying), and manufacturing (Kirchhoff et al. 1989a; Clapperton 1994; Beckett 2003; Whitefield 2005; Afoakwa et al. 2008; Lima et al. 2011; Rodriguez-Campos et al. 2011, 2012; Owusu et al. 2012; Saltini et al. 2013). Characteristic cocoa and chocolate flavor notes are generated during the roasting process by Maillard or by nonenzymatic browning reactions that involve the reactions of free amino groups of amino acids or peptides and reducing sugars (Schnermann and Schieberle 1997). e typical cocoa flavor is formed during roasting of fermented but not of unfermented cocoa beans (Rohan 1964; Voigt and Biehl 1995). erefore, essential flavor precursors are generated during the fermentation process (Figure 5.1). During fermentation, sugars in the pulp are transformed to acetic and lactic acid by environmental microorganisms, causing acidification of the cocoa beans (Ostovar and Keeney 1973). is acidification, but not the presence of microorganisms, is required for the formation of the cocoa-specific flavor precursors as revealed by bean incubations under aseptic conditions (Biehl et al. 1985). erefore, raw cocoa quality is strongly dependent on the degree and time course of acidification of
5.5.2 Typical Flavor Components of Fine Cocoa and Chocolate 214
5.5.3 Future Prospects 214 References 216
the cotyledons during the fermentation process, as well on the duration of the fermentation process and the final pH (Voigt and Biehl 1995; Schwan and Wheals 2004; Afoakwa et al. 2008, 2011). Flavor potential is considerably reduced by overfermentation (Figure 5.1). Under these conditions, aerophilic bacteria metabolize amino acids and peptides, causing a steep increase of nib pH, liberation of volatile fatty acids, and the development of ham-like odor (Lopez and Quesnel 1973; Ziegleder and Biehl 1988).
