Chocolate aroma

A more complex flavor development occurs in the production of chocolate. The chocolate beans are first fermented to develop fewer complex flavor precursors upon roasting, these give the chocolate aroma. The beans from unfermented cocoa do not develop the chocolate notes (84—88) (see Chocolate and cocoa). The flavor development process with vanilla beans also allows for the formation of flavor precursors. The green vanilla beans, which have Htfle aroma or flavor, are scalded, removed, and allowed to perspire, which lowers the moisture content and retards the enzymatic activity. This process results in the formation of the vanilla aroma and flavor, and the dark-colored beans that after drying are the product of commerce. 

The results of this survey of the aromas produced over time by heating glucose—amino acid mixtures at a series of temperatures in the range 100-220° proved of great interest. Many mixtures were heated in the "dry" statB for the first time. Some produced the expected result, for example, methionine and phenylalanine led to potato and to floral aromas, respectively. Others were unexpected, for example, the large number of amino acids that was capable of producing chocolate aroma under one or other set of conditions. 

Rohan had suggested that the operative reaction in the development of chocolate aroma might be a Strecker degradation of the amino acid fraction. Bailey et al. (8) demonstrated quantitatively that three aldehydes, which could be related to leucine, valine, and alanine, were prominent in the volatiles from a typical sample of roasted, ground cacao beans. 

There is no evidence that any of the manufacturers of cocoa and chocolate have adapted any part of the Maillard technology to their manufacturing processes. There are at least two reasons for this. First, the standard processes, as applied to beans of good quality, produce excellent products. Second, while the work just reviewed has given us a rather clear outline as to how chocolate aroma is developed in the roasting of fermented beans, the research work has not yet been done, or reported, that would serve as a basis for improving the industrial processing of cacao beans. 

One o-f the world s most popular -flavors, chocolate, is a product o-f both -fermentation and roasting. Early studies by Rohan (44-47) pointed out the importance o-f liberating the precusor materials (amino acid) so that roasting will generate chocolate aroma. 

Some 350 other volatiles have been identified in chocolate aroma, and about 10% are pyrazines (48— 51) and quinoxalines (52). During roasting 49% of the total free amino acids are lost with only 4% of the bound amino acid being lost (53). 

Besides their general flavor forming potential peptides are also reported to be unique precursors of composite food aromas. Peptides formed in the fermentative stage of cacao processing have been linked to roast generated chocolate aroma (5). Also, a methionine rich polypeptide has been associated vith roasted peanut volatiles (15). 

Destruction of Amino Acids and Peducing Sugars on Heating Chocolate Aroma Precursor Extract... 

To illustrate this definition, one can think about a piece of chocolate with the rising perception of an aroma (say coffee aroma) after several seconds. It is possible that the coffee aroma is not as strong as the chocolate aroma, but coffee aroma is still perceived as dominant because this is the sensory sensation that triggers most of your attention. 

Rohan TA, Connell M (1964) The precursors of chocolate aroma a study of the flavanoids and phenolic acids. J Food Sci 29 460-463... 

The main (key) components of chocolate aroma are Cj carboxylic acids with a sweet smell (2-methylbutyric), lactones (y-lactone with a sweet, peachy aroma), aldehydes (such as isovaleraldehyde with a sharp odour resembling malt), ( )-non-2-enal (with green and tallowy smell), (2 ,4 )-nona-2,4-dienal and (2 ,4 )-deca-2,4-dienal (with oily smell resembling fried foods), ketones, such as oct-l-en-3-one (with the mushroom-like smell), (2 ,5S)- and (2 ,5 )-5-methyl-hept-2-en-4-one (known as filbertone, which has the odour of hazelnuts, 8-204), 2-ethyl-3,5-dimethylpyrazine (with a smell reminiscent of fried potato chips), 2-ethyl-3,6-dimethylpyrazine (with the smell of nuts with earthy tones) and methyl 2-methyl-3-furyl disulfide with meaty and sulfur smell. 

Roozen, J.R and Legger-Huysman, A. 1994. Sensory analysis and oral vapour gas chromatography of chocolate flakes. In Aroma. Perception, Formation, Evaluation (M. Rothe and H.-P. Kruse, eds) pp.627-632. Eigenverlag Deutsches Institut fur Ernaehrungsforschung, Potsdam-Rehbruecke. 

Many bland, or even downright unpleasant-tasting, substances are transformed into some of the most desirable flavors and popular foods by roasting. Thus, those foods, representing such different tastes and aromas as chocolate, bread, roast beef, coffee, and toasted nuts have in common the fact that they are products of the Maillard browning... 

Being volatile, the aldehydes formed in the Strecker degradation have often been thought to be important contributors to the aroma of foodstuffs and many patents have been granted which use the Strecker degradation to produce flavouring materials of various types, such as, maple, chocolate, coffee, tea, honey, mushroom, and bread.66... 

Moisture content of the reaction mixture Influenced the degradation of amino acids. Rohan and Stewart (52) reported that chocolate precursor aroma extracts when heated in the dry state for one hour at 100°C., lost 30% of the amino acids by degradation. When very lightly moistened the amino acids degradation dropped to 9% under the same reaction conditions. 

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