Coffee aroma, AEDA

The results obtained for freshly roasted Arabica coffee are illustrated in Fig. 5 (17). From more than 1000 volatiles detected in the original aroma extract by FID, only about 60 odor-active regions were selected by GC-O. AEDA revealed 38 odorants with FD factors of 16 or higher. Odorants 5, 14, 19, 26, 30, and 32 have been newly identified in coffee aroma. Their identification stemmed from the high FD factors. They would most likely have been overlooked without using GC-O as a screening method for odor-active compounds. Odorants with FD factors of 128 or higher are shown in Fig. 6. 

The analysis of coffee aroma is an excellent example of the potential of static headspace GC-O (19). Compared to AEDA (17), compounds 1-4 and 7 were additionally detected (Table 1). The sensory contribution of odorants was different from that obtained by AEDA. In general, very volatile compounds were... 

In the case of boiled beef the results of AEDA were compared with those of AECA. Table 16.4 indicates that they agreed except in three cases. The odour potencies of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-mercapto-2-pentanone and methional were more than one dilution step higher in AECA than in AEDA [56]. Most likely, portions of these odorants had been lost during concentration of the extract for AEDA. AECA was also used in studies on the aroma of pepper [55], coffee [57] and Camembert cheese [58]. 

The composition of the aroma of coffee is extremely complex with more than 900 compounds determined146,147 (see Chapter 3.25). The aroma of tea is greatly influenced by the degree of fermentation (green tea148 and black tea149 to mention a representative example) (see Chapter 3.23). Research of cacao mass volatiles using AEDA was also conducted (Table 16).150... 

The aroma is changed when a brew is prepared from ground coffee. Caramel-like, buttery and phenolic notes become more intense. AEDA shows that this change in the aroma profile is caused by a shift in the concentrations [102]. As detailed in Table 6.52, the polar odorants are preferentially extracted by hot water leading to yields higher than 80% for S-compounds nos. 1 and 4, furanones nos. 13 and 14, vanillin (no. 20) and pentanedione (no. 28). On the other hand, the yield of the character impact odorant of ground coffee, 2-furfurylthiol, is with 19% relatively low. 

From a qualitative point of view, the main GC-0 methods seem to be equivalent for determining the impact odorants of a product, with the exception that some peaks can be missed when using only one or two panelists (Fig. 1). The aroma impact compounds of coffee brew found by GC- SNIF (29) were in agreement with those found by AEDA (41). Le Guen et al. compared OSME, AEDA, and GC- SNIF results to determine the most potent odorants of cooked mussels (32). They concluded that the three methods were well correlated. They also observed that GC- SNIE was twice as fast as AEDA and OSME. ... 

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