Characterization of the Key Aroma Compounds in the Beverage Prepared from Darjeeling Black Tea:  Quantitative Differences between Tea Leaves and Infusion

Abstract

By application of the aroma extract dilution analysis on the volatile fraction isolated from a black tea infusion (Darjeeling Gold Selection), vanillin (vanilla-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel), 2-phenylethanol (flowery), and (E,E,Z)-2,4,6-nonatrienal (oat-flake-like) were identified with the highest flavor dilution (FD) factors among the 24 odor-active compounds detected in the FD factor range of 4-128. Quantitative measurements performed by means of stable isotope dilution assays and a calculation of odor activity values (OAVs; ratio of concentration to odor threshold in water) revealed, in particular, the previously unknown tea constituent (E,E,Z)-2,4,6-nonatrienal as a key odorant in the infusion and confirmed the important role of linalool and geraniol for the tea aroma. An aroma recombinate performed by the 18 odorants for which OAVs > 1 were determined in their "natural" concentrations matched the overall aroma of the tea beverage. In the black tea leaves, a total of 42 odorants were identified, most of which were identical with those in the beverage prepared thereof. However, quantitative measurements indicated that, in particular, geraniol, but also eight further odorants were significantly increased in the infusion as compared to their concentration in the leaves.

Investigation of product quality, sensory profile and ultrastructure of breads made from a range of commercial gluten-free flours compared to their wheat counterparts

“…The results of each attribute were calculated as arithmetic mean. The assessors were trained immediately prior to analysis with aqueous odorant solutions in defined concentrations (factor 100 above the odour threshold) [24][25][26]. The odorant solutions reflected the evaluated characteristic odour attributes of the flours: buttery (butane-2,3-dione, 120 lg/L), cooked potato-like (3-(methylthio-) propanal, 140 lg/L), malty (3-methylbutanal, 120 lg/L), mouldy (geosmin, 2.1 lg/L), oat flakes-like [(E,E,Z)-nona-2, 4,6-trienal, 2,6 lg/L], pea-like (3-isobutyl-2-methoxypyrazine, 3.9 lg/L), popcorn-like, roasty (2-acetyl-1-pyrroline, 12 lg/L), vinegar-like (acetic acid, 18,000,000 lg/L), vomitlike and cheesy (butanoic acid, 120,000 lg/L).…”

Aroma changes of black tea prepared from methyl jasmonate treated tea plants

“…1). It was reported that β-linalool and geraniol play important roles in the formation of black tea aroma (Schuh and Schieberle, 2006). β-Linalool and its corresponding oxides contribute vitally to the formation of the sweet aroma of black tea, whereas geraniol has an effect on the formation of the floral aroma of black tea.…”

Identification of the Key Odorants in Tahitian Cured Vanilla Beans (Vanilla tahitensis) by GC-MS and an Aroma Extract Dilution Analysis

“…Part of the aroma concentrates could not be fully recovered during the distillation process, so we tried to quantify the amount by using the above-mentioned method. It is of interest from the results of this study that -damascenone, which is a well-known key odorant in rose, 12) wine 13) and black tea 14) was identified for the first time in Tahitian vanilla beans. 3-Methylnonane-2,4-dione was identified for the first time in vanilla beans, and phenylacetic acid was also identified for the first time in Tahitian vanilla beans.…”