Hexen odor threshold value

Ce compounds. All Rojal wines displayed higher concentration of Cn alcohols, principally 1-hexanol. C6 compounds, which supvply "vegetal" and "herbaceous" nuances to the wine, usually have a negative effect on wine quality when their concentration is above their odor threshold values (Ferreira et al., 1995). However, 1-hexanol and (Z)-3-hexen-l-ol were found... 

The rapid deterioration of food containing linolenic acid should not be ascribed solely to the preferential oxidation of this acid but also to the low odor threshold values of the carbonyl compounds formed, such as (Z)-3-hexenal, (E,Z)-2,6-nonadienal and (Z)-l,5-octadien-3-one (Table 3.32). Aldehydes with exceptionally strong aromas can be released in food by the autoxidation of some fatty acids, even if they are present in low amounts. An example is octadeca-(Z,Z)-11, 15-dienoic acid (the precursor for... 

Analysis of the vacuum volatile constituents of fresh tomatoes was carried out using capillary GLC-MS and packed column GLC separation with Infrared, NMR and CI-MS analysis. Evidence was obtained for the presence of the unusual components 3-damascenone, 1-nltro-2--phenylethane, 1-nltro-3-methylbutane, 3-cyclocltral and epoxy-3-1onone. A method for the quantitative analysis of the volatile aroma components In fresh tomato has been Improved and applied to fresh tomato samples. The quantitative data obtained have been combined with odor threshold data to calculate odor unit values (ratio of concentration / threshold) for 30 major tomato components. These calculations Indicate that the major contributors to fresh tomato aroma Include (Z)-3-hexenal, 3-lonone, hexanal, 3-damascenone, 1-penten-3-one, 3-methylbutanal, (E)-2-hexenal, 2-lso-butylthlazole, 1-nltrophenylethane and (E)-2-heptenal. 

Except for the pair (E/Z)-6-nonenal, the odor threshold of the E-isomer exceeds that of the corresponding Z-isomer. In particular, the values for (E)- and (Z)-3-hexenal differ greatly. Some of the aldehydes listed in Table 5.44 and 5.45 are formed by the peroxidation of unsaturated fatty acids (cf. 3.7.2.1.9). However, they play a role in aromas only when they are produced in foods in a concentration higher than their odor threshold concentration. The aroma active aldehydes usually include hexanal, which appears as the main product in the volatile fraction of peroxidized linoleic acid and, therefore, can surmount the relatively high odor threshold (Table 5.44). (E)-2-Nonenal also belongs to this... 

The fruity note in the aroma profile of both varieties is produced by acetic acid esters. On the other hand, there is a decrease in the ethyl esters, which are more odor active than the acetates (cf. 5.3.2.2) and dominate in some other fruits, e. g., oranges and olives. Hexanal, (Z)-3-hexenal and (Z)-3-nonenal are responsible for the green/apple-like note. (E)-P-Damascenone, which smells of cooked apples, has the highest aroma value in both varieties due to its much lower odor threshold. Eugenol and (E)-anethol contribute to the aniseed-like note which is a characteristic especially of the aroma of the peel of the Cox Orange. 

---