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citrus_paradisi [2018/04/22 14:25]
andreas
citrus_paradisi [2018/08/02 10:54] (aktuell)
andreas
Zeile 17: Zeile 17:
 "​Twenty-five odor-active compounds were quantified in the fresh, hand-squeezed juice of White Marsh seedless grapefruits using stable isotope dilution assays. By calculation of the odor activity values of the odorants (ratio of their concentrations in the juice to their odor thresholds in water) it was shown that the fruity esters ethyl 2-methylpropanoate,​ ethyl butanoate, and (S)-ethyl 2-methylbutanoate,​ and the fruity, sweet winelactone,​ as well as the grassy smelling (Z)-hex-3-enal,​ and trans-4,​5-epoxy-(E)-dec-2-enal with metallic odor, were among the most potent odorants of the fresh grapefruit juice. The typical sulfurous, grapefruit-like odor quality was mainly due to the catty, blackcurrant-like 4-mercapto-4-methylpentan-2-one and the grapefruit-like smelling 1-p-menthene-8-thiol. These findings were confirmed by reconstitution experiments to simulate the aroma of the fresh grapefruit juice." ​ \\ "​Twenty-five odor-active compounds were quantified in the fresh, hand-squeezed juice of White Marsh seedless grapefruits using stable isotope dilution assays. By calculation of the odor activity values of the odorants (ratio of their concentrations in the juice to their odor thresholds in water) it was shown that the fruity esters ethyl 2-methylpropanoate,​ ethyl butanoate, and (S)-ethyl 2-methylbutanoate,​ and the fruity, sweet winelactone,​ as well as the grassy smelling (Z)-hex-3-enal,​ and trans-4,​5-epoxy-(E)-dec-2-enal with metallic odor, were among the most potent odorants of the fresh grapefruit juice. The typical sulfurous, grapefruit-like odor quality was mainly due to the catty, blackcurrant-like 4-mercapto-4-methylpentan-2-one and the grapefruit-like smelling 1-p-menthene-8-thiol. These findings were confirmed by reconstitution experiments to simulate the aroma of the fresh grapefruit juice." ​ \\
 [Evaluation of key aroma compounds in hand-squeezed grapefruit juice (Citrus paradisi Macfayden) by quantitation and flavor reconstitution experiments.,​ Buettner, A., Schieberle, P., Journal of Agricultural and Food Chemistry, 49(3), 2001, 1358-1363] [Evaluation of key aroma compounds in hand-squeezed grapefruit juice (Citrus paradisi Macfayden) by quantitation and flavor reconstitution experiments.,​ Buettner, A., Schieberle, P., Journal of Agricultural and Food Chemistry, 49(3), 2001, 1358-1363]
 +
 +"It is important to note in the grapefruit example that the naturally occuring (+)-nootkatone has a threshold of 1ppb, whreas the (-)-enantiomer has a threshold of 1ppm. Hence, any addition of racemic nootkatone can drastically reduce the odour character of a grapefruit oil." \\
 +[Swift, Karl AD, ed. Advances in flavours and fragrances: From the sensation to the synthesis. Royal Society of Chemistry, 2007, 80] 
  
 "The sesquiterpene ketone [[http://​en.wikipedia.org/​wiki/​Nootkatone|(+)-nootkatone]],​ which possesses a citrus-like character and a bitter taste, also occurs as a typical constituent in almost all peel oils [of citrus fruits, like lemon peel 0.06%, grapefruit peel 0.5-1.8%, but grapefruit juice oil 3.3% (!)]. Due to its low odor treshold of 800μg/l water, this bicyclic sesquiterpene contributes much to the overall character of an essential oil even at concentrations below 0.001% (10.000ppb). Its enantiomer (-)-nootkatone lacks both the citrus character and the low treshold... The characteristic fresh fruity top-note of grapefruit juice is mainly due to p-menth-1-ene-8-thiol,​ which is present only in concentrations below 1ppb. [This] Compound has an odor treshold of 0.1ng/l water, ... one of the lowest odor tresholds of all naturall aroma chemicals."​ \\ "The sesquiterpene ketone [[http://​en.wikipedia.org/​wiki/​Nootkatone|(+)-nootkatone]],​ which possesses a citrus-like character and a bitter taste, also occurs as a typical constituent in almost all peel oils [of citrus fruits, like lemon peel 0.06%, grapefruit peel 0.5-1.8%, but grapefruit juice oil 3.3% (!)]. Due to its low odor treshold of 800μg/l water, this bicyclic sesquiterpene contributes much to the overall character of an essential oil even at concentrations below 0.001% (10.000ppb). Its enantiomer (-)-nootkatone lacks both the citrus character and the low treshold... The characteristic fresh fruity top-note of grapefruit juice is mainly due to p-menth-1-ene-8-thiol,​ which is present only in concentrations below 1ppb. [This] Compound has an odor treshold of 0.1ng/l water, ... one of the lowest odor tresholds of all naturall aroma chemicals."​ \\
citrus_paradisi.txt · Zuletzt geändert: 2018/08/02 10:54 von andreas