Aroma sesquiterpenoids

In a later study, the aroma constituents of a Bavarian (Pilsener) beer brewed in Hallertau, near Munich, which possessed a desirable fine hop aroma, was examined [58]. Neither the terpenes and sesquiterpenes nor the methyl esters characterized in hop oil were detected but fraction IV (Table 13.6), which contained terpenoids and sesquiterpenoids, possessed an intensive pleasant hoppy odour. Noteworthy amongst the identified constituents are the cyclic ethers (80)-(86) first found in Japanese hops, the flowery notes of which contribute to hop aroma, and the sesquiterpenoids derived from humulene such as humulene epoxide I, humulene epoxide II, humulol, and humulenol II. Similar results were found with American beers [60, 86]. Humuladienone (79)... 

Together with the monoterpenoid terpineol, the sesquiterpenoid longifolene has been characterized as one of the main components of the aroma of Chinese black... 

Whereas sesquiterpenoid hydrocarbons, with few exceptions, have inferior characteristic organoleptic properties, the ethers of this series — as far as they are known — are distinguished by outstanding odor qualities. Once the general value of these compounds as aroma components is recognized, as it is the case with the monoterpenoid ethers, the importance of this group of compounds will rapidly grow. 

The peppery character of grapes and wines is attributed to the presence of the sesquiterpenoid (-)-rotundone, (3S, 5R,8S)-5-(isoprop-2-en-l-yl)-3,8-dimethyl-3,4,5,6,7,8-hexahydro-2fT-azulen-l-one (8-199). Rotundone has a very distinctive aroma and low sensory threshold concentrations (16 ng/1 in red wine and 8ng/l in water). This guaiane-like compound was first found in Syrah (Siraz), Mourvedre and Durif wines produced in Australia, at concentrations of up to 145 ng/1 and later in higher amounts... 

Fresh, dried or otherwise prepared parts of some plants have an intense, pleasant and characteristic odour and taste, and are therefore used as spices for food flavouring. The main constituents of the aroma of spices are various volatile mono- and sesquiterpenoids, in particular hydrocarbons, alcohols, aldehydes, ketones, esters and ethers (T able 8.32). The total content of essential oils is in the tenths to units of percent. Some spices also contain components with characteristic spicy, sharp and burning taste and important pigments. 

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