Aroma octen

Uq 1.4378, may occur in the optically active form. It is found, for example, in lavender oil and is a steam-volatile component of mushrooms. l-Octen-3-ol is a liquid with an intense mushroom, forest-earthy odor that can be prepared by a Grignard reaction from vinylmagnesium bromide and hexanal. It is used in lavender compositions and in mushroom aromas. 

Important aroma compounds of black currant berries have been identified mainly by GC-O techniques by Latrasse et al. [119], Mikkelsen and Poll [115] and Varming et al. [7] and those of black currant nectar and juice by Iversen et al. [113]. The most important volatile compounds for black currant berry and juice aroma include esters such as 2-methylbutyl acetate, methyl butanoate, ethyl butanoate and ethyl hexanoate with fruity and sweet notes, nonanal, /I-damascenone and several monoterpenes (a-pinene, 1,8-cineole, linalool, ter-pinen-4-ol and a-terpineol) as well as aliphatic ketones (e.g. l-octen-3-one) and sulfur compounds such as 4-methoxy-2-methyl-butanethiol (Table 7.3, Figs. 7.3, 7.4, 7.6). 4-Methoxy-2-methylbutanethiol has a characteristic catty note and is very important to blackcurrant flavour [119]. 

Products of the LOX pathway or compounds formed by autoxidation of fatty acids (Scheme 7.2) are also important for leek aroma [31, 163]. Volatile compounds of the LOX pathway are not pronounced in the aroma profile of freshly cut leeks owing to a high content of thiosulfinates and thiopropanal-S-oxide [30]. In processed leeks that have been stored for a long time (frozen storage), however, these aliphatic aldehydes and alcohols have a greater impact on the aroma profile owing to volatilisation and transformations of sulfur compounds [31, 165]. The most important volatiles produced from fatty acids and perceived by GC-O of raw or cooked leeks are pentanal, hexanal, decanal and l-octen-3-ol (Table 7.5) [31, 35, 148, 163, 164]. 

Raw potato possesses little aroma. Approximately 50 compounds have been reported to contribute to raw potato aroma. Raw potatoes have a high content of LOX, which catalyses the oxidation of unsaturated fatty acids into volatile degradation products (Scheme 7.2) [187]. These reactions occur as the cells are disrupted, e.g. during peeling or cutting. Freshly cut, raw potatoes contain ( ,Z)-2,4-decadienal, ( ,Z)-2,6-nonadienal, ( )-2-octenal and hexanal, which are all products of LOX-initiated reactions of unsaturated fatty acids [188,189]. It is reported that two compounds represent typical potato aroma in raw potato methional and ( ,Z)-2,6-nonadienal [189]. Other important volatiles in raw potatoes produced via the LOX pathway are l-penten-3-one, heptanal, 2-pen-tyl furan, 1-pentanol and ( , )-2,4-heptadienal [189]. Pyrazines such as 3-iso-propyl-2-methoxypyrazine could be responsible for the earthy aroma of potato [35]. Some of the most important character-impact compounds of raw potatoes are summarised in Table 7.8. Aroma compounds from cooked, fried and baked potatoes have previously been reviewed [35]. 

Fig. 16.2 Flavour dilution (FD) chromatogram obtained by application of aroma extract dilution analysis on an extract prepared from parsley leaves. The odorants were identified as 1 methyl 2-methylbutanoate, 2 myrcene, 3 l-octen-3-one, 4 (2)-l,5-octadien-3-one, 5 2-isopropyl-3-me-thoxypyrazine, 6p-mentha-l,3,8-triene, 71inalool, 8 2-sec-butyl-3-methoxypyrazine, 9 (.Z)-6-dece-nal, 10 / -citronellol, 11 ( , )-2,4-decadienal, 12 / -ionone, 13 myristicin, 14 unknown. RI retention index. [30, 31]...

Crust volatiles were isolated immediately after baking by extraction with dichloromethane and sublimation in vacuo ( ). Application of aroma extract dilution analysis 6) to the acid-free crust extract led to the detection of 31 odorants. After separation and enrichment, these compounds were identified by comparison of the MS/EI, MS/Cl and retention data on two columns of different polarity to reference compounds. Aroma quality was also assessed. The results of the identification experiments (Table I) revealed that 2(E)-none-nal (No. 1), followed by 2(E),4(E)-decadienal (No. 2) and 3-methyl-butanal (No. 3) showed the highest FD-factors in the crust of the chemically leavened bread. Additionally l-octen-3-one, 2(Z)-nonenal, 2(E),4(E)-nonadienal and an unknown compound with a metallic odor contributed high FD-factors to the overall flavor (For a discussion of FD-factors, see Chapter by Schieberle and Grosch, this book). 

A series of alcohols (C4 - Cll) were identified in the tail meat. Odor threshold concentrations were generally higher for alcohols than the aldehyde counterparts. Except for 1-pentanol, the remainder of alcohol peaks were very small and might not be significant in overall arctna of boiled crayfish tail meat. Josephson et al. (23-25) found l-octen-3-ol, an enzymatic reaction product derived from lipids, to be one of the volatile ccxnponents widely distributed in fresh and saltwater fish. The compound 2-butoxyethanol identified in crayfish tail meat (3) has been reported in beef products (26-27). GC aroma perception of standard 2-butoxyethanol gave a spicy and woody note, hence this compound could be an important flavor component of the boiled crayfish tail meat. 

Hexenal (leaf aldehyde) is a constituent responsible for the smell of green leafs, ( )-2-octenal a main component of the aroma of raw potatoes ( )-2-nonenal is the organoleptic main constituent of the smell of cucumbers and is found in carot root oil, tomatoes, beef and raspberries 158). ( )-2-Decenal and ( )-2-dodecenal are components of some essential oils, ( )-2-tridecenal is responsible for the bug-like smell of coriander seed oil1S8). 

Some of the carbonyl compounds and alcohols form important aroma components in various foods. l-Octene-3-one and l-octene-3-ol are the main components of fresh mushroom aromas. From the series of aldehydes, 2-heptenal to 2-decenal are found in potato chips, and 2-nonenal forms an important component of the aroma in carrots. 

As shown in the case of l-octen-3-one in the beginning of this chapter, aroma-active compounds show an interesting indication as media in human-environment interactions the role of this often disliked compound has some similarity to alarm pheromones. Flavor or smell of food can be categorized into food attractant molecules from this point of view. Infants are able to recognize the body odor of their mother and are attracted to it.189 An opposite example is represented by the notorious ability of skunks to spray, in which thiol compounds such as (E)-2-butene-1 -thiol and 3-methyl-l-butanethiol are used as potent repellents190(see Chapter 4.09). 

Other volatile compounds present in oak wood can transmit unpleasant aromas to the wine, such as the sawdust aroma of dry wood that is perceptible in some wines aged in new barrels. The substances that cause these aromas have been identified in both American and European oak wood, for instance, ( )-2-nonenal, 3-octen-l-one, ( )-2-octenal, and 1-decanal. Their connection with the sawdust aroma has been established by olfactometry, and they have been identified in wines suffering from this flaw, though toasting the wood (Chatonnet and Dubourdieu 1998). 

By using aroma extract dilution analysis (AEDA) of the volatile fractions of fresh and stored butter oil, Widder et al. (29) determined diacetyl, butanoic acid, 8-octalactone, skatole, 8-decalactone, cw-6-dodeceno-8-decalactone, l-octen-3-one, and l-hexen-3-one as potent contributors to the flavor of butter oil. The concentration of l-octen-3-one, trani-2-nonenal, and i-l,5-octadien-3-one increased during the storage of the butter oil at room temperature. 

Table 5 shows the sensory evaluation by Schieberle et al. (30) of the different kinds of butter, namely, Irish sour cream (ISC), cultured butter (CB), sour cream (SC), sweet cream (SwC), and farmer sour cream (ESC). It revealed ISC butter and ESC butter with the highest overall odor intensities. Table 5 shows that 19 odor-active compounds were detected by aroma extract dilution analysis (AEDA) in a distillate of the ISC butter. The highest flavor dilution (ED) factors have been found for 5-decalactone, skatole, i-6-dodeceno-y-lactone, and diacetyl followed by trany-2-nonenal, cw,c -3,6-nonadienal, c/i-2-nonenal, and l-octen-3-one. 

Recovery of aroma compounds (l-octene-3-ol, ethyl acetate/butyrate/hexanoate) Recovery of picolines from aqueous solutions Recovery of aroma compounds... 

To approach the situation in food, OAVs are calculated on the basis of odour threshold values which have been estimated in a medium that predominates in the food, e.g. water, oil, starch. As an example the OAVs of the key odorants of baguette crust are listed in Table 6.26. The highest OAVs were found for the roasty smelling 2-acetyl-1-pyrroline (no. 7), followed by furaneol (no. 20), 2,3-butanedione (no. 2), (E)-2-nonenal (no. 13), l-octen-3-one (no. 9) and methional (no. 6). It is assumed that these odorants contribute strongly to the aroma of baguette crust. 

Among the odorants listed in Table 6.33, l-octen-3-ol (no. 4), the character impact aroma compound of mushrooms [62], is also responsible for the characteristic mush-room-like note of camembert, which is intensified by l-octen-3-one (no. 5). Although the concentration of this ketone is much lower than that of the alcohol, it can be aroma-active in cheese because its odour threshold is 100 times lower than that of the alcohol [60], Methanethiol, methional, dimethylsulphide, dimethyl trisulphide and methylene-bis(methylsulphide) generate the sulphurous odour note, whereas phenyle-thyl acetate is responsible for the floral odour note [61 ]. 

Generally, the volatile carbonyls found in fish exhibit coarse, heavy aromas whereas the volatile alcohols contribute smoother qualities. Lower threshold values for the volatile carbonyls, especially l-octen-3-one (0.005 ppb 39) ... 

Ney, K.H. and Freytag W.G. (1978) Aroma of mushrooms. Sensory properties of l-octen-3-ol structural analogues. Gordian 78, 144-6 (Chem. Abstr. 89, 174437a). 

In comparing the 12 aldehydes and their relative intensities shown in Table I, it is not surprising that seven of die 12 are found in both oils at essentially the same levels. However, the relative intensities of the other five are interesting in that three of the five differing aldehydes are totally absent in the other oil. For example, E-2-octenal (peak 14) was observed only in the Early-Mid season oil whereas Z-2-nonenal (peak 17) and p-sinensal (peak 28) were only found in the Valencia oil. Only two aldehydes, namely acetaldehyde (peak 1, with possible co-elution of ethyl propanoate) and nonanal (peak 13) had appreciable intensity differences. It is quite possible that the major aroma quality differences between these two oils is due to the marked differences in these five aldehydes. P-sinensal has long been considered a major quality factor in orange oils II) and the lack of this positive aroma component in the Early-Mid oil may explain in part the lower aroma quality of this oil. 

Another unusual component Is the potent odorant l-octen-3-one which has been reported to have a mushroom-metallic aroma and has been found in cooked mushroom ( 5) and artichoke ( ). 

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