2,4 -Decadienal

Model systems indicate that aldehydes may also be produced by the action of polyphenoloxidases on amino acids in the presence of catechin, all of which are present in coffee beans at some stage between green and roasted. For example, valine yields isobutanal, leucine yields isopentanal, and isoleucine yields 2-methyl-butanal.14 Some of these aldehydes probably undergo condensation reactions in the acidic medium of the roasted bean when moisture is present.15 Some dienals in green coffee beans have recently been identified as (E,E)-2,4- and (E,Z)-2,4-nonadienal and (E,E)-2,4- and (E,Z)-2,4-decadienal.18... 

Detailed investigation of T. rotula and other diatom species revealed that 2,4-decadienal (24) and 2,4,7-decatrienal (27) represent only members of a structurally diverse class of oc, 3,y,6-unsaturated aldehydes found in several... 

Decadienal has been reported as one of the most toxic lipid hydroperoxide breakdown products to ceUs . Besides l,Ai -etheno-2 -deoxyadenosine (edAdo) (156)... 

E,E)-2,4-Decadienal ppE222 3,4 - Dihy droxypheny le thy 1 4 -formyl -3 -formylmethyl-4-hexenoate Ijorui Acetaldehyde Call... 

The concentrations of aldel des extracted in fraction FI at 207 bar/lS0°C were 3 to 8 times higher than those extracted at 345 bar/50°C The concentrations of 2,4-dienaIs which are responsible for the deep-fat fried odor of mai fiits and oils 14) were very high compared to similar compounds found in beef fat, and they were concentrated up to 34-fold in firaction FI compared to non-extracted control. 2,4-Decadienal (E,E) is an apparent precursor of 2-pentylpyridine, and it has also been found that the 2,4-dien contribute to fatty, oUy and tallowy odor of fats 36). 

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]...

The overwhelming consideration in regard to lipid deterioration is the resulting off-flavors. Aldehydes, both saturated and unsaturated, impart characteristic off-flavors in minute concentrations. Terms such as painty, nutty, melon-like, grassy, tallowy, oily, cardboard, fishy, cucumber, and others have been used to characterize the flavors imparted by individual saturated and unsaturated aldehydes, as well as by mixtures of these compounds. Moreover, the concentration necessary to impart off-flavors is so low that oxidative deterioration need not progress substantially before the off-flavors are detectable. For example, Patton et al (1959) reported that 2,4-decadienal, which imparts a deep-fried fat or oily flavor, is detectable in aqueous solution at levels approaching 0.5 ppb. 

Conducting the same experiment using tril-inolein produced volatiles unique to the trili-nolein substrate, with the major classes being alkanals, 2-alkenals, 2,4-alkadienals, and hydrocarbons. Those volatiles, produced uniquely from this substrate and attributable to the breakdown of 9- and 13-hydroperoxides, include pentane, pentanal, 1 -pentanol, hexanal, 2-hexenal, 3-hexenal, 2-heptenal, 2-octenal, 2,4-decadienal, and acrolein. Addition of triolein afforded the added production of volatiles previously identified in triolein alone, but ad-... 

Thermoplastic Polyolefin (TPO) One batch of a thermoplastic polyolefin had a roasty off-odor. The important odorants 2,3-butandione, l-hexen-3-one, methional (3-methylthiopropanal), Z-2-nonenal, E-2-nonenal, l-octen-3-one, octanal, E,E-2,4-nonadienal, E,E-2,4-decadienal, and as the most important off-odorant 2-acetyl-l-pyrroline, could be identified (Mayer and Breuer, 2004b, 2006). 

Aldehyde Formation. Several investigators observed a marked dominance of hexanal in the volatile products of low-temperature oxidation. At the higher temperatures, however, 2,4-decadienal was the major aldehyde formed (19,20,21). Both aldehydes are typical scission products of linoleate hydroperoxides. Swoboda and Lea (20) explained this difference on the basis of a selective further oxidation of the dienal at the higher temperature, while Kimoto and Gaddis (19) speculated that the carbon-carbon bond between the carbonyl group and the double bond (Type B) is the most vulnerable to cleavage under moderate conditions of autoxidation, while scission at the carbon-carbon bond away from the olefinic linkage (Type A) is favored under stress such as heat or alkali. 

The 13-hydroperoxide of linoleate would thus produce more hexanal at lower temperatures while 2,4-decadienal from the 9-hydroperoxide isomer predominates at elevated temperatures. Although our quantitative work with propyl linoleate (21) supports this rationale, i.e., a temperature-dependent preferential cleavage, the pattern was not as clear when linoleate was oxidized at three different temperatures (18). The more unsaturated substrate oxidized much faster and many of the oxidation products, themselves polyunsaturated, readily underwent further decomposition. 

N-Heterocyclics. The reaction of primary amines with the carbonyl products derived from lipid oxidation is a major pathway in lipid-protein interactions. Formation of Schiff s base intermediates followed by cyclization and rearrangement can yield imines, pyridines and pyrroles (5,15,30,31). For example, 2-pentylpyridine may result from the reaction of ammonia with 2,4-decadienal, one of the principle aldehydes from the autoxidation of linoleate (5). 

This paper discusses model studies which indicate that lipid decomposition products such as 2,4-decadienal and hexanal may react with Maillard reaction intermediates to form heterocyclic compounds... 

The thermal interaction between 2,4-decadienal and cysteine was selected as a model for lipid-protein interaction. 2,4-Decadienal is the major degradation product of linoleic acid and cysteine is a sulfur-containing amino acid in foods. Some heterocyclic compounds identified in the reaction mixture of 2,4-decadienal and cysteine are listed in Table I. 

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