Acetaldehyde flavour

Alternatively, hydrogen sulfide could be produced alongside ammonia and acetaldehyde by the breakdown of the mercaptoimino-enol intermediate of the decarboxylation reaction of the cysteine-dicarbonyl condensation product. Fisher also points out that hydrogen sulfide is forms many odiferous an hence intensely flavoured products.2 Cysteine is important as it is one of the major sources of sulfur. 

Hydrogen sulphide is a key intermediate in the formation of many heterocyclic sulphur compounds. It is produced from cysteine by hydrolysis or by Strecker degradation ammonia, acetaldehyde and mercaptoacetaldehyde are also formed (Scheme 12.4). All of these are reactive compounds, providing an important source of reactants for a wide range of flavour compounds. Scheme 12.6 summarises the reactions between hydrogen sulphide and other simple intermediates formed in other parts of the Maillard reaction. 

Also heterocyclic flavour molecules can be formed from renewable resources. 3,5-Diethyl-1,2,4-trithiolane is an important molecule for onion flavours and can easily be prepared from propanal obtained by biotransformation and hydrogen sulflde (Scheme 13.17). A meat flavour molecule like thialdine [dihydro-2,4,6-trimethyl-l,3,5(4H)-dithiazine] can be prepared from acetaldehyde isolated from molasses and ammonium sulflde (Scheme 13.18). The bacon flavour substance 2,4,6-triisobutyl-5,6-dihydro-4H-l,3,5-dithiazine can be prepared from isovaleraldehyde prepared from essential oils and ammonium sulfide (Scheme 13.19). 

During the production of recovery flavours, apple wines or brandies, the interaction with ethanol, acetaldehyde and acetic acid represents the next level of interactions. The reaction products contain compounds which result from esterification and acetal formation reactions, which are summarised in Table 21.4. 

Short-chain aliphatic aldehydes, such as acetaldehyde, 2-methyl-1-propa-nal, 2-methylbutanal and 3-methylbutanal (isovaleraldehyde), impart fruity and roast characters to flavour compositions [49]. Natural acetaldehyde is an important compound naturally occurring in a broad range of fruit flavours, essential oils and distillates it augments fruit flavours and, for instance, it decisively contributes to the freshness and juiciness of foods and beverages, such as citrus juices [23, 50]. 

Analysis of the volatile compounds of tamarind revealed the presence of more than 80 compounds. Aromatic and furan derivatives were dominant. The major constituents were 2-phenyl acetaldehyde (25.4% of total volatiles), which has a fruity and honey-like odour, 2-furfural (20.7%), having a caramel-like flavour, followed by hexadecanoic acid (18.1%) and limonene, which has a citrus flavour. A list of the volatile compounds detected in tamarind is given in Table 20.5. 

Aldehydes can be formed by oxidizing alcohols-—in fact the liver detoxifies ethanol in the bloodstream by oxidizing it first to acetaldehyde (ethanal, CH3CHO). Acetaldehyde in the blood is the cause of hangovers. Aldehydes often have pleasant smells—2-methylundecanal is a key component of the fragrance of Chanel No 5 , and raspberry ketone is the major component of the flavour and smell of raspberries. 

Ethanol production is essentially redox neutral however metabolism associated with biomass production generates nett NADH, which is oxidised largely by glycerol production. Other important NADH oxidising reactions with flavour implications are the production of 2,3-butanediol, L-malic acid and succinic add. When glycerol production is stimulated by non-growth associated reactions (i.e. osmotic stress) NAD+ reduction occurs by other reactions including the oxidation of acetaldehyde to acetic acid... 

Lactic acid fermentation imparts the clean sour taste of lactic acid to yoghurt. In a side reaction, rather high concentrations of acetaldehyde are formed, which is responsible for the typical yoghurt flavour. 

After partial hydrolysis the starches lose a major part of their flavour binding properties. Examples of partially hydrolyzed starch products are dextrins (acid or enzymatic hydrolysis) and maltodextrins (generally enzymatically hydrolized). Acetaldehyde, ethanol, decanal and limonene only bind weakly to dextrins (presumably by adsorption) [22[, while ethylacetate is not adsorbed at all [1[. In the same way, alcohols (such as ethanol, propanol, butanol, pentanol and hexanol) and menthol are only weakly adsorbed on maltodextrins [11, 23]. 

Ethane-1,1-dithiol 1660 69382-62-3 HS SH No Europe 0.01 USA 0.01 Japan ND Yes. The NOELs of 125 mg/kg bw per day and 6.5 mg/kg bw per day for the hydrolysis products acetaldehyde (No. 80) (Til et al., 1988) and hydrogen sulfide (Chemical Industry Institute of Technology, 1983), respectively, are 625 million and >32 million times the estimated daily intake of ethane-1,1 -dithiol when used as a flavouring agent. See note 8 No safety concern... 

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