2- Methylfuran-3-thiol

Methylfuran-3-thiol from Xylose and Hydrogen Sulfide... 

Methylfuran-3-thiol is responsible for a boiled note in milk, chicken and beef flavours and this chemical as well as its disulfide are widely used in flavours. Both molecules can be prepared by heating xylose and hydrogen sulfide in an autoclave (Scheme 13.13). Alternatively, these sulfur compounds can also be synthesised from 2-methylfuran made from furfural derived from oat hulls. 

Among the major volatile sulfur compounds generated during the preparation of die ketopentose-L-cysteines are 2-methylfuran-3-thiol, 2-furfurylthiol and 3-mercapto-2-pentanone (13, Table I). These compoimds have also been identified as character impact compounds of boiled meat flavor (II, 12). This suggests that ketopentosese-L-cysteines are playing a role in the development of boiled meat flavor. Ketohexose-L-cysteines do not produce these character impact compounds in significant quantities (Table I) and are therefore unlikely to play a role in boiled meat flavor development. 

Furanthiol, 2-methyl-, 2-methylfuran-3-thiol, 3-mercapto-2-methylfuran [28588-74-1] FEMA 3188... 

A direct and more advanced analytical approach to screening important volatile compounds in cooked beef is based on the aroma extract dilution analysis (Section C.4). By this technique 35 compounds were identified as having dilution factors greater than 4 (Table 11.18). This technique evaluates compounds on the basis of their relative aroma intensities. The most significant aroma compounds with dilution factors greater than 512 included, 2-methylfuran-3-thiol, methional, tra 5 -2-nonenal, trani,rra 5-2,4-decadienal, )3-ionone and bis-(2-methyl-3-furyl)-disulfide. 2-Methylfuran-3-thiol had an odor threshold of 0.0025. 01 ng/1, and bis-(2-methyl-3-furyl)-disulfide, an odor threshold of 0.0007-0.0028 ng/1. In aged cured ham, methyl ketones representing 5% of the total volatiles are considered to have a positive impact on ham aroma. 

Particularly important substances for the basic flavour of baked and cooked meat are aliphatic thiols (such as methanethiol), sulfides (such as dimethyldisulfide, dimethytrisulfide and dimethyltetra-sulfide), aldehydes (such as acetaldehyde, 2-methylpropanal and 3-methylbutanal), furans, pyridines and thiophenes with a mer-capto group in position C-3 and their corresponding disulfides and some other aliphatic and heterocyclic sulfur compounds. Examples of important aliphatic thiols are 3-mercaptobutan-2-one (8-179) and 3-mercaptopentan-2-one found in cooked beef. A mixture of 3-mercapto-2-methylpentane-l-ol diastereoisomers (Figure 8.86) has a broth-like, sweaty and leek-hke flavour. Very low odour threshold concentrations and an odour reminiscent of roasted meat are found in 2-methylfuran-3-thiol (8-180), which also occurs in beef broth, roasted coffee and other foods, 2,5-dimethylfuran-3-thiol, their corresponding disulfides and 2-furanmethanethiol (furfuryl mercaptan). The typical aroma of roast beef is found in... 

Furanthiols, on the other hand, are stable, and it is the thione form that is usually not in evidence. Thus derivatives of benzo[6 ]furan-2-thiol could be readily studied by UV methods as regards their acidity (80KGS1313), while 5-methylfuran-2-thiol behaves as such... 

---