Of the detected aroma-active compounds, 2-methyl-
3-furanthiol (2-MF, 4), having a cooked rice/vitaminlike vitaminlike/
meaty aroma note, was the most intense compound
in process flavors from extruded E-HVP made with or
without the added precursors. This compound can be
formed via thermal degradation of thiamin (14) or by
Maillard reaction between ribose and cysteine (15). The
formation mechanism of 2-MF in the Maillard reaction
(ribose-cysteine model system) has been proposed to
occur between a ribose Amadori product and cysteine
capable of liberating hydrogen sulfide (16). 2-MF also
can be formed from the reaction of inosine-5¢-monophosphate,
which produces ribose, and hydrogen sulfide
under acidic conditions (17). However, Bolton et al. (18)
have proposed that thiamin degradation was the primary
formation pathway of 2-MF, which results from
direct cyclization of 5-hydroxy-3-mercaptopentan-2-one.
2-MF has been identified as the most potent aromaactive
compounds in cooked beef and has a low odor
detection threshold value (0.005-0.01 ppb) (7). 2-MF
also has been reported to be present in yeast extracts
(19) and processed tuna (20).