Sulfur volatile

Sulfur volatilizes at 600 °C, and cupric chloride is molten at this temperature. The products are thus readily separable from one another. 

GC/FID has been used for quantifying sulfur volatiles such as hydrogen sulfide in human saliva (Solis and Volpe 1973). This method included microcoulometric titrations and a procedure for incubation of saliva and sampling of headspace sulfur volatile components. The amount of total sulfur volatiles detected in control samples of saliva incubated at 37°C for 24 hours ranged from 4.55 to 13.13 ppm. 

Solis MC, Volpe AR. 1973. Determination of sulfur volatiles in putrefied saliva by a gas chromatography-microcoulometric titrating system. J Periodontal 44 775-778. 

Fruits have received extensive study one example is that of the passion fruit volatiles. Another fruit in which sulfur volatiles play an aroma role is musk-melon (Cucumis melo cv. Makdimon). A musky overtone is provided by 3-(methylthio)propanal ( stale ) and 5 -(methylthio)-butanoate ( pine, earthy )... 

Examination of 37 basidiomycetous yeasts indicated formation of several sulfur volatiles 3-(methylthio)-l-propanol, methanethiol (MT), S-methyl thio-acetate, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), allyl methyl sulfide and 4,5-dihydro-3(2//)-thiophenone. The component produced in the largest amounts, 40 100 mg L-1, was 3-(methylthio)-l-propanol29 Cheeseripening yeasts are considered later (Section 11.1.2.4.5). 

Fedrizzi, B., Magno, F., Badocco, D., Nicolini, G., and Versini, G. (2007). Aging effects and grape variety dependence on the content of sulfur volatiles in wine. J. Agric. Food Chem. 55,10880-10887. 

The sulfur ratio, defined as the ratio of weight percent sulfur in the char to the weight percent sulfur in the dye, provides an interesting parameter regarding sulfur volatilization. The three compounds with sulfur ratios between... 

The composition of the various blends and the data resulting from the pyrolysis of the blends appear in Table II. Sulfur volatilization by fragmentation is not directly related to the volatile matter of the blend as was true with model compounds. For the same model compound (Ciba Orange R) in the various blends this factor is considered constant and has been neglected. 

Figure 2 shows the results of the pyrolysis experiments conducted with the Spanish lignite at 750-960°C at residence times of 0.52-0.72 sec. It is seen that under the pyrolysis conditions used, 60 - 70% of the sulfur in this coal appears in the gaseous products as H2S, COS, and CS2. As in the previous sulfur study (1), the principal sulfur gaseous product at all temperatures is H2S, with some CS2 formed at T >840°C. The CS2 is apparently formed at the expense of the H2S, by any of several reactions H2S may react with the carbon of the coal and/or the methane evolved in the pyrolysis of the coal to form CS2- A small amount of COS is detected at all temperatures trace amounts of SO2 are also detected. Moreover, the total sulfur yield appears to reach a maximum about 900°C. The decrease in sulfur volatilization as pyrolysis temperature is increased above 900°C is attributed to sulfur retention in the char due to the reaction of H2S with coke or char to form more stable thiophenic structures (2). GC/MS analysis of the tars (diluted to 10 ml) from the pyrolysis at 750 and 850°C did not reveal any sulfur-containing structures. Tars from the pyrolysis at 900 and 950°C, however, contain dibenzothiophene. 

From the literature, 19 commonly reported beef flavor aroma compounds containing sulfur were chosen as representative of the capillaiy gas chromatographic spectrum of substances active in the FPD and are noted in Table I. The reproducibility of the instrument was demonstrated by repeated injections to identify the range of sulfur volatiles in beef samples. The internal standard chosen, benzothiophene is also listed in Table I. 

Another less common heterocyclic sulfur volatile is 1 - 7/]-pyrrolo-[2,1 c]-1,4-thi-azine, identified in bread crust by Baltes and Song 249 and previously obtained by Guntert et al.269 from a ribose-cysteine system. 

ATTIEH, J., DJIANA, R., KOONJUL, P., ETIENNE, C., SPARACE, S.A., SAINI, H.S., Cloning and functional expression of two plant thiol methyltransferases A new class of enzymes involved in the biosynthesis of sulfur volatiles., Plant Mol. Biol., 2002, 50,511-521. 

Volatiles with a meaty flavor note generally present in meats from different species are perhaps qualitatively the same, however, their quantities vary from one species to another (25.261. To date, only 13 non-sulfurous volatiles with meaty aromas have been identified in meats and some may indeed be artifacts (Table II). 

Additional Means for Manipulation of Methanethlol and Other Sulfur Volatile Compounds in Foods... 

Figure 6. Gas chromatogram of sulfur volatiles from Cheddar cheese containing encapsulated methioninase and ripened at 21°C for 21 days, then 3 months at 10°C (Carbopak BHT-100 column).

Since Reichstein and Staudinger, we have been aware that furan compounds containing one or more sulfur atoms play an essential role in the aroma of roasted coffee. A review of the sulfur volatile constituents of coffee, showing the importance for coffee flavor of furans substituted on the 3-position by a sulfur atom, has been published by Flament and Chevallier (1988). As can be seen in the values given for the furfuryl sulfur compounds, the concentrations are higher in robustas than in arabicas when there is no methyl substituent on the ring. When there is a 5-methyl the concentrations are lower overall but higher in the arabicas than in the robustas (compare for example 1.128 and 1.129). 

Sulfur redox reactions seem to be more reversible than those of nitrogen. Intermediate compounds in the reaction series from sulfate to sulfur or sulfide, and vice versa, do not appear in soils. Sulfur also differs from nitrogen in that little sulfur volatilizes from soils. Although H2S is a gas, apparently any HjS formed in soils reacts rapidly with Fe and other transition metal oxides to form sulfides. Some organic... 

There is no apparent variation of the zinc content before, during and after the test, indicating that the zinc content in the matte is negligible. The condensed sample has a higher Fe and S content, but a lower metallic zinc content than in Test-1. This may be attributable to the carryover of solid feed materials, such as iron ore because the gas flow rate is higher than in Test-1. This also explains the higher Fe/S ratio of the condensed sample than that of the matte. Furthermore, it is obvious that sulfur in the condensed zinc sample results fiom flashing and solid carryover rather than from sulfur volatilization. Otherwise, the Fe/S ratio in the condensed zinc sample should be lower than that in the matte. 

Thus, it can be assumed that the amount of nitrogen in the coal, and the way in which it is bound into the coal structure, affects the amount and distribution of NOx emissions. The proportion of the coal sulfur volatilized on partial gasification could be related to the coal substance gasified, using one equation for all the coals. For coal nitrogen however, a single equation can describe the data from both pyrolysis and partial gasification (Middleton et al., 1997). 

Sulfur compound investigation can be significantly aided by the use of the SCD. It has been proven to be a sensitive, selective GC detector for sulfur volatiles in food matrixes. In order to achieve accurate results, sample handling and analytical conditions need to be controlled carefully to minimize any reactions involving sulfur flavor volatiles. Thiols and sulfides have been shown to be susceptible to oxidation... 

Sulfur Volatiles in Cucumis melo cv. Makdimon (Muskmelon) Aroma... 

The presence of sulfur volatiles has now been reported in a wide range of fruits and has been found to correlate well with quality in strawberries (9) and black currant buds (JO). Detailed studies of the volatiles in pineapple (11,12,13) also reported the presence of several thioether esters including methyl (methylthio)acetate, ethyl (mediylthio)acetate, 3-(methylthio)propyl acetate, methyl 3-(methylthio)propanoate, ethyl 3-(methylthio)propanoate and the alcohol, 3-(methylthio)propan-l-ol. The sulfur esters 3-(meAylthio)propyl acetate and ethyl 3-(methylthio)propanoate were also detected in Asian pears (14), and fifteen sulfur volatiles, including 3-(methylthio)hexyl acetate, have recently been reported in yellow passionfruit (15). 

This work reports additional sulfur volatiles in Cucumis melo cv. Makdimon and investigates the sensoiy significance of sulfur volatiles in melon aroma as determined by gas chromatography-olfactometiy and aroma extraction dilution analysis (AEDA). The results of blending the melon flesh prior to extraction are also presented. 

The melon extract was analyzed for sulfur volatiles using a Hewlett-Packard 5890 Series II gas chromatograph coupled to a Hewlett-Packard Atomic Emission Detector (HP5921A). The gas chromatograph was fitted with an OVl column, 25 m X 0.25 mm i.d. and a film thickness of 0.5 pm. The carrier gas was helium, set at a head pressure of 15 psi. The oven was temperature programed as follows initial temperature 40°C held for 5 min program rate 5°C/min final temperature 220 C. 

To assess the relative sensory significance of the esters and the sulfur volatiles to the overall melon aroma, the SDE extract was analyzed by aroma extraction dilution analysis (AEDA) using gas chromatography-olfactometry (GCO). The FID and sensory responses to the most dilute extract are shown in Figure 2, and the complete AEDA data is summarized in Table II. Of the seven peaks identified as significant odorants at the highest dilution, four contain sulfur, S-methyl thiobutanoate, 3-(methylthio)propanal, 3-(methylthio)propyl acetate and. 

Sulfur volatiles play a significant role in the perceived aroma of Cucumis melo cv. Makdimon. In particular 3-(methylthio)propanal and S-methyl thiobutanoate and dimethyltetrasulfide (tentative) convey a musky overtone to the classical fruity aromas associated with 3-(methylthio)propyl acetate, ethyl 2-methylpropanoate, ethyl 2-methylbutanoate and methyl 2-methylbutanoate. Further work is required to confirm the contribution of the enantiomers of 2,3-butanediol diacetate and the unknown compound that conveys the sweaty, dirty socks component to the aroma of this melon. 

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