Sulfur, odours containing

Colour is not the only characteristic by which we recognize compounds. All too often it is their odour that lets us know they are around. There are some quite foul organic compounds loo the smell of the skunk is a mixture of two thiols—sulfur compounds containing SH groups. 

Sulfur compounds, e.g. arenesulfonic acids, used in conjunction with the unsaturated compounds mentioned above can provide level, bright films. After several hours of operation of the bath, the odour of the aromatic hydrocarbon can be detected and it is well known that the bright deposits contain sulfur. Thus reduction of organic species at the developing nickel surface is a general phenomenon. 

In relation to the aromas produced on exposure to microwave radiation, Yaylayan et al.2S1 examined many combinations of sugars and amino acids, grouping the latter into aliphatic, hydroxylated, aromatic, secondary, basic, amide, acid, and sulfur-containing ones. The odours observed were grouped into eight and they have been assigned to the above groups, as far as possible, below ... 

The chief culprits in generating armpit odours are the bacteria Corynebacterium xerosis and Micrococcus luteus, with Staphylococcus epidermis and Staphylococcus aureus playing minor roles. There can be as many as ten million bacteria cells per square centimetre of armpit skin compared to only 1,000 on the skin of the forearm, and this is as true for women s armpits as for men s, and yet the odour women give off is different because it lacks some of the ingredients that male sweat contains. Male underarm odour has three components an acrid one, a musky one, and a pungent one. The first of these comes from short-to-medium chain acids, the second from steroid type molecules, and especially androstenone, and the third from sulfur-containing molecules. 

While most bryozoan compounds which contain halogen or sulfur are alkaloids (Section 2.3), several having no nitrogen have been discovered. These compounds have been Implicated In various off-flavours and bad odours. 

Sulfur in canola oil is in the form of organic compounds as the decomposition products of glucosinolates. Although these sulfur components occur in trace quantities, they poison catalysts used for hydrogenation as well as giving a characteristic odour to the oil. Recent developments in analytical methods for sulfur determination revealed that soybean, sunflower and even coconut oils all contain sulfur at the level of 2-10 mg/kg. Only Brassica oils contain significant quantities of divalent sulfur components. Crude canola oils may contain 15-35 mg/kg of sulfur, while in RBD canola oils the amount of... 

Among these heat stabilisers, those containing tin (such as tin mercaptides, and tin carboxylates or maleates) are considered to be the most efficient, and can be used in a wide variety of applications. Metallic tin is harmless but there are suspicions that organotin-compounds can be toxic to the central nervous system and the liver. However, tin stabilisers have a low capacity for migrating, and hence they are still considered to be safe. Tin stabilisers such as methyl and octyl tins are used in food contact applications. For PVC, it is believed that tin stabilisers act as HCl scavengers (generating tin chloride) as well as an antioxidant. Thio-tin compounds (preferred for rigid pipe extrusions and profiles (for window frames) of PVC) may develop an odd odour due to sulfur. 

The lower fatty acid most frequently bound in esters is acetic acid, while formic, propionic, butyric and isobutyric adds occur less often. The common alcohol bound in esters is ethanol. However, esters of methanol, aUyl alcohol, butan-l-ol higher alcohols and very often esters of monoterpenic and aromatic alcohols also occur in foods, and esters of sulfur-containing alcohols are also common. Esters of low molecular weight acids and alcohols usually have a fruity odour esters of terpenic alcohols with low molecular weight adds tend to have fragrant odours resembling flowers. Esters of aromatic adds and aromatic alcohols generally have heavy balsamic odours. 

Very intense-smeUing sulfur compounds with low thresholds of perception often act as key aromatic compounds. They often have very similar structures and contain an important odorophore (a group responsible for the odour character), which is sulfur and oxygen in positions 1 and 3 of the molecule (8-120). This structure occurs in mercaptans, thioacetals, mercapto ethers, mer-capto ketones, alkylthio esters and other compounds listed in the following sections. 

---