Malodorous compounds

In contrast to the relatively limited number of organosulfur compounds in these species, the anal sac secretions of skunks contain large numbers of malodorous compounds, which are very effectively utilized in the defensive behavior of these species. During the early years of capillary gas chromatography, Andersen et al. [108] found that 150 of the 160 components detected in the anal gland secretion of the striped skunk, Mephitis mephitis, contained sulfur. The results of recent chemical studies on North American skunks by Wood et al. [109] are summarized in Table 4. Only three of the compounds reported in this table are common to the secretions of all four skunk species and, in two of these three secretions, the common compound is present in concentrations of about 1% or less. Although it is clear that skunks use their anal gland secretions primarily for defensive purposes, it does not rule out the possibility that the difference in the composition of these secretions could also be utilized for... 

SPOELSTRA, S.F.—Microbial aspects of the formation of malodorous compounds in anaerobically stored piggery wastes. Proefschrift—Agricultural University— Wageningen. 

BAILEY, J.C., and VINEY, N.J., The Analysis of Process Gases for Malodorous Compounds. Warren Spring Laboratory, Department of Industry, Stevenage. 

In chapter 2 a survey is given of the technics which can reduce the emission of malodorous compounds. 

Since more than 10 years much research is done on the anaerobic digestion from slurry. This research is mainly stimulated by the option of the renewable energy biogas. But there is also an effect on the presence of the malodorous compounds. In the next chapter more details are presented. 

According to V.d.Hoek (1) the aeration requires at least an input of 36 kWh per pig place per year, summarize all this literature. Just the principles are important. Under anaerobic conditions different types of microbes transported the volatile fatty acids and the aromatic compounds to CH4, C02, H20 and NH4OH. There is also some H2S produced from the digestion of several protein acids (cysteine and methionine). All these endproducts together, known as biogas, have a typical odour, mainly caused by H2S and NH3. Because of the breakdown of the malodorous compounds the slurry has lost its typical smell. 

Concerning odors, photocatalysis can be an interesting technique if the target malodorous compound has an olfactory threshold on the order of 1 ppbv or less, and if the concentration is low enough. In that case, the pollutant quantity to be eliminated per time unit may fall within the range of removal rates treatable by photocatalysis, depending on the flow rate. 

Proper research into finding better deodorants continues and new findings come to light. For example, underarm odour can also be reduced by applying derivatives of lactic acid and especially those with 12 or 13-carbon chains attached. Why this should work is somewhat puzzling but it has been suggested that the microbes that cause underarm odour prefer to consume this material in preference to natural body oils and in doing so they form non-odorous by-products instead of the usual malodorous compounds. 

Because of the increased internal pressure ( Hydroskelett ), dissected mawworms emit malodorous compounds, which are present in both perienteric fluid and tissues of these nematodes. During dissection, these volatiles may evoke pruritus, inflammation of the eye, and vomiting in humans. In Ascaris lumbricoides, and also in other species such as Parascaris equorum, formic, acetic, propionic, -butyric, 2-methylbutanoic, and caproic acids (C5- and C6-acids main compounds) were found along with unidentified C5-a,/3 unsaturated acids.53 These acids are probably derived from mawworm metabolism and are not formed by microbial activity. 

Malodorous Compounds Associated with Untreated Wastewater... 

Caution. Phosphine and the alkyl phosphines used in these experiments are toxic, malodorous compounds which must be handled with great care using vacuum-line manipulation. The pyrophoric nature of the methyl phosphines makes it advisable to prepare and use them on as small a scale as possible. 

Steam refining Vacuum-stripping process in which acid oil is treated to remove both free fatty acids and malodorous compounds to obtain fully refined oil. 

The odors of amines are quite unpleasant many of the malodorous compounds that are released as fish decay are low-molecular-weight amines. Amines of high molecular weight are nonvolatile, so they have little odor. One of the materials used to manufacture nylon, hexamethylenediamine, is an aliphatic amine. Many aromatic amines are used to prepare organic dyes that are widely used in industrial societies. Amines are also used to produce many medicinal products, including local anesthetics and sulfa drags. 

For all these reasons, it is useful to develop, when possible, a gas-liquid chromatographic headspace analysis for the malodorous compound, although often it is present in very low concentration. 

Table 2 Aqueous binding constants (in units of M for various malodorous compounds with cyclodextrins at 22°C. 

The gas-camouflage is of particular interest. It has been found that malodorous compounds (butyl mercaptan, dimethyl tricarbonate, etc.), are useful to mask the presence of other gases or to force the enemy to wear respirators when no other gases are... 

The large amount of physiological and nutritional work reported on mink does not include mention of the anal sac. It was not until 1976 that Sokolov reported the isolation of several volatile aliphatic acids from the anal sac secretion.Butyric acid was the most abundant, but acetic, propionic, 2-methylpropanoic, 3-methyl-butanoic, 2-methylbutanoic, and a small amount of pentanoic acids were also obtained. Schildknecht et al. published a communication reporting the volatile sulfur compounds in the anal sac secretions of the mink. Crump identified the major malodorous compound in the anal gland secretion of the male ermine or stoat (Mustela erminea)These results will be discussed subsequently together with our own. 

After extraction, com oil usually undergoes a refining process that comprises removal of gums, free fatty acids, adsorbable compounds, waxes and malodorous compounds (Dijkstra... 

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