Smell and taste

On approaching a water source one occasionally senses an unpleasant smell. In most cases this is caused by sulfur compounds, mainly FI2S. This information should be recorded in the field notes and taken into account during data interpretation because the presence of FI2S and related compounds indicates reducing conditions, bacterial activity, or possible occurrence of sewage or other pollutants. 

Human ability to smell H2S is limited to the parts per million range. At higher concentrations the odor is not noticed. Hence, if an H2S smell is noticed when approaching the site, but it disappears at the well or spring itself, a high H2S concentration should be suspected and relevant sampling is recommended. 

Smell is a crucial factor in the ranking of water quality. In some cases aeration of water is practiced in order to get rid of compounds causing unpleasant smells. 

Tasting of water provides immediate quality information, for example, 

Tasting ability can be developed by tasting waters of known compositions. The information gained by tasting is of immediate use in 

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Several aspects affect the extent and character of taste and smell. People differ considerably in sensitivity and appreciation of smell and taste, and there is lack of a common language to describe smell and taste experiences. A hereditary or genetic factor may cause a variation between individual reactions, eg, phenylthiourea causes a bitter taste sensation which may not be perceptible to certain people whose general abiUty to distinguish other tastes is not noticeably impaired (17). The variation of pH in saUva, which acts as a buffer and the charge carrier for the depolarization of the taste cell, may influence the perception of acidity differently in people (15,18). Enzymes in saUva can cause rapid chemical changes in basic food ingredients, such as proteins and carbohydrates, with variable effects on the individual. 

Additionally, color may also serve as a key to cataloging a food as safe. Undesirable colors of meats, fruits, and vegetables warn us about potential dangers or at least of the presence of undesirable flavors. Color and other sensory attributes are even misused as indicators for safety. Walker and co-authors demonstrated that in small and medium enterprises, more than 50% of food handlers thought that they could tell whether food was contaminated with food poisoning bacteria by sight, smell, and taste. Color is thus used as a way to identify a food and judge its quality."... 

The resnlting sludge can be nsed to mannfactnre bnilding materials, road cover materials, and the like. Adsorptive pnrihcation is able to liberate the water from contaminants that cause its bad smell and taste. It is highly effective for the removal of xenobiota and of traces of petrolenm prodncts. In some cases it can even decolorize the water. 

Later in intra-uterine life, the human infant is susceptible to early chemical prompting, but again the affector route is not known with certainty. Neonatal discrimination in favour of familiar (maternal) amniotic fluid is demonstrable, suggesting that the foetus already has active chemosensory capacities (Schaal, 1998). Smell and taste are operative in the near full-term foetus since it shows detection of about 120 mg/day maternal intake of anethole (as anise condiments) within a few days before parturition this exposure induced subsequent preferential responses by babies to anethole (Schaal et ai, 2000). The human neonate is not likely to have its organ as a fully functioning chemosensor,... 

Chadwick D., Marsh J. and Goode J., eds. (1993). The Molecular Basis of Smell and Taste Transduction. John Wiley, Chichester, p. 287. 

Laing D.G., ed (1989) Perception of Complex Smells and Tastes. Academic Press, San Diego, p. 322. 

Japanese Association for Smell and Taste Sciences http //epn.hal.kagoshima-u.ac.jp/JASTE... 

Farbman A. (1991). Developmental neurobiology of the olfactory system. In Smell and Taste in Health and Disease (Getchell T.V., ed.). Raven Press, N.Y., pp. 19-33. 

Wittemyer, G., Douglas-Hamilton, I. and Getz, W.M. (2005) The socioecology of elephants analysis of the processes creating multitiered social structures. Anim. Behav. 69, 1357-1371. Wyatt, T.D. (2003) Pheromones and Animal Behaviour Communication by Smell and Taste. Cambridge University Press, Cambridge. 

Wyatt, T.D. (2003) Pheromones and Animal Behavior Communication by Smell and Taste. Cambridge Cambridge University Press. 

Why does standing a bottle of wine cause it to smell and taste better ... 

Despite the wealth of information available on the biochemistry, genetics, and nutritional values of plant proteins, people eat foods that look, smell, and taste good not because of nutritional importance. Thus, new blended plant foods or protein-supplemented snacks or food products will have to look and taste like the traditional items if they are to gain sufficient acceptance to become commercially feasible. Absolute food... 

Lewis, R., When smell and taste go awry, PDA Cons., 25, 29, 1991. 

Research the organic compounds that are responsible for the smell and taste of oranges, pineapples, pears, oil of wintergreen, and apples. Find and record the chemical structure of each compound. 

It is perhaps too obvious to point out that everything we can see, touch, smell, and taste is a chemical or, more likely, a mixture of many different chemicals. In addition, there are many chemical substances in the environment that cannot be detected with the senses, but only indirectly, by the sophisticated instruments scientists have devised to look for them. The number of different chemicals in and on the earth is unknown, but is surely in the many millions. During the past 125 years scientists have been successful in creating hundreds of thousands of compounds that do not occur in nature, and they continue to add to the earth s chemical stores, although most of these synthesized chemicals never leave the research scientists laboratories. 

Spiny mice, Acomys cahirinus, use all senses interchangeably in locating prey (Langley, 1988). These are cases of adaptive redundancy at the level of the sensory modalities. As is well known, deaf-blind humans use smell and taste more. 

Three types of closely related cresols exist ortho-cresol (o-cresol), meta- cresol (m-cresol), and para-cresol (p-cresol). Pure cresols are colorless chemicals, but they may be found in brown mixtures such as creosote and cresylic acids (e.g., wood preservatives). Because these three types of cresols are manufactured separately and as mixtures, they can be found both separately and together. Cresols can be either solid or liquid, depending on how pure they are pure cresols are solid, while mixtures tend to be liquid. Cresols have a medicinal smell (odor) and when dissolved in water, they give it a medicinal smell and taste. Cresols do not evaporate quickly from water, but in rivers and lakes, they can be removed quickly by bacteria. Dissolved cresols can pass through soil into underground water sources. This may be a problem at hazardous waste sites where cresols are buried. Once cresols are in the water table, they may stay there for months without changing. Cresols in air quickly change and break down into smaller chemicals, some of which irritate the eyes. Cresols can also irritate the eyes. 

Chloral hydrate (Noctec, Somnos) was developed in the late 1800s and is still used as a sedative-hypnotic agent. It is a hydrated aldehyde with a disagreeable smell and taste that is rapidly reduced in vivo to trichloroethanol, which is considered to be the active metabohte. It produces a high incidence of gastric irritation and allergic responses, occasionally causes cardiac arrhythmias, and is unreliable in patients with liver damage. 

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