Odour and Taste

Structurally, vanillin belongs to a large group of benzenoid plant constituents with similar substitution patterns (Fig. 3.34) these produce the distinctive aro- 

34 Plant constituents related to vanillin (ethylvanillin is a synthetic analogue). 

From the biogenetic viewpoint, these are all phenylpropanoids, which are derived from the amino acid phenylalanine. 

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Nitrous oxide is a colourless, non-flammable, non-corrosive gas with a sweetish odour and taste. It is prepared both in the laboratory and on a commercial scale by heating ammonium nitrate ... 

The oil is of a greenish or gre>=niah-biue colour and o Intense odour and taste of the herb itself. It has the following charactera —... 

Esters often have pleasant odours and tastes, so they are used to produce perfumes and artificial flavours. In fact, the characteristic tastes and smells of many fruits come from esters. (See Figure 1.28.)... 

Arnold, G. W., de Boer, E. S., and Boundy, C. A. P. (1980). The influence of odour and taste on the food preferences and food intake of sheep. Australian Journal of Agricultural Research 31,571-587. 

The acetoxymethyl ester of benzylpenicillin is penamecillin (Havapen, 1). It is an almost white, free-flowing powder lacking the characteristic odour and taste which make penicillins generally unpalatable when administered in tablet or... 

It is a colourless gas with sweet odour and taste, available as liquid under pressure. It produces analgesia without loss of consciousness in 1 to 2 percent concentration, in 6 to 8 percent it produces loss of consciousness while... 

External and Objective Characters.—Observations are made of the colour (whether bright red or brownish-red), the consistency (whether compact and elastic or the reverse), and the odour (whether normal and not unpleasant, or, on the other hand, indicative of putrefaction). Note is also made of the odour and taste of the broth obtained by boiling a piece of the meat with water in a closed vessel—the odour at the moment the liquid begins to boil Observation is also made of the reaction—whether this is amphoteric,or acid, or alkaline the last indicates putrefaction. 

External and Objective Characters.—The appearance, odour and taste of the meat are compared with those of the corresponding fresh meat, note being taken of the retention or otherwise of the more or less deep red colour of the muscular parts the fat is observed to ascertain if it is white and of pleasant odour, and the mass of the meat to see if it is compact and without empty spaces and not excessively moist. 

When the tin is opened, the reaction is tested in different parts of the product with litmus paper the reaction should be faintly acid, any marked alkalinity rendering the product suspicious. The liquid should be gelatinous and transparent and its odour and taste and also those of the meat should be normal and pleasant. The internal condition of the meat is examined, the colour and consistency of a fresh cut and any formation of gas-bubbles being noted. 

This is the fat of milk, separated from the other components, but containing incorporated in it a certain quantity of curd it is semi-pasty, white or pale yellow, with agreeable odour and taste, and. turns, rancid easily-... 

This results from the transformation of starch by means of heat or by the action of dilute acid or diastase. It is prepared principally from potato, wheat or maize starch and rarely from rice or other exotic starches. Many varieties of dextrin, made in diverse ways, are sold under different names. It occurs as a fine powder, either wliite, dirty white, yellowish or light brown as granules, similar in appearance to gum arabic and as a thick syrup, more or less highly coloured and opaque. In general dextrin has a special odour and taste, which are particularly marked in the pulverulent varieties. It is soluble in water, but insoluble in alcohol. Its solution is strongly dextro-rotatory the value of [a]D varies from 173° to 2250,but is mostly about 200°. With iodine different dextrins give bluish violet to brownish red colorations (the colour is observed by adding the iodine solution drop by drop if the mass is mixed after the first drops are added, the colour disappears). 

External Characters.—The colour, odour and taste are to be noted. White or yellow dextrins are mostly prepared by means of acid (hydrochloric acid tends to give a reddish and nitric acid a greyish tint), whereas brown dextrins are those obtained by direct torrefaction without acid. 

External Characters.—Note is made especially of the colour, consistency, homogeneity, odour and taste of the product with practice, useful conclusions with regard to the quality can then be drawn. 

High up in the atmosphere, around 20 km from the surface of the earth, the ozone layer acts as a shield and protects the earth from the harmful UV rays present in the incoming solar radiation. But for this layer, all life on earth would have been scorched. Ozone is used to sterilize drinking water and to remove bad odours and tastes. 

Raw water collected in the reservoirs has to be purified before it is fit for drinking. Raw water has turbidity, certain dissolved salts that cause hardness, bad odour and taste, and harmful bacteria. These have to be removed. 

Odour and taste are important aspects of drug administration. A drug with a poor odour or too bitter a taste will be rejected by patients, especially children. Furthermore, a drug that causes pain when administered by injection can have a detrimental effect on a patient. The formation of a carrier prodrug can sometimes alleviate some of these problems. For example, palmitic acid and other long chain fatty acids are often used as carriers, since they usually form prodrugs with a bland taste. 

Villberg, K., Veijanen, A., Gustafsson, I., and Wickstrom, K. (1997). Analysis of odour and taste problems in high-density polyethene. ]. Chromatogr. 791, 213-219. 

Alcohols Linalool odour and taste. Floral woody with citrusy note, 2-10 1.4-4.5... 

Odour and taste Characteristic and persistent odour of ginger lacking pungent taste... 

The powdered seeds are yellowish-brown with an aromatic, slightly camphoraceous odour and taste. The characteristics are ... 

Slight perceptible Rather imperfect fruitness, anomalous odours and tastes 5... 

Considerable, on the border of acceptability Clearly imperfect, unpleasant odours and tastes 4... 

Great and/or serious, clearly perceptible Totally inadmissible odours and tastes for consumption 3 2 1... 

In organoleptic studies no significant changes in odour and taste could be found when the commercially available enzyme preparations were used even at concentrations many times the normal level. 

The overpressure only inhibits fermentation by yeasts, but does not inactivate enzymes and other microorganisms. These can cause changes in the colour, odour and taste of the juice. 

The primary product, usually cider or grape wine, must have completed alcoholic fermentation and he free of fermentation residues (lees), and should not he sulphurized. A further requirement is that it should he free of odour and taste defects (in this case the product may possibly he too vinegary). With vinegar, just as in other fruit products, the quality of the primary product determines the quality of the final product. 

The vapour from the pure liquid or concentrated aqueous solution causes an irritation at the back of the throat and a bitter taste in a short time. Diluted with air it is not very irritant, but has a less disagreeable odour which is somewhat aromatic. It is a peculiar property of this substance that even in minute quantity it paralyses the nerves of odour and taste, and after a few seconds the first sensitivity to the odour is lost. 

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