Fatty acid, bitter taste

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. 

Many bioactives have an undesirable taste and odour. Peptides are known for their bitter taste, mineral salts for their metaUic tastes and marine oils rich in omega-3 fatty acids for fishy taste and odour. Further, the addition of soluble iron salts to foods catalyses the oxidation of fats and amino acids and imparts undesirable metallic tastes to foods (Zimmermann 2004 Yang and Lawless 2006). A variety of added ingredients (e.g., sugar, flavours) have been used to mask these tastes, but with limited success. 

Direct esterification of glycerol, lactic acid and fatty acids is also a possible method. The lactic acid ester usually contains 15-35% esterified lactic acid. Free lactic acid and its glycerol ester are normally removed by washing with water since such water-soluble compounds can give a bitter off-taste in the finished product where the emulsifiers are used. 

Humans detect at least five primary taste stimuli, which include sweet, sour, salty, bitter, and umcmi taste. Representative taste stimuli for the five primary taste qualities consist of polar molecules that are generally presented as aqueous solutions to subjects for psychophysical studies. Medium- and long-chain fatty acids are non-polar molecules that do not readily dissolve in... 

All taste quality responses were normalized to 100%. Other taste represents a response that is not perceived as sweet, sour, salty, or bitter. Subjects who responded other were further asked to use a word description to identdy the taste quahty of fatty acid taste strips. Data in parenthesis in column seven represent the percentage of other tasters who ve a taste quality response of fatty/oily/waxy/sunflower seed taste. 

Shipe, W.F., G.F. Senyk, R.A. Ledford, D.K. Handler, E.T. Wolff, Elavor and chemical evaluations of fresh and aged market milk, J. Dairy Sci., 63(Suppl. 1), p. 43, 1980. Chandran, R.C., K.M. Shahani, Milk lipases a review, J. Dairy Sci., 47, p. 471, 1964. Kwak, H., I.J. Jeon, S.K. Pemg, Statistical patterns of lipase activities on the release of short-chain fatty acids in Cheddar cheese slurries, J. Food Sci., 54, p. 1559, 1989. Murry, T.K., B.E. Baker, Studies on protein hydrolysis I — preliminary observations on the taste of enzymic protein hydrolysates, J. Sci. Food Agric., 3, p. 470, 1952. Fujimaki, M., M. Yamashita, Y. Okazawa, S. Aral, Diffusible bitter peptides in peptic hydrolyzate of soybean protein, Agric. Biol. Chem., 32, p. 794, 1968. 

Unsaturated fatty acids emulsified in water taste bitter with a relatively low threshold value for a-linolenic acid (Table 3.9). Thus an off-taste can be present due to fatty acids liberated, as indicated in Table 3.9, by the enzymatic hydrolysis of unsaturated triacyl glycerides which are tasteless in an aqueous emulsion. 

Hydroperoxides formed enz)unatically in food are usually degraded further. This degradation can also be of a nonenzymatic nature. In nonspecific reactions involving heavy metal ions, heme(in) compounds or proteins, hydroperoxides are transformed into oxo, expoxy, mono-, di- and trihydroxy carboxylic acids (Table 3.35). Unlike hydroperoxides, i.e. the primary products of autoxidation, some of these derivatives are characterized as having a bitter taste (Table 3.35). Such compounds are detected in legumes and cereals. They may play a role in other foods rich in unsaturated fatty acids and proteins, such as fish and fish products. 

Foaming is an important criterion of the taste of beer. A distinction is made between foam volume (produced by the content of carbon dioxide), foam density, and especially foam stability (caused by protein degradation products, bitter hop compounds, and pentosans). Lower fatty acids that are present in beer bouquet act as de-foamers. 

The primary aromatic substances in beer are derived from raw materials (barley or hops) that confer the beer s typical odour and taste. Bitter acids of hops have a bitter taste (see Section 8.3.5.1.3), but hop cones also contain 0.3-1% m/m of terpenoids (60-80% of hop essential oil), which have a considerable influence on the smell of beer. The main components of aromatic hop oils are sesquiterpenic hydrocarbons in which a-humulene, P-caryophyllene and famesene dominate. The major monoter-penic hydrocarbon is myrcene. For example, the essential oil content of fine aromatic varieties, such as Saaz, is 0.8% m/m, of which 23% is myrcene, 20.5% a-humulene, 14% famesene 6% and P-caryophyUene. Significant components of the hop aroma in beer are mainly isomeric terpenoid monoepoxides resulting from autoxidation and diepoxides of a-humulene and fS-caryophyUene, but also other terpenoids. Important components of hops odour are also various alcohols (such as geraniol and hnalool), esters (ethyl 2-methylpropanoate, methyl 2-methylbutanoate, propyl 2-methylbutanoate and esters of terpenic alcohols, such as geranyl isobutanoate), hydrocarbons, aldehydes and ketones formed by oxidation of fatty acids, such as (3E,5Z)-undeca-l,3,5-triene, (Z)-hex-3-enal, nonanal, (Z)-octa-l,5-dien-3-one, their epoxides, such as ( )-4,5-epoxydec-2-enal and sulfur compounds. Other important components of hops are so-called polyphenols (condensed tannins) that influence the beer s taste and have antioxidant effects. Less important compounds are waxes and other hpids. Hop products, such as powder, pellets and extracts (by extraction with carbon... 

A number of organic compounds commonly present in foods have a bitter taste, such as certain fatty acids, amino acids, peptides, amines, amides, ketones, nitrogen-containing heterocyclic compounds (including alkaloids) and many other compounds. Their bitter taste in food is usually seen at higher concentrations. Certain inorganic salts are also bitter. 

Figure 7.62 During roasting of coffee beans chlorogenic acids are transformed resulting in the appearance of lactones (caffeoyl quinides) and phenylindans. In addition, trigonelline is converted to nicotinic acid (vitamin 83) and methylpyridiniums. Atractyligenins contribute to the bitter taste of roasted coffee. Cafestol, kahweol and 16-O-methyl cafestol occur as fatty acyl esters in unfiltered coffee, consumption of which can result in elevated plasma LDL cholesterol.

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