Ketones bitter taste

Figure 6. Bitter taste of some ketones (yj 2-alkanones cycloalkanones (n) total number of C-atoms...

Properties Water-white, stable liquid odorless bitter taste. Fp -40.5C, refr index 1.5002 (25C), surface tension 37.5 dynes/cm (20C), viscosity 31.3 centistokes (OC), vap press 14 mm Hg (163C), 30 mm Hg (182C), 734 mm Hg (295C), bp 298C, flash p325F (162.7C) (OC), wt/gal approximately 9.31 lb (20C), d 1.120 (25/25C). Miscible with alcohols, ketones, esters, aromatic hydrocarbons partly miscible with aliphatic solvents insoluble in water. Combustible. 

Properties Colorless clear vise, liq., si. bitter taste sol. in water, aliphatic ketones, alcohol insol. in ether, aliphatic hydrocarbons m.w. 400-2000 dens. 1.001 -1.007 m.p. does not cryst. flash pt. > 390 F Toxicology LD50 (oral, rat) 4190 mg/kg mildly toxic by ingestion skin and eye irritant linked to sensitive reactions TSCA listed Precaution Combustible exposed to heat or flame reactive with oxidizers... 

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. 

The resulting oil is water-white or almost colorless and has a cool, fresh, typically minty topnote (- odor decription), followed by a sweet-balsamic drydown (- odor description) note. Main constituents are - menthol, menthyl esters and traces of the bitter-tasting ketone menthone. Today s main producing countries are the USA, Brazil, China, Spain, France, Italy and Japan. 

Physical properties of isopropyl alcohol are characteristic of polar compounds because of the presence of the polar hydroxyl, —OH, group. Isopropyl alcohol is completely miscible ia water and readily soluble ia a number of common organic solvents such as acids, esters, and ketones. It has solubiUty properties similar to those of ethyl alcohol (qv). There is a competition between these two products for many solvent appHcations. Isopropyl alcohol has a slight, pleasant odor resembling a mixture of ethyl alcohol and acetone, but unlike ethyl alcohol, isopropyl alcohol has a bitter, unpotable taste. 

Most essential oils are complex mixtures of terpenic and sesquiterpenic hydrocarbons and their oxygenated terpenoid and sesquiterpenoid derivatives (alcohols, aldehydes, ketones, esters, and occasionally carboxylic acids), as well as aromatic (benzenoid) compounds such as phenols, phenolic ethers, and aromatic esters. So-called terpeneless and sesquiterpeneless essential oils are commonly used in the avor industry. Many terpenes are bitter in taste, and many, particularly the terpenic hydrocarbons, are poorly soluble or even completely insoluble in water-ethanol mixtures. Since the hydrocarbons rarely contribute aitything of importance to their avoring properties, their removal is a commercial necessity. They are removed by the so called washing process, a method used mostly for the treatment of citrus oils. This process takes advantage of the different polarities of individual essential oil constituents. The essential oil is added to a carefully selected solvent (usually a water-ethanol solution) and the mixture partitioned by prolonged stirring. This removes some of the more polar oil constituents into the water-ethanol phase (e.g., the solvent phase). Since... 

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