Taste thresholds alcohols

The formation of higher alcohols is associated in part with amino acids (90). Higher alcohols or fusel oils may occur as taste components in wines. Taste thresholds of isoamyl alcohol ranged from 100 to 900 ppm (average 300 ppm) in dry white wines for seven panelists (91). 

Despite the supposed universality of bitter taste rejection, many commonly consumed foods and beverages such as fruits, tea, coffee, chocolate, and alcohol have bitterness as a major sensory attribute which, in the overall taste profile of a food, is often appreciated by the consumers. Some alkaloids are certainly responsible for the bitter taste of known food the taste threshold is available only for atropine (0.1 mM), cocaine (0.5 mM), and morphine (0.5 mM) (Table 3.1). 

Sensory properties were presented in the same publication. The aroma strength of this mercaptan is very far from that of prenyl mercaptan (Q.10) which is also formed under roasting conditions. The pure substance has a sweet, soup-like odor, which is perceived as cooked meat and spicy when diluted in water to ca 0.1 ppm. Odor and taste thresholds, 2-6 and 8-10 ppb respectively, are relatively high compared to those of Q.10 and Q.20. The use of this alcohol and of its formate (see below) for artificial aromatizing of various foods has been patented (DE Patent 23.16465, 1973). At a concentration of 0.1 ppm it is characterized by a meaty, sulfury, skunky, cabbage flavor (Chemisis, 1999). 

Rankine, B.C. 1967. Eormation of higher alcohols by wine yeasts, and relationship to taste thresholds./ Sci. Food Agric. 18 583-589. 

Quinine, isolated from cinchona bark in the form of hydrochloride or sulfate, is mainly used in medicine as an antimalarial and antipyretic medication. In sensory analysis it is used as a standard of bitterness and in the food industry for the production of bitter soft drinks, such as bitter lemon and Indian tonic waters, and in some alcoholic beverages (such as the flavoured wine Barolo Chinato in Italy) for its distinctive bitter taste. The taste threshold concentration of bitter taste perception is about 10 mg/1. 

White crystalline solid or orthorhombic bipyramidal needles from alcohol. Coal tar-like odor. The lowest odor threshold concentration in water that may result in rejection of contaminated water ranged from 0.02 to 0.22 ppm (Lillard and Powers, 1975). In Wisconsin, the taste and odor threshold concentration in water that is nontoxic to humans is 20 pg/L (ATSDR, 1995). 

Tetrahydrate, monoclinic prisms. Also forms a dihydrate. Very bitter taste. Bitterness threshold 1 220,000. Very poisonousl Becomes anhydr at 100°. One gram dissolves in 0.8 ml methanol. 1.3 ml alcohol, 5 ml chloroform, 25 ml ethyl acetate, 36 ml glycerol, about 100 ml benzene, 187 ml ether, 1320 ml water, 750 ml boiling water. pH of satd water solo 9.5. pK, 6.04, pKj 11.7. Camion.- Handle dry powder in hood only. LDn Orally in rats 1 mg/kg, RTECS Vol. 1, R J. Lewis, R- L. Tatken. Eds. (1979) p 324. 

The studies cited in this paper show that for n-aliphatic alcohols (C1-C12) and -acids (C2 Cg), olfaction and taste act in similar ways as chemotaxis and anesthesia. Jain et al. ( ) came to a similar conclusion for many other membrane systems. Alcohols and fatty acids were used in the present study since olfactory and gustatory data on these compounds could be compared with those on many other systems. It should be kept in mind that threshold... 

During lipid oxidation, the primary oxidation products that are formed by the autoxidation of unsaturated lipids are hydroperoxides, which have little or no direct impact on the sensory properties of foods. However, hydroperoxides are degraded to produce additional radicals which further accelerates the oxidation process and produce secondary oxidation products such as aldehydes, ketones, acids and alcohols, of which some are volatiles with very low sensory thresholds and have potentially significant impact on the sensory properties namely odor and flavor [2, 3]. Sensory analysis of food samples are performed by a panel of semi to highly trained personnel under specific quarantined conditions. Any chemical method used to determine lipid oxidation in food must be closely correlated with a sensory panel because the human nose is the most appropriate detector to monitor the odorants resulting from oxidative and non-oxidative degradation processes. The results obtained from sensory analyses provide the closest approximation to the consumers approach. Sensory analyses of smell and taste has been developed in many studies of edible fats and oils and for fatty food quality estimation [1, 4, 5]. 

A series of increasing concentrations of a chemically pure stimulus material in a neutral substrate (water or oil) may be used to determine sensory thresholds to those compounds. The assessors have to indicate the concentration at which stimulus is perceived for two successive concentrations. Increasing concentrations of sucrose, sodium chloride, citric acid, and caffeine are used for the basic tastes sweet, salt, acid, and bitter. Likewise, the olfactory threshold is determined by using some odorants in aqueous or alcoholic solutions (absolute ethanol is often used as a solvent), to measure the ability of the panelists to identify an odor impression and evaluate their odor memory. 

The sensitivity of taste or odor panels can be measured by the ability of individuals to detect sensory characteristics. Threshold values are measures of the least concentrations of volatile compounds detected in a food matrix (oil or water) or minimum detectable level by at least 50% of the panelists. This definition is, however, now commonly used to refer to detection by 100% of the panelists. There is a considerable difference in the flavor significance of volatile decomposition products formed in oxidized or rancid lipids. Hydrocarbons have the highest threshold values ranging from 90 to 2150 ppm, and the least impact on flavor. Substituted furans with threshold values of 2-27 ppm, vinyl alcohols with threshold values of 0.5-0.3 ppm, and 1-alkenes... 

Sucrose has a particularly full taste, which is acceptable even at high concentrations. It is therefore used as a standard for sweet taste in the sensory evaluation of sweet substances. The threshold values of some sugars in aqueous solutions are listed in Table 8.37. For practical reasons, the sweetness of substances is expressed as a multiple of the sweetness of the sucrose solution (mainly 10% solution). The relative sweetness of certain sugars and sugar alcohols is given in Table 8.38. These values are only approximate, as they depend on sugar concentration, type and amount of anomers, temperature, presence of other substances and other factors. 

Properties Wh. to pale yel. vise, liq. odorless acid taste dec. on heating sol. in water, alcohol m.w. 660.06 (sat ) dens. 1.58 Texicolegy LDLo (IV, rat) 45 mg/kg poison by IV route may cause convulsions or effect on seizure threshold TSCA listed Hazardeus Decemp. Prods. Heated to decomp., emits toxic fumes of PO ... 

---